Impact of Day/Night Cycle Temperature Regimes on Zika Virus Replication in Mosquito Cells and Implications for Transmission Potential.

ZIKV is an emerging mosquito-borne pathogen with the unique capability to cause severe congenital abnormalities. Mosquito-borne viruses are reliant on an optimal temperature within the mosquito host to spread to humans. Few studies explore how day/night temperature variations impact virus replication within the mosquito. Most laboratory studies are conducted at constant temperatures, or with very minimal temperature oscillations. In consequence, ZIKV transmission models and risk maps utilize biological data derived from constant temperature studies. We sought to determine if the use of viral replication data obtained in more biologically relevant, fluctuating temperatures alters the geographic range for ZIKV transmission risk. We used a growing degree day (GDD)-based model to determine ZIKV transmission potential across the US. Replication curves were conducted at eight different average temperatures between 18°C and 32°C with daily fluctuations of either +/-2.5°C or +/-5°C from the baseline. We found that at lower temperatures (18-22°C), fluctuation was beneficial for virus replication, where it had less of an impact at more optimal temperatures (24-30°C). Our transmission potential map exhibited the highest proportion of infected mosquitoes in southeastern United States, with discrete pockets of elevated potential across interior regions, including the southern Great Plains and lower Mississippi Valley.