Global genomics ofAedes aegyptiunveils widespread and novel infectious viruses capable of triggering a small RNA response

Abstract

ABSTRACTThe mosquitoAedes aegyptiis a prominent vector for arboviruses, but the breadth of mosquito viruses that infects this specie is not fully understood. In the broadest global survey to date of over 200Ae. aegyptismall RNA samples, we detected viral small interfering RNAs (siRNAs) and Piwi interacting RNAs (piRNAs) arising from mosquito viruses. We confirmed that most academic laboratory colonies ofAe. aegyptilack persisting viruses, yet two commercial strains were infected by a novel tombus-like virus.Ae. aegyptifrom North to South American locations were also teeming with multiple insect viruses, with Anphevirus and a bunyavirus displaying geographical boundaries from the viral small RNA patterns. AsianAe. aegyptismall RNA patterns indicate infections by similar mosquito viruses from the Americas and reveal the first wild example of dengue virus infection generating viral small RNAs. AfricanAe. aegyptialso contained various viral small RNAs including novel viruses only found in these African substrains. Intriguingly, viral long RNA patterns can differ from small RNA patterns, indicative of viral transcripts evading the mosquitoes’ RNA interference (RNAi) machinery. To determine whether the viruses we discovered via small RNA sequencing were replicating and transmissible, we infected C6/36 and Aag2 cells withAe. aegyptihomogenates. Through blind passaging, we generated cell lines stably infected by these mosquito viruses which then generated abundant viral siRNAs and piRNAs that resemble the native mosquito viral small RNA patterns. This mosquito small RNA genomics approach augments surveillance approaches for emerging infectious diseases.