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Bibliography on: Wolbachia

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ESP: PubMed Auto Bibliography 22 Aug 2019 at 01:36 Created: 


WIKIPEDIA: Wolbachia is a genus of bacteria which "infects" (usually as intracellular symbionts) arthropod species, including a high proportion of insects, as well as some nematodes. It is one of the world's most common parasitic microbes and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex, and in some cases have evolved to be mutualistic rather than parasitic. Some host species cannot reproduce, or even survive, without Wolbachia infection. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70 percent of all insect species are estimated to be potential hosts. Wolbachia also harbor a temperate bacteriophage called WO. Comparative sequence analyses of bacteriophage WO offer some of the most compelling examples of large-scale horizontal gene transfer between Wolbachia coinfections in the same host. It is the first bacteriophage implicated in frequent lateral transfer between the genomes of bacterial endosymbionts. Gene transfer by bacteriophages could drive significant evolutionary change in the genomes of intracellular bacteria that were previously considered highly stable or prone to loss of genes overtime. Outside of insects, Wolbachia infects a variety of isopod species, spiders, mites, and many species of filarial nematodes (a type of parasitic worm), including those causing onchocerciasis ("River Blindness") and elephantiasis in humans as well as heartworms in dogs. Not only are these disease-causing filarial worms infected with Wolbachia, but Wolbachia seem to play an inordinate role in these diseases. A large part of the pathogenicity of filarial nematodes is due to host immune response toward their Wolbachia. Elimination of Wolbachia from filarial nematodes generally results in either death or sterility of the nematode.

Created with PubMed® Query: wolbachia NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-08-20

Mathé-Hubert H, Kaech H, Hertaeg C, et al (2019)

Non-random associations of maternally transmitted symbionts in insects: The roles of drift versus biased co-transmission and selection.

Molecular ecology [Epub ahead of print].

Virtually all higher organisms form holobionts with associated microbiota. To understand the biology of holobionts we need to know how species assemble and interact. Controlled experiments are suited to study interactions between particular symbionts, but they only accommodate a tiny portion of the diversity within each species. Alternatively, interactions can be inferred by testing if associations among symbionts in the field are more or less frequent than expected under random assortment. However, random assortment may not be a valid null hypothesis for maternally transmitted symbionts since drift alone can result in associations. Here we analyse a European field survey of endosymbionts in pea aphids (Acyrthosiphon pisum), confirming that symbiont associations are pervasive. To interpret them, we develop a model simulating the effect of drift on symbiont associations. We show that drift induces apparently non-random assortment, even though horizontal transmissions and maternal transmission failures tend to randomise symbiont associations. We also use this model in the approximate Bayesian computation framework to re-visit the association between Spiroplasma and Wolbachia in Drosophila neotestacea reported by Jaenike et al. (2010a). New field data reported here reveal that this association has disappeared in the investigated location, yet a significant interaction between Spiroplasma and Wolbachia can still be inferred. Our study confirms that negative and positive associations are pervasive and often induced by symbiont-symbiont interactions. Nevertheless, some associations are also likely to be driven by drift. This possibility needs to be considered when performing such analyses, and our model is helpful for this purpose. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-19

Huang HJ, Cui JR, Chen J, et al (2019)

Proteomic analysis of Laodelphax striatellus gonads reveals proteins that may manipulate host reproduction by Wolbachia.

Insect biochemistry and molecular biology pii:S0965-1748(19)30325-X [Epub ahead of print].

Wolbachia are intracellular bacteria that manipulate host reproduction by several mechanisms including cytoplasmic incompatibility (CI). However, the underlying mechanisms of Wolbachia-induced CI are not entirely clear. Here, we monitor the Wolbachia distribution in the male gonads of the small brown planthopper (Laodelphax striatellus, SBPHs) at different development stages, and investigated the influence of Wolbachia on male gonads by a quantitative proteomic analysis. A total of 276 differentially expressed proteins were identified, with the majority of them participating in metabolism, modification, and reproduction. Knocking down the expression of outer dense fiber protein (ODFP) and venom allergen 5-like (VA5L) showed decreased egg reproduction, and these two genes might be responsible for Wolbachia improved fecundity in infected L. striatellus; whereas knocking down the expression of cytosol amino-peptidase-like (CAL) significantly decreased the egg hatch rate in Wolbachia-uninfected L. striatellus, but not in the Wolbachia-infected one. Considering that the mRNA/protein level of CAL was downregulated by Wolbachia infection and dsCAL treatment closely mimicked Wolbachia-induced CI, we presumed that CAL might be one of the factors determining the CI phenotype.

RevDate: 2019-08-19

Doremus MR, Kelly SE, MS Hunter (2019)

Exposure to opposing temperature extremes causes comparable effects on Cardinium density but contrasting effects on Cardinium-induced cytoplasmic incompatibility.

PLoS pathogens, 15(8):e1008022 pii:PPATHOGENS-D-19-00998 [Epub ahead of print].

Terrestrial arthropods, including insects, commonly harbor maternally inherited intracellular symbionts that confer benefits to the host or manipulate host reproduction to favor infected female progeny. These symbionts may be especially vulnerable to thermal stress, potentially leading to destabilization of the symbiosis and imposing costs to the host. For example, increased temperatures can reduce the density of a common reproductive manipulator, Wolbachia, and the strength of its crossing incompatibility (cytoplasmic incompatibility, or CI) phenotype. Another manipulative symbiont, Cardinium hertigii, infects ~ 6-10% of Arthropods, and also can induce CI, but there is little homology between the molecular mechanisms of CI induced by Cardinium and Wolbachia. Here we investigated whether temperature disrupts the CI phenotype of Cardinium in a parasitic wasp host, Encarsia suzannae. We examined the effects of both warm (32°C day/ 29°C night) and cool (20°C day/ 17°C night) temperatures on Cardinium CI and found that both types of temperature stress modified aspects of this symbiosis. Warm temperatures reduced symbiont density, pupal developmental time, vertical transmission rate, and the strength of both CI modification and rescue. Cool temperatures also reduced symbiont density, however this resulted in stronger CI, likely due to cool temperatures prolonging the host pupal stage. The opposing effects of cool and warm-mediated reductions in symbiont density on the resulting CI phenotype indicates that CI strength may be independent of density in this system. Temperature stress also modified the CI phenotype only if it occurred during the pupal stage, highlighting the likely importance of this stage for CI induction in this symbiosis.

RevDate: 2019-08-16

Lorenzo-Carballa MO, Torres-Cambas Y, Heaton K, et al (2019)

Widespread Wolbachia infection in an insular radiation of damselflies (Odonata, Coenagrionidae).

Scientific reports, 9(1):11933 pii:10.1038/s41598-019-47954-3.

Wolbachia is one of the most common endosymbionts found infecting arthropods. Theory predicts symbionts like Wolbachia will be more common in species radiations, as host shift events occur with greatest frequency between closely related species. Further, the presence of Wolbachia itself may engender reproductive isolation, and promote speciation of their hosts. Here we screened 178 individuals belonging to 30 species of the damselfly genera Nesobasis and Melanesobasis - species radiations endemic to the Fiji archipelago in the South Pacific - for Wolbachia, using multilocus sequence typing to characterize bacterial strains. Incidence of Wolbachia was 71% in Nesobasis and 40% in Melanesobasis, and prevalence was also high, with an average of 88% in the Nesobasis species screened. We identified a total of 25 Wolbachia strains, belonging to supergroups A, B and F, with some epidemic strains present in multiple species. The occurrence of Wolbachia in both males and females, and the similar global prevalence found in both sexes rules out any strong effect of Wolbachia on the primary sex-ratio, but are compatible with the phenotype of cytoplasmic incompatibility. Nesobasis has higher species richness than most endemic island damselfly genera, and we discuss the potential for endosymbiont-mediated speciation within this group.

RevDate: 2019-08-16

Gonçalves DDS, Hooker DJ, Dong Y, et al (2019)

Detecting wMel Wolbachia in field-collected Aedes aegypti mosquitoes using loop-mediated isothermal amplification (LAMP).

Parasites & vectors, 12(1):404 pii:10.1186/s13071-019-3666-6.

BACKGROUND: The World Mosquito Program uses Wolbachia pipientis for the biocontrol of arboviruses transmitted by Aedes aegypti mosquitoes. Diagnostic testing for Wolbachia in laboratory colonies and in field-caught mosquito populations has typically employed PCR. New, simpler methods to diagnose Wolbachia infection in mosquitoes are required for large-scale operational use.

METHODS: Field-collected Ae. aegypti mosquitoes from North Queensland were tested using primers designed to detect the Wolbachia wsp gene, specific to the strain wMel. The results were analysed by colour change in the reaction mix. Furthermore, to confirm the efficiency of the LAMP assay, the results were compared to the gold-standard qPCR test.

RESULTS: A novel loop-mediated isothermal amplification (LAMP) colorimetric test for the wMel strain of Wolbachia was designed, developed and validated for use in a high-throughput setting. Against the standard qPCR test, the analytical sensitivity, specificity and diagnostic metrics were: sensitivity (99.6%), specificity (92.2%), positive predictive value (97.08%) and negative predictive value (99.30%).

CONCLUSIONS: We describe an alternative, novel and high-throughput method for diagnosing wMel Wolbachia infections in mosquitoes. This assay should support Wolbachia surveillance in both laboratory and field populations of Ae. aegypti.

RevDate: 2019-08-14

Zhu YX, Song ZR, Song YL, et al (2019)

The microbiota in spider mite faeces potentially reflects intestinal bacterial communities in the host.

Insect science [Epub ahead of print].

Microorganisms provide many physiological functions to herbivorous hosts. Spider mites (genus Tetranychus) are important agricultural pests throughout the world, however, the composition of spider mite microbial community, especially gut microbiome, remains unclear. Here, we investigated the bacterial community in five spider mite species and their associated faeces by deep sequencing of the 16S rRNA gene. The composition of the bacterial community was significantly different among the five prevalent spider mite species, and some bacterial symbionts showed host-species specificity. Moreover, the abundance of the bacterial community in spider mite faeces was significantly higher than that in the corresponding spider mite samples. However, Flavobacterium was detected in all samples, and represent a "core microbiome". Remarkably, the maternally inherited endosymbiont Wolbachia was detected in both spider mite and faeces. Overall, these results offer insight into the complex community of symbionts in spider mites, and give a new direction for future studies. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-14

Lucchetti C, Genchi M, Venco L, et al (2019)

Differential ABC transporter gene expression in adult Dirofilaria immitis males and females following in vitro treatment with ivermectin, doxycycline or a combination of both.

Parasites & vectors, 12(1):401 pii:10.1186/s13071-019-3645-y.

BACKGROUND: Combination doxycycline/macrocyclic lactone (ML) protocols have been shown to provide a more rapid adulticidal and microfilaricidal effect than either MLs or doxycycline alone, although female worms were reported to have a higher tolerance to treatments compared to male worms. The present study aimed to evaluate how ABC transporters may be involved in the synergic effect of the combination treatment. Adult worms of D. immitis were treated in vitro for 24 hours with doxycycline (DOXY), ivermectin (IVM) and a combination of both, and changes in the modulation of ABC transporter genes were measured. Levels of doxycycline inside different treatment media, post-treatment, were determined through HPLC analysis.

RESULTS: Quantitative RT-PCR analysis showed the presence of changes in the modulation of ABC transporter genes evaluated in this study. In particular, in female worms, the combination treatment induced a substantial increase in gene expressions, especially of Dim-pgp-10 and Dim-haf-4; whereas in male worms, the greatest increase in gene expression was observed for Dim-pgp-10 and Dim-pgp-11 when treated with DMSO + IVM and DMSO + DOXY/IVM. HPLC analysis of the DOXY concentrations in the media after in vitro treatments of male worms showed a slight difference between the DMSO + DOXY samples and the combination (DMSO + DOXY + IVM), while no difference was observed among females.

CONCLUSIONS: Further studies are required to explain whether the modulation of cellular efflux plays a role, even partially, in the adulticide effect of doxycycline/macrocyclic lactone combinations in heartworm-infected dogs. To the authors' knowledge, this is the first study to evaluate P-gp expression in adult D. immitis.

RevDate: 2019-08-13

Bockoven AA, Bondy EC, Flores MJ, et al (2019)

What Goes Up Might Come Down: the Spectacular Spread of an Endosymbiont Is Followed by Its Decline a Decade Later.

Microbial ecology pii:10.1007/s00248-019-01417-4 [Epub ahead of print].

Facultative, intracellular bacterial symbionts of arthropods may dramatically affect host biology and reproduction. The length of these symbiont-host associations may be thousands to millions of years, and while symbiont loss is predicted, there have been very few observations of a decline of symbiont infection rates. In a population of the sweet potato whitefly species (Bemisia tabaci MEAM1) in Arizona, USA, we documented the frequency decline of a strain of Rickettsia in the Rickettsia bellii clade from near-fixation in 2011 to 36% of whiteflies infected in 2017. In previous studies, Rickettsia had been shown to increase from 1 to 97% from 2000 to 2006 and remained at high frequency for at least five years. At that time, Rickettsia infection was associated with both fitness benefits and female bias. In the current study, we established matrilines of whiteflies from the field (2016, Rickettsia infection frequency = 58%) and studied (a) Rickettsia vertical transmission, (b) fitness and sex ratios associated with Rickettsia infection, (c) symbiont titer, and (d) bacterial communities within whiteflies. The vertical transmission rate was high, approximately 98%. Rickettsia infection in the matrilines was not associated with fitness benefits or sex ratio bias and appeared to be slightly costly, as more Rickettsia-infected individuals produced non-hatching eggs. Overall, the titer of Rickettsia in the matrilines was lower in 2016 than in the whiteflies collected in 2011, but the titer distribution appeared bimodal, with high- and low-titer lines, and constancy of the average titer within lines over three generations. We found neither association between Rickettsia titer and fitness benefits or sex ratio bias nor evidence that Rickettsia was replaced by another secondary symbiont. The change in the interaction between symbiont and host in 2016 whiteflies may explain the drop in symbiont frequency we observed.

RevDate: 2019-08-09

Anderson ML, Rustin RC, ME Eremeeva (2019)

Pilot survey of mosquitoes (Diptera: Culicidae) from southeastern Georgia, USA for Wolbachia and Rickettsia felis (Rickettsiales: Rickettsiaceae).

Journal of vector borne diseases, 56(2):92-97.

Background & objectives: Mosquito surveillance is one of the critical functions of local health departments, particularly in the context of outbreaks of severe mosquito-borne viral infections. Unfortunately, some viral and parasitic infections transmitted by mosquitoes, manifests non-specific clinical symptoms which may actually be of rickettsial etiology, including Rickettsia felis infections. This study tested the hypothesis that mosquitoes from southeastern Georgia, USA may be infected with Rickettsia felis and Wolbachia, an endosymbiotic bacterium of the order Rickettsiales.

Methods: Specimens of the five most common mosquito species occurring in the region were collected using gravid and light-traps and identified using morphological keys. Mosquitoes were then pooled by species, sex, trap and collection site and their DNA was extracted. Molecular methods were used to confirm mosquito identification, and presence of Wolbachia and R. felis.

Results: Wolbachia DNA was detected in 90.8% of the mosquito pools tested, which included 98% pools of Cx. quinquefasciatus Say (Diptera: Culicidae), 95% pools of Ae. albopictus Skuse (Diptera: Culicidae), and 66.7% of pools of Cx. pipiens complex. Samples of An. punctipennis Say (Diptera: Culicidae) and An. crucians Wiedemann (Diptera: Culicidae) were tested negative for Wolbachia DNA. Three genotypes of Wolbachia sp. belonging to Group A (1 type) and Group B (2 types) were identified. DNA of R. felis was not found in any pool of mosquitoes tested.

This study provides a pilot data on the high presence of Wolbachia in Cx. quinque-fasciatus and Ae. albopictus mosquitoes prevalent in the study region. Whether the high prevalence of Wolbachia and its genetic diversity in mosquitoes affects the mosquitoes' susceptibility to R. felis infection in Georgia will need further evaluation.

RevDate: 2019-08-09

Liu L, Zhang KJ, Rong X, et al (2019)

Identification of Wolbachia-Responsive miRNAs in the Small Brown Planthopper, Laodelphax striatellus.

Frontiers in physiology, 10:928.

Laodelphax striatellus is naturally infected with the Wolbachia strain wStri, which induces strong cytoplasmic incompatibility of its host. MicroRNAs (miRNAs) are a class of endogenous non-coding small RNAs that play a critical role in the regulation of gene expression at post-transcriptional level in various biological processes. Despite various studies reporting that Wolbachia affects the miRNA expression of their hosts, the molecular mechanism underlying interactions between Wolbachia and their host miRNAs has not been well understood. In order to better understand the impact of Wolbachia infection on its host, we investigated the differentially expressed miRNAs between Wolbachia-infected and Wolbachia-uninfected strains of L. striatellus. Compared with uninfected strains, Wolbachia infection resulted in up-regulation of 18 miRNAs and down-regulation of 6 miRNAs in male, while 25 miRNAs were up-regulated and 15 miRNAs were down-regulated in female. The target genes of these differentially expressed miRNAs involved in immune response regulation, reproduction, redox homeostasis and ecdysteroidogenesis were also annotated in both sexes. We further verified the expression of several significantly differentially expressed miRNAs and their predicted target genes by qRT-PCR method. The results suggested that Wolbachia appears to reduce the expression of genes related to fertility in males and increase the expression of genes related to fecundity in females. At the same time, Wolbachia may enhance the expression of immune-related genes in both sexes. All of the results in this study may be helpful in further exploration of the molecular mechanisms by which Wolbachia affects on its hosts.

RevDate: 2019-08-06

Klinges JG, Rosales SM, McMinds R, et al (2019)

Phylogenetic, genomic, and biogeographic characterization of a novel and ubiquitous marine invertebrate-associated Rickettsiales parasite, Candidatus Aquarickettsia rohweri, gen. nov., sp. nov.

The ISME journal pii:10.1038/s41396-019-0482-0 [Epub ahead of print].

Bacterial symbionts are integral to the health and homeostasis of invertebrate hosts. Notably, members of the Rickettsiales genus Wolbachia influence several aspects of the fitness and evolution of their terrestrial hosts, but few analogous partnerships have been found in marine systems. We report here the genome, phylogenetics, and biogeography of a ubiquitous and novel Rickettsiales species that primarily associates with marine organisms. We previously showed that this bacterium was found in scleractinian corals, responds to nutrient exposure, and is associated with reduced host growth and increased mortality. This bacterium, like other Rickettsiales, has a reduced genome indicative of a parasitic lifestyle. Phylogenetic analysis places this Rickettsiales within a new genus we define as "Candidatus Aquarickettsia." Using data from the Earth Microbiome Project and SRA databases, we also demonstrate that members of "Ca. Aquarickettsia" are found globally in dozens of invertebrate lineages. The coral-associated "Candidatus A. rohweri" is the first complete genome in this new clade. "Ca. A. rohweri" lacks genes to synthesize most sugars and amino acids but possesses several genes linked to pathogenicity including Tlc, an antiporter that exchanges host ATP for ADP, and a complete Type IV secretion system. Despite its inability to metabolize nitrogen, "Ca. A. rohweri" possesses the NtrY-NtrX two-component system involved in sensing and responding to extracellular nitrogen. Given these data, along with visualization of the parasite in host tissues, we hypothesize that "Ca. A. rohweri" reduces coral health by consuming host nutrients and energy, thus weakening and eventually killing host cells. Last, we hypothesize that nutrient enrichment, which is increasingly common on coral reefs, encourages unrestricted growth of "Ca. A. rohweri" in its host by providing abundant N-rich metabolites to be scavenged.

