HIV-2 Gag-specific CD8⁺T cells enumerated by peptide-MHC class I tetramers reveal a highly focused response. (A) Example of tetramer staining. (B) A greater proportion of HIV-2 controllers (16 of 19) have detectable immunodominant Gag-specific tetramer populations than viremic individuals (5 of 12) (P = .02). (C) A significant correlation exists between tetramer-positive cells and the IFN-γ response to the total Gag pool (n = 31; viremic donors in red; Spearman’s rank correlation coefficient). Where 2 different tetramer responses were present (in 4 subjects), these were added together. (D) The total Gag-specific IFN-γ response (as measured by ELISpot assays) according to presence or absence of responses to the 4 immunodominant epitopes (n = 64; data reanalyzed from Leligdowicz et al¹¹ ; 2-tailed Mann-Whitney U test).