Coxsackievirus B3 elicits a sex-specific CD8(+) T cell response which protects female mice

Sex is a significant contributor to the outcome of human infections. Males are frequently more susceptible to viral, bacterial, and fungal infections, often attributed to weaker immune responses. In contrast, a heightened immune response in females enables better pathogen elimination but leaves females more predisposed to autoimmune diseases. Unfortunately, the underlying basis for sex-specific immune responses remains poorly understood. Here, we show a sex difference in the CD8(+) T cell response to an enteric virus, Coxsackievirus B3 (CVB3). We found that CVB3 induced expansion of CD8(+) T cells in female mice but not in male mice. CVB3 also increased the proportion and number of CD11a(hi)CD62L(lo) CD8(+) T cells in female mice, indicative of activation. This response was independent of the inoculation route and type I interferon. Using a recombinant CVB3 virus expressing a model CD8(+) T cell epitope, we found that the expansion of CD8(+) T cells in females is viral-specific and not due to bystander activation. Finally, the depletion of CD8(+) T cells, prior to infection, led to enhanced mortality, indicating that CD8(+) T cells are protective against CVB3 in female mice. These data demonstrate that CVB3 induces a CD8(+) T cell response in female mice and highlight the importance of sex-specific immune responses to viral pathogens.