Adult animals harbored increased percentage of antigen‐specific MHV S‐tet+ cells compared to aged animals both acutely (11% vs. 4%) and following recovery from infection (10% vs. 2%), but because of the overall increase in total CD8+ cells in the aged brain, there was no difference in the number of MHV‐specific CD8+ T cells at either timepoint (Figure 2e,f). Here, CD8A is linked to infection.