The CD8+T cells of non-vaccinated mice responded to challenge infection with an increase in the markers of early activation (CD11a and CD69, Figure 6E), and effector (CD62LloCD44hi) or central memory (CD62LhiCD44hi) phenotype (Figure 6H) but failed to develop polyfunctional cytolytic response (Figures 6E–G). This evidence concerns the gene CD69 and infection.