Research on cytotoxic T cell responses to hepatitis C virus infection

丙型肝炎病毒（HCV）感染经常持续存在，并导致慢性肝炎，肝硬化，最终肝细胞癌。随着一次性医疗器械的普及和血液制品HCV检测的引入，急性HCV感染已显著下降。通过干扰素治疗可以消除慢性丙型肝炎患者的HCV。然而，仍然有许多患者对治疗没有反应。由于细胞毒性T淋巴细胞（CTL）在清除感染的病毒中起着重要作用，因此增强HCV特异性CTL应答的治疗可能对此类患者有效。我们开发了一套检测外周血对HCV全抗原的CTL应答的系统。应用该系统，我们发现干扰素治疗后患者的HCV特异性CTL应答下降与血清中HCV的下降雅阁，并且暂时中断治疗可通过刺激重现的HCV增强CTL应答。我们也尝试鉴定尽可能多的HCV特异性CTL表位，为将来开发HCV肽疫苗奠定基础。利用HCV抗原肽段中的HLA-A24结合肽段或重叠肽段，通过干扰素-β-ELISA法鉴定了16个新的HCV特异性CTL表位。用CTL表位肽-HLA-A24-IG二聚体和细胞表面标志物分析HCV特异性CTL的表型，发现外周血中HCV特异性CTL活性低下，分化程度不一。

Hepatitis C virus (HCV) infection frequently persists, and leads to chronic hepatitis, cirrhosis, and eventually hepatocellular carcinoma. Acute HCV infection has decreased dramatically after universal use of disposable medical instruments and introduction of HCV test for blood products. Elimination of HCV from chronic hepatitis C patients became possible by interferon therapies. However there are still many patients who do not respond to the therapy. Since cytotoxic T lymphocytes (CTL) play an important role in elimination of infected viruses, the therapy that augments HCV-specific CTL responses may be effective for such patients. We developed the system that assesses CTL responses of peripheral blood to whole HCV antigens. Using the system, we found that HCV-specific CTL responses of patients treated with interferon decreased in accord with the decrease of HCV in serum, and that a temporary interruption of the therapy augmented CTL responses by stimulation with re-appeared HCV. We also attempted to identify HCV-specific CTL epitopes as many as possible for future development of HCV peptide vaccines. Using HCV peptides with HLA-A24-binding motif or overlapping peptides encompassing the whole HCV protein, we identified 16 novel HCV-specific CTL epitopes by interferon-', ELISpot assay. We also analyzed the phenotypes of HCV-specific CTL using CTL epitope peptide-HLA-A24-Ig dimers and cell surface markers, and found that HCV-specific CTL in the peripheral blood were poorly activated and differentiated variously.