IFNG and infection: When BALB/c mice are infected with the reference mild virulence strain H37Rv, there is an initial cell-mediated immune response with a high number of activated macrophages and expression of Th1 cytokines such as IFN-γ and IL-12, which peak at 21-day post-infection that efficiently control bacterial growth (Hernandez-Pando et al., 1996).