Fig. 2.

Apoptosis in PRRSV-infected cells. (A) Adherent cells were harvested by trypsin treatment and combined with floating cells. Then cells were stained with annexin V–flour staining kit followed by flow cytometry analysis. (B) Cells infected with PRRSV were lysed at 24, 48, and 60 h p.i. DNA fragments in cell lysates were quantitatively measured using the DNA fragmentation ELISA. Values are shown as the mean ± SD of the optical density (O.D.) values from duplicate wells, and these results are representative of three independent experiments. (C) Chromatin condensation was visualized in MARC-145 cells fixed with ice-cold methanol and stained with PI solution containing RNaseA. *; P < 0.001 compared to mock-infected cells at the same time point.