FIG. 7.

Neutralization by the 17b and CG10 antibodies of viruses containing wild-type or mutant HXBc2 envelope glycoproteins. Envelope glycoprotein-mediated virus entry was determined in a single-round replication assay as described in Materials and Methods. Viruses bearing wild-type or mutant HXBc2 envelope glycoproteins were incubated for 90 min at room temperature with the 17b or CG10 antibody (open symbols) at the concentrations indicated. In parallel samples (closed symbols), viruses were incubated with both 17b or CG10 antibody and a subinhibitory concentration of sCD4 at 0.3 μg/ml. In the absence of added antibody, CAT conversion was the same in the absence or presence of sCD4 (0.3 μg/ml).