We next used pMHCII tetramers to investigate the functional profile of EBV-specific CD4+ T cells induced by primary infection, in which we have previously shown expansions of effector CD4+ T cells (CD45RA+, CCR7−, CD62L−) specific for a broad range of EBV Ags, with frequencies up to 10-fold greater than those detected in healthy carriers (22). The gene discussed is SELL; the disease is infection.