RevDate: 2019-08-05

Hübner MP, Koschel M, Struever D, et al (2019)

In vivo kinetics of Wolbachia depletion by ABBV-4083 in L. sigmodontis adult worms and microfilariae.

PLoS neglected tropical diseases, 13(8):e0007636 pii:PNTD-D-19-00664 [Epub ahead of print].

Depletion of Wolbachia endosymbionts of human pathogenic filariae using 4-6 weeks of doxycycline treatment can lead to permanent sterilization and adult filarial death. We investigated the anti-Wolbachia drug candidate ABBV-4083 in the Litomosoides sigmodontis rodent model to determine Wolbachia depletion kinetics with different regimens. Wolbachia reduction occurred in mice as early as 3 days after the initiation of ABBV-4083 treatment and continued throughout a 10-day treatment period. Importantly, Wolbachia levels continued to decline after a 5-day-treatment from 91.5% to 99.9% during a 3-week washout period. In jirds, two weeks of ABBV-4083 treatment (100mg/kg once-per-day) caused a >99.9% Wolbachia depletion in female adult worms, and the kinetics of Wolbachia depletion were recapitulated in peripheral blood microfilariae. Similar to Wolbachia depletion, inhibition of embryogenesis was time-dependent in ABBV-4083-treated jirds, leading to a complete lack of late embryonic stages (stretched microfilariae) and lack of peripheral microfilariae in 5/6 ABBV-4083-treated jirds by 14 weeks after treatment. Twice daily treatment in comparison to once daily treatment with ABBV-4083 did not significantly improve Wolbachia depletion. Moreover, up to 4 nonconsecutive daily treatments within a 14-dose regimen did not significantly erode Wolbachia depletion. Within the limitations of an animal model that does not fully recapitulate human filarial disease, our studies suggest that Wolbachia depletion should be assessed clinically no earlier than 3-4 weeks after the end of treatment, and that Wolbachia depletion in microfilariae may be a viable surrogate marker for the depletion within adult worms. Furthermore, strict daily adherence to the dosing regimen with anti-Wolbachia candidates may not be required, provided that the full regimen is subsequently completed.

RevDate: 2019-08-05

Yoshida K, Sanada-Morimura S, Huang SH, et al (2019)

Influences of two coexisting endosymbionts, CI-inducing Wolbachia and male-killing Spiroplasma, on the performance of their host Laodelphax striatellus (Hemiptera: Delphacidae).

Ecology and evolution, 9(14):8214-8224 pii:ECE35392.

The small brown planthopper Laodelphax striatellus (Hemiptera: Delphacidae) is reported to have the endosymbiont Wolbachia, which shows a strong cytoplasmic incompatibility (CI) between infected males and uninfected females. In the 2000s, female-biased L. striatellus populations were found in Taiwan, and this sex ratio distortion was the result of male-killing induced by the infection of another endosymbiont, Spiroplasma. Spiroplasma infection is considered to negatively affect both L. striatellus and Wolbachia because the male-killing halves the offspring of L. striatellus and hinders the spread of Wolbachia infection via CI. Spiroplasma could have traits that increase the fitness of infected L. striatellus and/or coexisting organisms because the coinfection rates of Wolbachia and Spiroplasma were rather high in some areas. In this study, we investigated the influences of the infection of these two endosymbionts on the development, reproduction, and insecticide resistance of L. striatellus in the laboratory. Our results show that the single-infection state of Spiroplasma had a negative influence on the fertility of L. striatellus, while the double-infection state had no significant influence. At late nymphal and adult stages, the abundance of Spiroplasma was lower in the double-infection state than in the single-infection state. In the double-infection state, the reduction of Spiroplasma density may be caused by competition between the two endosymbionts, and the negative influence of Spiroplasma on the fertility of host may be relieved. The resistance of L. striatellus to four insecticides was compared among different infection states of endosymbionts, but Spiroplasma infection did not contribute to increase insecticide resistance. Because positive influences of Spiroplasma infection were not found in terms of the development, reproduction, and insecticide resistance of L. striatellus, other factors improving the fitness of Spiroplasma-infected L. striatellus may be related to the high frequency of double infection in some L. striatellus populations.

RevDate: 2019-08-05

Hu G, Zhang L, Yun Y, et al (2019)

Taking insight into the gut microbiota of three spider species: No characteristic symbiont was found corresponding to the special feeding style of spiders.

Ecology and evolution, 9(14):8146-8156 pii:ECE35382.

Microorganisms in insect guts have been recognized as having a great impact on their hosts' nutrition, health, and behavior. Spiders are important natural enemies of pests, and the composition of the gut microbiota of spiders remains unclear. Will the bacterial taxa in spiders be same as the bacterial taxa in insects, and what are the potential functions of the gut bacteria in spiders? To gain insight into the composition of the gut bacteria in spiders and their potential function, we collected three spider species, Pardosa laura, Pardosa astrigera, and Nurscia albofasciata, in the field, and high-throughput sequencing of the 16S rRNA V3 and V4 regions was used to investigate the diversity of gut microbiota across the three spider species. A total of 23 phyla and 150 families were identified in these three spider species. The dominant bacterial phylum across all samples was Proteobacteria. Burkholderia, Ralstonia, Ochrobactrum, Providencia, Acinetobacter, Proteus, and Rhodoplanes were the dominant genera in the guts of the three spider species. The relative abundances of Wolbachia and Rickettsiella detected in N. albofasciata were significantly higher than those in the other two spider species. The relative abundance of Thermus, Amycolatopsis, Lactococcus, Acinetobacter Microbacterium, and Koribacter detected in spider gut was different among the three spider species. Biomolecular interaction networks indicated that the microbiota in the guts had complex interactions. The results of this study also suggested that at the genus level, some of the gut bacteria taxa in the three spider species were the same as the bacteria in insect guts.

RevDate: 2019-08-05

Su Q, Wang X, Ilyas N, et al (2019)

Combined effects of elevated CO2 concentration and Wolbachia on Hylyphantes graminicola (Araneae: Linyphiidae).

Ecology and evolution, 9(12):7112-7121 pii:ECE35276.

The increasing concentration of carbon dioxide in atmosphere is not only a major cause of global warming, but it also adversely affects the ecological diversity of invertebrates. This study was conducted to evaluate the effect of elevated CO2 concentration (ambient, 400 ppm and high, 800 ppm) and Wolbachia (Wolbachia-infected, W+ and Wolbachia-uninfected, W-) on Hylyphantes graminicola. The total survival rate, developmental duration, carapace width and length, body weight, sex ratio, net reproductive rate, nutrition content, and enzyme activity in H. graminicola were examined under four treatments: W- 400 ppm, W- 800 ppm, W+ 400 ppm, and W+ 800 ppm. Results showed that Wolbachia-infected spiders had significantly decreased the total developmental duration. Different instars showed variations up to some extent, but no obvious effect was found under elevated CO2 concentration. Total survival rate, sex ratio, and net reproductive rate were not affected by elevated CO2 concentration or Wolbachia infection. The carapace width of Wolbachia-uninfected spiders decreased significantly under elevated CO2 concentration, while the width, length and weight were not significantly affected in Wolbachia-infected spiders reared at ambient CO2 concentration. The levels of protein, specific activities of peroxidase, and amylase were significantly increased under elevated CO2 concentration or Wolbachia-infected spiders, while the total amino content was only increased in Wolbachia-infected spiders. Thus, our current finding suggested that elevated CO2 concentration and Wolbachia enhance nutrient contents and enzyme activity of H. graminicola and decrease development duration hence explore the interactive effects of factors which were responsible for reproduction regulation, but it also gives a theoretical direction for spider's protection in such a dynamic environment. Increased activities of enzymes and nutrients caused by Wolbachia infection aids for better survival of H. graminicola under stress.

RevDate: 2019-08-03

Dimopoulos G (2019)

Combining Sterile and Incompatible Insect Techniques for Aedes albopictus Suppression.

Trends in parasitology pii:S1471-4922(19)30172-2 [Epub ahead of print].

Traditional control strategies are failing to contain Aedes albopictus as an emerging major vector for dengue. A combination of approaches (Zheng et al., Nature, 2019) involving an artificial triple Wolbachia superinfection and low-dose irradiation enabled mass production of adult sterile males for release. The resulting suppression of field populations suggests feasibility for area-wide vector control.

RevDate: 2019-07-31

Satjawongvanit H, Phumee A, Tiawsirisup S, et al (2019)

Molecular Analysis of Canine Filaria and Its Wolbachia Endosymbionts in Domestic Dogs Collected from Two Animal University Hospitals in Bangkok Metropolitan Region, Thailand.

Pathogens (Basel, Switzerland), 8(3): pii:pathogens8030114.

Canine filariasis is caused by several nematode species, such as Dirofilaria immitis, Dirofilaria repens, Brugia pahangi, Brugia malayi, and Acanthocheilonema reconditum. Zoonotic filariasis is one of the world's neglected tropical diseases. Since 2000, the World Health Organization (WHO) has promoted a global filarial eradication program to eliminate filariasis by 2020. Apart from vector control strategies, the infection control of reservoir hosts is necessary for more effective filariasis control. In addition, many studies have reported that Wolbachia is necessary for the development, reproduction, and survival of the filarial nematode. Consequently, the use of antibiotics to kill Wolbachia in nematodes has now become an alternative strategy to control filariasis. Previously, a case of subconjunctival dirofilariasis caused by Dirofilaria spp. has been reported in a woman who resides in the center of Bangkok, Thailand. Therefore, our study aimed to principally demonstrate the presence of filarial nematodes and Wolbachia bacteria in blood collected from domestic dogs from the Bangkok Metropolitan Region, Thailand. A total of 57 blood samples from dogs with suspected dirofilariasis who had visited veterinary clinics in Bangkok were collected. The investigations for the presence of microfilaria were carried out by using both microscopic and molecular examinations. PCR was used as the molecular detection method for the filarial nematodes based on the COI and ITS1 regions. The demonstration of Wolbachia was performed using PCR to amplify the FtsZ gene. All positive samples by PCR were then cloned and sequenced. The results showed that the filarial nematodes were detected in 16 samples (28.07%) using microscopic examinations. The molecular detection of filarial species using COI-PCR revealed that 50 samples (87.72%) were positive; these consisted of 33 (57.89%), 13 (22.81%), and 4 (7.02%) samples for D. immitis, B. pahangi, and B. malayi, respectively. While the ITS1-PCR showed that 41 samples (71.93%) were positive-30 samples (52.63%) were identified as containing D. immitis and 11 samples (19.30%) were identified to have B. pahangi, whereas B. malayi was not detected. Forty-seven samples (82.45%) were positive for Wolbachia DNA and the phylogenetic tree of all positive Wolbachia was classified into the supergroup C clade. This study has established fundamental data on filariasis associated with Wolbachia infection in domestic dogs in the Bangkok Metropolitan Region. An extensive survey of dog blood samples would provide valuable epidemiologic data on potential zoonotic filariasis in Thailand. In addition, this information could be used for the future development of more effective prevention and control strategies for canine filariasis in Thailand.

RevDate: 2019-07-30

Liu XD, HF Guo (2019)

Importance of endosymbionts Wolbachia and Rickettsia in insect resistance development.

Current opinion in insect science, 33:84-90.

Endosymbionts play important roles in protecting hosts from environmental stress, such as natural enemies, heat, and toxins. Many insects are infected with the facultative nonessential endosymbionts Wolbachia and Rickettsia, which are the crux in this review, although other relevant symbiont genera will also be treated. Insecticide resistance of hosts can be related to infections with Wolbachia and Rickettsia. These endosymbionts commonly increase host susceptibility to chemical insecticides, but cases of increased resistance also exist. The symbiont-mediated insecticide resistance/susceptibility varies with species of insect, species of symbiont, and chemical compound. Changes in insecticide resistance levels of insects can be associated with fluctuations in population density of endosymbionts. Effects of endosymbionts on host fitness, metabolism, immune system, and gene expression may determine how endosymbionts influence insecticide resistance. A clearer understanding of these interactions can improve our knowledge about drivers of decreasing insecticide resistance.

RevDate: 2019-07-27

Martin E, Borucki MK, Thissen J, et al (2019)

Adaptation of a microbial detection array as a monitoring tool revealed the presence of mosquito-borne viruses and insect-specific viruses in field-collected mosquitoes.

Applied and environmental microbiology pii:AEM.01202-19 [Epub ahead of print].

Several mosquito-borne diseases affecting humans are emerging or re-emerging in the United States. The early detection of pathogens in mosquito populations is essential to prevent and control the spread of these diseases. In this study, we tested the potential applicability of the Lawrence Livermore Microbial Detection Array (LLMDA) to enhance bio-surveillance by detecting microbes present in Aedes aegypti, Aedes albopictus and Culex mosquitoes that are major vector species globally, including in Texas. The sensitivity and reproducibility of the LLMDA was tested in mosquito samples spiked with different concentrations of dengue virus (DENV) revealing a detection limit of >100 but <1000 pfu/mL. Additionally, field-collected mosquitoes from Chicago, Illinois and College Station, Texas of known infection status (West Nile virus (WNV) and Culex flavivirus (CxFLAV) positive) were tested on the LLMDA to confirm its efficiency. Mosquito field samples of unknown infection status, collected in San Antonio, TX and the Lower Rio Grande Valley (LRGV), TX were run on the LLMDA and further confirmed by PCR or qPCR. The analysis of the field samples with the LLMDA revealed the presence of cell fusing agent virus (CFAV) in Ae. aegypti populations. Wolbachia was also detected in several of the field samples (Ae. albopictus and Culex spp.) by the LLMDA. Our findings demonstrated that the LLMDA can be used to detect multiple arboviruses of public health importance including viruses that belong to the Flavivirus, Alphavirus and Orthobunyavirus genera. Additionally, insect-specific viruses and bacteria were also detected from field-collected mosquitoes. Another strength of this array is its ability to detect multiple viruses in the same mosquito pool allowing for the detection of co-circulating pathogens in an area, and the identification of potential ecological associations between different viruses. This array can aid in the bio-surveillance of mosquito borne viruses circulating in specific geographical areas.ImportanceViruses associated with mosquitoes have made a large impact on public and veterinary health. In the US, several viruses including WNV, DENV and chikungunya virus (CHIKV) are responsible for human disease. From 2015-2018, imported Zika cases were reported in the US and in 2016-2017, local Zika transmission occurred in the states of Texas and Florida. With globalization and a changing climate, the frequency of outbreaks linked to arboviruses will increase, revealing a need to better detect viruses in vector populations. With its capacity to detect viruses, bacteria and fungi, this study highlights the ability of the LLMDA to broadly screen field-collected mosquitoes and contribute to the surveillance and management of arboviral diseases.

RevDate: 2019-07-26

Khanmohammadi M, Falak R, Meamar AR, et al (2019)

Molecular Detection and Phylogenetic Analysis of Endosymbiont Wolbachia pipientis (Rickettsiales: Anaplasmataceae) Isolated from Dirofilaria immitis in Northwest of Iran.

Journal of arthropod-borne diseases, 13(1):83-93.

Background: The purpose of this study was molecular detection and phylogenetic analysis of Wolbachia species of Dirofilaria immitis.

Methods: Adult filarial nematodes were collected from the cardiovascular and pulmonary arterial systems of naturally infected dogs, which caught in different geographical areas of Meshkin Shahr in Ardabil Province, Iran, during 2017. Dirofilaria immitis genomic DNA were extracted. Phylogenetic analysis for proofing of D. immitis was carried out using cytochrome oxidase I (COI) gene. Afterward, the purified DNA was used to determine the molecular pattern of the Wolbachia surface protein (WSP) gene sequence by PCR.

Results: Phylogeny and homology studies showed high consistency of the COI gene with the previously-registered sequences for D. immitis. Comparison of DNA sequences revealed no nucleotide variation between them. PCR showed that all of the collected parasites were infected with W. pipientis. The sequence of the WSP gene in Wolbachia species from D. immitis was significantly different from other species of Dirofilaria as well as other filarial species. The maximum homology was observed with the Wolbachia isolated from D. immitis. The greatest distance between WSP nucleotides of Wolbachia species found between D. immitis and those isolated from Onchocerca lupi.

Conclusion: PCR could be a simple but suitable method for detection of Wolbachia species. There is a pattern of host specificity between Wolbachia and Dirofilaria that can be related to ancestral evolutions. The results of this phylogenetic analysis and molecular characterization may help us for better identification of Wolbachia species and understanding of their coevolution.

RevDate: 2019-07-25

Carvajal TM, Hashimoto K, Harnandika RK, et al (2019)

Detection of Wolbachia in field-collected Aedes aegypti mosquitoes in metropolitan Manila, Philippines.

Parasites & vectors, 12(1):361 pii:10.1186/s13071-019-3629-y.

BACKGROUND: Recent reports reveal the presence of Wolbachia in Ae. aegypti. Our study presents additional support for Wolbachia infection in Ae. aegypti by screening field-collected adult mosquitoes using two Wolbachia-specific molecular makers.

METHODS: A total of 672 Ae. aegypti adult mosquitoes were collected from May 2014 to January 2015 in Metropolitan Manila. Each individual sample was processed and screened for the presence of Wolbachia by selected markers, Wolbachia-specific 16S rDNA and its surface protein (wsp), under optimized PCR conditions and sequenced.

RESULTS: Totals of 113 (16.8%) and 89 (13.2%) individual mosquito samples were determined to be infected with Wolbachia using the wsp and 16S rDNA markers, respectively. The Ae. aegpyti wsp sample sequences were similar or identical to five known Wolbachia strains belonging to supergroups A and B while the majority of 16S rDNA sample sequences were similar to strains belonging to supergroup B. Overall, 80 (11.90%) individual mosquito samples showed positive amplifications in both markers and 69% showed congruence in supergroup identification (supergroup B).

CONCLUSIONS: By utilizing two Wolbachia-specific molecular makers, our study demonstrated the presence of Wolbachia from individual Ae. aegypti samples. Our results showed a low Wolbachia infection rate and inferred the detected strains belong to either supergroups A and B.

RevDate: 2019-07-25

He Z, Zheng Y, Yu WJ, et al (2019)

How do Wolbachia modify the Drosophila ovary? New evidences support the "titration-restitution" model for the mechanisms of Wolbachia-induced CI.

BMC genomics, 20(1):608 pii:10.1186/s12864-019-5977-6.

BACKGROUND: Cytoplasmic incompatibility (CI) is the most common phenotype induced by endosymbiont Wolbachia and results in embryonic lethality when Wolbachia-modified sperm fertilize eggs without Wolbachia. However, eggs carrying the same strain of Wolbachia can rescue this embryonic death, thus producing viable Wolbachia-infected offspring. Hence Wolbachia can be transmitted mainly by hosts' eggs. One of the models explaining CI is "titration-restitution", which hypothesized that Wolbachia titrated-out some factors from the sperm and the Wolbachia in the egg would restitute the factors after fertilization. However, how infected eggs rescue CI and how hosts' eggs ensure the proliferation and transmission of Wolbachia are not well understood.

