IFNG and infection: Also, at 60 and 270 days post-infection, not only were the percentages of CD8+ T cells expressing IFN-γ less than PBS treated mice (Fig. 6B), but the geometric mean fluorescence of IFN-γ staining cells in infected mice was significantly less than PBS treated mice (p<0.0002; data not shown), suggesting suppression or lack of IFN-γ production in Brucella infected mice.