Exposure to cold impairs interferon-induced antiviral defense.

It is commonly believed that exposure to low temperature increases susceptibility to viral infection in the human respiratory tract, but a molecular mechanism supporting this belief has yet to be discovered. In this study, we investigated the effect of low temperature on viral infection and innate defense in cell lines from the human respiratory tract and found that interferon-induced antiviral responses were impaired at low temperatures. Cells maintained at 25°C and 33°C expressed lower levels of myxovirus resistance protein 1 (MxA) and 2'5'-oligoadenylate synthetase 1 (OAS1) mRNAs when compared to cells maintained at 37°C after infection by seasonal influenza viruses. Exogenous β-interferon treatment reduced the viral replication at 37°C, but not at 25°C. Our results suggest that the impairment of interferon-induced antiviral responses by low temperature is one of several mechanisms that could explain an increase in host susceptibility to respiratory viruses after exposure to cold temperature.