A broadly neutralizing monoclonal antibody that recognizes the V3 region of human immunodeficiency virus type 1 glycoprotein gp120.

Abstract

Previous studies have demonstrated that the principal neutralizing determinant of human iunodeficiency virus type 1 (HIV-1) is located in the V3 loop of glycoprotein gpl20. Antibodies prepared against this region using gp120 or peptides as immunogens have been predonminantly HIV-1-isolate-specific. In the present studies, murine monoclonal antibodies (mAbs) were prepared against the HIV-1MN strain. One mAb, designated NM-01, was selected for its ability to neutralize both the MN and TUB strains. Neutralization of H9-cell infectivity as determined by reverse transcriptase assay demonstrated an lDl5 of <1 jig/ml for both MN and ITB. mAb NM-01 also blocked MN and IIIB infectivity in the MT-2 assay and inhibited their reactivity in syncytium formation. The results further demonstrate that mAb NM-01 binds to the V3 loop of gpl20 at amino acids 312-326. This mAb reacted equally well with loop peptides from the MN, TUB, RF, and CDC4 isolates. In contrast, there was less afflnity with a similar peptide from the NY5 strain and little if any reactivity with ioop peptides from the Z2, Z6, and ELI strains. We also demonstrate that peptides corresponding to the V3 loops of MN and IIIB, but not Z6, block neutralization of TUB virus by mAb NM-O1. These rindings indicate that mAb NM-01 reacts with diverse HIV-1 isolates through the Gly-Pro-Gly-Arg sequence of the V3 loop.Human immunodeficiency virus type 1 (HIV-1) infects a variety oflineages, such as T cells, monocytes/macrophages, and neuronal cells, that express CD4 (1, 2). Studies demonstrating binding of gpl20, the major HIV-1 external envelope glycoprotein, to the CD4 receptor supported the role of this viral glycoprotein in HIV-1 infectivity (3-7). Moreover, several epitopes on gpl20 have been associated with the development of neutralizing antibodies. A conserved domain of gpl20 implicated in HIV-1 infectivity elicits specific neutralization (8). Other conformation-dependent epitopes on gpl20 have resulted in the development of antibodies that broadly neutralize diverse strains of this virus (9, 10). However, the principal neutralizing determinant (PND) has been located in the V3 loop of gp120 (11)(12)(13)(14).The V3 loop consists of a hypervariable 36-amino acid (aa) domain (aa 302-338) that is cross-linked by disulfide bonds (12,14). Recombinant and synthetic protein fragments containing the V3 loop elicit isolate-specific neutralizing antibodies (14-16). More recent studies have demonstrated that the type 2 P-turn structure of the V3 loop, which contains the relatively conserved Gly-Pro-Gly-Arg (GPGR) sequence, is the site recognized by isolate-specific antibodies (11,17). This epitope has been identified by a variety of neutralizing monoclonal antibodies (mAbs) prepared in rodents, whereas other findings indicate that the PND also induces MN-isolatespecific antibodies during HIV-1 infection in humans (18).The hypervariable PND domain may account for the isolatespecific neutralizing activity generated by this epitope. However, several studies have indicated t...

Clustering of Th Cell Epitopes on Exposed Regions of HIV Envelope Despite Defects in Antibody Activity

“…Specifically, we found that Th epitopes are clustered within hot spots on one exposed face of HIV gp120 (14,15). Many of these T cell epitopes overlap with known Ab binding domains (16,17). Studies of influenza and parainfluenza viral membrane proteins have similarly shown that immunodominant Th cell epitopes can be localized to exposed protein surfaces (18 -21).…”

Purification and Characterization of Oligomeric Envelope Glycoprotein from a Primary R5 Subtype B Human Immunodeficiency Virus

“…Historically, it has been difficult to induce neutralizing antibody responses against diverse primary HIV type 1 (HIV-1) strains by utilizing monomeric HIV Env (i.e., gp120) glycoprotein. Furthermore, it has been shown by several groups that the antibody responses induced by gp120 are directed primarily against the V3 loop and other linear epitopes (22,34,43,44,70,81,82,102,109,110,117) and that limited responses are directed towards the conserved conformational epitopes (9,41,75,88,95,107). Due to the high degree of variability in gp120, these nonconformational anti-gp120-specific antibodies were found to be predominantly subtype specific and, to some extent, isolate specific.…”

Anti-Human Immunodeficiency Virus Type 1 Activity of R-95288, a Phosphodiester Hexadeoxyribonucleotide Modified by Dibenzyloxybenzyl and Hydroxyethyl Residues at the 5′- and 3′-Ends

“…Interaction of R-95288 with the V3 loop seems to be an electrostatic attraction because all anti-V3 MAbs which competed with R-95288 recognized a basic amino acid sequence, RKSIR, rather than GPGRAF as the principal neutralizing domain for antibodies in gp120 ofHIV-1 IIIB (Javaherian et al, 1990;Ohno et al, 1991). Recent reports suggest that heparin binds to the consensus amino acid sequence BBXB, BBXXB orBBXXXB (B, basic amino acid; X, non-basic amino acid ;Cardin & Weintraub, 1989) and interacts with the RKSIR amino acid sequence of V3 peptide (Javaherian et al, 1994).…”