Breadth of vaccine-induced T cell responses against Env. (A) Number of peptides/epitopes recognized in nine volunteers. Env-specific T cell responses were identified using peptide pools in preliminary experiments. The peptides of the relevant pool were then organized in a matrix setting to perform peptide/epitope mapping. Peptide/epitope mapping was performed combining the IFN-γ ELISPOT assay with polychromatic flow cytometry. (B) Example of a peptide/epitope mapping recognized by CD4 T cells. (C) Epitope mapping of the YSENSSEYY CD8 T cell epitope in two representative volunteers vaccinated with DNA C plus NYVAC C. (D) YSENSSEYY-specific CD8 T cells after staining with the relevant HLA-A*0101–YSENSSEYY pentameric complex.