CD4 and cytomegalovirus infection: Cytomegalovirus is often asymptomatic and adversely affects the immune system through cytomegalovirus-specific memory CD4+ and CD8+ T-cell activation.7, 8, 29, 31, 32 Studies8, 15 have postulated that children with cytomegalovirus infection might have an increased risk of tuberculosis disease; however, there are few epidemiological studies supporting this hypothesis.