RESULTS: By RNA-seq analyses, we first compared the transcription profiles of Drosophila melanogaster adult ovaries with and without the wMel Wolbachia and identified 149 differentially expressed genes (DEGs), of which 116 genes were upregulated and 33 were downregulated by Wolbachia infection. To confirm the results obtained from RNA-seq and to screen genes potentially associated with reproduction, 15 DEGs were selected for quantitative RT-PCR (qRT-PCR). Thirteen genes showed the same changing trend as RNA-seq analyses. To test whether these genes are associated with CI, we also detected their expression levels in testes. Nine of them exhibited different changing trends in testes from those in ovaries. To investigate how these DEGs were regulated, sRNA sequencing was performed and identified seven microRNAs (miRNAs) that were all upregulated in fly ovaries by Wolbachia infection. Matching of miRNA and mRNA data showed that these seven miRNAs regulated 15 DEGs. Wolbachia-responsive genes in fly ovaries were involved in biological processes including metabolism, transportation, oxidation-reduction, immunity, and development.

CONCLUSIONS: Comparisons of mRNA and miRNA data from fly ovaries revealed 149 mRNAs and seven miRNAs that exhibit significant changes in expression due to Wolbachia infection. Notably, most of the DEGs showed variation in opposite directions in ovaries versus testes in the presence of Wolbachia, which generally supports the "titration-restitution" model for CI. Furthermore, genes related to metabolism were upregulated, which may benefit maximum proliferation and transmission of Wolbachia. This provides new insights into the molecular mechanisms of Wolbachia-induced CI and Wolbachia dependence on host ovaries.

RevDate: 2019-07-24

Pogorevc D, Panter F, Schillinger C, et al (2019)

Production optimization and biosynthesis revision of corallopyronin A, a potent anti-filarial antibiotic.

Metabolic engineering pii:S1096-7176(19)30026-6 [Epub ahead of print].

Corallopyronins (COR) are α-pyrone antibiotics from myxobacteria representing highly promising lead structures for the development of antibacterial therapeutic agents. Their ability to inhibit RNA polymerase through interaction with the "switch region", a novel target, distant from binding sites of previously characterized RNA polymerase inhibitors (e.g. rifampicin), makes them particularly promising as antibiotic candidates. Corallopyronin A is currently also investigated as a lead compound for the treatment of lymphatic filariasis because of its superb activity against the nematode symbiont Wolbachia. As total synthesis is not a valid production option biotechnological optimization of compound supply is of utmost importance to further develop this highly potent compound class. Here we describe decisive improvements of the previously reported heterologous COR production and engineering platform yielding production of ∼100 mg/L COR A. Furthermore, we provide a revised model of COR biosynthesis shedding light on the function of several biosynthetic proteins, including an unusual ECH-like enzyme providing dehydration functionality in trans and an uncharacterized protein conferring COR self-resistance in the myxobacterial heterologous host Myxococcus xanthus DK1622. We also report two new COR derivatives, COR D and oxyCOR A discovered in genetically engineered strains.

RevDate: 2019-07-23

Treanor D, WOH Hughes (2019)

Limited female dispersal predicts the incidence of Wolbachia across ants (Hymenoptera: Formicidae).

Journal of evolutionary biology [Epub ahead of print].

The endosymbiotic bacterium Wolbachia is perhaps the greatest panzootic in the history of life on Earth, yet remarkably little is known regarding the factors that determine its incidence across species. One possibility is that Wolbachia more easily invades species with structured populations, due to the increased strength of genetic drift and higher initial frequency of infection. This should enable strains that induce mating incompatibilities to more easily cross the threshold prevalence above which they spread to either fixation or a stable equilibrium infection prevalence. Here, we provide empirical support for this hypothesis by analysing the relationship between female dispersal (as a proxy for population structure) and the incidence of Wolbachia across 250 species of ants. We show that species in which the dispersal of reproductive females is limited are significantly more likely to be infected with Wolbachia than species whose reproductive ecology is consistent with significant dispersal of females, and that this relationship remains after controlling for host phylogeny. We suggest that structured host populations, in this case resulting from limited female dispersal, may be an important feature determining how easily Wolbachia becomes successfully established in a novel host, and thus its occurrence across a wide diversity of invertebrate hosts. This article is protected by copyright. All rights reserved.

RevDate: 2019-07-23

Barash NR, Thomas B, Birkenheuer AJ, et al (2019)

Prevalence of Babesia spp. and clinical characteristics of Babesia vulpes infections in North American dogs.

Journal of veterinary internal medicine [Epub ahead of print].

BACKGROUND: Babesiosis is an important cause of thrombocytopenia and hemolytic anemia in dogs. Babesia vulpes, reported in European dogs and North American foxes, rarely has been reported in domestic North American dogs. Newly optimized polymerase chain reaction (PCR) primers facilitate more sensitive amplification of B. vulpes DNA.

OBJECTIVES: To determine the prevalence of Babesia sp. infections in dogs being tested for Babesia infection, and to describe co-infections and clinicopathologic abnormalities in B. vulpes positive dogs.

ANIMALS: Dog blood or tissue samples (n = 9367) submitted to a diagnostic laboratory between June 2015 and June 2018 were tested using an optimized Babesia PCR assay.

METHODS: Comprehensive canine vector-borne disease diagnostic testing was performed on convenience samples.

RESULTS: Babesia sp. DNA was amplified from 269/9367 (2.9%) North American dogs. Babesia sp. infections included B. gibsoni monoinfection (157; 1.7%), B. vulpes monoinfection (19; 0.20%), and B. gibsoni and B. vulpes coinfection (29; 0.31%). Forty-three of the 48 total B. vulpes-infected dogs were American Pit Bull Terrier-type breeds, of which 36 historically were involved with dog fights. Coinfections with Mycoplasma, Dirofilaria immitis, or Wolbachia and coexposures to Bartonella, Ehrlichia, and Rickettsia spp. were documented in B. vulpes-infected dogs. Clinicopathologic data in B. vulpes-infected dogs both with and without coinfections included anemia, thrombocytopenia, hyperglobulinemia, hypoalbuminemia, and proteinuria.

Babesia vulpes infection in domestic North American dogs is commonly found in conjunction with other coinfections, including B. gibsoni and hemotropic Mycoplasma. Similar to B. gibsoni, dog-to-dog transmission of B. vulpes may be a frequent mode of transmission.

RevDate: 2019-07-20

Bakowski MA, CW McNamara (2019)

Advances in Antiwolbachial Drug Discovery for Treatment of Parasitic Filarial Worm Infections.

Tropical medicine and infectious disease, 4(3): pii:tropicalmed4030108.

The intracellular bacteria now known as Wolbachia were first described in filarial worms in the 1970s, but the idea of Wolbachia being used as a macrofilaricidal target did not gain wide attention until the early 2000s, with research in filariae suggesting the requirement of worms for the endosymbiont. This new-found interest prompted the eventual organization of the Anti-Wolbachia Consortium (A-WOL) at the Liverpool School of Tropical Medicine, who, among others have been active in the field of antiwolbachial drug discovery to treat filarial infections. Clinical proof of concept studies using doxycycline demonstrated the utility of the antiwolbachial therapy, but efficacious treatments were of long duration and not safe for all infected. With the advance of robotics, automation, and high-speed computing, the search for superior antiwolbachials shifted away from smaller studies with a select number of antibiotics to high-throughput screening approaches, centered largely around cell-based phenotypic screens due to the rather limited knowledge about, and tools available to manipulate, this bacterium. A concomitant effort was put towards developing validation approaches and in vivo models supporting drug discovery efforts. In this review, we summarize the strategies behind and outcomes of recent large phenotypic screens published within the last 5 years, hit compound validation approaches and promising candidates with profiles superior to doxycycline, including ones positioned to advance into clinical trials for treatment of filarial worm infections.

RevDate: 2019-07-19

Cheng D, Chen S, Huang Y, et al (2019)

Symbiotic microbiota may reflect host adaptation by resident to invasive ant species.

PLoS pathogens, 15(7):e1007942 pii:PPATHOGENS-D-18-02136 [Epub ahead of print].

Exotic invasive species can influence the behavior and ecology of native and resident species, but these changes are often overlooked. Here we hypothesize that the ghost ant, Tapinoma melanocephalum, living in areas that have been invaded by the red imported fire ant, Solenopsis invicta, displays behavioral differences to interspecific competition that are reflected in both its trophic position and symbiotic microbiota. We demonstrate that T. melanocephalum workers from S. invicta invaded areas are less aggressive towards workers of S. invicta than those inhabiting non-invaded areas. Nitrogen isotope analyses reveal that colonies of T. melanocephalum have protein-rich diets in S. invicta invaded areas compared with the carbohydrate-rich diets of colonies living in non-invaded areas. Analysis of microbiota isolated from gut tissue shows that T. melanocephalum workers from S. invicta invaded areas also have different bacterial communities, including a higher abundance of Wolbachia that may play a role in vitamin B provisioning. In contrast, the microbiota of workers of T. melanocephalum from S. invicta-free areas are dominated by bacteria from the orders Bacillales, Lactobacillales and Enterobacteriales that may be involved in sugar metabolism. We further demonstrate experimentally that the composition and structure of the bacterial symbiont communities as well as the prevalence of vitamin B in T. melanocephalum workers from S. invicta invaded and non-invaded areas can be altered if T. melanocephalum workers are supplied with either protein-rich or carbohydrate-rich food. Our results support the hypothesis that bacterial symbiont communities can help hosts by buffering behavioral changes caused by interspecies competition as a consequence of biological invasions.

RevDate: 2019-07-18

Zheng X, Zhang D, Li Y, et al (2019)

Incompatible and sterile insect techniques combined eliminate mosquitoes.

Nature pii:10.1038/s41586-019-1407-9 [Epub ahead of print].

The radiation-based sterile insect technique (SIT) has successfully suppressed field populations of several insect pest species, but its effect on mosquito vector control has been limited. The related incompatible insect technique (IIT)-which uses sterilization caused by the maternally inherited endosymbiotic bacteria Wolbachia-is a promising alternative, but can be undermined by accidental release of females infected with the same Wolbachia strain as the released males. Here we show that combining incompatible and sterile insect techniques (IIT-SIT) enables near elimination of field populations of the world's most invasive mosquito species, Aedes albopictus. Millions of factory-reared adult males with an artificial triple-Wolbachia infection were released, with prior pupal irradiation of the released mosquitoes to prevent unintentionally released triply infected females from successfully reproducing in the field. This successful field trial demonstrates the feasibility of area-wide application of combined IIT-SIT for mosquito vector control.

RevDate: 2019-07-17

Dietrich CF, Chaubal N, Hoerauf A, et al (2019)

Review of Dancing Parasites in Lymphatic Filariasis.

Ultrasound international open, 5(2):E65-E74.

Lymphatic filariasis is an infection transmitted by blood-sucking mosquitoes with filarial nematodes of the species Wuchereria bancrofti, Brugia malayi und B. timori . It is prevalent in tropical countries throughout the world, with more than 60 million people infected and more than 1 billion living in areas with the risk of transmission. Worm larvae with a length of less than 1 mm are transmitted by mosquitoes, develop in human lymphatic tissue to adult worms with a length of 7-10 cm, live in the human body for up to 10 years and produce millions of microfilariae, which can be transmitted further by mosquitoes. The adult worms can be easily observed by ultrasonography because of their size and fast movements (the so-called "filarial dance sign"), which can be differentiated from other movements (e. g., blood in venous vessels) by their characteristic movement profile in pulsed-wave Doppler mode. Therapeutic options include (combinations of) ivermectin, albendazole, diethylcarbamazine and doxycycline. The latter depletes endosymbiotic Wolbachia bacteria from the worms and thus sterilizes and later kills the adult worms (macrofilaricidal or adulticidal effect).

RevDate: 2019-07-17

Ke F, You S, Huang S, et al (2019)

Herbivore range expansion triggers adaptation in a subsequently-associated third trophic level species and shared microbial symbionts.

Scientific reports, 9(1):10314 pii:10.1038/s41598-019-46742-3.

Invasive species may change the life history strategies, distribution, genetic configuration and trophic interactions of native species. The diamondback moth, Plutella xylostella L., is an invasive herbivore attacking cultivated and wild brassica plants worldwide. Here we present phylogeographic analyses of P. xylostella and one of its major parasitoids, Cotesia vestalis, using mitochondrial markers, revealing the genetic diversity and evolutionary history of these two species. We find evidence that C. vestalis originated in Southwest China, then adapted to P. xylostella as a new host by ecological sorting as P. xylostella expanded its geographic range into this region. Associated with the expansion of P. xylostella, Wolbachia symbionts were introduced into local populations of the parasitoid through horizontal transfer from its newly associated host. Insights into the evolutionary history and phylogeographic system of the herbivore and its parasitoid provide an important basis for better understanding the impacts of biological invasion on genetic configuration of local species.

RevDate: 2019-07-14

Iftikhar M, Iftikhar S, Sohail A, et al (2019)

AI- modelling of molecular identification and feminization of wolbachia infected Aedes aegypti.

Progress in biophysics and molecular biology pii:S0079-6107(19)30120-8 [Epub ahead of print].

BACKGROUND: The genetic control strategies of vector borne diseases includes the replacement of a vector population by "disease-refractory" mosquitoes and the release of mosquitoes with a gene to control the vector's reproduction rates. Wolbachia are common intracellular bacteria that are found in arthropods and nematodes. Wolbachia infected male mosquitos have been used in different experimental trials around the world to suppress the target population of Aedes aegypti and this genetic control strategy has proved to be a promising alternative to other treatment strategies. Due to certain limitations, the successful application of this strategy is still awaited.

METHODS: Mathematical frame work for Wolbachia induced genetic control strategy has been developed in this article. With the aid of Artificial Intelligence (AI) tools, accurate parametric values are depicted. For the first time, the model is well synchronized with the experimental findings. The model is comprised of the generalized varying coefficient and multiple mating rates between infected and uninfected compartments of Aedes aegypti dengue to forecast the disease control.

RESULTS: Two mathematical models are developed in this article to demonstrate different mating rates of the genetic control strategy. The important parameters and time varying coefficients are well demonstrated with the aid of numerical computations. The resulting thresholds and forecasting may prove to be a useful tool for future experimental studies.

CONCLUSIONS: From our analysis, we have concluded that the genetic control strategy is a promising technique and the role of Wolbachia infected male mosquitos, in genetic control strategies, can be better interpreted in an inexpensive manner with the aid of a theoretical model.

RevDate: 2019-07-13

White JA, Styer A, Rosenwald LC, et al (2019)

Endosymbiotic Bacteria Are Prevalent and Diverse in Agricultural Spiders.

Microbial ecology pii:10.1007/s00248-019-01411-w [Epub ahead of print].

Maternally inherited bacterial endosymbionts are common in arthropods, but their distribution and prevalence are poorly characterized in many host taxa. Initial surveys have suggested that vertically transmitted symbionts may be particularly common in spiders (Araneae). Here, we used diagnostic PCR and high-throughput sequencing to evaluate symbiont infection in 267 individual spiders representing 14 species (3 families) of agricultural spiders. We found 27 operational taxonomic units (OTUs) that are likely endosymbiotic, including multiple strains of Wolbachia, Rickettsia, and Cardinium, which are all vertically transmitted and frequently associated with reproductive manipulation of arthropod hosts. Additional strains included Rickettsiella, Spiroplasma, Rhabdochlamydia, and a novel Rickettsiales, all of which could range from pathogenic to mutualistic in their effects upon their hosts. Seventy percent of spider species had individuals that tested positive for one or more endosymbiotic OTUs, and specimens frequently contained multiple symbiotic strain types. The most symbiont-rich species, Idionella rugosa, had eight endosymbiotic OTUs, with as many as five present in the same specimen. Individual specimens within infected spider species had a variety of symbiotypes, differing from one another in the presence or absence of symbiotic strains. Our sample included both starved and unstarved specimens, and dominant bacterial OTUs were consistent per host species, regardless of feeding status. We conclude that spiders contain a remarkably diverse symbiotic microbiota. Spiders would be an informative group for investigating endosymbiont population dynamics in time and space, and unstarved specimens collected for other purposes (e.g., food web studies) could be used, with caution, for such investigations.

RevDate: 2019-07-13

Reveillaud J, Bordenstein SR, Cruaud C, et al (2019)

Author Correction: The Wolbachia mobilome in Culex pipiens includes a putative plasmid.

Nature communications, 10(1):3153 pii:10.1038/s41467-019-11234-5.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

RevDate: 2019-07-13

Boucheikhchoukh M, Mechouk N, Benakhla A, et al (2019)

Molecular evidence of bacteria in Melophagus ovinus sheep keds and Hippobosca equina forest flies collected from sheep and horses in northeastern Algeria.

Comparative immunology, microbiology and infectious diseases, 65:103-109.

The sheep ked, Melophagus ovinus, and the forest fly, Hippobosca equina, are parasitic dipteran insects of veterinary importance. As hematophagous insects, they might be considered as potential vectors of diseases which may be transmissible to humans and animals. The purpose of this study was to present initial primary data about these two species in Algeria. To do so, we conducted a molecular survey to detect the presence of bacterial DNA in flies collected in Algeria. A total of 712 flies including, 683 Melophagus ovinus and 29 Hippobosca equina were collected from two regions in northeastern Algeria. Monitoring the monthly kinetics of M. ovinus infestations showed something resembling annual activity, with a high prevalence in January (21.67%) and May (20.94%). Real-time quantitative PCR assays showed that for 311 tested flies, 126 were positive for the Bartonella spp. rRNA intergenic spacer gene and 77 were positive for Anaplasmataceae. A random selection of positive samples was submitted for sequencing. The DNA of Bartonella chomelii and Bartonella melophagi were amplified in, respectively, five and four H. equina. 25 M. ovinus positive samples were infected by Bartonella melophagi. Amplification and sequencing of the Anaplasma spp. 23S rRNA gene revealed that both species were infected by Wolbachia sp. which had previously been detected in Cimex lectularius bed bugs. Overall, this study expanded knowledge about bacteria present in parasitic flies of domestic animals in Algeria.

RevDate: 2019-07-07

Nebbak A, Dahmana H, Almeras L, et al (2019)

Co-infection of bacteria and protozoan parasites in Ixodes ricinus nymphs collected in the Alsace region, France.

Ticks and tick-borne diseases pii:S1877-959X(18)30483-7 [Epub ahead of print].

Fifty nymphal Ixodes ricinus ticks collected in Alsace, France, identified by morphological criteria and using MALDI-TOF MS, were tested by PCR to detect tick-associated bacteria and protozoan parasites. Seventy percent (35/50) of ticks contained at least one microorganism; 26% (9/35) contained two or more species. Several human pathogens were identified including Borrelia burgdorferi s.s. (4%), Borrelia afzelii (2%), Borrelia garinii (2%), Borrelia valaisiana (4%), Borrelia miyamotoi (2%), Rickettsia helvetica (6%) and "Babesia venatorum" (2%). Bartonella spp. (10%) and a Wolbachia spp. (8%) were also detected. The most common co-infections involved Anaplasmataceae with Borrelia spp. (4%), Anaplasmataceae with Bartonella spp. (6%) and Anaplasmataceae with Rickettsia spp. (6%). Co-infection involving three different groups of bacteria was seen between bacteria of the family Anaplasmataceae, Borrelia spp. and Bartonella spp. (2%). Results highlight the panel of infectious agents carried by Ixodes ricinus. Co-infection suggests the possibility of transmission of more than one pathogen to human and animals during tick blood feeding.

