Periodic Reporting for period 3 - NIRV_HOST_INT (Population genomics of co-evolution between non-retroviral RNA viruses and their hosts)
Reporting period: 2019-05-01 to 2020-10-31
This project uses the model system “Aedes albopictus-Flavivirus” and combines molecular work in a laboratory setting with sampling of mosquitoes in the wild to investigate whether integration of sequences from nonretroviral RNA viruses is a common phenomenon in nature, which viruses integrate into the genome of Ae. albopictus, whether there are hot spot of integrations in the genome which could lead to hypothesis on mechanisms of integrations and whether the presence of viral integrations affect the outcome of subsequent viral infections.
Aim 1) Population genomics analyses of NIRVs in Ae. albopictus
TASK. Characterise the pattern of viral integrations in wild-caught mosquitoes from the native home range and derived populations. Assess the prevalence of viral integrations in natural populations and correlate NIRVs presence with flavivirus infections.
WORK PERFORMED and RESULTS. We generated a new genome assembly of Ae. albopicuts based on long read sequencing approaches (published in Genome Biology in August 2020, 21:215) and a bioinformatic program called ViR (posted in BioArchive in June 2020) and annotated viral integrations in the genome of Ae. albopictus. Using these resources we looked for viral integrations in wild-collected mosquitoes and were able to identify a total of 11. We demonstrated that viral integrations occur in repetitive regions of the genome in close association with trasposable elements, mostly in piRNA clusters and produce piRNAs.
We also generated a public database (http://www.nreves.com) for the viral integrations of Aedes spp. mosquitoes
Aim 2) Biological Impact of NIRVs in Ae. albopictus.
TASK1: MOSQUITO FITNESS.
WORK PERFORMED and RESULTS. Life-table parameters of different Ae. albopictus strains were built and data are being analysed.
TASK2: TISSUE-TROPISM AND HERITABILITY.
WORK PERFORMED and RESULTS. We generated an Ae. albopictus transgenic line by inserting into a viral integration within a piRNA cluster a synthetic viral integration made of fragments from the genome of different viruses. We aim to use this line to test for fitness and impact on subsequent infection.
TASK 3: NIRVs and DENGUE INFECTION.
WORKED PERFORMED and RESULTS. Data from infection experiments with different Ae. albopictus strains and the arboviruses Dengue and Chukungunya viruses, which were done at the Institut Pasteur were analysed and are part of the publication currently under review in PLOS NTDs (MS PNTD-D-20-01726 ""Unravelling the crosstalk between small RNA response and transcriptional changes during persistent Chikungunya virus infection in Aedes albopictus"")."