Currently, access to memory cell precursors is limited, since in vitro memory CD8 T cell differentiation protocols described in the literature have not achieved classical central-memory characteristics, and isolation of memory precursors from in vivo infection models rely on the use of ex-vivo labeled naïve cells exhibiting transgenic TCRs or poorly defined lineage surface markers, transferred in vivo for activation (12, 18). Here, CD8A is linked to infection.