PRF1 and cyst: Consistent with the presence of equivalent levels of bradyzoite-specific BAG1 mRNA and cyst numbers in the brains of infected HLA-A2.1-transgenic and WT control mice shown in Figures 1B and 2B, the ratios of perforin (Prf1) mRNA levels to BAG1 mRNA levels did not differ between the brains of these two strains of mice (0.687 ± 0.074 in the HLA-A2.1-transgenic mice [n=12] vs.0.851 ± 0.247 in the WT mice [n=14], P=0.274).