The Susceptibility of Medically Important Mosquito Species to Insect-Specific Virus Infection

Abstract

Arthropod-borne viruses (arboviruses) cause disease in humans and animals throughout the world. Many factors exacerbate the risk of virus transmission over time, including climate change and global transport. Developing methods to control their transmission is of interest, and insect-specific viruses (ISVs) pose a novel avenue for biocontrol of arboviruses at the vectorial level. Cell-fusing agent virus (CFAV) (Flaviviridae: Flavivirus) is an insect-specific flavivirus that has been seen to influence the replication of arboviruses in vitro and in vivo. The maintenance of this virus within a persistently infected colony of Aedes aegypti was investigated. Between 2022 and 2023, the colony infection rate decreased. The capacity of the virus to be horizontally transmitted through cohabitation was also assessed with Ae. aegypti, by housing infected mosquitoes with uninfected mosquitoes for 7 days. No horizontal transmission was observed. The use of CFAV-infectious cell culture to infect Ae. aegypti larvae was also tested. Infection was successful in low proportions. These results gave insight into CFAV transmission pathways and raised questions about the factors that can affect stability of CFAV over time. Negev virus (NEGV) and Piura virus (PIUV) are part of a recently discovered genus called Nelorpivirus. Not much is known about their transmission or their effects on arboviruses. Here, Ae. aegypti and Culex pipiens larvae were successfully infected via infectious cell culture. There were higher infection rates in Ae. aegypti. Both species were able to vertically transmit PIUV while only Cx. pipiens could transmit NEGV to offspring. These results demonstrate that both medically important mosquito species are susceptible to infection by NEGV and PIUV. This is also the first experimental evidence of their capacity for vertical transmission