Evaluation of the immune response induced in balb/c mice by a viral vector expressing env gene of the circulating recombinant form of HIV-1 in Argentina, CRF12_BF

D. MÓNACO; MF. PASCUTTI; M. CAROBENE; JL. NAJERA; AM RODRÍGUEZ; G. SCHULMAN; M. ESTEBAN; H. SALOMÓN; MM. GHERARDI

Ciudad de Mexico-Mexico

Conferencia; XVII International AIDS Conference; 2008

IAS

Background: Genetic diversity of HIV-1 is one of the main obstacles in the development of a vaccine, being difficult to find immunogens that can protect against all circulating forms. In Argentina, infections are caused principally by CRF12_BF and subtype B viruses in similar proportions. In order to study cross-immunity between these two strains, we evaluated the immune response generated by a recombinant Vaccinia virus (rVV) expressing Env of the CRF12_BF. Methods: We generated the viral vector by homologous recombination between a VV and a transference plasmid harboring a synthetic envBF gene. Expression of Env was confirmed by Western blot and confocal microscopy in murine and human cell lines. Vector-stability was assesed by evaluating protein expression of individual plaques after 8 consecutive infections. Replicative capacity was assayed by growth curves and compared with that of the wild-type strain. Immunogenicity was evaluated in the Balb/c model using a regime of one or two doses, separated in 14 days, and compared with that generated by a rVV expressing EnvB from IIIB/LAI strain. Twelve days after the second immunization, we analyzed the specific cellular immune response in the spleen stimulating the splenocytes with pools of overlapping peptides that represented the conserved and variable regions of EnvB and then quantifying specific IFN-ƒ×ƒnsecreted by ELISpot after 24hs of stimulation and by ELISA after 72hs of incubation. Results: Levels of immune response were significantly higher and broader when evaluated with peptides homologous to the vector strain. We observed that the first conserved region of gp120 (aa 1-125), which shows the higher homology between subtypes, was the one that induced the higher immune response with both viral vectors. We also evidenced that the two doses scheme increased the number of EnvB regions recognized.        Conclusion: Cross-immunity between subtypes was only detected for the most conserved regions of Env although with a low magnitude.