Establishment of a novel animal model of hepatitis C virus (HCV) infection and effecti induction of cellular immune responses against HCV

Research Project

Project/Area Number	09670540
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Gastroenterology
Research Institution	Mie University
Principal Investigator	TAMAKI Shigenori Mie University, Hospital, Assistant, 医学部附属病院, 助手 (80260602)
Co-Investigator(Kenkyū-buntansha)	KURIBAYASHI Kagemasa Mie University, Faculty of Medicine, Professor, 医学部, 教授 (10064578)
Project Period (FY)	1997 – 1998
Project Status	Completed (Fiscal Year 1998)
Budget Amount *help	¥3,000,000 (Direct Cost: ¥3,000,000) Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000) Fiscal Year 1997: ¥1,900,000 (Direct Cost: ¥1,900,000)
Keywords	HCV / CTL / vaccine / hepatitis / gene transfer / C型肝炎 / マウスモデル
Research Abstract	Hepatitis C virus (HCV)-specific cytotoxic T lymphocytes (CTL) play important roles in the prevention of viral spread and viral clearance during HCV infection. The results of our study contributed to gain more insights into the pathogenesis of HCV infection and allowed the generation of various vaccines against HCV.First, we established a novel mouse model of HCV infection by direct gene transfer using in vivo electroporation. Mice were intrahepatically inoculated with plasmid DNA driven with the promoter of human elongation factor 1- alpha gene (EFI- alpha) encoding HCV structural proteins (pEFCE1E2). The expression of HCV-core, El, and E2 antigens were determined in hepatocytes immunohistochemically 16 weeks after the inoculation. Secondly, we assessed the possibility of intrahepatic or intramuscular immunization with HCVcDNA to elicit HCV specific CTL.The spleen cells of intrahepatically cDNA-inoculated mice showed HCV specific CTL activities, The promoter of EFl- alpha is highly active in many kinds of mammalian cells. Miceimmunized with pEFCE1E2 but not the cytomegarovirus promoter plasmid DNA encoding HCV-core, El andE2 proteins developed HCV specific CTL activities after the first immunization. These results provide evidence for the potential usefulness, of the promoter of EF1- alpha for DNA inoculation as HCV vaccines. Thirdly, we demonstrated the anti-viral effects elicited using the helper T cell (Th) epitope peptide. Mice were immunized against the CTL epitope peptide of HCV core, the Th epitope peptide of HCV core, the mixture of CTL and Th epitope peptide or the CTL and Th conjugated peptide. Cytotoxic activity induced by immunization with conjugated peptide was much higher than that of mixed and CTL peptide alone. However, rapid and high cytotoxic activity was detected not only with CTL epitope including peptide immunization but also with Th epitope immunization alone after injection with recombinant vaccinia virus carrying the HCVcore gene.