Multiple distinct exhausted CD8+ T cell subsets were defined, by expression of Ly108 and CD69, with transcriptional, phenotypical, functional, and anatomical differences (Beltra et al., 2020), and by using parabiosed mice it was shown that the resident CD8+ T cells in lymphoid tissues after LCMV clone 13 infection have a PD-1+ stem-like phenotype (Im et al., 2020). The gene discussed is CD8A; the disease is infection.