Moreover, T-bet+ Th1 cells from WSX-1−/− mice produced significantly more IFN-γ on a per cell basis (as measured by mean fluorescence intensity (MFI) of IFN-γ expression) on days 9, 11 and 14, and significantly more TNF on day 14 of infection (Figure 1D, G). This evidence concerns the gene IFNG and infection.