Identification And Function Study Of Cytotoxic T Cell Epitopes Derived From HBV Core Protein Of Genotype B And C

Hepatitis B virus (HBV) is a strictly hepatotropic DNA virus and has a worldwide distribution, especially in China. As the pathogenic role of HBV, it is a great threat to the health of human and can cause huge losses to our society. Many previous reports suggest that cytotoxic T lymphocyte (CTL) response plays a critical role in clearing HBV infection. CTL response induced by HBV infection is a "double-edge sword". It can clear virus infection as well as cause liver injury. As a highly prevalent hepadnavirus, HBV can evolve by mutations to increase its adaption against environmental selection, and these mutants are closely correlated with the pathogenesis of HBV infection. Based on these results, study of CTL response exhibits important theoretical and practical significances.Most of the reported CTL epitopes have been defined in HBV genotype A and D, lacking from genotype B and C, which is the most prevalent HBV genotype in China. In this study, the overlapping9-mer peptide pool (8amino acids overlap) covering HBV core protein (HBc)1-150and its variants was built to identify HBc of genotype B and C derived CTL epitopes. A total of191nonapeptides were included. Four peptides of high binding capacity to HLA-A2molecular were selected by MHC stabilization assay (HBc60-68*, HBc123-131, HBcl23-131*, HBc141-149) and the structures of MHC-peptide complex showed these four peptides are typical HLA-A2restricted peptides but also with their own characteristics, which may expand understandings of binding features of HLA-A2restricted epitopes. Of note, HBc60-68*(V60) generated by the L60V variation in HBc was carefully studied by structural and immunogenic analysis. Clinical researches showed that The HBc L60V variation is correlated with hepatic necroinflammation and higher viral levels, and it may be associated with poor prognosis in CHB patients. Immunization with the defined HBV epitope V60peptide elicited specific CTL-induced liver injury in HLA-A2+/HBV transgenic mice. In addition, in vitro and in vivo experiments both demonstrated that the HBc L60V variation facilitates viral capsid assembly and increases HBV replication. These data suggest that the HBc L60V variation can impact both HBV replication and HBV-specific T cell responses. Therefore, our work provides further dissection of the impact of the HBc L60V variation. which orchestrates HBV replication, viral persistence, and immunopathogenesis during chronic viral infection.