Prediction and identification-based prediction of Chinese hepatitis C viral-specific cytotoxic T lymphocyte epitopes

Cytotoxic T lymphocytes (CTLs) play a critical role in the host immune response to infection by the Hepatitis C Virus (HCV). In the current study, a number of HCV CTL epitopes that represent the HLA polymorphisms found in the majority of Chinese people were predicted based on genomic and bioinformatic approaches. The predicted epitopes were evaluated for validity by examining the peptide-binding affinity for MHC class I molecules, the stability of peptide-MHC complexes, and frequencies of IFN γ-positive T cells. Among the predicted epitope peptides, HLA-A2 restricted epitopes [NS4B (1793-1801) SMMAFSAAL] and HLA-B7 restricted epitopes [P7 (774-782) AAWYIKGRL] were able to induce high frequencies of IFN γ-producing T cells, and the specific CTLs for other epitopes were not detected in peripheral blood lymphocytes from patients with HCV. Moreover, NS4B (1793-1801) exhibited high binding affinity for HLA-A2 molecules, and its stability of peptide-MHC class I complexes was sufficient, indicating that the high binding affinity for MHC class I molecules is an important factor for immunogenicity. Primary analyses of the immunogenicity of predicted epitopes, such as in the current study, will contribute to the future design of an efficient vaccine that will be able to induce vigorous, sustainable, and broad HCV-specific CTL responses for the Chinese population.