Evaluation of apoptosis in uninfected and HHV-7–infected SupT1 cells treated with rTRAIL or rHis6-tag control peptide.

(A) Flow cytometric evaluation of apoptosis and cell cycle profile in uninfected and HHV-7–infected SupT1cells after 20 hours of treatment with rHis6-tag control peptide (left panels) or rTRAIL (1 μg/mL) (right panels). The x-axis shows the DNA content, determined based on fluorescence resulting from PI staining, and the y-axis reflects the relative number of cells. Cells in apoptosis (Apo) or in the gap1 (G1), synthesis (S), gap2 (G2), and mitosis (M) phases of the cell cycle are indicated. These results are representative of 4 experiments performed in duplicate. (B) Combined immunofluorescence analysis of HHV-7 antigen expression and apoptotic nuclei after TRAIL-challenge in HHV-7–infected SupT1 cells. Cells are scored by fluorescence microscopy. Note that enlarged cells, characteristic of HHV-7–infected cultures, are positively stained for viral antigens, whereas apoptotic nuclei (arrows) are more frequent among small, uninfected cells. Original magnification is × 400. Representative fields of 5 separate experiments are shown.