CD8A and infection: Not only did TKO mice have diminished CD8+ T cell immune responses to parasite-derived epitopes, but they were also no longer resistant to infection with T. cruzi. It is reasonable to hypothesize that the susceptibility to infection and the weak CD8+ T cell-mediated immunity are linked because in the mouse models that we used (naïve and vaccinated), CD8+ T cells have been described as being critically involved in the control of parasitemia and in survival [30, 32].