IFNG and infection: Infection with Y induced 2- to 4-fold decreases in expression of IL-2 at 7 days pi, IFN-γ at 3 and 5 days pi, TNF-β at 5 and 7 days pi, and CD8 at 3 dpi (P<0.05) and 2- to 4-fold increases in CD8 expression at 5 and 7 dpi (P<0.05) in spleen, as compared to infection with PS, suggesting that strain Y exerts an inhibitory effect on expression of cytokines in spleen.