RevDate: 2019-07-05

Naciri M (2019)

[Wolbachia bacteria inhibits mosquito infection by various human pathogens].

Medecine sciences : M/S, 35(6-7):584-585.

RevDate: 2019-07-04
CmpDate: 2019-07-04

Leftwich PT, Hutchings MI, T Chapman (2018)

Diet, Gut Microbes and Host Mate Choice: Understanding the significance of microbiome effects on host mate choice requires a case by case evaluation.

BioEssays : news and reviews in molecular, cellular and developmental biology, 40(12):e1800053.

All organisms live in close association with microbes. However, not all such associations are meaningful in an evolutionary context. Current debate concerns whether hosts and microbes are best described as communities of individuals or as holobionts (selective units of hosts plus their microbes). Recent reports that assortative mating of hosts by diet can be mediated by commensal gut microbes have attracted interest as a potential route to host reproductive isolation (RI). Here, the authors discuss logical problems with this line of argument. The authors briefly review how microbes can affect host mating preferences and evaluate recent findings from fruitflies. Endosymbionts can potentially influence host RI given stable and recurrent co-association of hosts and microbes over evolutionary time. However, observations of co-occurrence of microbes and hosts are ripe for misinterpretation and such associations will rarely represent a meaningful holobiont. A framework in which hosts and their microbes are independent evolutionary units provides the only satisfactory explanation for the observed range of effects and associations.

RevDate: 2019-07-03

Lima-Barbero JF, Díaz-Sanchez S, Sparagano O, et al (2019)

Metaproteomics characterization of the alphaproteobacteria microbiome in different developmental and feeding stages of the poultry red mite Dermanyssus gallinae (De Geer, 1778).

Avian pathology : journal of the W.V.P.A [Epub ahead of print].

The poultry red mite, Dermanyssus gallinae (De Geer, 1778), is a worldwide distributed ectoparasite and considered a major pest affecting the laying hen industry in Europe. Based on available information in other ectoparasites, the mite microbiome might participate in several biological processes and the acquisition, maintenance and transmission of pathogens. However, little is known about the role of poultry red mite in the transmission of pathogenic bacteria as a mechanical carrier or a biological vector. Herein, we used a metaproteomics approach to characterize the alphaproteobacteria in the microbiota of poultry red mite, and variations in its profile with ectoparasite development (nymphs vs. adults) and feeding (unfed vs. fed). The results showed that the bacterial community associated with D. gallinae was mainly composed of environmental and commensal bacteria. Putative symbiotic bacteria of the genera Wolbachia, C. Tokpelaia and Sphingomonas were identified, together with potential pathogenic bacteria of the genera Inquilinus, Neorickettsia and Roseomonas. Significant differences in the composition of alphaproteobacterial microbiota were associated with mite development and feeding, suggesting that bacteria have functional implications in metabolic pathways associated with blood feeding. These results support the use of metaproteomics for the characterization of alphaproteobacteria associated with the D. gallinae microbiota that could provide relevant information for the understanding of mite-host interactions and the development of potential control interventions. Research Highlights - Metaproteomics is a valid approach for microbiome characterization in ectoparasites. - Alphaproteobacteria putative bacterial symbionts were identified in D. gallinae. - Mite development and feeding were related to variations in bacterial community. - Potentially pathogenic bacteria were identified in mite microbiota.

RevDate: 2019-07-02

Yang K, Xie K, Zhu YX, et al (2019)

Wolbachia dominate Spiroplasma in the co-infected spider mite Tetranychus truncatus.

Insect molecular biology [Epub ahead of print].

Wolbachia and Spiroplasma are both maternally inherited endosymbionts in arthropods, and they can co-infect the same species. However, how they interact with each other in the same host is not clear. Here we investigate a co-infected Tetranychus truncatus spider mite strain that shares the same genetic background with singly-infected and uninfected strains to detect the impacts of the two symbionts on their host. We found that Wolbachia-infected and Spiroplasma-infected mites can suffer significant fitness costs involving decreased fecundity, although with no effect on lifespan or development. Wolbachia induced incomplete cytoplasmic incompatibility (CI) in T. truncatus both in singly-infected and doubly-infected strains, resulting in female killing. In both females and males of the co-infected spider mite strain, Wolbachia density was higher than Spiroplasma density. Transcriptome analysis of female adults showed that the most differently expressed genes (DEGs) were found between the co-infected strain and both the singly-infected Spiroplasma strain and uninfected strain. The Wolbachia strain had the fewest DEGs compared to the co-infected strain, consistent with the higher density of Wolbachia in the co-infected strain. Wolbachia therefore appears to have a competitive advantage in host mites over Spiroplasma and is likely maintained in populations by cytoplasmic incompatibility despite having deleterious fitness effects.

RevDate: 2019-07-01

Rocha MN, Duarte MM, Mansur SB, et al (2019)

Pluripotency of Wolbachia against Arboviruses: the case of yellow fever.

Gates open research, 3:161.

Background: Yellow fever outbreaks have re-emerged in Brazil during 2016-18, with mortality rates up to 30%. Although urban transmission has not been reported since 1942, the risk of re-urbanization of yellow fever is significant, as Aedes aegypti is present in most tropical and sub-tropical cities in the World and still remains the main vector of urban YFV. Although the YFV vaccine is safe and effective, it does not always reach populations at greatest risk of infection and there is an acknowledged global shortage of vaccine supply. The introgression of Wolbachia bacteria into Ae. aegypti mosquito populations is being trialed in several countries ( as a biocontrol method against dengue, Zika and chikungunya. Here, we studied the ability of Wolbachia to reduce the transmission potential of Ae. aegypti mosquitoes for Yellow fever virus (YFV). Methods: Two recently isolated YFV (primate and human) were used to challenge field-derived wild-type and Wolbachia-infected (wMel +) Ae. aegypti mosquitoes. The YFV infection status was followed for 7, 14 and 21 days post-oral feeding (dpf). The YFV transmission potential of mosquitoes was evaluated via nano-injection of saliva into uninfected mosquitoes or by inoculation in mice. Results: We found that Wolbachia was able to significantly reduce the prevalence of mosquitoes with YFV infected heads and thoraces for both viral isolates. Furthermore, analyses of mosquito saliva, through indirect injection into naïve mosquitoes or via interferon-deficient mouse model, indicated Wolbachia was associated with profound reduction in the YFV transmission potential of mosquitoes (14dpf). Conclusions: Our results suggest that Wolbachia introgression could be used as a complementary strategy for prevention of urban yellow fever transmission, along with the human vaccination program.

RevDate: 2019-06-29

Kelly M, Price SL, de Oliveira Ramalho M, et al (2019)

Diversity of Wolbachia Associated with the Giant Turtle Ant, Cephalotes atratus.

Current microbiology pii:10.1007/s00284-019-01722-8 [Epub ahead of print].

Symbiotic relationships between organisms are common throughout the tree of life, and often these organisms share an evolutionary history. In turtle ants (Cephalotes), symbiotic associations with bacteria are known to be especially important for supplementing the nutrients that their herbivorous diets do not provide. However, much remains unknown about the diversity of many common bacterial symbionts with turtle ants, such as Wolbachia. Here, we surveyed the diversity of Wolbachia, focusing on one species of turtle ant with a particularly wide geographic range, Cephalotes atratus. Colonies were collected from the entire range of C. atratus, and we detected the presence of Wolbachia by sequencing multiple individuals per colony for wsp. Then, using the multilocus sequence typing (MLST) approach, we determined each individual's unique sequence type (ST) based on comparison to sequences published in the Wolbachia MLST Database ( The results of this study suggest that there is a high level of diversity of Wolbachia strains among colonies from different regions, while the diversity within colonies is very low. Additionally, 13 novel variants (alleles) were uncovered. These results suggest that the level of diversity of Wolbachia within species is affected by geography, and the high level of diversity observed among Cephalotes atratus populations may be explained by their wide geographic range.

RevDate: 2019-06-27

Sicard M, Bonneau M, M Weill (2019)

Wolbachia prevalence, diversity, and ability to induce cytoplasmic incompatibility in mosquitoes.

Current opinion in insect science, 34:12-20 pii:S2214-5745(19)30010-0 [Epub ahead of print].

To protect humans and domestic animals from mosquito borne diseases, alternative methods to chemical insecticides have to be found. Pilot studies using the vertically transmitted bacterial endosymbiont Wolbachia were already launched in different parts of the world. Wolbachia can be used either in Incompatible Insect Technique (IIT), to decrease mosquito population, or to decrease the ability of mosquitoes to transmit pathogens. Not all mosquito species are naturally infected with Wolbachia: while in Culex pipiens and Aedes albopictus almost all individuals harbor Wolbachia, putative infections have to be further investigated in Anopheles species and in Aedes aegypti. All Wolbachia-based control methods rely on the ability of Wolbachia to induce cytoplasmic incompatibility (CI) resulting in embryonic death in incompatible crossings. Knowledge on CI diversity in mosquito is required to find the better Wolbachia-mosquito associations to optimize the success of both 'sterile insect' and 'pathogen blocking' Wolbachia-based methods.

RevDate: 2019-06-26

Shropshire JD, SR Bordenstein (2019)

Two-By-One model of cytoplasmic incompatibility: Synthetic recapitulation by transgenic expression of cifA and cifB in Drosophila.

PLoS genetics, 15(6):e1008221 pii:PGENETICS-D-19-00228.

Wolbachia are maternally inherited bacteria that infect arthropod species worldwide and are deployed in vector control to curb arboviral spread using cytoplasmic incompatibility (CI). CI kills embryos when an infected male mates with an uninfected female, but the lethality is rescued if the female and her embryos are likewise infected. Two phage WO genes, cifAwMel and cifBwMel from the wMel Wolbachia deployed in vector control, transgenically recapitulate variably penetrant CI, and one of the same genes, cifAwMel, rescues wild type CI. The proposed Two-by-One genetic model predicts that CI and rescue can be recapitulated by transgenic expression alone and that dual cifAwMel and cifBwMel expression can recapitulate strong CI. Here, we use hatch rate and gene expression analyses in transgenic Drosophila melanogaster to demonstrate that CI and rescue can be synthetically recapitulated in full, and strong, transgenic CI comparable to wild type CI is achievable. These data explicitly validate the Two-by-One model in wMel-infected D. melanogaster, establish a robust system for transgenic studies of CI in a model system, and represent the first case of completely engineering male and female animal reproduction to depend upon bacteriophage gene products.

RevDate: 2019-06-26

Ritchie SA, KM Staunton (2019)

Reflections from an old Queenslander: can rear and release strategies be the next great era of vector control?.

Proceedings. Biological sciences, 286(1905):20190973.

In this perspective, I discuss the great eras of vector control, centring on Aedes aegypti, the primary vector of dengue, Zika and several other viruses. Since the discovery and acceptance of the role of mosquitoes as vectors of disease agents, several significant strategies have been developed and deployed to control them and the diseases they transmit. Environmental management, insecticides and, to a lesser extent, biological control have emerged as great eras of vector control. In the past decade, the release of massive numbers of specifically modified mosquitoes that mate with wild populations has emerged as a significant new strategy to fight vector-borne diseases. These reared and released mosquitoes have been modified by the addition of a symbiont (e.g. Wolbachia bacteria), radiation or introduction of a genetic construct to either sterilize the wild mosquitoes they mate with, crashing the population, or to reduce the wild population's capacity to vector pathogens. Will these new rear and release strategies become the next great era of vector control? From my vantage point as a dengue control manager and researcher involved in two Wolbachia programmes, I will discuss the hurdles that rear and release programmes face to gain widespread acceptance and success.

RevDate: 2019-06-25

Zueva T, Morchón R, Carretón E, et al (2019)

Angiogenic response in an in vitro model of dog microvascular endothelial cells stimulated with antigenic extracts from Dirofilaria immitis adult worms.

Parasites & vectors, 12(1):315 pii:10.1186/s13071-019-3570-0.

BACKGROUND: Angiogenesis can occur under pathological conditions when stimuli such as inflammation, vascular obstruction or hypoxia exist. These stimuli are present in cardiopulmonary dirofilariosis (Dirofilaria immitis). The aim of this study was to analyze the capacity of D. immitis antigens to modify the expression of angiogenic factors and trigger the formation of pseudocapillaries (tube-like structures) in an in vitro model of endothelial cells.

METHODS: The expression of VEGF-A, sFlt, mEndoglin and sEndoglin in cultures of canine microvascular endothelial cells stimulated with extract of adult worms of D. immitis obtained from an untreated dog (DiSA) and from a dog treated for 15 days with doxycycline (tDiSA), was determined by using commercial kits. The capacity of pseudocapillary formation was evaluated analyzing cell connections and cell groups in Matrigel cell cultures stimulated with DiSA and tDiSA. In both cases non-stimulated cultures were used as controls.

RESULTS: First, we demonstrated that worms obtained from the dog treated with doxycycline showed a significantly lower amount of Wolbachia (less than 60%) than worms removed from the untreated dog. Only DiSA was able to significantly increase the expression of the proangiogenic factor VEGF-A in the endotelial cells cultures. None of the D. immitis extracts modified the expression of sFlt. tDiSA extract was able to modify the expression of the endoglins, significantly decreasing the expression of the pro-angiogenic mEndoglin and increasing the anti-angiogenic sEndoglin. The formation of pseudocapillaries was negatively influenced by tDiSA, which reduced the organization and number of cellular connections.

CONCLUSIONS: The ability of antigens from adult D. immitis worms to modify the expression of pro and anti-angiogenic factors in endotelial cell cultures was demonstrated, as well as the trend to form pseudocapillaries in vitro. The capacity of stimulation may be linked to the amount of Wolbachia present in the antigenic extracts.

RevDate: 2019-06-25

Thapa S, Zhang Y, MS Allen (2019)

Bacterial microbiomes of Ixodes scapularis ticks collected from Massachusetts and Texas, USA.

BMC microbiology, 19(1):138 pii:10.1186/s12866-019-1514-7.

BACKGROUND: The blacklegged tick, Ixodes scapularis, is the primary vector of the Lyme disease spirochete Borrelia burgdorferi in North America. Though the tick is found across the eastern United States, Lyme disease is endemic to the northeast and upper midwest and rare or absent in the southern portion of the vector's range. In an effort to better understand the tick microbiome from diverse geographic and climatic regions, we analysed the bacterial community of 115 I. scapularis adults collected from vegetation in Texas and Massachusetts, representing extreme ends of the vector's range, by massively parallel sequencing of the 16S V4 rRNA gene. In addition, 7 female I. scapularis collected from dogs in Texas were included in the study.

RESULTS: Male I. scapularis ticks had a more diverse bacterial microbiome in comparison to the female ticks. Rickettsia spp. dominated the microbiomes of field-collected female I. scapularis from both regions, as well as half of the males from Texas. In addition, the male and female ticks captured from Massachusetts contained high proportions of the pathogens Anaplasma and Borrelia, as well as the arthropod endosymbiont Wolbachia. None of these were found in libraries generated from ticks collected in Texas. Pseudomonas, Acinetobacter and Mycobacterium were significantly differently abundant (p < 0.05) between the male ticks from Massachusetts and Texas. Anaplasma and Borrelia were found in 15 and 63% of the 62 Massachusetts ticks, respectively, with a co-infection rate of 11%. Female ticks collected from Texas dogs were particularly diverse, and contained several genera including Rickettsia, Pseudomonas, Bradyrhizobium, Sediminibacterium, and Ralstonia.

CONCLUSIONS: Our results indicate that the bacterial microbiomes of I. scapularis ticks vary by sex and geography, with significantly more diversity in male microbiomes compared to females. We found that sex plays a larger role than geography in shaping the composition/diversity of the I. scapularis microbiome, but that geography affects what additional taxa are represented (beyond Rickettsia) and whether pathogens are found. Furthermore, recent feeding may have a role in shaping the tick microbiome, as evident from a more complex bacterial community in female ticks from dogs compared to the wild-caught questing females. These findings may provide further insight into the differences in the ability of the ticks to acquire, maintain and transmit pathogens. Future studies on possible causes and consequences of these differences will shed additional light on tick microbiome biology and vector competence.

RevDate: 2019-06-24

Hinojosa JC, Koubínová D, Szenteczki M, et al (2019)

A mirage of cryptic species: genomics uncover striking mito-nuclear discordance in the butterfly Thymelicus sylvestris.

Molecular ecology [Epub ahead of print].

Mitochondrial DNA (mtDNA) sequencing has led to an unprecedented rise in the identification of cryptic species. However, it is widely acknowledged that nuclear DNA (nuDNA) sequence data are also necessary to properly define species boundaries. Next generation sequencing techniques provide a wealth of nuclear genomic data, which can be used to ascertain both the evolutionary history and taxonomic status of putative cryptic species. Here, we focus on the intriguing case of the butterfly Thymelicus sylvestris (Lepidoptera: Hesperiidae). We identified six deeply diverged mitochondrial lineages; three distributed all across Europe and found in sympatry, suggesting a potential case of cryptic species. We then sequenced these six lineages using double-digest restriction-site associated DNA sequencing (ddRADseq). Nuclear genomic loci contradicted mtDNA patterns and genotypes generally clustered according to geography, i.e., a pattern expected under the assumption of postglacial recolonization from different refugia. Further analyses indicated that this strong mtDNA/nuDNA discrepancy cannot be explained by incomplete lineage sorting, sex-biased asymmetries, NUMTs, natural selection, introgression or Wolbachia-mediated genetic sweeps. We suggest that this mito-nuclear discordance was caused by long periods of geographic isolation followed by range expansions, homogenizing the nuclear but not the mitochondrial genome. These results highlight T. sylvestris as a potential case of multiple despeciation and/or lineage fusion events. We finally argue, since mtDNA and nuDNA do not necessarily follow the same mechanisms of evolution, their respective evolutionary history reflects complementary aspects of past demographic and biogeographic events. This article is protected by copyright. All rights reserved.

RevDate: 2019-06-23

Ammini P, Vijayan J, Krishna AV, et al (2019)

Dominance of Wolbachia sp. in the deep-sea sediment bacterial metataxonomic sequencing analysis in the Bay of Bengal, Indian Ocean.

Genomics pii:S0888-7543(18)30676-1 [Epub ahead of print].

The Bay of Bengal, located in the north-eastern part of the Indian Ocean is world's largest bay occupying an area of ~8,39,000 mile2. The variability in bacterial community structure and function in sediment ecosystems of the Bay of Bengal is examined by Illumina high-throughput metagenomic sequencing. Of five metataxonomics data sets presented, two (SD1 and SD2) were from stations close to the shore and three (SD4, SD5, and SD6) were from the deep-sea (~3000 m depth). Phylum Proteobacteria (90.27 to 92.52%) dominated the deep-sea samples, whereas phylum Firmicutes (65.35 to 90.98%) dominated the coastal samples. Comparative analysis showed that coastal and deep-sea sediments showed distinct microbial communities. Wolbachia species, belonging to class Alphaproteobacteria was the most dominant species in the deep-sea sediments. The gene functions of bacterial communities were predicted for deep-sea and coastal sediment ecosystems. The results indicated that deep-sea sediment bacterial communities were involved in metabolic activities like dehalogenation and sulphide oxidation.

