Specific immune responses induced by a hepatitis B virus preS2S DNA vaccine in BALB/c mice.

Objective To investigate the specific immune responses induced by a hepatitis B virus(HBV) preS2S DNA vaccine on BALB/c mice.Methods BALB/c mice were randomly divided into 4 groups,and intramuscularly injected with pCMV-S2S,HBsAg,pCMV or normal saline thrice,at week 0,4 and 8 respectively.The expression of preS2S antigen in mice muscle was detected by immunohistochemistry assays.The specific CTL activity of mice was measured by lactate dehydrogenase(LDH) release assays.The anti-HBs in mice serum was measured by ELISA assays.Results The expression of preS2S antigen was detected in the muscles of pCMV-S2S group mice,but not detected in the muscles of other group mice.The specific CTL lysis value of pCMV-S2S group mice was[(32.10±1.93)%)](E/T ratio was 25∶1),remarkably higher than that of other groups(P0.05).The highest anti-HBs rate of pCMV-S2S group mice was 42.9%,8 weeks post the initial injection.However anti-HBs rate of HBsAg group mice was 100%,4 weeks post the initial injection.No anti-HBs were detected in the other gwo groups.Conclusion The HBV DNA vaccine pCMV-S2S may elicit HBV preS2S antigen expression,induce substantial HBV preS2S-specific CTL response in vivo,and may induce anti-HBs to some extent.