Identification in humans of HPV-16 E6 and E7 protein epitopes recognized by cytolytic T lymphocytes in association with HLA-B18 and determination of the HLA-B18-specific binding motif

Human papilloma virus type 16 (HPV-16) is the HPV most frequently associate d with cervical carcinoma in humans. For the prevention or treatment of cer vical carcinoma, the E6 and E7 oncoproteins appear to be good targets for v accine-induced cytotoxic T lymphocytes (CTL). Lipopeptide vaccination is an efficient way of stimulating cellular responses. However, to synthesize ef fective lipopeptides, it is necessary to define which epitopes are immunoge nic. In this study we first determined that peptide 80-88 of the E6 protein was recognized by CTL from a healthy donor in association with the HL4-B18 molecule. We then defined the HLA-B18 anchoring peptide motif by testing t he binding of various short peptides with the HLA-B18 molecule and showed t hat it was related to the HLA-A1-specific peptide motif. Furthermore, in an alyzing the potential E7 epitopes susceptible to associating with HL4-B18, we demonstrated that peptide E7 44-52 gave the strongest binding. It could also be recognized by CTL from peripheral blood mononuclear cells (PBMC) of the same healthy donor. Finally, with PBMC from a patient with a cervical intraepithelial neoplasia grade 3, we found CTL which recognized the E6 80- 88 epitope. We have hence identified two peptides encoded by the E6 and E7 proteins which are presented by the HLA-B18 molecule and could be included in a vaccine against HPV-16.