Construction And Immunogenicity Study Of DNA And MVA Vaccine Expressing HIV-1 CRF01_AE Gp145

Since HIV was identified as the causative agent of HIV/AIDS in the world, it spread and expended quickly. Though a variety of intervention and prevention programs have been instituted, there is still a big challenge we should face. Currently, there is no effective HIV vaccine. Because of high rates of genetic recombination and mutation during viral replication, new subtypes and circulating recombinants forms（CRF） of HIV-1 are increasingly being reported. In recent years CRF01_AE spreads very quickly in China, it has become the main subtype in people living with HIV/AIDS. Our team has focused on the study of therapeutic vaccines. In our previous study sequential and repeated immunization with multiple vaccines could induce potent and long-lasting specific immune responses in mice and rhesus macaques. It indicated that this immune strategy is promising. So it’s necessary to construct multiple vaccines expressing structural genes of HIV-1 CRF₀1AE.In this study, the intracellular region of codon-modified HIV-1 CRF01_AE consensus env gene obtained in our preliminary study was removed to get gp145 gene. The modified gp145 gene was cloned into plasmid pVR to obtain recombinant DNA vaccine pVR-AEgp145. Then the same gp145 gene was cloned into shuttle plasmid pSC11. BHK-21 cells infected with wild-type MVA in advance were transfected with the recombinant shuttle plasmid. Then the recombinant MVA vaccine expressing gp145 rMVA-AEgp145 was generated by homologous recombination. WB assay confirmed that both DNA and recombinant MVA vaccine could express Gp145 efficiently. BALB/c mice were immunized with the recombinant DNA vaccine at week 0 and week 3, the Gp145-specific cellular immune responses were evaluated by ELISPOT assay at different time points post the last immunization. The results indicated that the specific cellular immune responses could be detected in immunized mice at 2 weeks post the last immunization, it reached peak level at 3 weeks and declined significantly at 5 weeks. Then the immunogenicity of rMVA-AEgp145 used alone or in combination with DNA vaccine pVR-AEgp145 was evaluated in mice. Both can induce high level of specific cellular immune responses and they are comparable. The group of the immunogenicity of rMVA-AEgp145 in combination with DNA vaccine can induce a fairly level humoral immunity of env specificity combined immunization after 1 week of the last immune. It can induce a higher humoral immune respose obviously than the group of rMVA-AE gp145 used alone.Above all, the recombinant DNA and MVA vaccine encoding HIV-1 CRF01_AE gp145 gene were constructed successfully. It can induce a certain level specificity humoral immunity in combination.Potent Gp145-specific CTL responses could be elicited in mice when both vaccines were used alone or in combination. It is necessary to construct other vector based vaccines encoding the CRF01_AE gp145 gene and evaluate the immunogenicity of sequential and repeated immunization with these vaccines.