J Virol. 2011 Nov; 85(21):11502-19.

PubMed ID: 21849452

Polyclonal B cell responses to conserved neutralization epitopes in a subset of HIV-1-infected individuals

Tomaras GD, Binley JM, Gray ES, Crooks ET, Osawa K, Moore PL, Tumba N, Tong T, Shen X, Yates NL, Decker J, Wibmer CK, Gao F, Alam SM, Easterbrook P, Abdool Karim S, Kamanga G, Crump JA, Cohen M, Shaw GM, Mascola JR, Haynes BF, Montefiori DC, Morris L

A small proportion of HIV-infected individuals generate a neutralizing antibody (NAb) response of exceptional magnitude and breadth. A detailed analysis of the critical epitopes targeted by broadly neutralizing antibodies should help to define optimal targets for vaccine design. HIV-1-infected subjects with potent cross-reactive serum neutralizing antibodies were identified by assaying sera from 308 subjects against a multiclade panel of 12 ""tier 2"" viruses (4 each of subtypes A, B, and C). Various neutralizing epitope specificities were determined for the top 9 neutralizers, including clade A-, clade B-, clade C-, and clade A/C-infected donors, by using a comprehensive set of assays. In some subjects, neutralization breadth was mediated by two or more antibody specificities. Although antibodies to the gp41 membrane-proximal external region (MPER) were identified in some subjects, the subjects with the greatest neutralization breadth targeted gp120 epitopes, including the CD4 binding site, a glycan-containing quaternary epitope formed by the V2 and V3 loops, or an outer domain epitope containing a glycan at residue N332. The broadly reactive HIV-1 neutralization observed in some subjects is mediated by antibodies targeting several conserved regions on the HIV-1 envelope glycoprotein.