FIG. 7.

ICAM-1 incorporation favors cytosolic delivery of internalized virions. (A) PM1 cells (3 × 10⁶) were incubated at 37°C for 90 min with similar amounts of isogenic NL4-3 particles either bearing or not bearing ICAM-1 (300 ng of p24). PM1 cells were also exposed to HIV-1 particles pseudotyped with VSV-G envelope (100 ng of p24). (B and C) In some instances, PBMCs (B) and purified CD4⁺ T lymphocytes (C) (7 × 10⁶) were incubated at 37°C for 240 min with similar amounts of isogenic NL4-3 particles either bearing or not bearing ICAM-1 (700 ng of p24). After virus exposure, the cells were washed, trypsinized, and resuspended in a swelling buffer. The cells were then disrupted by Dounce homogenization, and the cellular fractions (i.e., cytoslic and vesicular) were separated as described in Materials and Methods. The level of p24 in each fraction was monitored by a p24 assay. The percentages of cytosolic and vesicular p24 are indicated inside each bar. Experiments were performed in triplicate, and the data shown are representative of three separate experiments. The error bars indicate standard deviations.