Study On Recombinant Plasmid And Recombinant Adenovirus Expressing HBsAg In Mice

Hepatitis B virus (HBV) is one of the main pathogens of viral hepatitis, which can cause serious diseases such as acute hepatitis, chronic hepatitis, cirrhosis and liver cancer. China is one of the high HBV prevalence areas. There is no effective way to cure HBV infection. Drugs can only slow down the process of cirrhosis and reduce the incidence of liver cancer. Therefore, it is urgent to develop a HBV-specific treatment to cure these patients, in which therapeutic vaccine is of great potential.In the present study, S gene from HBV (adr-serotype) was used to construct recombinant DNA plasmid named pVR-S and recombinant adenovirus named rAdV-S, respectively. The immune effects of pVR-S and rAdV-S were evaluated preliminarily. Firstly, to optimize the immune effect of pVR-S, Balb/c mice were injected with pVR-S by two methods, including electroporation and intramuscular injection. Secondly, Balb/c mice were immunized with different immunization intervals including 3 and 4 weeks. Thirdly, two group of mice were injected with rAdV-S and pVR-S, respectively. Humoral and cellular immune response were detected by ELISA and ELISpot to evaluate the immune effects. Finally, DNA prime-Adenovirus boost strategy was used. Level of HBsAb was detected by ELISA and cellular response was detected by ELISpot to evaluate the effect of combined immune strategy.Our results showed that intramuscular immunization of pVR-S elicited quite low level of HBsAb. However, electroporation-mediated immunization could elicit strong humoral immune response. For pVR-S,4-week-interval strategy could induce high HBsAb antibody level after boosting once, and 3-week-interval strategy induced high HBsAb antibody level after boosting twice. rAdV-S could induce immune response two weeks after primary immunization, which was much more effective than pVR-S. What’s more, rAdV-S could induce much higher level of humoral and cellular immune response than the level pVR-S induced. In addiction, pVR-S prime-rAdV-S boost strategy could induce much stronger humoral and cellular response than independent pVR-S and independent rAdV-S immunization.In summary, electroporation-mediated immunization of pVR-S with 4 weeks interval could elicit high level of humoral immune response. Recombinant adenovirus rAdV-S could elicited strong immune responses both humorally and cellularly. pVR-S prime-rAdV-S boost immunization could elicit much stronger cellular immune effect than independent rAdV-S immunization with the same rAdV-S immunization times.