RevDate: 2019-06-23

Bock W, Y Jayathunga (2019)

Optimal control of a Multi-patch Dengue Model under the Influence of Wolbachia Bacterium.

Mathematical biosciences pii:S0025-5564(18)30309-2 [Epub ahead of print].

In this work, a multi-patch model for dengue transmission dynamics including the bacterium Wolbachia is studied and by that the control efforts to minimize the disease spread by host and vector control are investigated. The multi-patch system models the host movement within the patches which coupled via a residence-time budgeting matrix P. Numerical results confirm that the control mechanism embedded in incidence rates of the disease transmission, effectively reduce the spread of the disease.

RevDate: 2019-06-22

Cooper BS, Vanderpool D, Conner WR, et al (2019)

Wolbachia Acquisition by Drosophila yakuba-clade Hosts and Transfer of Incompatibility Loci Between Distantly Related Wolbachia.

Genetics pii:genetics.119.302349 [Epub ahead of print].

Maternally transmitted Wolbachia infect about half of insect species, yet the predominant mode(s) of Wolbachia acquisition remains uncertain. Species-specific associations could be old, with Wolbachia and hosts co-diversifying (i.e., cladogenic acquisition), or relatively young and acquired by horizontal transfer or introgression. The three Drosophila yakuba-clade hosts ((D. santomea, D. yakuba), D. teissieri) diverged about three million years ago and currently hybridize on Bioko and São Tomé, west African islands. Each species is polymorphic for nearly identical Wolbachia that cause weak cytoplasmic incompatibility (CI)-reduced egg hatch when uninfected females mate with infected males. D. yakuba-clade Wolbachia are closely related to wMel, globally polymorphic in D. melanogaster We use draft Wolbachia and mitochondrial genomes to demonstrate that D. yakuba-clade phylogenies for Wolbachia and mitochondria tend to follow host nuclear phylogenies. However, roughly half of D. santomea individuals, sampled both inside and outside of the São Tomé hybrid zone, have introgressed D. yakuba mitochondria. Both mitochondria and Wolbachia possess far more recent common ancestors than the bulk of the host nuclear genomes, precluding cladogenic Wolbachia acquisition. General concordance of Wolbachia and mitochondrial phylogenies suggests that horizontal transmission is rare, but varying relative rates of molecular divergence complicate chronogram-based statistical tests. Loci that cause CI in wMel are disrupted in D. yakuba-clade Wolbachia; but, a second set of loci predicted to cause CI are located in the same WO prophage region. These alternative CI loci seem to have been acquired horizontally from distantly related Wolbachia, with transfer mediated by flanking Wolbachia-specific ISWpi1 transposons.

RevDate: 2019-06-21

Mateos M, Silva NO, Ramirez P, et al (2019)

Effect of heritable symbionts on maternally-derived embryo transcripts.

Scientific reports, 9(1):8847 pii:10.1038/s41598-019-45371-0.

Maternally-transmitted endosymbiotic bacteria are ubiquitous in insects. Among other influential phenotypes, many heritable symbionts of arthropods are notorious for manipulating host reproduction through one of four reproductive syndromes, which are generally exerted during early developmental stages of the host: male feminization; parthenogenesis induction; male killing; and cytoplasmic incompatibility (CI). Major advances have been achieved in understanding mechanisms and identifying symbiont factors involved in reproductive manipulation, particularly male killing and cytoplasmic incompatibility. Nonetheless, whether cytoplasmically-transmitted bacteria influence the maternally-loaded components of the egg or early embryo has not been examined. In the present study, we investigated whether heritable endosymbionts that cause different reproductive phenotypes in Drosophila melanogaster influence the mRNA transcriptome of early embryos. We used mRNA-seq to evaluate differential expression in Drosophila embryos lacking endosymbionts (control) to those harbouring the male-killing Spiroplasma poulsonii strain MSRO-Br, the CI-inducing Wolbachia strain wMel, or Spiroplasma poulsonii strain Hyd1; a strain that lacks a reproductive phenotype and is naturally associated with Drosophila hydei. We found no consistent evidence of influence of symbiont on mRNA composition of early embryos, suggesting that the reproductive manipulation mechanism does not involve alteration of maternally-loaded transcripts. In addition, we capitalized on several available mRNA-seq datasets derived from Spiroplasma-infected Drosophila melanogaster embryos, to search for signals of depurination of rRNA, consistent with the activity of Ribosome Inactivating Proteins (RIPs) encoded by Spiroplasma poulsonii. We found small but statistically significant signals of depurination of Drosophila rRNA in the Spiroplasma treatments (both strains), but not in the symbiont-free control or Wolbachia treatment, consistent with the action of RIPs. The depurination signal was slightly stronger in the treatment with the male-killing strain. This result supports a recent report that RIP-induced damage contributes to male embryo death.

RevDate: 2019-06-19

Su QC, Wang X, Deng C, et al (2019)

Transcriptome responses to elevated CO2 level and Wolbachia-infection stress in Hylyphantes graminicola (Araneae: Linyphiidae).

Insect science [Epub ahead of print].

Hylyphantes graminicola is a resident spider species found in maize and cotton fields and is an important biological control agent of various pests. Previous studies have demonstrated that stress from elevated CO2 and Wolbachia infection can strongly affect spider species. Thus, based on CO2 levels (400 ppm, current atmospheric CO2 concentration and 800 ppm, high CO2 concentration) and Wolbachia status (Wolbachia-infected, W+ and Wolbachia-uninfected, W-), we divided H. graminicola individuals into four treatment groups: i.e., W- 400 ppm, W- 800 ppm, W+ 400 ppm, and W+ 800 ppm. To investigate the effects of elevated CO2 levels (W- 400 vs W- 800), Wolbachia-infection (W- 400 vs W+ 400), and the interactions between these two factors (W- 400 vs W+ 800), high-throughput transcriptome sequencing was employed to characterize the de novo transcriptome of the spiders and identify stress-related differentially expressed genes (DEGs). De novo assembly of cDNA sequences generated 86 688 unigenes, 23 938 of which were annotated in public databases. A total of 84, 21, and 157 DEGs were found among W- 400 vs W- 800, W- 400 vs W+ 400, and W- 400 vs W+ 800, respectively. Functional enrichment analysis revealed that metabolic processes, signaling, and catalytic activity were significantly affected by elevated CO2 levels and Wolbachia infection. Our findings suggest that the impact of elevated CO2 levels and Wolbachia infection on the H. graminicola transcriptome was, to a large extent, on genes involved in metabolic processes. This study is the first description of transcriptome changes in response to elevated CO2 levels and Wolbachia infection in spiders. This article is protected by copyright. All rights reserved.

RevDate: 2019-06-19

Konecka E, Z Olszanowski (2019)

First Evidence of Intracellular Bacteria Cardinium in Thermophilic Mite Microzetorchestes emeryi (Acari: Oribatida): Molecular Screening of Bacterial Endosymbiont Species.

Current microbiology pii:10.1007/s00284-019-01717-5 [Epub ahead of print].

We undertook the issue of the distribution of intracellular bacteria among Oribatida (Acari). Six genera of bacteria were detected by PCR and Sanger DNA sequencing: Wolbachia, Cardinium, Rickettsia, Spiroplasma, Arsenophonus, and Hamiltonella. Our research, for the first time, revealed the presence of Cardinium in Microzetorchestes emeryi in two subpopulations separated from each other by 300 m. The percentages of infected animals were the same in both subpopulations-ca. 20%. The identity of 16S rDNA sequences of Cardinium between these two subpopulations of M. emeryi was 97%. Phylogenetic analysis showed that the Cardinium in M. emeryi was clustered into the group A. The occurrence of M. emeryi in Poland has not been reported before and our report is the first one. Cardinium maybe help the thermophilic M. emeryi to adapt to low temperatures in the Central Europe.

RevDate: 2019-06-18

Schebeck M, Feldkirchner L, Stauffer C, et al (2019)

Dynamics of an Ongoing Wolbachia Spread in the European Cherry Fruit Fly, Rhagoletis cerasi (Diptera: Tephritidae).

Insects, 10(6): pii:insects10060172.

Numerous terrestrial arthropods are infected with the alphaproteobacterium Wolbachia. This endosymbiont is usually transmitted vertically from infected females to their offspring and can alter the reproduction of hosts through various manipulations, like cytoplasmic incompatibility (CI), enhancing its spread in new host populations. Studies on the spatial and temporal dynamics of Wolbachia under natural conditions are scarce. Here, we analyzed Wolbachia infection frequencies in populations of the European cherry fruit fly, Rhagoletis cerasi (L.), in central Germany-an area of an ongoing spread of the CI-inducing strain wCer2. In total, 295 individuals from 19 populations were PCR-screened for the presence of wCer2 and their mitochondrial haplotype. Results were compared with historic data to understand the infection dynamics of the ongoing wCer2 invasion. An overall wCer2 infection frequency of about 30% was found, ranging from 0% to 100% per population. In contrast to an expected smooth transition from wCer2-infected to completely wCer2-uninfected populations, a relatively scattered infection pattern across geography was observed. Moreover, a strong Wolbachia-haplotype association was detected, with only a few rare misassociations. Our results show a complex dynamic of an ongoing Wolbachia spread in natural field populations of R. cerasi.

RevDate: 2019-06-17

Watanabe A, Takaku S, Yokota K, et al (2019)

A survey of Lasioderma serricorne (Fabricius) in Japanese Dental Clinics.

Biocontrol science, 24(2):117-121.

This study was to survey the capturing rate in Japanese dental clinics of the Lasioderma serricorne (cigarette beetles) , and to evaluate the beetle's potential as a carrier for transmission of nosocomial pathogens. L. serricorne imagoes were captured in pheromone traps in 14 Japanese dental clinics in August and September 2012 and 2013, and their numbers recorded. Polymerase chain reaction (PCR) for the bacterial antibiotic-resistant genes mecA, vanA, vanB, blaIMP, and blaVIM was performed on the captured L. serricorne imagoes. Bacterial species in the captured specimens were identified by 16S rRNA PCR and sequencing analysis. The L. serricorne imagoes were captured from 10 dental clinics (71.4%) . We failed to detect the presence of nosocomial antibiotic-resistant pathogens in L. serricorne imagoes. The bacterial species detected most commonly in the imagoes was Wolbachia sp., an intracellular proteobacterium infecting certain insect species. Monitoring of insects including L. serricorne should be incorporated into regiment of the infection control.

RevDate: 2019-06-17
CmpDate: 2019-06-17

Shaw WR, F Catteruccia (2019)

Vector biology meets disease control: using basic research to fight vector-borne diseases.

Nature microbiology, 4(1):20-34.

Human pathogens that are transmitted by insects are a global problem, particularly those vectored by mosquitoes; for example, malaria parasites transmitted by Anopheles species, and viruses such as dengue, Zika and chikungunya that are carried by Aedes mosquitoes. Over the past 15 years, the prevalence of malaria has been substantially reduced and virus outbreaks have been contained by controlling mosquito vectors using insecticide-based approaches. However, disease control is now threatened by alarming rates of insecticide resistance in insect populations, prompting the need to develop a new generation of specific strategies that can reduce vector-mediated transmission. Here, we review how increased knowledge in insect biology and insect-pathogen interactions is stimulating new concepts and tools for vector control. We focus on strategies that either interfere with the development of pathogens within their vectors or directly impact insect survival, including enhancement of vector-mediated immune control, manipulation of the insect microbiome, or use of powerful new genetic tools such as CRISPR-Cas systems to edit vector genomes. Finally, we offer a perspective on the implementation hurdles as well as the knowledge gaps that must be filled in the coming years to safely realize the potential of these novel strategies to eliminate the scourge of vector-borne disease.

RevDate: 2019-06-13

Ant TH, Herd C, Louis F, et al (2019)

Wolbachia transinfections in Culex quinquefasciatus generate cytoplasmic incompatibility.

Insect molecular biology [Epub ahead of print].

Culex quinquefasciatus is an important mosquito vector of a number of viral and protozoan pathogens of humans and animals, and naturally carries the endosymbiont Wolbachia pipientis, strain wPip. Wolbachia are being used in two distinct vector control strategies: firstly, population suppression caused by mating incompatibilities between mass-released transinfected males and wild females; and secondly, the spread of pathogen transmission-blocking strains through populations. Using embryonic microinjection, two novel Wolbachia transinfections were generated in Cx. quinquefasciatus using strains native to the mosquito Aedes albopictus: a wAlbB single infection, and a wPip plus wAlbA superinfection. The wAlbB infection showed full bi-directional cytoplasmic incompatibility (CI) with wild-type Cx. quinquefasciatus in reciprocal crosses. The wPipwAlbA superinfection showed complete unidirectional CI, and therefore population invasion potential. While the wAlbB strain showed comparatively low overall densities, similar to the native wPip, the wPipwAlbA superinfection reached over 400-fold higher densities in the salivary glands compared to the native wPip, suggesting it may be a candidate for pathogen transmission blocking. This article is protected by copyright. All rights reserved.

RevDate: 2019-06-13

Koh C, Audsley MD, Di Giallonardo F, et al (2019)

Sustained Wolbachia-mediated blocking of dengue virus isolates following serial passage in Aedes aegypti cell culture.

Virus evolution, 5(1):vez012 pii:vez012.

Wolbachia is an intracellular endosymbiont of insects that inhibits the replication of a range of pathogens in its arthropod hosts. The release of Wolbachia into wild populations of mosquitoes is an innovative biocontrol effort to suppress the transmission of arthropod-borne viruses (arboviruses) to humans, most notably dengue virus. The success of the Wolbachia-based approach hinges upon the stable persistence of the 'pathogen blocking' effect, whose mechanistic basis is poorly understood. Evidence suggests that Wolbachia may affect viral replication via a combination of competition for host resources and activation of host immunity. The evolution of resistance against Wolbachia and pathogen blocking in the mosquito or the virus could reduce the public health impact of the symbiont releases. Here, we investigate if dengue 3 virus (DENV-3) is capable of accumulating adaptive mutations that improve its replicative capacity during serial passage in Wolbachia wMel-infected cells. During the passaging regime, viral isolates in Wolbachia-infected cells exhibited greater variation in viral loads compared to controls. The viral loads of these isolates declined rapidly during passaging due to the blocking effects of Wolbachia carriage, with several being lost all together and the remainder recovering to low but stable levels. We attempted to sequence the genomes of the surviving passaged isolates but, given their low abundance, were unable to obtain sufficient depth of coverage for evolutionary analysis. In contrast, viral loads in Wolbachia-free control cells were consistently high during passaging. The surviving isolates passaged in the presence of Wolbachia exhibited a reduced ability to replicate even in Wolbachia-free cells. These experiments demonstrate the challenge for dengue in evolving resistance to Wolbachia-mediated blocking.

RevDate: 2019-06-12

Chrostek E, M Gerth (2019)

Is Anopheles gambiae a Natural Host of Wolbachia?.

mBio, 10(3): pii:mBio.00784-19.

Wolbachia (Alphaproteobacteria, Rickettsiales) is an intraovarially transmitted symbiont of insects able to exert striking phenotypes, including reproductive manipulations and pathogen blocking. These phenotypes make Wolbachia a promising tool to combat mosquito-borne diseases. Although Wolbachia is present in the majority of terrestrial arthropods, including many disease vectors, it was considered absent from Anopheles gambiae mosquitos, the main vectors of malaria in sub-Saharan Africa. In 2014, Wolbachia sequences were detected in A. gambiae samples collected in Burkina Faso. Subsequently, similar evidence came from collections all over Africa, revealing a high Wolbachia 16S rRNA sequence diversity, low abundance, and a lack of congruence between host and symbiont phylogenies. Here, we reanalyze and discuss recent evidence on the presence of Wolbachia sequences in A. gambiae. We find that although detected at increasing frequencies, the unusual properties of these Wolbachia sequences render them insufficient to diagnose natural infections in A. gambiae Future studies should focus on uncovering the origin of Wolbachia sequence variants in Anopheles and seeking sequence-independent evidence for this new symbiosis. Understanding the ecology of Anopheles mosquitos and their interactions with Wolbachia will be key in designing successful, integrative approaches to limit malaria spread. Although the prospect of using Wolbachia to fight malaria is intriguing, the newly discovered strains do not bring it closer to realization.IMPORTANCEAnopheles gambiae mosquitos are the main vectors of malaria, threatening around half of the world's population. The bacterial symbiont Wolbachia can interfere with disease transmission by other important insect vectors, but until recently, it was thought to be absent from natural A. gambiae populations. Here, we critically analyze the genomic, metagenomic, PCR, imaging, and phenotypic data presented in support of the presence of natural Wolbachia infections in A. gambiae We find that they are insufficient to diagnose Wolbachia infections and argue for the need of obtaining robust data confirming basic Wolbachia characteristics in this system. Determining the Wolbachia infection status of Anopheles is critical due to its potential to influence Anopheles population structure and Plasmodium transmission.

RevDate: 2019-06-08

Baião GC, Schneider DI, Miller WJ, et al (2019)

The effect of Wolbachia on gene expression in Drosophila paulistorum and its implications for symbiont-induced host speciation.

BMC genomics, 20(1):465 pii:10.1186/s12864-019-5816-9.

BACKGROUND: The Neotropical fruit fly Drosophila paulistorum (Diptera: Drosophilidae) is a species complex in statu nascendi comprising six reproductively isolated semispecies, each harboring mutualistic Wolbachia strains. Although wild type flies of each semispecies are isolated from the others by both pre- and postmating incompatibilities, mating between semispecies and successful offspring development can be achieved once flies are treated with antibiotics to reduce Wolbachia titer. Here we use RNA-seq to study the impact of Wolbachia on D. paulistorum and investigate the hypothesis that the symbiont may play a role in host speciation. For that goal, we analyze samples of heads and abdomens of both sexes of the Amazonian, Centro American and Orinocan semispecies of D. paulistorum.

RESULTS: We identify between 175 and 1192 differentially expressed genes associated with a variety of biological processes that respond either globally or according to tissue, sex or condition in the three semispecies. Some of the functions associated with differentially expressed genes are known to be affected by Wolbachia in other species, such as metabolism and immunity, whereas others represent putative novel phenotypes involving muscular functions, pheromone signaling, and visual perception.

CONCLUSIONS: Our results show that Wolbachia affect a large number of biological functions in D. paulistorum, particularly when present in high titer. We suggest that the significant metabolic impact of the infection on the host may cause several of the other putative and observed phenotypes. We also speculate that the observed differential expression of genes associated with chemical communication and reproduction may be associated with the emergence of pre- and postmating barriers between semispecies, which supports a role for Wolbachia in the speciation of D. paulistorum.

RevDate: 2019-06-07

Xie K, Lu YJ, Yang K, et al (2019)

Co-infection of Wolbachia and Spiroplasma in spider mite Tetranychus truncatus increases male fitness.

Insect science [Epub ahead of print].

