T he present study was designed to determine if highly conserved hepatitis B virus (HBV)-derived peptides that bind multiple HLA class I alleles with high affinity are recognized as cytotoxic T lymphocyte (CTL) epitopes in acutely infected patients. Peripheral blood mononuclear cells from 67 patients with acute hepatitis B, and 12 patients convalescent from acute hepatitis B, were stimulated with three panels of peptides, each of which bind with high affinity to several class I alleles from the HLA-A2-, HLA-A3-, or HLA-B7-supertypes. In these patients, 8 of the 19 peptides tested were found to represent CTL epitopes recognized by two or more alleles in each supertype. Two sets of nested peptides were recognized in the context of alleles with completely unrelated peptide binding specificities. Finally, promiscuous recognition by the same CTL of a given peptide presented by target cells expressing different A2 subtypes was also commonly observed. In conclusion, several HBV-specific CTL epitopes, recognized by acutely infected or convalescent patients in the context of a wide range of HLA alleles have been identified. These results demonstrate the functional relevance of the supertype grouping of HLA class I molecules in a human viral disease setting. Furthermore, they represent a significant advance in the development of a totally synthetic vaccine to terminate chronic HBV infection and support the feasibility of a systematic approach to development of similar vaccines for prevention and treatment of other chronic viral infections.