Therefore, the analyses of RNA microarray data are in conformity with our cytometry results and indicate that CD4+ T cell-intrinsic MyD88 signaling is necessary for sustaining a more robust Th1 differentiation program, proliferation and resistance to apoptosis, resulting in selective expansion of WT IFN-γ+CD4+ T cells in response to infection with T. cruzi. This evidence concerns the gene CD4 and infection.