Expression of CTLA-4 on CD4+T cells from mice. The CD4+ T cells from infected and control mice were purified at different hours post infection (PI) and stained with anti mouse CTLA-4 antibody conjugated with allo-phycocyanin (APC). The percentage of CD4+ T cells positive for CTLA-4 were calculated by formula mentioned in methods. The biexponential transformation of dot plot represents the percentage of CD4+ population which showed expression of CTLA-4 receptor at different hour post infection. Values in upper right corner are Mean ± SE of three independent experiments.