FIG. 3.

Neither HSV-1 nor HSV-2 inhibits the membrane PS exposure associated with apoptosis. HL-60 cells were mock infected or infected with HSV-1 strain E115 or HSV-2 strain 333 for 5 h and then mock treated or treated with 5% ethanol. Annexin V-FITC (x axis)-propidium iodide (y axis) labeling, followed by flow cytometry, was performed as described in the text. Quadrants: 2, necrotic cells; 3, nonnecrotic, PS-negative cells; 4, viable, PS-positive cells. The percentage of nonnecrotic, PS-positive cells is shown in quadrant 4. The small decrease in quadrant 4 cells in HSV-1-infected cells seen in this representative experiment was within the range of error of the assay and was not reproducible in multiple repeat experiments.