CD8A and viral infectious disease: Although readily cleared acute viral infections give rise to effector (TEFF) and TM cells, including TCM and TSCM cells, persistent infections such as hepatitis virus, human immunodeficiency virus in humans and certain strains of lymphocytic choriomeningitis virus (LCMV) in mice also give rise to CD8+ TSCM cells, even though CD8+ TPEX cell populations contribute significantly to the propagation of CD8+ TEX cells in these chronic infections10,15.