Investigating Flavivirus Infection, Dissemination, and Transmission Dynamics Using Zika virus, West Nile virus, and their Mosquito Vectors

Abstract

Flaviviruses (family Flaviviridae, genus Flavivirus) are a group viral pathogens responsible for causing disease and death in both humans and animals. Mosquito saliva potentiates Flavivirus infection in both in vitro and in vivo models; however, it remains unknown whether saliva from different species differentially potentiates infection. By inoculating the saliva of different mosquito species plus WNV onto Vero cells, plaque assays were used to study if saliva could differentially potentiate WNV infection. It was found that while there was no significant difference between Ae. aegypti and Ae albopictus saliva (p=0.19), more interestingly was that both saliva treatments had a significant reduction in plaques formed compared to virus alone (p= 0.01 and p=0.00). The presence of mosquito saliva appears to exert a protective effect in vitro when WNV is present. It also remains to be elucidated as to whether Canadian mosquitoes are able to spread Zika virus. By orally infecting wild caught mosquitoes with a ZIKV infected sugar meal and detecting the presence of virus 10 and 14 days post infection (d.p.i.), the vector competence of Canadian mosquitoes was evaluated. It was found that after 10 (n=50) and 14 d.p.i. (n=32), 2% and 0% of a population of Culex pipiens mosquitoes were found to be able to become infected and transmit the virus, respectively. Although Culex pipiens mosquitoes from the Niagara region may not be vectors of ZIKV, that does not negate other Canadian mosquitoes as being potential vectors.