Construction of suicidal DNA vaccine of CSFV E2 gene and immunity induction in animals

The complete E2 gene of classical swine fever virus(CSFV) with the BamHⅠ restriction site was cloned from the recombinant plasmid pMD18-T-E2 and inserted into pMD19-T plasmid to construct the recombinant plasmid pMD19-T-E2.E2 gene was obtained from pMD19-T-E2 digested with BamHⅠ,and was inserted into the suicidal DNA vaccine vector pSCA1 which was treated with the same enzyme.The recombinant plasmid pSCA1-E2 was obtained and identified the length,insert sites,orientation and reading frame of E2 gene in pSCA1-E2 by polymerase chain reaction(PCR),enzyme digesting and sequencing.E2 protein was determined in PK15 cells transfected with purified recombinant plasmid pSCA1-E2 at 48 h post-transfection.The stimulation index(SI) of T lymphoid cell in experimental mice immunized with pSCA1-E2(10 μg/each) were analyzed at 10 d,20 d,30 d after the second vaccination.Experimental pigs were immunized with pSCA1-E2(600 μg/each) and the anti-CSFV serum antibody was screened at 7 d,14 d,21 d and 28 d after the second vaccination.The results showed that the insert site,orientation and reading frame of E2 gene were correct in pSCA1-E2.The E2 protein of CSFV was detected in transfected PK-15 cell.A high SI of T lymphoid cell was detected in vaccinated mice and the anti-CSFV serum antibody was screened in immunized pigs.The experiments demonstrated that the pSCA1-E2 could trigger immune responses in experimental animals.