The CD4 T cell subset may have deleterious effects in exacerbating collateral diseases such as myocarditis, immune senescence as well as graft-versus-host disease in CMV-seropositive patients (Cray and Levy, 1993; Lenzo et al., 2002; Karrer et al., 2009), and in EBV infection CD4 T cells, especially with a Th2 phenotype, may sustain primary infection via the expansion of EBV-transformed B cells (Veronese et al., 1992; Fu and Cannon, 2000; Johannessen et al., 2000; Wagar et al., 2000; MacArthur et al., 2007). The gene discussed is CD4; the disease is myocarditis.