CD4 and infection: Further, vaccinated mice exhibited up to 57%, 29% and 79% increase in antigen-specific IFNγ+, TNFα+, and IFNγ+TNFα+ CD4+T cells, respectively, following challenge infection (compare Fig 3C with 2C); and a majority (70–72%) of the IFNγ+CD4+T cells were proliferative (Ki67+) with effector (CD44+CD62L-) phenotype (Fig 3C and 3E, p<0.05–0.01).