The effect of fluctuating incubation temperatures on West Nile virus infection in Culex mosquitoes

Authors: McGregor, Bethany; KENNEY, JOAN - Centers For Disease Control And Prevention (CDC) - United States; CONNELLY, C. ROXANNE - Centers For Disease Control And Prevention (CDC) - United States

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2021
Publication Date: 9/14/2021
Citation: McGregor, B.L., Kenney, J.L., Connelly, C. 2021. The effect of fluctuating incubation temperatures on West Nile virus infection in Culex mosquitoes. Viruses. 13(9):1822. https://doi.org/10.3390/v13091822.
DOI: https://doi.org/10.3390/v13091822

Interpretive Summary: Temperature is an important factor in the study of mosquito-transmitted diseases as it can impact the biology of mosquitoes and the infection dynamics of viruses. Most laboratory experiments with mosquitoes use a static incubation temperature that does not reflect natural conditions, which could potentially compromise the application of results to the real world. In this experiment, we studied how fluctuating versus static temperatures affected infection of mosquitoes with West Nile virus (WNV) using two mosquito species: Culex tarsalis and Culex quinquefasciatus. While we found no difference in the number of mosquitoes that became infected between treatments, there were differences in the amount of infectious virus present in the bodies and legs of the mosquitoes at fluctuating and static temperatures. These results have implications for future studies on WNV infections in mosquitoes. In order to reflect interactions between viruses, vector insects, and the environment most accurately, researchers should consider using realistic temperature regimens when studying mosquito-borne infections in the laboratory.

Technical Abstract: Temperature plays a significant role in the vector competence, extrinsic incubation period, and intensity of infection of arboviruses within mosquito vectors. Most laboratory infection studies use static incubation temperatures that may not accurately reflect daily temperature ranges (DTR) to which mosquitoes are exposed. This could potentially compromise the application of results to real world scenarios. We evaluated the effect of fluctuating DTR versus static temperature treatments on the infection, dissemination, and transmission rates and viral titers of Culex tarsalis and Culex quinquefasciatus mosquitoes for West Nile virus. Two DTR regimens were tested including an 11°C and 15°C range, both fluctuating around an average temperature of 28°C. Overall, no significant differences were found between DTR and static treatments for infection, dissemination, or transmission rates for either species. However, significant treatment differences were identified for both Cx. tarsalis and Cx. quinquefasciatus viral titers. These effects were species-specific and most prominent later in the infection. These results indicate that future studies on WNV infections in Culex mosquitoes should consider employing realistic DTRs to reflect interactions most accurately between the virus, vector, and environment.