BALB/c mice (n=5) were primed and boosted with indicated DNAs at weeks 0 and 4, respectively. A, Summary of Gag-specific IFN-γ producing CD4 T cells in spleen as evaluated by intracellular cytokine staining. B, Summary of Gag-specific IFN-γ+ IL-2+ CD4 T cells in spleen. The bars represent mean frequency ± SEM. *, p <0.05. NA, Not available.