Dynamics of Simultaneous Arboviral Infection in Host and Vector Cells

Abstract

In this study, simultaneous infection dynamics were investigated in mammalian and insect cells. Mayaro virus (MAYV; genus Alphavirus), West Nile virus (WNV; genus Flavivirus), and Zika virus (ZIKV; genus Flavivirus) were the arboviruses used in the pairings. Arboviruses are transmitted by arthropods, and Aedes sp. mosquitoes are vectors of multiple viruses, including all three used in this study. In addition to sharing some of the same vectors, MAYV, WNV, and ZIKV can all infect humans. To understand whether the presence of another virus affected viral infection dynamics, mammalian-derived Vero and insect-derived C6/36 cells were infected with either MAYV and ZIKV or WNV and ZIKV. In nature, a simultaneous infection can occur through either coinfection or superinfection, and both conditions were studied here. Infection dynamics were assessed by quantifying viral RNA production for 6 days following infection, using RT-qPCR. Simultaneous MAYV + ZIKV and ZIKV + WNV infections impacted infection dynamics. Interestingly, the outcomes seen in simultaneous infections of Vero cells were similar for both pairings. Viral accommodation was seen in coinfection conditions, as no change was seen in RNA levels for either virus in the pairing. The order in which the viruses infected the cells changed the outcome in superinfection conditions in Vero cells – viral accommodation was observed when ZIKV was the first to infect the cells, while superinfection exclusion was seen when ZIKV tried to infect Vero cells already infected with either MAYV or WNV. In C6/36, replication differed between the virus pairings studied but did not differ between coinfection and superinfections. Viral interference was observed for conditions where MAYV and ZIKV simultaneously infected C6/36 cells, while virus accommodation was at play when the virus pairing consisted of WNV and ZIKV.