Characterization of CD4-Induced Epitopes on the HIV Type 1 gp120 Envelope Glycoprotein Recognized by Neutralizing Human Monoclonal Antibodies

Authors

Shi-Hua Xiang, University of Nebraska-LincolnFollow
Najah Doka, Harvard Medical School
Rabeéa K. Choudhary, Harvard Medical School
Joseph Sodroski, Harvard Medical SchoolFollow
James E. Robinson, Tulane University Medical Center

Date of this Version

2002

Comments

Published in AIDS RESEARCH AND HUMAN RETROVIRUSES Volume 18, Number 16, 2002, pp. 1207–1217. Copyright © 2002 Mary Ann Liebert, Inc. Used by permission.

Abstract

The entry of human immunodeficiency virus (HIV-1) into target cells typically requires the sequential binding of the viral exterior envelope glycoprotein, gp120, to CD4 and a chemokine receptor. CD4 binding exposes gp120 epitopes recognized by CD4-induced (CD4i) antibodies, which can block virus binding to the chemokine receptor. We identified three new CD4i antibodies from an HIV-1-infected individual and localized their epitopes. These epitopes include a highly conserved gp120 β-strand encompassing residues 419–424, which is also important for binding to the CCR5 chemokine receptor. All of the CD4i antibodies inhibited the binding of gp120–CD4 complexes to CCR5. CD4i antibodies and CD4 reciprocally induced each other’s binding, suggesting that these ligands recognize a similar gp120 conformation. The CD4i antibodies neutralized laboratory-adapted HIV-1 isolates; primary isolates were more resistant to neutralization by these antibodies. Thus, all known CD4i antibodies recognize a common, conserved gp120 element overlapping the binding site for the CCR5 chemokine receptor.