Studies On Immunization With DNA Vaccine Of Hepatitis Bvirus

Hepatitis B is a serious health problem, with over 350 million people worldwide affected by chronic HBV infection. There are some 10 million people dead of cirrhosis of liver or primary carcinoma of liver every year. In China the carriers of HBV is approximately 130 million and there are 30 million hepatitis B patients. The main problem is no specific methods could be used to deal with it. So looking for a novel access to control and prevent HBV infection is our urgent responsibility. In these year, the presence and development of gene immunization provides a new way for us to control and prevent hepatitis B. DNA immunization is a novel strategy which has been made in resent years and progressed rapidl~? In this approach, an eukaryotic expression plasmid encoding exogenous protein is introduced 3 ~ua ~ ~ ~ 4 .~. ~ directly into mammalian tissue to elicit specific humoral and cellular immune response. Compared with traditional protein vaccines, DNA vaccine can induce strong cellular immune response especially cytotoxic T lymphocyte activity, which maybe particularly desirable in the prevention of viral infection. In order to study the possibility of DNA vaccine to control and prevent hepatitis B after HBV infection, here eukaryotic expression plasmid and HBV gene were selected to construct recombinant plasmid of pCR3.1-S. Because in l-JBV genome, the S antigen can induced specific antibody for HBV as well as cytotoxic T lymphocyte activity. Experiments of transfecting PB 15 cells or HCC cells with pCR3. 1-S in vitro showed that, recombinant plasmid of pCR3. 1-S could express some HbsAg protein in mammalian cells. Injected recombinant plasmid of pCR3.1-S directly into quadriceps femoris of Balb/c mice as HBV DNA vaccines. Then HBV specific humoral and cellular immune response were detected by ELISA assay, 51Cr 4h releas assay, etc. In addition, the eukaiyotic expression vector encoding for mouse IL-2or IL-12 were coimmunized to mice with pCRJ.l-S and their effects as adjuvants for immune response were sdudied. Conclusion: 1. Recombinant plasmid of pCR3.1-S could express some HbsAg protein in mammalian cells. 2. DNA-based immunization could induce not only HBV-specific hwnoral immune response, but also cellular immune response in Balbk mice. The CTh activity induced by 1-IBV DNA vaccines in vitro is mediated by cells expressing CDS+ surface phenotype. 3. The eukaiyotic expression vector encoding for mouse IL-2or IL- 12 as adjuvants can increase humoral and cellular immune response induced by recombinant plasmid of pCR3. 1- S. 4. Recombinant plasmid of pCR3.1-S coimmunized to mice with the eukaryotic expression vector encoding for mouse IL- 12 must get batter therapeutic effects, and it might represent an approach for the gene therapy for against HBV infection.