Evaluating temperature effects on bluetongue virus serotype 10 and 17 coinfection in Culicoides sonorensis

Authors: CARPENTER, MOLLY - Colorad0 State University; KOPANKE, JENNIFER - Oregon Health & Science University; LEE, JUSTIN - Centers For Disease Control And Prevention (CDC) - United States; RODGERS, CASE - Colorad0 State University; REED, KIRSTEN - Colorad0 State University; SHERMAN, TYLER - Colorad0 State University; GRAHAM, BARBARA - Colorado State University; Cohnstaedt, Lee; Wilson, William - Bill; STENGLEIN, MARK - Colorad0 State University; MAYO, CHRISTIE - Colorad0 State University

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2024
Publication Date: 3/6/2024
Citation: Carpenter, M., Kopanke, J., Lee, J., Rodgers, C., Reed, K., Sherman, T., Graham, B., Cohnstaedt, L.W., Wilson, W.C., Stenglein, M., Mayo, C. 2024. Evaluating temperature effects on bluetongue virus serotype 10 and 17 coinfection in Culicoides sonorensis. International Journal of Molecular Sciences. 25(5):3063. https://doi.org/10.3390/ijms25053063.
DOI: https://doi.org/10.3390/ijms25053063

Interpretive Summary: Bluetongue virus is a segmented RNA virus consisting of 10 segments and it is transmitted by Culicoides biting midges to animals such as sheep and deer. The central question of this paper is can these segments reassort or change if there are two viruses infecting the same biting midge insect. If so, is this ability to make new viruses impacted by temperature. Therefore, this study looked at biting midge survival and virus changes at three temperatures with two virus serotypes. The midges were fed a blood meal containing BTV serotype 10, BTV serotype 17, or BTV serotype 10+17 and maintained at 20°C, 25°C, or 30°C. Midge survival was assessed, and pools of midges were collected every other day to evaluate virogenesis via pan BTV qRT-PCR. Additional pools of coinfected midges were collected for BTV plaque-isolation to find live virus. Next-generation sequencing was used to identify if the segments were mixed. Midges maintained at warmer temperatures produced plaques earlier; however, midges maintained at cooler temperatures had longer survival times. Overall, plaques with BTV-17 genotype dominated, but BTV-10 was detected in some plaques suggesting that parental strain fitness may play a role in reassortment outcomes. BTV reassortment will add an important dimension to the understanding viral evolution in the context of climate change.

Technical Abstract: Bluetongue virus (BTV) is a segmented, double-stranded RNA virus transmitted by Culicoides midges and infects ruminants. In concert with climate change, BTV outbreaks are characterized by expanding geographical ranges and incursions of novel serotypes into endemic regions. However, an understanding of the effect of temperature on reassortment is lacking. The objectives of this study include comparing how ambient temperatures affected Culicoides survival, virogenesis, and potential reassortment in Culicoides sonorensis coinfected with two BTV serotypes. Midges were fed a blood meal containing BTV serotype 10, BTV serotype 17, or BTV serotype 10+17 and maintained at 20°C, 25°C, or 30°C. Midge survival was assessed, and pools of midges were collected every other day to evaluate virogenesis via pan BTV qRT-PCR. Additional pools of coinfected midges were collected for BTV plaque-isolation. The complete genotypes of isolated plaques were determined using next-generation sequencing. Midges maintained at warmer temperatures produced plaques earlier; however, midges maintained at cooler temperatures had longer survival times. Overall, plaques with BTV-17 genotype dominated, but BTV-10 was detected in some plaques suggesting that parental strain fitness may play a role in reassortment outcomes. BTV reassortment will add an important dimension to the understanding viral evolution in the context of climate change.