Persistent Wolbachia and Cultivable Bacteria Infection in the Reproductive and Somatic Tissues of the Mosquito Vector Aedes albopictus

University of Hyderabad, India
PLoS ONE (Impact Factor: 3.23). 02/2009; 4(7):e6388. DOI: 10.1371/journal.pone.0006388
Source: PubMed


Commensal and symbiotic microbes have a considerable impact on the behavior of many arthropod hosts, including hematophagous species that transmit pathogens causing infectious diseases to human and animals. Little is known about the bacteria associated with mosquitoes other than the vectorized pathogens. This study investigated Wolbachia and cultivable bacteria that persist through generations in Ae. albopictus organs known to host transmitted arboviruses, such as dengue and chikungunya.
We used culturing, diagnostic and quantitative PCR, as well as in situ hybridization, to detect and locate bacteria in whole individual mosquitoes and in dissected tissues. Wolbachia, cultivable bacteria of the genera Acinetobacter, Comamonas, Delftia and Pseudomonas co-occurred and persisted in the bodies of both males and females of Ae. albopictus initially collected in La Réunion during the chikungunya outbreak, and maintained as colonies in insectaries. In dissected tissues, Wolbachia and the cultivable Acinetobacter can be detected in the salivary glands. The other bacteria are commonly found in the gut. Quantitative PCR estimates suggest that Wolbachia densities are highest in ovaries, lower than those of Acinetobacter in the gut, and approximately equal to those of Acinetobacter in the salivary glands. Hybridization using specific fluorescent probes successfully localized Wolbachia in all germ cells, including the oocytes, and in the salivary glands, whereas the Acinetobacter hybridizing signal was mostly located in the foregut and in the anterior midgut.
Our results show that Proteobacteria are distributed in the somatic and reproductive tissues of mosquito where transmissible pathogens reside and replicate. This location may portend the coexistence of symbionts and pathogens, and thus the possibility that competition or cooperation phenomena may occur in the mosquito vector Ae. albopictus. Improved understanding of the vectorial system, including the role of bacteria in the vector's biology and competence, could have major implications for understanding viral emergences and for disease control.

