Potent broad cross-neutralizing sera inhibit attachment of primary HIV-1 isolates (groups M and O) to peripheral blood mononuclear cells

Gp160-directed antibody-mediated neutralization is thought to function by a t least two different mechanisms that impair virus entry into the host cell : inhibition of virus attachment and inhibition of virus-cell membrane fusi on. Previously, the neutralization spectra of sera derived from human immun odeficiency virus type 1 (HIV-1) infected patients were determined using 17 primary isolates belonging to HIV-1 group M (env clades A-H) and group O. The sera could be categorized as potent broad cross-neutralizing, limited c ross-neutralizing, and nonneutralizing sera. The aim of this study was to e xamine whether the neutralizing capacity of polyclonal human sera correlate s with their capacity to inhibit the attachment of infectious virions to th e surface of peripheral blood mononuclear cells. A 100% correlation was fou nd between the broad cross-neutralizing capacity and the ability to inhibit binding of primary isolates belonging to different genetic clades and grou ps to peripheral blood mononuclear cells. These results may indicate that b road cross-neutralizing antibodies are directed against those conserved reg ions on gp120 that interact with the cell receptor(s) and that those antibo dies can therefore interfere with the binding of virus to the host cell. (C ) 2001 Academic Press.