The expression of HLA-DR was observed on 2.50±0.81% of CD4+ T cells and 3.00±0.80% of CD8+ T cells before infection and jumped to 39.28±2.90% (n = 4) and 49.98±2.24% (n = 4) respectively for CD4+ and CD8+ T cells after infection (Fig. 5C). Here, CD4 is linked to infection.