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Available from: Denis Voronin, Oct 05, 2015
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    • "The insect gut is a key organ in insect physiology and immunity . Moreover , previous studies have demonstrated that this organ harbored low concentration of Wolbachia in Ae . albopictus adults ( Zouache et al . , 2009 ) , opening up the possibility to extend the depth of analysis of the gut - associated microbial community . For this purpose , V5 - V6 rrs amplicons from 32 individual midgut samples ( from 3 to 5 individuals per sampling site ) were sequenced with MiSeq technology ."
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    ABSTRACT: The Asian tiger mosquito Aedes albopictus is one of the most significant pathogen vectors of the twenty-first century. Originating from Asia, it has invaded a wide range of eco-climatic regions worldwide. The insect-associated microbiota is now recognized to play a significant role in host biology. While genetic diversity bottlenecks are known to result from biological invasions, the resulting shifts in host-associated microbiota diversity has not been thoroughly investigated. To address this subject, we compared four autochthonous Ae. albopictus populations in Vietnam, the native area of Ae. albopictus, and three populations recently introduced to Metropolitan France, with the aim of documenting whether these populations display differences in host genotype and bacterial microbiota. Population-level genetic diversity (microsatellite markers and COI haplotype) and bacterial diversity (16S rDNA metabarcoding) were compared between field-caught mosquitoes. Bacterial microbiota from the whole insect bodies were largely dominated by Wolbachia pipientis. Targeted analysis of the gut microbiota revealed a greater bacterial diversity in which a fraction was common between French and Vietnamese populations. The genus Dysgonomonas was the most prevalent and abundant across all studied populations. Overall genetic diversities of both hosts and bacterial microbiota were significantly reduced in recently established populations of France compared to the autochthonous populations of Vietnam. These results open up many important avenues of investigation in order to link the process of geographical invasion to shifts in commensal and symbiotic microbiome communities, as such shifts may have dramatic impacts on the biology and/or vector competence of invading hematophagous insects.
    Frontiers in Microbiology 09/2015; 6. DOI:10.3389/fmicb.2015.00970 · 3.99 Impact Factor
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    • "Until now the composition of bacterial communities associated with Ae. albopictus has mainly been investigated using classical microbiological and molecular techniques. Various culture-dependent isolation methods were used to identify cultivable bacteria (Zouache et al., 2009; Chouaia et al., 2010; Minard et al., 2013a,b; Valiente Moro et al., 2013). In parallel , non-culture-based methods such as DGGE fingerprinting (Chouaia et al., 2010; Zouache et al., 2011) or taxonomic microarray hybridization (Zouache et al., 2012) were employed. "
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    ABSTRACT: The Asian tiger mosquito Aedes (Stegomya) albopictus is an invasive species that has spread across the world in the last two decades, showing a great capacity to adapt to contrasting climates and environments. While demonstrated in many insects, the contribution of bacterial symbionts in Aedes ecology is a challenging aspect that needs to be investigated. Also some bacterial species have already been identified in Ae. albopictus using classical methods, but a more accurate survey of mosquito-associated bacterial diversity is needed to decipher the potential biological functions of bacterial symbionts in mediating or constraining insect adaptation. We surveyed the bacteria associated with field populations of Ae. albopictus from Madagascar by pyrosequencing 16S rRNA gene amplicons. Different aspects of amplicon preparation and sequencing depth were tested to optimize the breadth of bacterial diversity identified. The results revealed that all mosquitoes collected from different sites have a bacterial microbiota dominated by a single taxon, Wolbachia pipientis, which accounted for about 99% of all 92,615 sequences obtained. As Ae. albopictus is known to harbor two Wolbachia strains (wAlbA and wAlbB), a quantitative PCR was used to estimate the relative densities, (i.e., the bacteria-to-host gene ratios) of each strains in individual mosquitoes. Relative densities were between 6.25 × 10(0.01) and 5.47 × 10(0.1) for wAlbA and between 2.03 × 10(0.1) and 1.4 × 10(1) for wAlbB. Apart from Wolbachia, a total of 31 bacterial taxa were identified at the genus level using different method variations. Diversity index values were low and probably underestimated the true diversity due to the high abundance of Wolbachia sequences vastly outnumbering sequences from other taxa. Further studies should implement alternative strategies to specifically discard from analysis any sequences from Wolbachia, the dominant endosymbiotic bacterium in Ae. albopictus from this area.
    Frontiers in Cellular and Infection Microbiology 05/2014; 4:59. DOI:10.3389/fcimb.2014.00059 · 3.72 Impact Factor
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    • "In fact, Wolbachia has been observed in virtually all major tissues in numerous arthropods (e.g. Drosophila, the mosquitoes Aedes albopictus and Culex pipiens, the butterfly Eurema hecabe, the bean beetle Callosobruchus chinensis and leafcutter ants) (Min & Benzer 1997; Dobson et al. 1999; Ijichi et al. 2002; Goto et al. 2006; Narita et al. 2007; Zouache et al. 2009b; Andersen et al. 2012; Osborne et al. 2012). "
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    ABSTRACT: Animal-bacterial symbioses are highly dynamic in terms of multipartite interactions, both between the host and its symbionts as well as between the different bacteria constituting the symbiotic community. These interactions will be reflected by the titers of the individual bacterial taxa, e.g. via host regulation of bacterial loads or competition for resources between symbionts. Moreover, different host tissues represent heterogeneous microhabitats for bacteria, meaning that host-associated bacteria might establish tissue-specific bacterial communities. Wolbachia are widespread endosymbiotic bacteria, infecting a large number of arthropods and filarial nematodes. However, relatively little is known regarding direct interactions between Wolbachia and other bacteria. This study represents the first quantitative investigation of tissue-specific Wolbachia-microbiota interactions in the terrestrial isopod Armadillidium vulgare. To this end, we obtained a more complete picture of the Wolbachia distribution patterns across all major host tissues, integrating all three feminizing Wolbachia strains (wVulM, wVulC, wVulP) identified to date in this host. Interestingly, the different Wolbachia strains exhibited strain-specific tissue distribution patterns, with wVulM reaching lower titers in most tissues. These patterns were consistent across different host genetic backgrounds and might reflect different co-evolutionary histories between the Wolbachia strains and A. vulgare. Moreover, Wolbachia-infected females carried higher total bacterial loads in several, but not all, tissues, irrespective of the Wolbachia strain. Taken together, this quantitative approach indicates that Wolbachia is part of a potentially more diverse bacterial community, as exemplified by the presence of highly abundant bacterial taxa in the midgut caeca of several A. vulgare populations.This article is protected by copyright. All rights reserved.
    Molecular Ecology 04/2014; 23(10). DOI:10.1111/mec.12760 · 6.49 Impact Factor
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