440 Design, Construction, and Testing of a Multi-valent Recombinant Modified Vaccinia Ankara Vaccine for Use Against the Dominant Circulating C/B Recombinant Form of HIV-1 in China Z. Chen*1,2, Y. Huang1,2, X. Zhao1,2, L. Ba1,2, W. Zhang1,2, Y. Song1,2, D. Gurner1,2, D. D.Ho1,2 1Aaron Diamond AIDS Res Ctr, New York, NY and 2The Rockefeller Univ, New York, NY
Background: The rapid spread of HIV-1 in China has called for the urgent development of a prophylactic vaccine. Using live Modified Vaccinia Ankara (MVA) as a vehicle, we have successfully designed and constructed a multivalent vaccine specifically for Yunnan, China, where a circulating C/B recombinant form of HIV-1 is dominant.
Methods: Five (5) HIV-1 genes (gag, pol, env, tat, and nef) were introduced into 2 separate regions of the MVA genome using our modified single- and dual-promoter insertion vectors. Recombinant MVA was selected by immunofluorescence staining and further plaque purified.
Results: The vaccine is a single recombinant MVA (ADMVA) that expresses HIV-1 Env as well as fusion proteins Gag-Pol and Nef-Tat. Several modifications were made to improve vaccine safety, including the elimination of potential negative effects of regulatory genes, and to enhance viral gene expression. By Western blot analysis, all expected HIV-1 proteins were expressed in chicken embryo fibroblasts and various human cell lines. Importantly, 2 sequential injections of 106 TCID50 of ADMVA intramuscularly into BALB/c and B6xB10 mice elicited strong cell-mediated immune responses against all 5 viral proteins as determined by ELIspot assay for IFN-gamma secretion. Both CD4 and CD8 T-cell responses were detected. The number of spot-forming cells (SFC) was in the range of 200 to > 1,000 per million splenocytes. Moreover, a high serum titer (> 1:20,000) of antibodies against HIV-1 gp120 was also elicited. ADMVA was highly immunogenic regardless of the route of immunization. The magnitude of immune responses correlated with the dose of ADMVA. The immunized mice tolerated ADMVA well, up to 107 TCID50 per injection. In addition, even greater immune responses were observed when mice were primed with DNA vaccines containing the same viral genes followed by boosting with ADMVA.
Conclusions: We have constructed a recombinant MVA vaccine that is effective in inducing both cellular and humoral immune responses to 5 HIV-1 proteins. ADMVA is a candidate for testing in humans, either alone or in combination with a priming vaccine.
