To assess the breadth of T cell response to a novel HIV-1 DNA vaccine (multiHIV) encompassing several HIV-1 proteins, Mölder et al. used domestic pigs as an animal model. Pigs were used in preference to mice as they are outbred and thus express a wider range of MHC alleles that also have a degree of similarity to human MHC alleles. A PEPscreen® peptide library of 15-mer peptides overlapping by 11 amino acids from the proteins encoded in the MultiHIV vaccine was generated including the Rev, Nef, Tat, p17, 24, Pol and Env proteins of HIV-1. The peptides were divided into pools and used to stimulate PBMCs from the immunized pigs in IFN gamma ELISPOT assays. For a number of pigs, responses were observed with all peptide pools and these were further investigated to identify specific epitopes using individual peptides. Several of the antigenic regions identified in pigs correlated with known human HIV-1 epitopes.
Figure 1: Representative ELISPOT plate showing reactivity to five sub-pools of peptides in screening experiments. Animals that responded to all five sub-pools were selected for more detailed epitope mapping analysis.