Immunogenicity Of DNA, Ad5 And DC Vaccine Expressing HIV Genes In Mice

The Acquired Immune Deficiency Syndrome(AIDS) caused by Human Immunodeficiency Virus(HIV) is considered as one of the most life-threatening diseases that has been widespread for more than 30 years. There is no cure for HIV or AIDS yet. Our team focuses on the study of therapeutic HIV vaccines, and put forward the strategy of sequential and repeated immunization with multi-vector HIV vaccines for the first time. Our animal experiment results showed that potent and long-lasting HIV-specific cellular immune responses could be induced in mice and rhesus macaques by this strategy, indicating that it is likely to be a promising treatment strategy for AIDS. In addition, current preclinical and clinical trials showed dendritic cell-based therapeutic HIV vaccines could help immune cells control HIV replication. So we want to combine above multi-vector HIV vaccines and DC vaccines in our sequential and repeated immunization strategy in our future study. The main objective of this study is to construct new HIV vaccines expressing HIV gene from different subtypes and evaluate their immunogenicity in mice. Meanwhile the immunogenicity of DC vaccine loaded with Ad5-HIV gag/env would be also tested in order to provide experimental basis for further application of this sequential and repeated immunization strategy.Firstly, we compared the immunogenicity between two DNA vaccines encoding gp145 and gp160 gene of HIV-1 CRF01_AE subtype(pVR-AE gp145 and pVR-AE gp160) in BALB/c mice. The results showed that both pVR-AE gp145 and pVR-AE gp160 could induce antigen-specific cellular immune responses. The immune responses reached peak level at 3 weeks and 4 weeks after immunization respectively. The immunogenicity of pVR-AE gp145 was significantly higher than pVR-AE gp160 So pVR-AE gp145 would be further used in the sequential and repeated immunization strategy with other HIV vaccines. Secondly, we constructed a recombinant adenovirus vaccine that expresses gag gene of HIV-1 B/C subtype(rAd5-HIV B/C gag) and explored its immune responses induced in BALB/c mice. ELISPOT results showed that high levels of Gag-specific cellular immune response could be detected at 2 weeks after immunization. Moreover, we evaluated the immunogenicity of DCs vaccine loaded with Ad5-HIVgag/env in mice. BALB/c mouse DCs were generated by culture of adherent bone marrow cells in the presence of several cytokines. The purity of matured DCs were determined by flow cytometry. DC vaccines were prepared by loading them with replication-deficient recombinant adenovirus Ad5-HIVgag or Ad5-HIVenv. BALB/c mice were immunized by intramuscular injection of above DC vaccines alone or in combination, at different time points post immunization HIV specific cellular immune responses detected by ELISPOT assay. The results showed that high levels of HIV-specific cellular immune responses were induced in mice immunized with above DC vaccines. In summary, the aforementioned DNA vaccines, Ad5 vaccine and DC vaccines loaded with Ad5-HIVgag/env could induce high levels of HIV specific cellular immune response, which laid a good foundation for further evaluate the sequential and repeated immunization strategies with these vaccines.