Therefore, since IL-17- and IL-2-producing CD4 T cells are known to be more susceptible to HIV infection than IFN-γ-producing CD4 T cells, this differential Th1 vs. Th1/Th17 phenotype for ALVAC- and Ad5-specific CD4 T cells is consistent with their susceptibility to HIV infection. This evidence concerns the gene IFNG and HIV infectious disease.