Immunization effect of a recombinant adenovirus expressing the non-structural protein 3 of hepatitis C virus on mice

Objective To construct a recombinant adenovirus expressing the non structural protein(NS)3 of hepatitis C virus(HCV)and to evaluate its immunization effect on BALB/c mice. Methods The HCV NS3 gene encoding 329-935 amino acid was amplified from plasmid pRC/NS3 by polymerase chain reaction(PCR)and cloned into the transfer vector pAdTrack-CMV.The recombi- nant plasmid and adenoviral backbone plasmid pAdEasy-1 were co-transfected into E.coli strain BJ5183. Taking the advantage of the high efficient homologous recombinant machinery presented in bacteria,the re- combinant adenoviral backbone plasmid was generated in BJ5183.and then was transfected into 293 cells. Recombinant adenovirus was propagated in 293 cells with high titers.BALB/c mice were injected subcutane- ously with 1×10~8 pfu recombinant adenovirus and intramuscularly with 100μg pRC/NS3 recombinant plasmids.The antibody immune responses were measured by enzyme-linked immunosorbentassay (ELISA)and a standard 4-hour ~(51)Cr release assay was utilized to determine cytotoxicity T lymphocyte (CTL)activity after immunization.Results The humoral and cellular immune responses to HCV- NS3 antigen were higher in mice immunized with recombinant adenovirus infection than those in mice immunized with recombinant pRC/NS3 plasmids.Antibody positive rate was 100%(20/20)in recom- binant adenovirus RAd/NS3 group and was 30%(3/10)in pRC/NS3 group after 2 weeks immuniza tion.No obvious side effect was observed.Conclusion The recombinant adenovirus expressing HCV NS3 protein can stimulate specific humoral and cellular immune response in mice.