Volume 9 Supplement 2
Cross-group neutralization of HIV-1 and evidence for conservation of the PG9/PG16 epitopes within divergent groups of HIV-1
© Braibant et al; licensee BioMed Central Ltd. 2012
Published: 13 September 2012
HIV-1 has been classified into 4 groups: M, N, O and P. The aim was to revisit the cross-group neutralization using a highly diverse panel of primary isolates (PI) and human monoclonal neutralizing antibodies (mAb).
The panel of viruses included 9 HIV-1 group O PIs, 1 recombinant M/O PI, 1 group N PI, 1 group P PI, 2 group M (subtype B) PIs and the HIV-1 group M adapted strain MN. All the viruses were tested for neutralization in TZM-bl cells, using a panel of sera issued from patients infected by HIV-1 group M viruses (n=11), HIV-1 groups O (n=12) and P (n=1). The mAbs were b12, 2G12, 2F5, 4E10, PG9, PG16, VRC01, VRC03 and HJ16.
The 12 group O sera neutralized from 1 to 6 group O viruses, and 6 of them cross-neutralized one group M PI. Five of the 10 group M sera cross-neutralized from 4 to 9 group O PIs. The group N and P viruses were neutralized by 1-4 of 12 and 4-5 of 11 sera from groups O and M patients, respectively. The human mAbs did not show any cross-group neutralization, except PG9 and PG16. Two group O PIs were neutralized by both PG9 and PG16, and one group O PI was neutralized by PG9 only. The group N PI was highly sensitive to neutralization by PG9 and PG16. The N-linked glycans at positions 156 and 160 and the cationic residues of strand C of the V1/V2 domain that have been identified as part of the PG9 epitope are conserved among the group N.
The cross-group neutralization of HIV-1 has been demonstrated. The conservation of the PG9 and PG16 epitopes between groups provides an argument for their relevance as components of a potentially efficient HIV vaccine.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.