FIG. 4.

Virus-anchored host ICAM-1 confers faster kinetics of HIV-1 internalization. PM1 cells (A), PBMCs (B), and purified CD4⁺ T lymphocytes (C) (3 × 10⁶) were incubated at 37°C for the indicated times with similar amounts of isogenic NL4-3 particles either bearing or not bearing ICAM-1 (300 ng of p24). The cells were next extensively washed with PBS and treated with trypsin to remove uninternalized virions before lysis to quantify the amount of virus that had entered the cells. Experiments were performed in triplicate, and standard deviations are indicated. The data shown are representative of three separate experiments.