We are comparing the bacterial communities of domestic and sylvatic  breeding sites and midguts of Aedes aegypti collected in Gabon.

The genome of the yellow fever mosquito (Aedes Aegypti) is not fully annoyed, and this project aims at discovering novel transcripts using RNAseq data.

The goal of the project is to determine if there are differences in the midgut microbiome of our lab colonies of Aedes aegypti. We frequently observe various phenotypic differences between different colonies of mosquitoes and it is a recurring question whether these phenotypic differences are a result of differences in the microbiome. We will sequence the microbiome of 6 representative established lab colonies that have been collected from geographically diverse areas and compare the bacterial communities between the them. This data will help us dissect the importance that variation of the midgut microbiome of lab colonies of Aedes aegypti has on the phenotypic differences we observe in the lab.

Aedes albopictus is an important vector for transmitting arboviruses, such as Dengue, Chikungunya, West Nile or Zika viruses. Its worldwide distribution due to its high ability to adapt to variable environments makes this species a serious threat. This mosquito also better transmits Chikungunya than Dengue virus, and many studies are still trying to understand the deep relationships between these viruses and their vectors in order to develop new control strategies. Moreover, it is now well known that retroviruses partially integrate into host's genomes since it is mandatory for their replication cycle. Interestingly, Retroviridae are not the only viral family capable of host integration. Indeed, in the last decade, owing to new molecular technologies such as next-generation sequencing and bioinformatic tools, non-retroviral integrated RNA virus sequences (NIRVS) have been found into many animal genomes, including Aedes mosquitoes. This came as a surprise since RNA viruses do not have DNA intermediate in their replication cycle. However, little is known about these integrations and many questions remained unsolved. The aim of this project is to assess the production of NIRVS in persistently-infected cells from Ae. albopictus and Ae. aegypti. It is divided in several critical points : the first one is to know how fast the virus can integrate into the cell genome. The second one is to determine which part of the viral genome can integrate and finally, where can it integrate in the genome. This will allow us to understand the virus/host interaction and if NIRVS formation is a mechanism that vectors/hosts evolved as a general response to RNA viruses.

Although the microbiota of mosquitoes is known to play an important role in their vectorial capacity for human pathogens, most earlier studies have focused on mosquito-bacteria interactions at the adult stage. Mosquitoes are holometabolous insects whose larvae develop in aquatic habitats, whereas the adults are terrestrial. Larval and adult stages are not independent from each other because the larval environment can influence adult life-history traits through carry-over effects. We recently provided experimental evidence for such carry-over effects in the mosquito Aedes aegypti, the main vector of dengue, yellow fever and Zika viruses. Using gnotobiotic mosquitoes, we demonstrated that larval exposure to different bacteria can cause variation in Ae. aegypti adult traits underlying vectorial capacity (Dickson et al. 2017). This proof of principle is an important first step toward a more comprehensive understanding of how the environment shapes the risk of vector-borne disease. However, the larval microbiota has not been thoroughly characterized across ecologically diverse breeding sites in the field. The aim of this project is to characterize the bacterial and fungal microbiota of Ae. aegypti breeding sites and larvae in Gabon using targeted metagenomics and metatranscriptomics.

Our research team recently identified an Aedes aegypti mosquito population that is partially resistant to dengue virus infection. We also have candidate genes that potentially innerly this phenotype. In this project, we would like to test wether specific SNPs are associated with virus infection in those mosquitoes. Sequencing data has already been generated with the Omics platform and handled by C3BI.

We are currently characterising a set of genes that are involved in the yellow fever mosquito, Aedes aegypti, vector competence. We would like to investigate the polymorphisms of those genes using exome sequencing data.

Investigating the genetic basis of an organism’s phenotype typically focuses on genomic sequences annotated as genes. This traditional approach ignores repeated sequences such as transposable elements (TEs) that often make up a large fraction of the genome and contribute significantly to genetic diversity, including variation in genome size. TEs are mainly known to play an important role in genome architecture and evolution through their mutational potential but TE expression itself can also regulate gene expression and chromatin accessibility, activate cellular signaling pathways, and trigger aging or antiviral activities. In the mosquito Aedes aegypti, more than half of the genome consists of TEs but their contribution to phenotypic variation is virtually unknown. This aim of this project is to survey the variation in TE content and expression of Aedes aegypti mosquitoes using existing RNA-seq and DNA-seq datasets. It will lay the foundation for future studies on the functional relationships between TEs and phenotypes of interest.

This projects aims at performing transcriptomics on mosquitoes infected with arboviruses such as Dengue or Zika virus.

To better understand the vector specificity of Aedes aegypti mosquito in the transmission of CHIK virus, we try to identify genes involved in the primary responses of the viral infection when the virus is still in the midgut of mosquitoes, prior to the crossing of the gut epithelium. This investigation will be performed via mRNAseq from sequences of pools of 8 mosquitoes that fed on blood (controls) or on blood +CHIKV (infected mosquitoes).

Before the WHO considered it as a public health emergency of international concern in February 2016, Zika virus (ZIKV, Flavivirus, Flaviviridae) was a neglected mosquito-borne virus. First identified in Uganda in a sylvatic cycle, ZIKV has caused in few months millions cases, emerging in the five continents (Latin America, the Caribbean, Southeast Asia/Pacific Ocean, Africa/Indian Ocean, European countries (Portugal, Spain, France, Switzerland, the Netherlands)). We have initiated the most comprehensive study on vector competence with almost 50 mosquito populations belonging to five main species (Aedes aegypti, Aedes albopictus, Aedes japonicus, Culex pipiens, Culex quinquefasciatus) infected with 3 different ZIKV and examined at 3 days post-infection (7, 14, and 21). The objective of the project will be to run a meta analysis on vector competence and to assess to which extent each mosquito species contributes to ZIKV transmission according to the geographical location and the viral genotype. It will help to improve our understanding of the vector status and adapt surveillance, prevention, and control of Zika.

To better understand the vector specificity of Aedes aegypti mosquito in the transmission of the alphaviruses CHIKV and ONNV, we are using an in vitro system to specifically depict critical viral infection steps at the molecular level: transcription and replication of the viral genome. This in vitro system requires mosquito cell transfections followed by luciferase quantification. For better describe the viral replication in mosquito cells, we need to characterize our mosquito cell lines since it is well established that some insect specific viruses (ISVs) modulate arbovirus infection in vectors. In order to determine whether our mosquito cell lines are infected by ISVs , we have already sequenced respectively total and small RNAs of our cell lines: Aedes aegypti Aag2 cells and Anopheles cells ( 4A3a, 4A3a and SUA4). The analysis of these data will furnish global and comprehensive cell features regarding the presence of ISVs which may interfere with viral infections in mosquitoes.

Several arboviruses have emerged and/or reemerged in the New World in the past decades. While yellow fever and dengue are historical diseases which continue to cause deadly epidemics, Zika and chikungunya have recently invaded the South American continent, causing great concern. In Colombia, Aedes aegypti is the vector of most of human arboviruses. We collected Ae. aegypti eggs in Medellin in Colombia in 2020 and infected adults with dengue (DENV), chikungunya (CHIKV), yellow fever (YFV) and Zika virus (ZIKV). We show that Ae. aegypti Nor Oriental was more prone to become infected, to disseminate and transmit CHIKV and ZIKV than DENV and YFV. In this project, we aim at determining the diversity of viral populations at the crossing of two anatomical barriers in mosquitoes: midgut and salivary glands.