Exposure of Culicoides sonorensis to enzootic strains of bluetongue virus demonstrates temperature- and virus-specific effects on virogenesis

Authors: KOPANKE, JENNIFER - Colorado State University; LEE, JUSTIN - Colorado State University; STENGLEIN, MARK - Colorado State University; CARPENTER, MOLLY - Colorado State University; Cohnstaedt, Lee; Wilson, William; MAYO, CHRISTIE - Colorado State University

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2021
Publication Date: 5/28/2021
Citation: Kopanke, J., Lee, J., Stenglein, M., Carpenter, M., Cohnstaedt, L.W., Wilson, W.C., Mayo, C. 2021. Exposure of Culicoides sonorensis to enzootic strains of bluetongue virus demonstrates temperature- and virus-specific effects on virogenesis. Viruses. 13(6):1016. https://doi.org/10.3390/v13061016.
DOI: https://doi.org/10.3390/v13061016

Interpretive Summary: Bluetongue virus (BTV) is an insect transmitted virus of livestock in North America. Many factors affect insect transmitted viruses such as climatic factors, animal movement, insect vector species, and viral mutation and reassortment (changing viral segments). In the United States, the main identified BTV vector species is the biting midge, Culicoides sonorensis. To evaluate the viral mutations and reassortment in biting midges, we used two strains of BTV (BTV-2 and BTV-10) to explore how Culicoides sonorensis, can be successfully infected with these viruses, as well as whether variations in temperature affected virus formation during infection. While BTV-10 replicated readily in C. sonorensis following an infectious blood meal, BTV-2 was less likely to result in productive infection at biologically relevant exposure levels. Moreover, when C. sonorensis were co-exposed to both viruses, we did not detect reassortment between the two viruses, despite previous in vitro findings indicating that BTV-2 and BTV-10 are able to recombine (reassort) successfully. These results highlight that numerous factors, including vector species and virus exposure dose, may impact the likelihood of reassortment between BTV strains, and underscore the complexities of BTV ecology in North America.

Technical Abstract: Bluetongue virus (BTV) is a segmented RNA virus transmitted by Culicoides midges. Climatic factors, animal movement, vector species, and viral mutation and reassortment may all play a role in the occurrence of BTV outbreaks among susceptible ruminants. We used two enzootic strains of BTV (BTV-2 and BTV-10) to explore whether Culicoides sonorensis, a key North American vector, could be successfully infected with these viruses, as well as whether variations in temperature affected virogenesis during infection. While BTV-10 replicated readily in C. sonorensis following an infectious blood meal, BTV-2 was less likely to result in productive infection at biologically relevant exposure levels. Moreover, when C. sonorensis were co-exposed to both viruses, we did not detect reassortment between the two viruses, despite previous in vitro findings indicating that BTV-2 and BTV-10 are able to reassort successfully. These results highlight that numerous factors, including vector species and exposure dose, may impact the likelihood of reassortment between BTV strains, and underscore the complexities of BTV ecology in North America.