IFNG and infection: Therefore, for comparing the efficiency of the T cells to produce IFN-γ in the brains of infected HLA-A2.1-transgenic and WT mice during reactivation of the infection, we measured the ratios of IFN-γ mRNA levels to tachyzoite-specific SAG1 mRNA levels in their brains at 4-5 weeks after discontinuation of sulfadiazine treatment.