Fig 3. ICOS KO and ICOS YF mice have severely impaired parasite-specific IgG antibody production and have increased cyst burden in the brain compared to WT infected mice.

(A) Parasite-specific total IgG was measured by ELISA using serum from chronically infected WT, ICOS KO, and ICOS YF mice as well as naïve controls (n = 3–4 per group, data is representative of two independent experiments and analyzed using two-way ANOVA). (B) Total cyst numbers from the brains of chronically infected mice were enumerated by light microscopy (n = 3–4 per group, data is representative of two independent experiments and analyzed by one-way ANOVA). (C) Representative H&E stained sections from the brains of chronically infected WT, ICOS KO, and ICOS YF mice. White arrows indicated individual parasite cysts ranging in size. Scale bar is 50 μm. ** denotes p<0.01, and *** denotes p<0.001 for all panels.