Wolbachia and Spiroplasma are intracellular bacteria that are of great interest to entomologists, because of their ability to alter insect host biology in multiple ways. In the spider mite Tetranychus truncatus, co-infection of Wolbachia and Spiroplasma can induce cytoplasmic incompatibility (CI) and fitness costs; however, little is known about the effect of co-infection at the genetic level and the molecular mechanisms underlying CI. In this study, we explored the influence of the two symbionts on male mite host fitness and used RNA-Seq to generate the transcriptomes of T. truncatus with four different types of infection. In total, we found that symbiont-infected lines had a higher hatch proportion than the uninfected line, and the development time of the uninfected line was longer than that of the other lines. Co-infection changed the expression of many genes related to digestion detoxification, reproduction, immunity and oxidation reduction. Our results indicate that co-infection of Wolbachia and Spiroplasma confers multiple effects on their hosts, and help illuminate the complex interactions between endosymbionts and arthropods. This article is protected by copyright. All rights reserved.

RevDate: 2019-06-06

Bonning BC (2019)

The Insect Virome: Opportunities and Challenges.

Current issues in molecular biology, 34:1-12 pii:v34/1 [Epub ahead of print].

The insect virome is composed of a myriad of viruses. Both field populations and laboratory colonies of insects harbour diverse viruses, including viruses that infect the insect itself, viruses of microbes associated with the insect, and viruses associated with ingested materials. Metagenomics analysis for identification of virus-derived sequences has allowed for new appreciation of the extent and diversity of the insect virome. The complex interactions between insect viruses and host antiviral immune pathways (RNA interference and apoptosis), and between viruses and other members of the microbiome (e.g. Wolbachia) are becoming apparent. In this chapter, an overview of the diversity of viruses in insects and recent virus discovery research for specific insects and insect-derived cell lines is provided. The opportunities and challenges associated with the insect virome, including the potential impacts of viruses on both research and insect management programs are also addressed.

RevDate: 2019-06-04

Batsa Debrah L, Phillips RO, Pfarr K, et al (2019)

The Efficacy of Doxycycline Treatment on Mansonella perstans Infection: An Open-Label, Randomized Trial in Ghana.

The American journal of tropical medicine and hygiene [Epub ahead of print].

Treating Mansonella perstans is challenged by the low efficacy of registered antihelminthics. Wolbachia endobacteria provide an alternative treatment target because depletion results in amicrofilaremia in filarial infections with Wuchereria bancrofti and Onchocerca volvulus infections. This open-label, randomized study sought to confirm that i) Wolbachia are present in M. perstans in Ghana and ii) doxycycline treatment will deplete Wolbachia and cause a slow, sustained decline in microfilariae (MF). Two hundred and two Ghanaians with M. perstans infection were randomized into early (immediate) and delayed (6 months deferred) treatment groups, given doxycycline 200 mg/day for 6 weeks, and monitored for MF and Wolbachia levels at baseline, 4, 12, and 24 months after the study onset (= time of randomization and start of treatment for the early group). Per protocol analysis revealed that the median MF/mL in the early group declined from 138 at baseline to 64 at month 4 and further to 0 at month 12. In the delayed group, MF load did not change from a baseline median of 97 to 102 at month 4 but declined to 42 at month 12, that is, 6 months after receiving treatment, trailing the early group as expected. By month 24, both treatment groups had reached a median MF level of 0. After treatment, Wolbachia were depleted from MF by ≥ 1-log drop compared with baseline levels. We conclude that M. perstans in Ghana harbor Wolbachia that are effectively depleted by doxycycline with subsequent reduction in MF loads, most likely because of interruption of fertility of adult worms.

RevDate: 2019-06-10

Kulkarni A, Yu W, Jiang J, et al (2019)

Wolbachia pipientis occurs in Aedes aegypti populations in New Mexico and Florida, USA.

Ecology and evolution, 9(10):6148-6156 pii:ECE35198.

The mosquitoes Aedes aegypti (L.) and Ae. albopictus Skuse are the major vectors of dengue, Zika, yellow fever, and chikungunya viruses worldwide. Wolbachia, an endosymbiotic bacterium present in many insects, is being utilized in novel vector control strategies to manipulate mosquito life history and vector competence to curb virus transmission. Earlier studies have found that Wolbachia is commonly detected in Ae. albopictus but rarely detected in Ae. aegypti. In this study, we used a two-step PCR assay to detect Wolbachia in wild-collected samples of Ae. aegypti. The PCR products were sequenced to validate amplicons and identify Wolbachia strains. A loop-mediated isothermal amplification (LAMP) assay was developed and used for detecting Wolbachia in selected mosquito specimens as well. We found Wolbachia in 85/148 (57.4%) wild Ae. aegypti specimens from various cities in New Mexico, and in 2/46 (4.3%) from St. Augustine, Florida. Wolbachia was not detected in 94 samples of Ae. aegypti from Deer Park, Harris County, Texas. Wolbachia detected in Ae. aegypti from both New Mexico and Florida was the wAlbB strain of Wolbachia pipientis. A Wolbachia-positive colony of Ae. aegypti was established from pupae collected in Las Cruces, New Mexico, in 2018. The infected females of this strain transmitted Wolbachia to their progeny when crossed with males of Rockefeller strain of Ae. aegypti, which does not carry Wolbachia. In contrast, none of the progeny of Las Cruces males mated to Rockefeller females were infected with Wolbachia.

RevDate: 2019-06-04

Gichuhi J, Khamis FM, Van den Berg J, et al (2019)

Unexpected Diversity of Wolbachia Associated with Bactrocera dorsalis (Diptera: Tephritidae) in Africa.

Insects, 10(6): pii:insects10060155.

Bactrocera dorsalis (Hendel) is an important pest of fruit-bearing plants in many countries worldwide. In Africa, this pest has spread rapidly and has become widely established since the first invasion report in 2003. Wolbachia is a vertically transmitted endosymbiont that can significantly influence aspects of the biology and, in particular, the reproduction of its host. In this study, we screened B. dorsalis specimens collected from several locations in Africa between 2005 and 2017 for Wolbachia using a PCR-based assay to target the Wolbachia surface protein wsp. Of the 357 individuals tested, 10 were positive for Wolbachia using the wsp assay. We identified four strains of Wolbachia infecting two B. dorsalis mitochondrial haplotypes. We found no strict association between the infecting strain and host haplotype, with one strain being present in two different host haplotypes. All the detected strains belonged to Super Group B Wolbachia and did not match any strains reported previously in B. dorsalis in Asia. These findings indicate that diverse Wolbachia infections are present in invasive populations of B. dorsalis.

RevDate: 2019-06-10

Yashiro T, N Lo (2019)

Comparative screening of endosymbiotic bacteria associated with the asexual and sexual lineages of the termite Glyptotermes nakajimai.

Communicative & integrative biology, 12(1):55-58 pii:1592418.

Males provide opportunities both for sexual reproduction and for sex-based phenotypic differences within animal societies. In termites, the ubiquitous presence of both male and female workers and soldiers indicate that males play a critical role in colonies of these insects. However, we have recently reported all-female asexual societies in a lineage of the termite Glyptotermes nakajimai - a dramatic transition from mixed-sex to all-female asexual societies. It is known that female-producing parthenogenesis in insects can be induced by maternally inherited endosymbiotic bacteria, such as Wolbachia, Cardinium, and Rickettsia. Here, we screen for the presence of endosymbiotic bacteria in the asexual and sexual lineages of G. nakajimai. Our bacterial screening of the asexual lineage did not reveal any likely causal agents for parthenogenetic reproduction, whereas screening of the sexual lineage resulted in Wolbachia being detected. Our findings suggest that the asexuality in G. nakajimai is likely to be maintained without manipulation by endosymbiotic bacteria.

RevDate: 2019-06-10

Wasala SK, Brown AMV, Kang J, et al (2019)

Variable Abundance and Distribution of Wolbachia and Cardinium Endosymbionts in Plant-Parasitic Nematode Field Populations.

Frontiers in microbiology, 10:964.

The bacterial endosymbiont Wolbachia interacts with different invertebrate hosts, engaging in diverse symbiotic relationships. Wolbachia is often a reproductive parasite in arthropods, but an obligate mutualist in filarial nematodes. Wolbachia was recently discovered in plant-parasitic nematodes, and, is thus far known in just two genera Pratylenchus and Radopholus, yet the symbiont's function remains unknown. The occurrence of Wolbachia in these economically important plant pests offers an unexplored biocontrol strategy. However, development of Wolbachia-based biocontrol requires an improved understanding of symbiont-host functional interactions and the symbiont's prevalence among nematode field populations. This study used a molecular-genetic approach to assess the prevalence of a Wolbachia lineage (wPpe) in 32 field populations of Pratylenchus penetrans. Populations were examined from eight different plant species in Washington, Oregon, and California. Nematodes were also screened for the endosymbiotic bacterium Cardinium (cPpe) that was recently shown to co-infect P. penetrans. Results identified wPpe in 9/32 and cPpe in 1/32 of P. penetrans field populations analyzed. No co-infection was observed in field populations. Wolbachia was detected in nematodes from 4/8 plant-hosts examined (raspberry, strawberry, clover, and lily), and in all three states surveyed. Cardinium was detected in nematodes from mint in Washington. In the wPpe-infected P. penetrans populations collected from raspberry, the prevalence of wPpe infection ranged from 11 to 58%. This pattern is unlike that in filarial nematodes where Wolbachia is an obligate mutualist and occurs in 100% of the host. Further analysis of wPpe-infected populations revealed female-skewed sex ratios (up to 96%), with the degree of skew positively correlating with wPpe prevalence. Uninfected nematode populations had approximately equal numbers of males and females. Comparisons of 54 wPpe 16S ribosomal RNA sequences revealed high similarity across the geographic isolates, with 45 of 54 isolates being identical at this locus. The complete absence of wPpe among some populations and low prevalence in others suggest that this endosymbiont is not an obligate mutualist of P. penetrans. The observed sex ratio bias in wPpe-infected nematode populations is similar to that observed in arthropods where Wolbachia acts as a reproductive manipulator, raising the question of a similar role in plant-parasitic nematodes.

RevDate: 2019-06-04

Guo Y, Gong JT, Mo PW, et al (2019)

Wolbachia localization during Laodelphax striatellus embryogenesis.

Journal of insect physiology, 116:125-133.

Wolbachia are intracellular bacteria carried by thousands of arthropod species. The success of Wolbachia is due to efficient vertical transmission by the host maternal germline. Wolbachia's behavior during host oogenesis is well characterized, although their behavior during embryogenesis is unclear. Vertical transmission of Wolbachia wStri in the small brown planthopper, Laodelphax striatellus is extraordinarily efficient. To understand why, we investigated its localization and dynamics in L. striatellus embryos. Microscopic observations indicated that the Wolbachia were mainly localized at the anterior region of the embryo during early embryogenesis. The distribution of Wolbachia within the anterior region was established during oogenesis, and according to a phylogenetic analysis, may be due to intrinsic factors in Wolbachia. We observed that wStri migrated to the posterior part cells during late embryogenesis, in the region where gonads were formed. An expression profile of Wolbachia-infected host embryonic development genes revealed Ddx1 mRNAs, which is required for host viability and in the germ line, accumulated in the posterior region of 3-day-old embryos, while other development genes mRNAs were significantly more abundant in the posterior region of 6-day-old embryos. These genes thus appear to be associated with the localization of Wolbachia wStri in the anterior region, although their functions remain unclear. These results can explain Wolbachia wStri high prevalence in L. striatellus.

RevDate: 2019-05-23

Hubert J, Nesvorna M, Klimov P, et al (2019)

Differential allergen expression in three Tyrophagus putrescentiae strains inhabited by distinct microbiome.

RevDate: 2019-05-23

Chouin-Carneiro T, Ant TH, Herd C, et al (2019)

Wolbachia strain wAlbA blocks Zika virus transmission in Aedes aegypti.

Medical and veterinary entomology [Epub ahead of print].

Transinfections of the maternally transmitted endosymbiont Wolbachia pipientis can reduce RNA virus replication and prevent transmission by Aedes aegypti, and also have the capacity to invade wild-type populations, potentially reaching and maintaining high infection frequencies. Levels of virus transmission blocking are positively correlated with Wolbachia intracellular density. Despite reaching high densities in Ae. aegypti, transinfections of wAlbA, a strain native to Aedes albopictus, showed no blocking of Semliki Forest Virus in previous intrathoracic injection challenges. To further characterize wAlbA blocking in Ae. aegypti, adult females were intrathoracically challenged with Zika (ZIKV) and dengue viruses, and then fed a ZIKV-containing bloodmeal. No blocking was observed with either virus when challenged by intrathoracic injection. However, when ZIKV was delivered orally, wAlbA-infected females showed a significant reduction in viral replication and dissemination compared with uninfected controls, as well as a complete absence of virus in saliva. Although other Wolbachia strains have been shown to cause more robust viral blocking in Ae. aegypti, these findings demonstrate that, in principle, wAlbA could be used to reduce virus transmission in this species. Moreover, the results highlight the potential for underestimation of the strength of virus-blocking when based on intrathoracic injection compared with more natural oral challenges.

RevDate: 2019-06-10
CmpDate: 2019-05-31

Gómez-Díaz JS, Montoya-Lerma J, V Muñoz Valencia (2019)

Prevalence and Diversity of Endosymbionts in Cassava Whiteflies (Hemiptera: Aleyrodidae) From Colombia.

Journal of insect science (Online), 19(3):.

Whiteflies cause huge economic losses for cassava (Manihot esculenta Crantz) cultivation. Damage can be caused directly when the insects feed on the phloem and/or indirectly by the transmission of viruses. It has been found that whiteflies maintain a close relationship with some endosymbiotic bacteria and that this interaction produces different effects on host biology and can also facilitate viral transmission. This study aimed to characterize the diversity of secondary endosymbionts (SE) present in whiteflies associated with cassava. Whitefly adults and nymphs were collected from cassava crops at nine locations in Southwestern Colombia. Molecular identification of insects and endosymbionts was carried out using specific mtCOI, wsp, 23s rRNA, and 16s rRNA primers. Phylogenetic trees were constructed from these sequences, both for whitefly species and the endosymbionts found. In addition, morphological identification of whitefly species was made using last instar nymphs. Molecular and morphological evaluation revealed that the most abundant whitefly species was Trialeurodes variabilis (Quaintance) followed by Aleurotrachelus socialis Bondar and Bemisia tuberculata Bondar. One hundred percent of the individuals contained the primary endosymbiont Portiera. The SE Rickettsia, Hamiltonella, Wolbachia, and Fritschea were not detected in the samples tested. Prevalence of Cardinium and Arsenophonus were variable at each locality, Cardinium being most prevalent in A. socialis adults. This study is the first report on the presence of Cardinium and Arsenophonus in A. socialis and T. variabilis. It is also the first report of endosymbiotic diversity in whiteflies associated with cassava in Colombia.

RevDate: 2019-05-31

Caragata EP, Rocha MN, Pereira TN, et al (2019)

Pathogen blocking in Wolbachia-infected Aedes aegypti is not affected by Zika and dengue virus co-infection.

PLoS neglected tropical diseases, 13(5):e0007443 pii:PNTD-D-18-02063.

BACKGROUND: Wolbachia's ability to restrict arbovirus transmission makes it a promising tool to combat mosquito-transmitted diseases. Wolbachia-infected Aedes aegypti are currently being released in locations such as Brazil, which regularly experience concurrent outbreaks of different arboviruses. A. aegypti can become co-infected with, and transmit multiple arboviruses with one bite, which can complicate patient diagnosis and treatment.

Using experimental oral infection of A. aegypti and then RT-qPCR, we examined ZIKV/DENV-1 and ZIKV/DENV-3 co-infection in Wolbachia-infected A. aegypti and observed that Wolbachia-infected mosquitoes experienced lower prevalence of infection and viral load than wildtype mosquitoes, even with an extra infecting virus. Critically, ZIKV/DENV co-infection had no significant impact on Wolbachia's ability to reduce viral transmission. Wolbachia infection also strongly altered expression levels of key immune genes Defensin C and Transferrin 1, in a virus-dependent manner.

CONCLUSIONS/SIGNIFICANCE: Our results suggest that pathogen interference in Wolbachia-infected A. aegypti is not adversely affected by ZIKV/DENV co-infection, which suggests that Wolbachia-infected A. aegypti will likely prove suitable for controlling mosquito-borne diseases in environments with complex patterns of arbovirus transmission.

RevDate: 2019-05-18

Rahayu A, Saraswati U, Supriyati E, et al (2019)

Prevalence and Distribution of Dengue Virus in Aedes aegypti in Yogyakarta City before Deployment of Wolbachia Infected Aedes aegypti.

International journal of environmental research and public health, 16(10): pii:ijerph16101742.

Indonesia is one of the countries where dengue infection is prevalent. In this study we measure the prevalence and distribution of dengue virus (DENV) DENV-infected Aedes aegypti in Yogyakarta City, Indonesia, during the wet season when high dengue transmission period occurred, as baseline data before implementation of a Wolbachia-infected Aedes aegypti trial for dengue control. We applied One-Step Multiplex Real Time PCR (RT-PCR) for the type-specific-detection of dengue viruses in field-caught adult Aedes aegypti mosquitoes. In a prospective field study conducted from December 2015 to May 2016, adult female Aedes aegypti were caught from selected areas in Yogyakarta City, and then screened by using RT-PCR. During the survey period, 36 (0.12%) mosquitoes from amongst 29,252 female mosquitoes were positive for a DENV type. In total, 22.20% of dengue-positive mosquitoes were DENV-1, 25% were DENV-2, 17% were DENV-3, but none were positive for DENV-4. This study has provided dengue virus infection prevalence in field-caught Aedes aegypti and its circulating serotype in Yogyakarta City before deployment of Wolbachia-infected Aedes aegypti.

RevDate: 2019-06-10

Hosseinzadeh S, Ramsey J, Mann M, et al (2019)

Color morphology of Diaphorina citri influences interactions with its bacterial endosymbionts and 'Candidatus Liberibacter asiaticus'.

PloS one, 14(5):e0216599 pii:PONE-D-18-30769.

Diaphorina citri is a vector of 'Candidatus Liberibacter asiaticus,' (CLas), associated with Huanglongbing, (HLB, or citrus greening) disease in citrus. D. citri exhibits three different color morph variants, blue, gray and yellow. Blue morphs have a greater capacity for long-distance flight as compared to non-blue morphs, but little else is known about how color morphology influences vector characteristics. In this study, we show that the color morphology of the insect is derived from pigmented cells of the fat body. Blue morphs acquire a lower level of CLas in their bodies from infected trees as compared to their gray and yellow conspecifics, referred to in this paper collectively as non-blue morphs. Accordingly, CLas titer in citrus leaves inoculated by non-blue insects was 6-fold higher than in leaves inoculated by blue insects. Blue color morphs harbored lower titers of Wolbachia and 'Candidatus Profftella armatura,' two of the D. citri bacterial endosymbionts. Expression of hemocyanin, a copper-binding oxygen transport protein responsible for the blue coloration of hemolymph of other arthropods and mollusks, was previously correlated with blue color morphology and is highly up-regulated in insects continuously reared on CLas infected citrus trees. Based on our results, we hypothesized that a reduction of hemocyanin expression would reduce the D. citri immune response and an increase in the titer of CLas would be observed. Surprisingly, a specific 3-fold reduction of hemocyanin-1 transcript levels using RNA silencing in blue adult D. citri morphs had an approximately 2-fold reduction on the titer of CLas. These results suggest that hemocyanin signaling from the fat body may have multiple functions in the regulation of bacterial titers in D. citri, and that hemocyanin is one of multiple psyllid genes involved in regulating CLas titer.

