Metagenomic analysis of biodiversity of the virome in wild vector mosquitoes

Informations

Funding country

France

Acronym

VIRVEC

URL

-

Start date

5/1/2012

End date

-

Budget

220,783 EUR

Fundings

Abstract

The goal of this application is to investigate the viral biodiversity in wild mosquitoes and address possible effects of this diversity on host-pathogen interactions. The study of biodiversity is important to understand the biology of any single species within an ecosystem and to help design strategies to control specific interactions between organisms. Viruses contribute to a large amount to genetic diversity in all ecosystems. However, the study of biodiversity and genetic diversity of microscopic life is hampered by our ability to isolate, grow and identify microorganisms. Metagenomic approaches can be used to determine the collective genetic diversity of ecosystems by direct sequencing of genetic material in environmental samples. This permits the analysis of the microbial communities present in environmental samples without the need to grow, isolate and identify specific individuals Different mosquito species are vectors for a large number of arthopod-borne viruses (arboviruses) and also other important non-viral human diseases. Viruses transmitted by mosquito vectors such as West Nile, Dengue (DENV), Yellow Fever (YFV) and Japanese encephalitis viruses are a serious threat to public health worldwide, affecting both developing and developed countries. More than 500 different viruses are currently classified as arboviruses, and over a hundred of them have been documented to cause human illnesses. Worldwide, there is a growing need for effective surveillance, prevention and therapeutic tools to help control the emergence of new and old arboviral diseases. The aim of this project is to use a novel approach to characterize the biodiversity of RNA viruses infecting mosquitoes in different areas of Brazil. This approach is based on the properties of the antiviral innate immune system of insects, which leads to the dicing of viral double stranded RNAs into 21 nucleotide small interfering RNAs (siRNAs). These 21nt virus-derived small RNAs produced by the immune system of the mosquito show a relatively homogenous coverage of the whole genome, and can be used to assemble contigs thus allowing to reconstitute the viral genome. Here, we propose to perform a global survey of 21nt RNAs present in wild Aedes aegypti and Culex fasciculatus mosquitoes by deep sequencing of small RNA libraries prepared from single insects. The key points of this approach are that (i) no prior knowledge of these viruses is necessary to identify them in the samples, ensuring a high potential for the discovery of novel viruses; (ii) the focus on 21nt small RNAs will considerably increase the specificity for virus-derived sequences and facilitate the bioinformatic analysis. This franco-brazilian collaborative project, proposed by three groups with complementary expertise and common interests, will develop innovative strategies and methods to generate and analyze high throughput RNA sequencing data. It will also provide an unprecedented view of the virome diversity in vector mosquitoes, as well as of its seasonal and geographical variability. In addition, it has a strong potential for the discovery of novel viruses, including arboviruses. Finally, the characterization of the novel genes (both viral and mosquitoes) identified through RNA sequencing will improve our knowledge on the molecular mechanisms of virus-host interactions in vector mosquitoes, with a special focus on the antiviral defense pathways.