FIG. 11.

Neutralization of HIV-1 infection by MAb 2D7 and rabbit anti-2D7-2SK peptide antibodies. (A) Antibody preparations (at 50 μg/ml) were added to CCR5-expressing PM1 cells or activated human PBMCs for 1 h prior to addition of R5 tropic HIV-1 BaL (or JR-CSF) virus at 50 TCID₅₀/well (5 replicates per group). After 24 h, plates were washed extensively to remove unbound virus and antibodies. Virus production was determined by measuring p24 in the supernatants every 2 days. Virus neutralization by the different antibodies is expressed as percent inhibition of p24 production (data represent average p24 values in 5 wells of a 96-well plate). Data shown are for day 5 (PM1) or day 7 (PBMC). Infection inhibition was compared with that of a control culture with no antibody added (PBS), which was defined as 100% infection (equivalent to p24 values of 64,484 pg/ml for HIV-1 BaL infection of PM1 cells and 40,567 pg/ml for infection of human PBMCs). Data shown are representative of one of four independent experiments for infection of PM1 cells and three independent experiments with human PBMCs. (B) Dose-dependent inhibition of infection by R5-tropic primary isolate 92US657 in human PBMC. The experiment was performed as described for panel A but with lower starting concentrations of rabbit anti-2D7-2SK antibodies, as shown on the x axis, with infection by virus at 50 TCID₅₀/well (four replicates per group). No inhibition was observed with preimmune rabbit IgG.