Furthermore, similar to previous studies showing high cytotoxic activity and effector memory phenotype of extrathymic DP cells in cynomolgus monkeys [42] and in a chimpanzee with experimental hepatitis C virus infection [43], our results indicate that the DP cells purified from peripheral lymphoid tissues of chagasic animals show cytotoxic activity as compared to naïve single-positive CD4+ or CD8+ T cells. The gene discussed is CD4; the disease is hepatitis C virus infection.