Construction Of HCV Core And Envelope 2 Fusion DNA Vaccine And Its Immunogenicity In Mice

Nucleic acid vaccine, a distinctive vaccine, was developed from the field of gene therapy and composed of double strand DNA encoding certain antigens. Because of its high efficiency in inducing immune response, high stability in chemical property and simplicity in mass production, nucleic acid vaccine has become a focus of vaccine research.Hepatitis C virus (HCV) is a member of the Flaviviridae family of viruses. HCV has been shown to be the major cause of acute and chronic liver diseases worldwide. Accordingly it is urgent to develop successful vaccines to prevent HCV infection. This experiment observed the immunogenicity of a novel HCV fusion protein DNA vaccine in BALB/c mice and determined its value as an agent against hepatitis C. Envelope proteins are considerably important in the design of an HCV vaccine for containing the neutralization domains. HCV core gene is highly reserved among various genotypes, containing many T-cell epitopes, so it is rational to use HCV core gene to develop efficient HCV vaccine. It had been previously found that some signal peptide could efficiently deliver antigenic peptide enhancing both cellular and humoral immune responses. Helper T lymphocyte (HTL) responses play an important role in the induction of immune responses, which can activate CD4+ T cell to secrete IL-2 and IL-12 cells.In our research, A DNA fragment encoding signal peptide of murine IgG kappa chain and a universal helper T lymphocyte epitope PADRE were spliced by overlapping PCR. HCV core gene and envelope 2 (E2) gene were amplified by PCR respectively. The three DNA fragments were inserted into an eukaryotic expression vector pcDNAS. 1. The three DNA fragments were inserted into a eukaryotic expression vector pcDNAS. 1. The resultant recombinant expression plasmid pST-CE2t was then transfected into COS? cells and its expressed product was detected by immunohistochemical staining. BALB/c mice were vaccinated intramuscularly with pST-CE2t and pCE2t (only encoding HCV core-E2 fusion gene) . The serum antibodies, T lymphocyte proliferative response of the mice were detected. pST-CE2t could express -HCV core and E2 antigens in COS? cells and induce humoral and cellular immune responses in BALB/c mice effectively. The immune responses against HCV core protein elicited by pST~CE2t are stronger and more inclined to Thl type than that of pCE2t did. This optimal HCV core and E2 fusion protein DNA vaccine may be potentially useful for prevention and treatment of hepatitis C.