Sustained CD8+ T-cell immune response to a novel immunodominant HLA-B*0702-associated epitope derived from an Epstein-Barr virus helicase-primase-associated protein.

Generation of a peptide-based vaccine against persistent viral infections, such as Epstein-Barr virus (EBV), requires identification of immunodominant epitopes recognized by anti-viral cytotoxic T-cells. Using available computer algorithms, we have screened the entire translated EBV genome for potential HLA-B7-binding peptides. The binding to HLA-B7 of 18 selected peptides was assessed by competitive binding assays and was found to correlate with the computer-assigned scores, confirming the predictive value of these algorithms in selection of HLA-B7-associated peptides. Screening of the immune responses to these peptides by ELISpot assays identified a novel immunodominant epitope, termed LPRA, derived from an EBV helicase-primase-associated protein encoded by BBLF2/3. Peptide-specific cells constituted up to 0.8% LPRA-specific CD8+ T-cells in the matured anti-viral response. Cytotoxic and proliferative cytotoxic T lymphocytes (CTL) responses to the LPRA peptide were readily demonstrated ex vivo. In addition, mutational studies of this epitope demonstrated a highly specific recognition by LPRA-specific CD8+ T-cells. Taken together, our data suggest that the novel lytic-phase HLA-B7-associated epitope contains essential features required of a component in an EBV peptide-based vaccine. Copyright 2004 Wiley-Liss, Inc.