XVIII International AIDS Conference


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Comparable antigenicity between B and F Nef consensus and viral isolate sequences among Brazilian HIV-1 positive subjects

F.H. Côrtes1, G. Bello1, C. Vorsatz2, J.H. Pilotto2, M.G. Morgado1

1Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Laboratory of Aids and Molecular Immunology, Rio de Janeiro, Brazil, 2Evandro Chagas Clinical Research Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil

Background: Centralized viral sequences reduce genetic distance from circulating viruses. However it is not clear whether these sequences offer any advantages in terms of coverage of immunogenic epitopes. In Brazil the B subtype is predominant followed by F1 and B/F1 recombinants. The aim of the present study is to compare the magnitude and frequency of response on INF-γ ELISpot assay to nef HIV-1 peptides based on consensus and viral isolate sequences from B and F1 subtypes.
Methods: The B and F1 consensus (CON) sequences were based on alignments, performed by CLUSTALW, with 50 (clade B) and 36 (clade F) Brazilian sequences, which were submitted in DAMBE v.5.0 to get the consensus. The individual viral B or F sequence presenting the minor genetic distance when compared to the set of sequences were selected (ISO). Nef-specific responses were evaluated with IFN-γ ELISpot assay using peptides based on consensus and viral isolates to both subtypes covering 3 regions (R). PBMCs from 14 subjects infected with B and 9 with F1 clade were analyzed.
Results: The frequency of response to consensus and isolate pools of peptides was similar to both subtypes, clade B (CONB: 93%[R1], 28%[R2] vs ISOB: 93%[R1], 21%[R2]; R3 sequence is identical on both) and clade F (CONF: 44%[R1], 66%[R2], 66%[R3] vs ISOF: 55%[R1], 44%[R2], 66%[R3]). No statistically significant differences were found in magnitude of response between consensus and isolates. The median values were 1220[R1] spots/106 PBMC (IC95%: 596-2226), 147[R2] (-2,96-298) to consensus B and 1380[R1] (799-2546), 220[R2] (88-314) to isolate B; and 617[R1] (120-1062), 315[R2] (- 296-1491), 1705[R3] (IC95%: 369-3362) and 555[R1] (IC95%: 221-1060), 290[R2] (- 195-972), 842[R3] (22,7-2104) to consensus and isolate F respectively.
Conclusions: None of four peptides sets showed a significantly superior ability to detect more numerous or stronger responses, suggesting they all provide equally powerful antigens.

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