Cross-recognition of TL9 epitope variants is largely determined by the infecting subtype and the presenting HLA class I molecule. Peptide recognition was assessed in IFN-γ ELISpot assays across a range of concentrations as indicated. Individual peptide sequences are identified in the key; autologous sequences are listed with the subject code. Data from 2 representative subjects in each of the 4 groups, defined by the infecting HIV subtype and the presenting HLA class I molecule, are shown; the entire dataset is shown in supplemental Figure 1. Subtype A– and subtype C–specific TL9 epitope variants are represented in blue and red, respectively; responses to autologous TL9 sequences are shown as dashed lines in each case.