FIG. 1.

HIV-1 replication in normal and CCR5-deficient macrophages. Monocytes were isolated from individuals homozygous for the wild-type CCR5 allele or ccr5Δ32, plated at 2 × 10⁵ per well in 48-well plastic tissue culture plates, and allowed to differentiate into macrophages in vitro. After 7 days in culture they were infected overnight with 20 ng of p24 antigen of M-tropic (SF162 or ADA), T-tropic (NL43), or dual-tropic (89.6) strains. Cultures were then washed, and the supernatant was sampled periodically for p24 antigen. Cells infected with 89.6 were incubated for 1 h prior to and during infection with the anti-CD4 MAb no. 19 or the control MAb B33.1 (each at 10 μg/ml), which was then maintained in the medium throughout the experiment.