IL-12 and GM-CSF Administration During the Prime in DNA-MVA Schemes Improves Magnitude, Breadth and Avidity of Cellular Response against NefBF

ANA MARÍA RODRIGUEZ; CYNTHIA MAETO; MARÍA FERNANDA PASCUTTI; JULIANA FALIVENE; GABRIELA TURK; GHERARDI MM

Bangkok

Conferencia; AIDS Vaccine Conference 2011; 2011

Background In Argentina, the HIV epidemic is characterized by the co-circulation of subtype B and BF variants, mostly CRF12_BF. Nef is a highly variable protein among subtypes, making it a good tool to study the impact of HIV-1 inter-variant variability in the vaccine design setting (aa difference between B and BF:24%). We previously reported a highly specific response against NefBF with low cross-reactivity to NefB in mice. The aim of this work was to analyze the possibility to improve the immune response induced by the co-delivery of cytokines during the priming doses. Methods Mice received an intramuscular prime: 3xDNAnefBF (Group I, GI), 3xDNAnefBF+DNA-IL-12 (GII), or 3xDNAnefBF+DNA-GM-CSF (GIII), or 3xDNAnefBF+DNA-IL-12+DNA-GM-CSF (GIV). Afterwards, all the groups received MVAnefBF as intraperitoneal boost. Nine days after the last immunization, the specific cellular immune response (CIR) was evaluated in the spleen using overlapping peptides representing NefBF or NefB by ELISPOT. Results The highest responses were detected in GII (p=0.0317) and GIV. The observed increments vs. GI were (median [range]): GII 2.38 [1.21-2.71], GIV 1.535 [1.05-2.86]. After fine mapping the response, the peptides targeted were identified: all groups recognized two peptides, located on the N-terminal (BF) and the loop of the protein (BF and cross-reactivity against B). GII and GIV also recognized a peptide located on the central core region (BF). Even more, GII recognized the B peptide with a frequency higher than the other groups, showing an enhanced cross-reactivity. We evaluated the cell avidity against the loop peptide (comparing sequences BF vs. B). We found that GII showed a higher avidity against the peptide B compared to GI (p=0.0011), whereas in both groups the highest avidity was detected against the peptide BF (BF vs. B: p