Aedes aegypti(Aag2)-derived clonal mosquito cell lines reveal impact of pre-existing persistent co-infection with the insect-specific Bunyavirus Phasi Charoen-like virus on arbovirus replication

Abstract

Aedes aegyptiis a vector mosquito of major public health importance, transmitting arthropod-borne viruses (arboviruses) such as chikungunya, dengue, yellow fever and Zika viruses. Wild mosquito populations are persistently infected at high prevalence with insect-specific viruses that do not replicate in vertebrate hosts. In experimental settings, acute infections with insect-specific viruses have been shown to modulate arbovirus infection and transmission in Ae. aegypti and other vector mosquitoes, however the impact of persistent insect-specific virus infections that more accurately mimic the situation in nature has not been investigated extensively. Cell lines are useful models for studying virus-host interactions, however the available Ae. aegypti cell lines are poorly defined and heterogenous cultures. We generated single cell-derived clonal cell lines from the commonly used Ae. aegypticell line Aag2. Two of the fourteen Aag2-derived clonal cell lines studied in detail harboured markedly and consistently reduced levels of the insect-specific bunyavirus Phasi Charoen-like virus (PCLV) known to persistently infect Aag2 cells. In contrast to studies with acute insect-specific virus infections in cell culture and in vivo, we found that pre-existing persistent PCLV infection had no major impact on the replication of the flaviviruses dengue virus and Zika virus, the alphavirus Sindbis virus or the rhabdovirus vesicular stomatitis virus. Our findings highlight the need for further in vivo studies that more closely recapitulate natural arbovirus transmission settings in which arboviruses encounter mosquitoes harbouring persistent rather than acute insect-specific virus infections. Furthermore, we provide well-characterised Aag2-derived clonal cell lines as a valuable resource to the arbovirus research community.