| Chronic hepatitis B is an important public health problem all over the world. Unfortunately, there are no satisfactory drugs to cure HBV- related diseases till now. Viral persistence is thought to be related to poor HBV-specific T-cell responses. Immunization with a nucleic acid vaccine usually elicits specific antibody and T lymphocyte responses. In animal models, intramuscular injection of a plasmid encoding HBV envelope protein induces rapid, strong and sustained humoral and cell-mediated immune responses. Furthermore, in a transgenic mouse lineage, which constitutively express the HBsAg, a complete clearance of circulating HBsAg and HBV DNA is demonstrated. Meanwhile, protective antibody is introduced when healthy volunteers who are non-responders of recommbinant subunit HBV vaccine are enrolled. To act as a tool to abolish viral replication and to eliminate residual infected hepatoctyes, there are still lots of hard works to do with HB DNA vaccine. Assurance of security and improvement of effectiveness are important. Immunoadjuvant, cytokine and different delivery systems are usually engaged to improve the immunity of DNA vaccine. In this study, preS2/PreC and HBV regulatory element, an enhancer gene, was inserted into HBV recombinant plasmids, the immunity of DNA vaccine is improved by the activation of the expression of purpose protein. The vector is surely safe because it is engaged in HIV DNA vaccine which is now studied in clinical trial permitted by FDA. All of the recombinant plasmids constructed in this study can be used in clinical trial for further investigation.DNA fragment of HBsAg,PreS2-HBsAg, HBsAg-enhancer I , HBcAg and enhancer II -PreC-HBcAg region of HBV were amplified by PCR using the complete genome DNA of HBV adr subtype, and inserted into VR1012 vectors, respectively .The recombinant plasmids were transfected into HepG2 cells and COS-7 cells, and injected into BALB/C mice and HBV transgenic mice. The expression of protein in HepG2 cells...
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