Synthesis of vDNA forms upon acute and persistent Tahyna virus infection in mosquito cells

Mosquitoes of the genus Aedes are vectors of several orthobunyaviruses and display a remarkable tolerance to viral infection. This tolerance allows mosquitoes to sustain viral replication and transmit pathogens during blood feeding while experiencing limited pathogenic effects. Although antiviral RNA interference is considered a key component of mosquito antiviral immunity, the mechanisms underlying viral tolerance remain incompletely understood. During RNA virus infection, mosquito cells can use endogenous reverse transcriptases to generate virus-derived DNA forms (vDNAs), which are thought to contribute to antiviral immunity by enhancing the production of antiviral small RNAs. However, the biology and functional relevance of vDNAs remain poorly characterized, particularly for orthobunyaviruses, for which evidence is currently limited to a single report involving La Crosse virus. Here, using end-point PCR, we investigated the synthesis of vDNA during acute and persistent infection of Ae. albopictus C6/36 cells with Tahyna virus (TAHV; orthobunyavirus) we isolated from a pool of Ae. caspius collected in Emilia-Romagna, Italy. Following infection, mosquito cells established a persistent infection characterized by the absence of cytopathic effects. Molecular analyses revealed the generation of small and fragmented vDNA forms derived from the viral genomic segments, suggesting a potential role in the control of TAHV replication and persistence. Ongoing functional analyses, will further characterize the interactions between TAHV and its mosquito host and clarify the contribution of vDNA-mediated pathways to viral tolerance in mosquito vectors.