[Boosting with HBV subunit particle vaccine enhance immune response of novel DNA vaccine consisting of S-PreS1 fusion gene in mice].

To develop novel and effective HBV therapeutic vaccine, we constructed an expression vector, pVRC-HBSS1, in which PreS1 (21-47aa) coding gene fused to the C-terminal of the S (1-223 aa) coding gene of HBV, and prepared the protein particle vaccine HBSS1 that consist of S and PreS1 fusion antigen derived from CHO system. We immunized mice by priming three times with DNA vaccine via different methods (i.e., intramuscular injection, intradermal injection with electroporation), then boosting once with protein particle vaccine. We analyzed the immune response among various vaccination groups. The higher level of S or PreS1 specific antibodies was detected in the group via intradermal injection with electroporation, compared with that of direct intramuscular injection. We further found that the specific cellular immune responses (IFN-gamma ELISpot analysis) in the group priming with DNA vaccines and boosting with protein subunit vaccine particles, was significantly higher than that of the DNA or protein particle subunit alone. Moreover, combination vaccination priming with intradermal injection DNA via electroporation and boosting with protein particle induced the strongest cellular immune response. These results provide a basis for rational design and application of the novel HBV therapeutic vaccine.