SIVmac239-specific T cell responses detected by individual IFN- γ ELISPOT assays. Comparison of the location and magnitude of SIVmac239-specific T cell responses detected by individual peptide IFN-γ ELISPOT assays from 18 MCM with the M1/M1, M1/M3, or M3/M3 haplotype. Animals were divided into pairs by MHC class I haplotype and each pair was screened against approximately one third of the SIV proteome. Responses against the most immunogenic peptides within amino acid regions that elicited a response are shown and responses are numbered for reference in Figure 2. Because no responses were detected by ELISPOT in group 3 animals screened against the Pol protein, these animals are not shown. Due to high background IFN-γ secretion by cy0322, the M1/M1 Group 1 pair of cy0321 and cy0322 (asterisk) was not included in our comparison of responses detected by ELISPOT; however, responses mounted by cy0321 are shown.