DNA forms of arboviral RNA genomes are generated following infection in mosquito cell cultures

•Arboviral RNA genomes are converted into DNA forms following infection in mosquito cells.•A full complement of the viral RNA genome is not converted into the DNA form.•Patches of viral RNA in DNA forms can be detected as early as 24 h post infection in RNAi-deficient cells.•The DNA forms are highly pronounced in RNAi-deficient cells compared to RNAi-proficient cells.

Although infections of vertebrate hosts by arthropod-borne viruses may lead to pathogenic outcomes, infections of vector mosquitoes result in persistent infections, where the virus replicates in the host without causing apparent pathological effects. It is unclear how persistent infections are established and maintained in mosquitoes. Several reports revealed the presence of flavivirus-like DNA sequences in the mosquito genome, and recent studies have shown that DNA forms of RNA viruses restrict virus replication in Drosophila, suggesting that DNA forms may have a role in developing persistent infections. Here, we sought to investigate whether arboviruses generate DNA forms following infection in mosquitoes. Our results with West Nile, Dengue, and La Crosse viruses demonstrate that DNA forms of the viral RNA genome are generated in mosquito cells; however, not the entire viral genome, but patches of viral RNA in DNA forms can be detected 24 h post infection.