Margolick JB, et al. - In view of the fact that both aging and treated human immunodeficiency virus (HIV)-infected populations exhibit low-level chronic immune activation of unknown etiology, which correlates with morbidity and mortality, researchers determined the relationship between T-cell responses to cytomegalovirus (CMV) (common in both populations), markers of inflammation, and frailty in HIV-uninfected and HIV-infected men. Outcomes reveal that T-cell responses to CMV could strongly influence chronic immune activation in HIV-uninfected and virologically suppressed HIV-infected men, and could predict frailty in HIV-uninfected men.