Most strikingly, the phenotypes traditionally associated with exhaustion for NK cells was reflective of HCMV status in HIV/HCV co-infection (Figure S3F in Supplementary Material) as patients with elevated anti-HCMV IgG antibodies titers (=500 U/ml) presented lower frequencies of CD57+ NK cells that expressed Tim-3, NKG2C, T-bet, and Eomes. This evidence concerns the gene KLRC2 and coinfection.