That a similar need for CD4+ Th exists in protection against HCMV is suggested by studies showing that durable HCMV-specific T cell immunity depends on the presence of HCMV-specific CD4+ T cells [20], [27], [28], by observations that specific CD8+ T cells can clear ongoing HCMV infection, but not establish lasting immunity[27], [28], and by the association of suppression of CD4+ T cell responses and HCMV disease in HIV patients[29]. The gene discussed is CD4; the disease is cytomegalovirus infection.