Adjuvant Effects Of Fullerene Derivant Nanoparticle To DNA Vaccine And Broader T Cell Responses To HIV Antigen By Fragmentation Strategy

HIV DNA vaccine is largely limited to develop because of the relatively modest immunogenicity of DNA vaccine and high variability of HIV. In this study, we succeed in using Fullerene derivant nanoparticle adjuvant (named C60(OH)20) to enhance the immunogenicity of HIV DNA vaccine. Meanwhile, we also obtained broader T cell responses by splitting the whole antigen into smaller fragments.For the first part, we evaluated the adjuvant effects of C60(OH)20 that C60(OH)20 enhanced HIV Env specific immune responses in BalB/C mice. The data showed that low dose (4μg) of HIV Env DNA vaccine plus right concentration C60(OH)20 indeed induced the same strong Env-specific T cell response which was induced by higher dose (20μg) of naked DNA vaccine respectively. On the other hand, C60(OH)20 also improved significantly Env-specific T cell response by three different immunization ways (subcutaneous injection, intracutaneous injection and intramuscular injection). Finally, Env-specific binding antibodys also were enhanced significantly by C60(OH)20.For the second part, we seek to gain broader T Cell responses to HIV Gag DNA (delivered as a plasmid) in BalB/C mice by splitting the whole Gag into fragments for reducing competition of recognizing to TCRs expressed on the surface of T cells between dominant and sub-dominant epitopes. As expected, mice immunized with mixture of DNA fragments elicited significantly broader T cell responses than whole-length gag. We also further studied the effects when fragments and full-length DNA vaccines are combined for prime-boost vaccination. Interestingly, mice primed with full-length gag and boosted with DNA vaccine fragments induced similar T-cell responses breadth as mice both primed and boosted by fragments DNA. In contrast, mice primed with DNA vaccine fragments and boosted with full-length gag failed to broaden T cell responses, once again, only the dominant epitopes were recognized. Our study demonstrated that fragmentation strategy can indeed broaden T cell responses. This enhancement is more likely achieved in boosting stage.In summary, our study offered the ways to improve immunogenicity of DNA vaccine (use nanoparticle adjuvant) and broaden T cell responses of HIV antigen (fragmentation strategy). It's useful to design an effective HIV DNA vaccine with higher chance covering the highly diversified circulating strains.