RevDate: 2019-05-16

Teramoto T, Huang X, Armbruster P, et al (2019)

wMelpop strain of Wolbachia infection of Aedes albopictus mosquito C6/36 cells modulates dengue virus-induced host cellular transcripts and induces critical sequence alterations in dengue viral genome.

Journal of virology pii:JVI.00581-19 [Epub ahead of print].

The dengue virus (DENV) cause frequent epidemics infecting ∼390 million people annually in over 100 countries. There are no approved vaccines or antiviral drugs for treatment of infected patients. However, there is a novel approach to control DENV transmission by the mosquito vectors, Aedes aegypti and Ae. albopictus, using the Wolbachia symbiont. The wMelPop strain of Wolbachia suppresses DENV transmission and shortens the mosquito life span. However, the underlying mechanism is poorly understood. To clarify this mechanism, either naïve Ae. albopictus (C6/36) or wMelPop-C6/36 cells were infected with DENV2. Analysis of host transcript profiles by RNAseq revealed that the presence of wMelPop dramatically altered the mosquito host cell transcription in response to DENV2 infection. The viral RNA evolved from wMelPop-C6/36 cells contained low frequency mutations (∼25%) within the coding region of transmembrane domain-1 (TMD1) of E protein. Mutations with >97 % frequencies were distributed within other regions of E, NS5 RNA-dependent RNA polymerase (NS5POL) domain, the TMDs of NS2A, NS2B, and NS4B. Moreover, while DENV2-infected naïve C6/36 cells showed syncytia formation, DENV2-infected wMelPop-C6/36 cells did not. The Wolbachia-induced mutant DENV2 can readily infect and replicate in naïve C6/36 cells; whereas, in the mutant DENV2- infected BHK-21 or Vero cells, the virus replication was delayed. In LLC-MK2 cells, the mutant failed to produce plaques. Additionally, in BHK-21 cells, many mutations in the viral genome reverted to WT and compensatory mutations in NS3 gene appeared. Our results indicate that wMelPop impacts significantly the interactions of DENV2 with mosquito and mammalian host cells.Importance:Mosquito-borne diseases are of global significance causing considerable morbidity and mortality throughout the world. The dengue virus (DENV, serotypes 1-4), a member of flavivirus genus of Flaviviridae family, causes millions of infections annually. Development of a safe vaccine is hampered due to absence of cross-protection and increased risk in secondary infections due to antibody-mediated immune enhancement. Infection of vector mosquitoes with Wolbachia bacteria offers a novel countermeasure to suppress DENV transmission, but the mechanisms are poorly understood. In this study, the host transcription profiles and viral RNA sequences were analyzed in naïve Ae. albopictus (C6/36) and wMelPop-C6/36 cells by RNAseq. Our results showed that the wMelPop symbiont caused profound changes in host transcription profiles and morphology of DENV2-infected C6/36 cells. Accumulation of several mutations throughout DENV2 RNA resulted in loss of infectivity of progeny virions. Our findings offer new insights into the mechanism of Wolbachia-mediated suppression of DENV transmission.

RevDate: 2019-05-22

Shah A, Hoffman JI, H Schielzeth (2019)

Transcriptome assembly for a colour-polymorphic grasshopper (Gomphocerus sibiricus) with a very large genome size.

BMC genomics, 20(1):370 pii:10.1186/s12864-019-5756-4.

BACKGROUND: The club-legged grasshopper Gomphocerus sibiricus is a Gomphocerinae grasshopper with a promising future as model species for studying the maintenance of colour-polymorphism, the genetics of sexual ornamentation and genome size evolution. However, limited molecular resources are available for this species. Here, we present a de novo transcriptome assembly as reference resource for gene expression studies. We used high-throughput Illumina sequencing to generate 5,070,036 paired-end reads after quality filtering. We then combined the best-assembled contigs from three different de novo transcriptome assemblers (Trinity, SOAPdenovo-trans and Oases/Velvet) into a single assembly.

RESULTS: This resulted in 82,251 contigs with a N50 of 1357 and a TransRate assembly score of 0.325, which compares favourably with other orthopteran transcriptome assemblies. Around 87% of the transcripts could be annotated using InterProScan 5, BLASTx and the dammit! annotation pipeline. We identified a number of genes involved in pigmentation and green pigment metabolism pathways. Furthermore, we identified 76,221 putative single nucleotide polymorphisms residing in 8400 contigs. We also assembled the mitochondrial genome and investigated levels of sequence divergence with other species from the genus Gomphocerus. Finally, we detected and assembled Wolbachia sequences, which revealed close sequence similarity to the strain pel wPip.

CONCLUSIONS: Our study has generated a significant resource for uncovering genotype-phenotype associations in a species with an extraordinarily large genome, while also providing mitochondrial and Wolbachia sequences that will be useful for comparative studies.

RevDate: 2019-06-10

Fabre B, Korona D, Lees JG, et al (2019)

Comparison of Drosophila melanogaster Embryo and Adult Proteome by SWATH-MS Reveals Differential Regulation of Protein Synthesis, Degradation Machinery, and Metabolism Modules.

Journal of proteome research, 18(6):2525-2534.

An important area of modern biology consists of understanding the relationship between genotype and phenotype. However, to understand this relationship it is essential to investigate one of the principal links between them: the proteome. With the development of recent mass-spectrometry approaches, it is now possible to quantify entire proteomes and thus relate them to different phenotypes. Here, we present a comparison of the proteome of two extreme developmental states in the well-established model organism Drosophila melanogaster: adult and embryo. Protein modules such as ribosome, proteasome, tricarboxylic acid cycle, glycolysis, or oxidative phosphorylation were found differentially expressed between the two developmental stages. Analysis of post-translation modifications of the proteins identified in this study indicates that they generally follow the same trend as their corresponding protein. Comparison between changes in the proteome and the transcriptome highlighted patterns of post-transcriptional regulation for the subunits of protein complexes such as the ribosome and the proteasome, whereas protein from modules such as TCA cycle, glycolysis, and oxidative phosphorylation seem to be coregulated at the transcriptional level. Finally, the impact of the endosymbiont Wolbachia pipientis on the proteome of both developmental states was also investigated.

RevDate: 2019-05-10

Xu Z, Fang SM, Bakowski MA, et al (2019)

Discovery of Kirromycins with Anti- Wolbachia Activity from Streptomyces sp. CB00686.

ACS chemical biology [Epub ahead of print].

Lymphatic filariasis and onchocerciasis diseases caused by filarial parasite infections can lead to profound disability and affect millions of people worldwide. Standard mass drug administration campaigns require repetitive delivery of anthelmintics for years to temporarily block parasite transmission but do not cure infection because long-lived adult worms survive the treatment. Depletion of the endosymbiont Wolbachia, present in most filarial nematode species, results in death of adult worms and therefore represents a promising target for the treatment of filariasis. Here, we used a high-content imaging assay to screen the pure compounds collection of the natural products library at The Scripps Research Institute for anti- Wolbachia activity, leading to the identification of kirromycin B (1) as a lead candidate. Two additional congeners, kirromycin (2) and kirromycin C (3), were isolated and characterized from the same producing strain Streptomyces sp. CB00686. All three kirromycin congeners depleted Wolbachia in LDW1 Drosophila cells in vitro with half-maximal inhibitory concentrations (IC50) in nanomolar range, while doxycycline, a registered drug with anti- Wolbachia activity, showed lower activity with an IC50 of 152 ± 55 nM. Furthermore, 1-3 eliminated the Wolbachia endosymbiont in Brugia pahangi ovaries ex vivo with higher efficiency (65%-90%) at 1 μM than that of doxycycline (50%). No cytotoxicity against HEK293T and HepG2 mammalian cells was observed with 1-3 at the highest concentration (40 μM) used in the assay. These results suggest kirromycin is an effective lead scaffold, further exploration of which could potentially lead to the development of novel treatments for filarial nematode infections.

RevDate: 2019-05-09

Bakowski MA, Shiroodi RK, Liu R, et al (2019)

Discovery of short-course antiwolbachial quinazolines for elimination of filarial worm infections.

Science translational medicine, 11(491):.

Parasitic filarial nematodes cause debilitating infections in people in resource-limited countries. A clinically validated approach to eliminating worms uses a 4- to 6-week course of doxycycline that targets Wolbachia, a bacterial endosymbiont required for worm viability and reproduction. However, the prolonged length of therapy and contraindication in children and pregnant women have slowed adoption of this treatment. Here, we describe discovery and optimization of quinazolines CBR417 and CBR490 that, with a single dose, achieve >99% elimination of Wolbachia in the in vivo Litomosoides sigmodontis filarial infection model. The efficacious quinazoline series was identified by pairing a primary cell-based high-content imaging screen with an orthogonal ex vivo validation assay to rapidly quantify Wolbachia elimination in Brugia pahangi filarial ovaries. We screened 300,368 small molecules in the primary assay and identified 288 potent and selective hits. Of 134 primary hits tested, only 23.9% were active in the worm-based validation assay, 8 of which contained a quinazoline heterocycle core. Medicinal chemistry optimization generated quinazolines with excellent pharmacokinetic profiles in mice. Potent antiwolbachial activity was confirmed in L. sigmodontis, Brugia malayi, and Onchocerca ochengi in vivo preclinical models of filarial disease and in vitro selectivity against Loa loa (a safety concern in endemic areas). The favorable efficacy and in vitro safety profiles of CBR490 and CBR417 further support these as clinical candidates for treatment of filarial infections.

RevDate: 2019-06-08

Hodson CN, SJ Perlman (2019)

Population biology of a selfish sex ratio distorting element in a booklouse (Psocodea: Liposcelis).

Journal of evolutionary biology [Epub ahead of print].

Arthropods harbour a variety of selfish genetic elements that manipulate reproduction to be preferentially transmitted to future generations. A major ongoing question is to understand how these elements persist in nature. In this study, we examine the population dynamics of an unusual selfish sex ratio distorter in a recently discovered species of booklouse, Liposcelis sp. (Psocodea: Liposcelididae) to gain a better understanding of some of the factors that may affect the persistence of this element. Females that carry the selfish genetic element only ever produce daughters, although they are obligately sexual. These females also only transmit the maternal half of their genome. We performed a replicated population cage experiment, varying the initial frequency of females that harbour the selfish element, and following female frequencies for 20 months. The selfish genetic element persisted in all cages, often reaching very high (and thus severely female-biased) frequencies. Surprisingly, we also found that females that carry the selfish genetic element had much lower fitness than their nondistorter counterparts, with lower lifetime fecundity, slower development and a shorter egg-laying period. We suggest that differential fitness plays a role in the maintenance of the selfish genetic element in this species. We believe that the genetic system in this species, paternal genome elimination, which allows maternal control of offspring sex ratio, may also be important in the persistence of the selfish genetic element, highlighting the need to consider species with diverse ecologies and genetic systems when investigating the effects of sex ratio manipulators on host populations.

RevDate: 2019-05-21
CmpDate: 2019-05-21

Farnesi LC, Belinato TA, Gesto JSM, et al (2019)

Embryonic development and egg viability of wMel-infected Aedes aegypti.

Parasites & vectors, 12(1):211 pii:10.1186/s13071-019-3474-z.

BACKGROUND: Aedes aegypti is a major disease vector in urban habitats, involved in the transmission of dengue, chikungunya and Zika. Despite innumerous attempts to contain disease outbreaks, there are neither efficient vaccines nor definite vector control methods nowadays. In recent years, an innovative strategy to control arboviruses, which exploits the endosymbiotic bacterium Wolbachia pipientis, emerged with great expectations. The success of the method depends on many aspects, including Wolbachia's cytoplasmic incompatibility and pathogen interference phenotypes, as well as its effect on host fitness. In this work, we investigated the influence the Wolbachia strain wMel exerts on embryo development and egg viability and speculate on its field release use.

METHODS: Wild-type (Br or Rockefeller) and Wolbachia-harboring specimens (wMelBr) were blood-fed and submitted to synchronous egg laying for embryo development assays. Samples were analyzed for morphological markers, developmental endpoint and egg resistance to desiccation (ERD). Quiescent egg viability over time was also assessed.

RESULTS: wMelBr samples completed embryogenesis 2-3 hours later than wild-type. This delay was also observed through the onset of both morphological and physiological markers, respectively by the moments of germband extension and ERD acquisition. Following the end of embryonic development, wMelBr eggs were slightly less resistant to desiccation and showed reduced viability levels, which rapidly decayed after 40 days into quiescence, from approximately 75% to virtually 0% in less than a month.

CONCLUSIONS: Our data revealed that the wMel strain of Wolbachia slightly delays embryogenesis and also affects egg quality, both through reduced viability and desiccation resistance. These findings suggest that, although embryonic fitness is somehow compromised by wMel infection, an efficient host reproductive manipulation through cytoplasmic incompatibility seems sufficient to overcome these effects in nature and promote bacterial invasion, as shown by successful ongoing field implementation.

RevDate: 2019-05-04

Cao LJ, Jiang W, AA Hoffmann (2019)

Life History Effects Linked to an Advantage for wAu Wolbachia in Drosophila.

Insects, 10(5): pii:insects10050126.

Wolbachia endosymbiont infections can persist and spread in insect populations without causing apparent effects on reproduction of their insect hosts, but the mechanisms involved are largely unknown. Here, we test for fitness effects of the wAu infection of Drosophila simulans by comparing multiple infected and uninfected polymorphic isofemale lines derived from nature. We show a fitness advantage (higher offspring number) for lines with the wAu Wolbachia infection when breeding on grapes, but only where there was Talaromyces and Penicillium fungal mycelial growth. When breeding on laboratory medium, the wAu infection extended the development time and resulted in larger females with higher fecundity, life history traits, which may increase fitness. A chemical associated with the fungi (ochratoxin A) did not specifically alter the fitness of wAu-infected larvae, which developed slower and emerged with a greater weight regardless of toxin levels. These findings suggest that the fitness benefits of Wolbachia in natural populations may reflect life history changes that are advantageous under particular circumstances, such as when breeding occurs in rotting fruit covered by abundant mycelial growth.

RevDate: 2019-05-03

Crunkhorn S (2019)

Inhibiting Wolbachia to treat parasitic diseases.

RevDate: 2019-05-01

Kaushik S, Sharma KK, Ramani R, et al (2019)

Detection of Wolbachia Phage (WO) in Indian Lac Insect [Kerria lacca (Kerr.)] and Its Implications.

Indian journal of microbiology, 59(2):237-240.

Wolbachia, a maternally inherited bacterium induces reproductive alterations in its hosts such as feminization of males, male killing and parthenogenesis. It is the most diverse endosymbiont infecting more than 70% of the insects ranging from pests to pollinators. Kerria lacca-a hemipteran is a sedentary, oriental insect known to produce lac-the only resin of animal origin. The present study was conducted to screen the presence of Wolbachia and its associated phages in the two infrasubspecific forms (four insect lines) of K. lacca viz. kusmi and rengeeni differing from each other on the basis of host preference. Wolbachia and its associated phage were found to be prevalent in all the insect lines analyzed. We, hereby, report the presence of WO-phage (Wolbachia phage) for the first time in K. lacca. Further, phylogenetic data differentiated the kusmi and rengeeni infrasubspecific forms into two different groups on the basis of WO-phage sequences.

RevDate: 2019-05-14

Anonymous (2019)

Evolutionary Genetics of Cytoplasmic Incompatibility Genes cifA and cifB in Prophage WO of Wolbachia.

Genome biology and evolution, 11(4):1320.

RevDate: 2019-04-28

Monteiro VVS, Navegantes-Lima KC, de Lemos AB, et al (2019)

Aedes-Chikungunya Virus Interaction: Key Role of Vector Midguts Microbiota and Its Saliva in the Host Infection.

Frontiers in microbiology, 10:492.

Aedes mosquitoes are important vectors for emerging diseases caused by arboviruses, such as chikungunya (CHIKV). These viruses' main transmitting species are Aedes aegypti and Ae. albopictus, which are present in tropical and temperate climatic areas all over the globe. Knowledge of vector characteristics is fundamentally important to the understanding of virus transmission. Only female mosquitoes are able to transmit CHIKV to the vertebrate host since they are hematophagous. In addition, mosquito microbiota is fundamentally important to virus infection in the mosquito. Microorganisms are able to modulate viral transmission in the mosquito, such as bacteria of the Wolbachia genus, which are capable of preventing viral infection, or protozoans of the Ascogregarina species, which are capable of facilitating virus transmission between mosquitoes and larvae. The competence of the mosquito is also important in the transmission of the virus to the vertebrate host, since their saliva has several substances with biological effects, such as immunomodulators and anticoagulants, which are able to modulate the host's response to the virus, interfering in its pathogenicity and virulence. Understanding the Aedes vector-chikungunya interaction is fundamentally important since it can enable the search for new methods of combating the virus' transmission.

RevDate: 2019-04-22

Mains JW, Kelly PH, Dobson KL, et al (2019)

Localized Control of Aedes aegypti (Diptera: Culicidae) in Miami, FL, via Inundative Releases of Wolbachia-Infected Male Mosquitoes.

Journal of medical entomology pii:5475244 [Epub ahead of print].

As part of the response to autochthonous Zika transmission in the United States, the City of South Miami implemented a 6-mo period in which Wolbachia-infected WB1 Aedes aegypti (L.) males were released into an ~170-acre area. Intracellular Wolbachia bacteria infections in Ae. aegypti cause early embryonic arrest (known as cytoplasmic incompatibility [CI]) and egg hatch failure, and inundative introductions have been suggested as a potential control tool. Throughout the release period, the Ae. aegypti population was monitored within both the release area and an equivalent area that did not receive WB1 male releases. The results show a significant reduction in egg hatch at the area receiving WB1 males, which is consistent with expectations for CI. Similarly, the number of Ae. aegypti was significantly reduced at the area receiving WB1 males, relative to the untreated area. The observed population reduction and results encourage additional work and replication of the Wolbachia biopesticide approach against Ae. aegypti, as an additional tool to be integrated with existing control tools for the control of this medically important vector and nuisance pest.

RevDate: 2019-05-24

Vila A, Estrada-Peña A, Altet L, et al (2019)

Endosymbionts carried by ticks feeding on dogs in Spain.

Ticks and tick-borne diseases, 10(4):848-852.

Studies on tick microbial communities historically focused on tick-borne pathogens. However, there is an increasing interest in capturing relationships among non-pathogenic endosymbionts and exploring their relevance for tick biology. The present study included a total of 1600 adult ticks collected from domestic dogs in 4 different biogeographical regions of Spain. Each pool formed by 1 to 10 halves of individuals representing one specific ticks species was examined by PCR for the presence of Coxiellaceae, Rickettsia spp., Rickettsiales, Wolbachia spp., and other bacterial DNA. Of the pools analyzed, 92% tested positive for endosymbiont-derived DNA. Coxiella spp. endosymbionts were the most prevalent microorganisms, being always present in Rhipicephalus sanguineus sensu lato (s.l.) pools. Rickettsia spp. DNA was detected in 60% of Dermacentor reticulatus pools and 40% of R. sanguineus s.l. pools, with a higher diversity of Rickettsia species in R. sanguineus s.l. pools. Our study reveals a negative relationship of Rickettsia massiliae with the presence of tick-borne pathogens in the same pool of ticks. An additional endosymbiont, 'Candidatus Rickettsiella isopodorum', was only detected in D. reticulatus pools. Data from this study indicate that dogs in Spain are exposed to several endosymbionts. Due to the importance of tick-borne pathogens, characterizing the role of endosymbionts for tick physiology and prevalence, may lead to novel control strategies.

