Given the abovementioned effect of HCMV infection on NK cell imprinting and the near ubiquitous HCMV seropositivity of HIV+ MSM, we used a novel longitudinal MSM cohort to study the effect of HIV and cART on the prevalence of FcRγ− NK cells by comparison with appropriately matched HIV− MSM. Here, FCER1G is linked to cytomegalovirus infection.