Dual Insect specific virus infection limits Arbovirus replication in Aedes mosquito cells

Highlights: • Insect-specific viruses can be detected in an array of Aedes mosquito cell lines. • Phasi Charoen-like virus is found in A. aegypti but not A. albopictus cell lines. • albopictus cell lines are permissive to Phasi Charoen-like virus. • Zika, dengue, and La crosse virus growth are hindered by insect virus coinfection. Aedes mosquitoes are vectors for many pathogenic viruses. Cell culture systems facilitate the investigation of virus growth in the mosquito vector. We found Zika virus (ZIKV) growth to be consistent in A. albopictus cells but hypervariable in A. aegypti cell lines. As a potential explanation of this variability, we tested the hypothesis that our cells harbored opportunistic viruses. We screened Aedes cell lines for the presence of insect specific viruses (ISVs), Cell-fusing agent virus (CFAV) and Phasi charoen-like virus (PCLV). PCLV was present in the ZIKV-growth-variable A. aegypti cell lines but absent in A. albopictus lines, suggesting that these ISVs may interfere with ZIKV growth. In support of this hypothesis, PCLV infection of CFAV-positive A. albopictus cells inhibited the growth of ZIKV, dengue virus and La Crosse virus. These data suggest ISV infection of cell lines can impact arbovirus growth leading to significant changes in cell permissivity to arbovirus infection.