RESUMO
Objective:To investigate the feasibility of treating chronic HBV infection by inducing spe cific humoral immune response to HBV middle envelope protiens in normal and HBV transgenic mice with HBV DNA based immunization. Methods: The eukaryotic expression vector pCMV S2.S (PS) containing HBV S2.S gene and pc DNA3.0 were used respectively to immunize 5 C57BL/6 normal mice and HBV transgen ic mice. Each mouse was injected intramuscularly with one of those plasmids at t he same dose (100 ?g). Sera of mice were detected for anti HBs, anti preS2, HBsAg and HBeAg with ELISA. Pathological changes of transgenic mice liver were o bserved by microscopy. Results:PS can stimulate immune respons es of anti HBs and anti preS2 in normal and transgenic mice.The appearance of a nti preS2 was 1 2 weeks earlier than that of anti HBs. HBsAg and HBeAg in se ra turned negative 8 weeks after immunization. At the 8th week, hepatocytes show ed extensive granular degeneration and hydropic degeneration. There was no obvious difference in the amount of mononuclear lymphocytes between pre and post gen e immunization. Conclusion: It is showed that specific humoral immune response can be effectively induced by PS after DNA based immunization, and PS seems to be responsible for the disapearance of HBsAg and HBeAg in sera o f HBV transgenic mice. The results provide an evidence for furth er investigation of genetic vaccine in the treatment of chronic HBV infection.