Upon challenge infection, the overall splenic percentage of CD8+T cells (range: 10.3–13%) contracted in vaccinated mice, yet, CD8+T cells in vaccinated mice responded to challenge infection with an increase in the expression of phenotypic markers of T cell recruitment and early activation (CD69: 14.3–18.3% of CD8+T cells, CD11a: 6.7–10.2% of CD8+T cells, compare Figures 6A,E). This evidence concerns the gene CD69 and infection.