Influence of sex and age on natural resistance to St. Louis encephalitis virus infection in mice

Abstract

A difference was observed in susceptibility of adult male and female mice to St. Louis encephalitis (SLE) virus as measured by the death rate after intravenous challenge. Female mice that had susceptibility similar to that of males at 2 mth of age had increased resistance to SLE virus at 3 and 4 mth of age. The increased resistance occurred after sexual maturity, indicating that the resistance factor possibly was related to an aging process in the female. The susceptibility of male mice remained unchanged over the 2 to 4 mth period. Neither pregnancy nor castration had any effect on resistance of adult mice to St. Louis encephalitis virus.