Sex differences in susceptibility to viral infection

Males and females differ in their susceptibility to a variety of viral pathogens. Although behavioral factors can influence exposure to viruses, several studies illustrate that physiological differences between males and females cause dimorphic responses to infection. Females often exhibit reduced susceptibility to viral infections because they typically mount stronger immune responses than males. Innate recognition and response to viruses as well as downstream adaptive immune responses differ between males and females during viral infections. This often results in sex differences in cytokine responses to infection that play a critical role in determining susceptibility to viruses. Immune responses to viruses can vary with changes in hormone concentrations naturally observed over the menstrual or estrous cycle, from contraception use, and during pregnancy.