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]
(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),
(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
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