IFNG and AIDS: The objective of this study was to address the question “to what extent does HIV-1 escape from CTL contribute to HLA-associated AIDS progression?” We combined an analysis of 21 escape events in longitudinally-studied HIV-1 infected people with a population-level analysis of the functional CTL response in 150 subjects (by IFNg ELISpot) and an analysis of the HIV-1 sequence database to quantify the contribution of escape to the HLA-associated rate of AIDS progression.