Specific immune responses induced by a multi-epitope antigen of hepatitis C virus in mice and rabbits

Five highly conserved and immunogenic epitopes of hepatitis C virus (HCV) h ave been chosen to form a multi-epitope antigen gene and fused with beta-ga lactosidase gene to express a hybrid GZ-PCX antigen, which could be specifi cally recognized by human HCV sera. High level of anti-GZ-PCX IgG has been induced when mice or rabbits were immunized with GZ-PCX antigen emulsificat ed with complete Freund's adjuvant or mixed with killed attenuated Salmonel la typhimurium SL3261. The specific anti-GZ-PCX IgG reached a high titer of 10(-6), which remained for several months. Specific cytotoxic T lymphocyte (CTL) effects, delayed type hypersensitivity reaction (DTH) and proliferat ion of peripheral lymphocytes have been induced by GZ-PCX antigen or synthe tic peptides. High level of anti-GZ-PCX slgG has been detected in mice's in testinal washing fluids, which indicates that the antigen induced mucosal i mmunity as well as systematic immunity. The studies show that the HCV multi -epitope antigen induces high level of specific immune responses without ob vious toxicity, which might be able to provide protectivity to any HCV geno types and isolates.