HIV binding phenotypes of PBMC donors are maintained across multiple virus strains. Freshly isolated PBMC were incubated with 2000 pg of p24 (HIVGP, HIVNL4-3, HIVTH, or HIVSF2) in serum-free medium for 45 minutes on ice. After incubation with HIV, cells were washed to remove unattached virus. Cells and bound virus were lysed and HIV p24 was measured by ELISA. Results are the means ± SD of triplicate determinations.