Antigen-specific cell-mediated immune responses. HIV-specific IFN-γ–secreting lymphocytes were detected by ELISpot assay (A) and ICCS assay (B). The number of CD8⁺ lymphocytes expressing T-cell receptor (TCR) that recognized the MHC class I–restricted p18 tetramer from HIV Env was examined by tetramer assay (C). The assays were performed one week after the final immunization. The figures represented one mouse of each group, and the data represent the average of 4-6 mice/group. LN indicates intestinal lymph node; * and **, mean values significantly different between the groups. Error bars indicate the standard error deviation from the mean of 4-6 mice (A). The data represent the average and SEM of 4-6 mice per group in panels B-C.