Expression of the IL-7R α-chain (CD127) on CD8+ T cells during the acute phase of the response is also essential, although not sufficient on its own, for identifying the memory precursors at the acute time of infection (Kaech et al., 2003; Huster et al., 2004; Hand et al., 2007; Croom et al., 2011). The gene discussed is CD8A; the disease is infection.