Importantly, upregulation of CD25 and production of IFN‐γ by NK cells after in vitro restimulation with vaccine antigens was consistently greater among HCMV seronegative than HCMV seropositive subjects, whereas degranulation responses were relatively unaffected by HCMV infection 2, 6. The gene discussed is IFNG; the disease is cytomegalovirus infection.