In early infection, the stimulation of naïve CD8+ T cells induces their proliferation and differentiation into two T cell subsets with distinct expression of the memory T (TM) cell marker IL-7 receptor (IL-7R) and the senescent effector T (TE) cell marker killer cell lectin-like receptor subfamily G member-1 (KLRG1) [2]. This evidence concerns the gene CD8A and infection.