RevDate: 2019-05-17

Shropshire JD, Leigh B, Bordenstein SR, et al (2019)

Models and Nomenclature for Cytoplasmic Incompatibility: Caution over Premature Conclusions - A Response to Beckmann et al.

Trends in genetics : TIG, 35(6):397-399.

RevDate: 2019-05-19

Ross PA, Ritchie SA, Axford JK, et al (2019)

Loss of cytoplasmic incompatibility in Wolbachia-infected Aedes aegypti under field conditions.

PLoS neglected tropical diseases, 13(4):e0007357 pii:PNTD-D-18-01933.

Wolbachia bacteria are now being introduced into Aedes aegypti mosquito populations for dengue control. When Wolbachia infections are at a high frequency, they influence the local transmission of dengue by direct virus blocking as well as deleterious effects on vector mosquito populations. However, the effectiveness of this strategy could be influenced by environmental temperatures that decrease Wolbachia density, thereby reducing the ability of Wolbachia to invade and persist in the population and block viruses. We reared wMel-infected Ae. aegypti larvae in the field during the wet season in Cairns, North Queensland. Containers placed in the shade produced mosquitoes with a high Wolbachia density and little impact on cytoplasmic incompatibility. However, in 50% shade where temperatures reached 39°C during the day, wMel-infected males partially lost their ability to induce cytoplasmic incompatibility and females had greatly reduced egg hatch when crossed to infected males. In a second experiment under somewhat hotter conditions (>40°C in 50% shade), field-reared wMel-infected females had their egg hatch reduced to 25% when crossed to field-reared wMel-infected males. Wolbachia density was reduced in 50% shade for both sexes in both experiments, with some mosquitoes cleared of their Wolbachia infections entirely. To investigate the critical temperature range for the loss of Wolbachia infections, we held Ae. aegypti eggs in thermocyclers for one week at a range of cyclical temperatures. Adult wMel density declined when eggs were held at 26-36°C or above with complete loss at 30-40°C, while the density of wAlbB remained high until temperatures were lethal. These findings suggest that high temperature effects on Wolbachia are potentially substantial when breeding containers are exposed to partial sunlight but not shade. Heat stress could reduce the ability of Wolbachia infections to invade mosquito populations in some locations and may compromise the ability of Wolbachia to block virus transmission in the field. Temperature effects may also have an ecological impact on mosquito populations given that a proportion of the population becomes self-incompatible.

RevDate: 2019-06-10

Meany MK, Conner WR, Richter SV, et al (2019)

Loss of cytoplasmic incompatibility and minimal fecundity effects explain relatively low Wolbachia frequencies in Drosophila mauritiana.

Evolution; international journal of organic evolution, 73(6):1278-1295.

Maternally transmitted Wolbachia bacteria infect about half of all insect species. Many Wolbachia cause cytoplasmic incompatibility (CI) and reduced egg hatch when uninfected females mate with infected males. Although CI produces a frequency-dependent fitness advantage that leads to high equilibrium Wolbachia frequencies, it does not aid Wolbachia spread from low frequencies. Indeed, the fitness advantages that produce initial Wolbachia spread and maintain non-CI Wolbachia remain elusive. wMau Wolbachia infecting Drosophila mauritiana do not cause CI, despite being very similar to CI-causing wNo from Drosophila simulans (0.068% sequence divergence over 682,494 bp), suggesting recent CI loss. Using draft wMau genomes, we identify a deletion in a CI-associated gene, consistent with theory predicting that selection within host lineages does not act to increase or maintain CI. In the laboratory, wMau shows near-perfect maternal transmission; but we find no significant effect on host fecundity, in contrast to published data. Intermediate wMau frequencies on the island of Mauritius are consistent with a balance between unidentified small, positive fitness effects and imperfect maternal transmission. Our phylogenomic analyses suggest that group-B Wolbachia, including wMau and wPip, diverged from group-A Wolbachia, such as wMel and wRi, 6-46 million years ago, more recently than previously estimated.

RevDate: 2019-04-19

Michalik K, Szklarzewicz T, Kalandyk-Kołodziejczyk M, et al (2019)

Bacterial associates of Orthezia urticae, Matsucoccus pini, and Steingelia gorodetskia - scale insects of archaeoccoid families Ortheziidae, Matsucoccidae, and Steingeliidae (Hemiptera, Coccomorpha).

Protoplasma pii:10.1007/s00709-019-01377-z [Epub ahead of print].

The biological nature, ultrastructure, distribution, and mode of transmission between generations of the microorganisms associated with three species (Orthezia urticae, Matsucoccus pini, Steingelia gorodetskia) of primitive families (archaeococcoids = Orthezioidea) of scale insects were investigated by means of microscopic and molecular methods. In all the specimens of Orthezia urticae and Matsucoccus pini examined, bacteria Wolbachia were identified. In some examined specimens of O. urticae, apart from Wolbachia, bacteria Sodalis were detected. In Steingelia gorodetskia, the bacteria of the genus Sphingomonas were found. In contrast to most plant sap-sucking hemipterans, the bacterial associates of O. urticae, M. pini, and S. gorodetskia are not harbored in specialized bacteriocytes, but are dispersed in the cells of different organs. Ultrastructural observations have shown that bacteria Wolbachia in O. urticae and M. pini, Sodalis in O. urticae, and Sphingomonas in S. gorodetskia are transovarially transmitted from mother to progeny.

RevDate: 2019-04-26

Sabūnas V, Radzijevskaja J, Sakalauskas P, et al (2019)

Dirofilaria repens in dogs and humans in Lithuania.

Parasites & vectors, 12(1):177 pii:10.1186/s13071-019-3406-y.

BACKGROUND: In Lithuania, the first case of canine subcutaneous dirofilariosis was recorded in 2010. Since then, an increasing number of cases of canine dirofilariosis have been documented in different veterinary clinics throughout the country. Human dirofilariosis was diagnosed in Lithuania for the first time in September 2011. However, to the authors' knowledge, there are no published data on the presence and prevalence of autochthonous dirofilariosis in dogs and humans in the country. The present study provides information about the predominant species and prevalence of Dirofilaria in dogs and describes the cases of human dirofilariosis in Lithuania. It also outlines PCR detection of the bacterial endosymbiont Wolbachia that contributes to the inflammatory features of filarioid infection.

RESULTS: A total of 2280 blood samples and six adult worms from pet and shelter dogs were collected in the central and eastern regions of Lithuania in 2013-2015. Based on their morphological appearance, morphometric measurements and molecular analysis, all the adult nematodes were identified as Dirofilaria repens. The diagnosis of microfilariae in blood samples was based on blood smear analysis and Knott's test. The PCR and sequence analysis of the ribosomal DNA ITS2 region and cox1 gene confirmed the presence of D. repens. Overall, 61 (2.7%) of the 2280 blood samples were found to be positive for the presence of D. repens. The infection rate of D. repens was significantly higher in shelter dogs (19.0%; 19/100) than in pet dogs (1.9%; 42/2180) (χ2 = 100.039, df = 1, P < 0.0001). Forty-nine DNA samples of D. repens-infected dogs were tested for the presence of the bacterial endosymbiont Wolbachia and, of these, 40 samples (81.6%) were found to be positive. Three ocular and six subcutaneous cases of human dirofilariosis were diagnosed in Lithuania in the period 2011-2018.

CONCLUSIONS: To the authors' knowledge, this is the first report of autochthonous D. repens infection in dogs and humans in Lithuania. The present data demonstrate that D. repens is the main etiological agent of dirofilariosis in Lithuania. The DNA of the filarioid endosymbiotic bacterium Wolbachia was detected in the vast majority of dogs infected with D. repens.

RevDate: 2019-04-18

Carvajal TM, Capistrano JDR, Hashimoto K, et al (2018)

Detection and distribution of Wolbachia endobacteria in Culex quinquefasciatus populations (Diptera : Culicidae) from Metropolitan Manila, Philippines.

Journal of vector borne diseases, 55(4):265-270.

Background & objectives: Culex quinquefasciatus is a peridomestic mosquito known for its ability to transmit pathogenic diseases such as filariasis and Japanese encephalitis. The development and use of novel and innovative vector control measures such as the utilization of Wolbachia, along with the existing ones, are necessary to prevent the transmission of these diseases. Studies exploring the diversity of Wolbachia, particularly in Cx. quinquefasciatus are very limited in the Philippines. Thus, the aim of the study was to detect the presence, distribution, and phylogenetic relationship of Wolbachia infections in Cx. quinquefasciatus in Metropolitan Manila, Philippines.

Methods: Adult Cx. quinquefasciatus mosquitoes were collected using a commercially available light-trap from May 2014-January 2015. Based on their sampling grids (n = 51), the adult mosquito abdomens were pooled and subjected to Wolbachia surface protein (wsp) gene amplification assay. Five selected wsp-positive samples were then sequenced and further analyzed to infer their phylogenetic relationship with known Wolbachia strains.

Results: A total of 1090 adult Cx. quinquefasciatus mosquitoes were collected. Pooled abdomens (n = 53) were then sorted based on their sampling grids for subsequent screening of wsp gene. Wolbachia infection rate was 59% (31/53). These infections were located at 29 (57%) sampling grids, and were observed to be widely distributed in the study area. Phylogenetic analysis indicated that the sample sequences were Wolbachia pipientis isolated from known hosts, Cx. pipiens and Cx. quinquefasciatus belonging to supergroup B clade.

The study was able to demonstrate the prevalence and distribution of Wolbachia in Cx. quinquefasciatus in Metropolitan Manila, Philippines. The findings of this study are geared towards proposing a vector control program that utilizes the potential of Wolbachia as a biological control agent in preventing the transmission of Culex-borne diseases.

RevDate: 2019-05-24

Muñoz-Leal S, Macedo C, Gonçalves TC, et al (2019)

Detected microorganisms and new geographic records of Ornithodoros rietcorreai (Acari: Argasidae) from northern Brazil.

Ticks and tick-borne diseases, 10(4):853-861.

Reliable data on distributional ranges of soft ticks (Argasidae) and assessments of putative tick-borne agents enhance the understanding on tick-associated microorganisms. A total of 96 ticks morphologicaly and molecularly identified as Ornithodoros rietcorreai were collected in Tocantins State, Brazil, using Noireau traps with living bait as CO2 source. Ninety-six ticks (54 nymphs, 32 males, 10 females) with different engorgement degrees were collected. Fourty-seven (48.9%) of them were individually screened by PCR for detecting bacteria of Anaplasmataceae family and genera Rickettsia, and Borrelia. The presence of protozoans of the genus Babesia was assessed as well. Fourty seven ticks were submitted to analysis. Nine ticks (19.1%) yielded sequences for gltA and htrA genes most identical with a series of endosymbiont rickettsiae and Rickettsia bellii, respectively. Upon two ticks (4.2%) we retrieved DNA of a potential new Wolbachia sp., and DNA of a putative novel Hepatozoon was characterized from three (6.4%) specimens. No DNA of Babesia or Borrelia was detected. Remarkably, amplicons of unidentified eukaryotic organisms, most closely related with apicomplexans but also with dinoflagellates (91% of identity after BLAST analyses), were recovered from two ticks (4.2%) using primers designed for Babesia 18S rRNA gene. Our records expand the distribution of O. rietcorreai into Brazilian Cerrado biome and introduce the occurrence of microorganisms in this tick species.

RevDate: 2019-04-24

Dhaygude K, Nair A, Johansson H, et al (2019)

The first draft genomes of the ant Formica exsecta, and its Wolbachia endosymbiont reveal extensive gene transfer from endosymbiont to host.

BMC genomics, 20(1):301 pii:10.1186/s12864-019-5665-6.

BACKGROUND: Adapting to changes in the environment is the foundation of species survival, and is usually thought to be a gradual process. However, transposable elements (TEs), epigenetic modifications, and/or genetic material acquired from other organisms by means of horizontal gene transfer (HGTs), can also lead to novel adaptive traits. Social insects form dense societies, which attract and maintain extra- and intracellular accessory inhabitants, which may facilitate gene transfer between species. The wood ant Formica exsecta (Formicidae; Hymenoptera), is a common ant species throughout the Palearctic region. The species is a well-established model for studies of ecological characteristics and evolutionary conflict.

RESULTS: In this study, we sequenced and assembled draft genomes for F. exsecta and its endosymbiont Wolbachia. The F. exsecta draft genome is 277.7 Mb long; we identify 13,767 protein coding genes, for which we provide gene ontology and protein domain annotations. This is also the first report of a Wolbachia genome from ants, and provides insights into the phylogenetic position of this endosymbiont. We also identified multiple horizontal gene transfer events (HGTs) from Wolbachia to F. exsecta. Some of these HGTs have also occurred in parallel in multiple other insect genomes, highlighting the extent of HGTs in eukaryotes.

CONCLUSION: We present the first draft genome of ant F. exsecta, and its endosymbiont Wolbachia (wFex), and show considerable rates of gene transfer from the symbiont to the host. We expect that especially the F. exsecta genome will be valuable resource in further exploration of the molecular basis of the evolution of social organization.

RevDate: 2019-05-10

Zheng B, Liu X, Tang M, et al (2019)

Use of age-stage structural models to seek optimal Wolbachia-infected male mosquito releases for mosquito-borne disease control.

Journal of theoretical biology, 472:95-109.

Due to the lack of vaccines and effective clinical cures, current methods to control mosquito-borne viral diseases such as dengue and Zika are primarily targeting to eradicate the major mosquito vectors. However, traditional means, including larval source reduction and applications of insecticides etc, are not sufficient to keep vector population density below the epidemic risk threshold. An innovative and operational strategy is to release Wolbachia-infected male mosquitoes into wild areas to sterilize wild female mosquitoes by cytoplasmic incompatibility. To help design optimal release strategies before large scale and expensive operations, we started with an age-stage discrete model to track daily abundances of wild female mosquitoes, which fitted the field data collected by Guangzhou Center for Disease Control and Prevention from 2015 to 2017 with an average Pearson correlation coefficient 0.7283. Then, we modeled the Wolbachia interference by introducing the proportional releases of Wolbachia-infected males, and eight optimal release policies which guarantee more than 95% suppression efficiency were sought. Finally, we assessed the robustness of the optimality of the eight release policies by allowing the migration of females or the contamination of Wolbachia-infected females by two further extended mathematical models.

RevDate: 2019-04-17

Lefoulon E, Vaisman N, Frydman HM, et al (2019)

Large Enriched Fragment Targeted Sequencing (LEFT-SEQ) Applied to Capture of Wolbachia Genomes.

Scientific reports, 9(1):5939 pii:10.1038/s41598-019-42454-w.

Symbiosis is a major force of evolutionary change, influencing virtually all aspects of biology, from population ecology and evolution to genomics and molecular/biochemical mechanisms of development and reproduction. A remarkable example is Wolbachia endobacteria, present in some parasitic nematodes and many arthropod species. Acquisition of genomic data from diverse Wolbachia clades will aid in the elucidation of the different symbiotic mechanisms(s). However, challenges of de novo assembly of Wolbachia genomes include the presence in the sample of host DNA: nematode/vertebrate or insect. We designed biotinylated probes to capture large fragments of Wolbachia DNA for sequencing using PacBio technology (LEFT-SEQ: Large Enriched Fragment Targeted Sequencing). LEFT-SEQ was used to capture and sequence four Wolbachia genomes: the filarial nematode Brugia malayi, wBm, (21-fold enrichment), Drosophila mauritiana flies (2 isolates), wMau (11-fold enrichment), and Aedes albopictus mosquitoes, wAlbB (200-fold enrichment). LEFT-SEQ resulted in complete genomes for wBm and for wMau. For wBm, 18 single-nucleotide polymorphisms (SNPs), relative to the wBm reference, were identified and confirmed by PCR. A limit of LEFT-SEQ is illustrated by the wAlbB genome, characterized by a very high level of insertion sequences elements (ISs) and DNA repeats, for which only a 20-contig draft assembly was achieved.

RevDate: 2019-05-02
CmpDate: 2019-04-18

Lee WS, Webster JA, Madzokere ET, et al (2019)

Mosquito antiviral defense mechanisms: a delicate balance between innate immunity and persistent viral infection.

Parasites & vectors, 12(1):165 pii:10.1186/s13071-019-3433-8.

Mosquito-borne diseases are associated with major global health burdens. Aedes spp. and Culex spp. are primarily responsible for the transmission of the most medically important mosquito-borne viruses, including dengue virus, West Nile virus and Zika virus. Despite the burden of these pathogens on human populations, the interactions between viruses and their mosquito hosts remain enigmatic. Viruses enter the midgut of a mosquito following the mosquito's ingestion of a viremic blood meal. During infection, virus recognition by the mosquito host triggers their antiviral defense mechanism. Of these host defenses, activation of the RNAi pathway is the main antiviral mechanism, leading to the degradation of viral RNA, thereby inhibiting viral replication and promoting viral clearance. However, whilst antiviral host defense mechanisms limit viral replication, the mosquito immune system is unable to effectively clear the virus. As such, these viruses can establish persistent infection with little or no fitness cost to the mosquito vector, ensuring life-long transmission to humans. Understanding of the mosquito innate immune response enables the discovery of novel antivectorial strategies to block human transmission. This review provides an updated and concise summary of recent studies on mosquito antiviral immune responses, which is a key determinant for successful virus transmission. In addition, we will also discuss the factors that may contribute to persistent infection in mosquito hosts. Finally, we will discuss current mosquito transmission-blocking strategies that utilize genetically modified mosquitoes and Wolbachia-infected mosquitoes for resistance to pathogens.

RevDate: 2019-05-13

Sigle LT, EA McGraw (2019)

Expanding the canon: Non-classical mosquito genes at the interface of arboviral infection.

Insect biochemistry and molecular biology, 109:72-80.

Mosquito transmitted viruses cause significant morbidity and mortality in human populations. Despite the use of insecticides and other measures of vector control, arboviral diseases are on the rise. One potential solution for limiting disease transmission to humans is to render mosquitoes refractory to viral infection through genetic modification. Substantial research effort in Drosophila, Aedes and Anopheles has helped to define the major innate immune pathways, including Toll, IMD, Jak/Stat and RNAi, however we still have an incomplete picture of the mosquito antiviral response. Transcriptional profiles of virus-infected insects reveal a much wider range of pathways activated by the process of infection. Within these lists of genes are unexplored mosquito candidates of viral defense. Wolbachia species are endosymbiotic bacteria that naturally limit arboviral infection in mosquitoes. Our understanding of the Wolbachia-mediated viral blocking mechanism is poor, but it does not appear to operate via the classical immune pathways. Herein, we reviewed the transcriptomic response of mosquitoes to multiple viral species and put forth consensus gene types/families outside the immune canon whose expression responds to infection, including cytoskeleton and cellular trafficking, the heat shock response, cytochromes P450, cell proliferation, chitin and small RNAs. We then examine emerging evidence for their functional role in viral resistance in diverse insect and mammalian hosts and their potential role in Wolbachia-mediated viral blocking. These candidate gene families offer novel avenues for research into the nature of insect viral defense.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

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Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )