In immunocompetent individuals, CMV infection is typically controlled by the immune system, but the virus persists and can reactivate when immunity is compromised.[21] The results of this study showed that, regardless of whether the patients had COPD, the CD4+ T cell count in the CMV-infected group was significantly lower than that in the uninfected group. The gene discussed is CD4; the disease is chronic obstructive pulmonary disease.