We next evaluated the effect of CD4+ T cells on weight loss and liver pathology of IL-27R-/- mice infected with T. congolense. Infected IL-27R-/- mice treated with anti-CD4 mAb had significantly less weight loss at the later stage of infection, compared to infected IL-27R-/- mice treated with rat IgG or anti-CD8 mAb (p<0.01; S2A Fig). This evidence concerns the gene CD4 and infection.