An expansion of vaccine-induced CD8+T cells in response to challenge infection was evidenced by a >2-fold increase in IFNγ+ and TNFα+ and a 4-fold increase in IFNγ+TNFα+ CD8+T cells (compare Fig 3D with Fig 2D, p<0.05–0.01); of which 80–84% exhibited proliferative (Ki67+) and effector (CD44+CD62L-) phenotype (Fig 3D and 3F, p<0.01). Here, SELL is linked to infection.