Effect of NgK or MgK on apoptosis and cell death in vitro. RS cells were infected with the NgK, MgK, or RgK at an MOI of 5 PFU/cell for 24 h or were mock infected. At 24 h p.i., the cells were harvested and reacted with annexin V and 7-AAD dye to analyze apoptosis and cell death, respectively. Stained cells were fixed, and FACS analysis was performed as described in Materials and Methods. The percentages of cells determined to be positive in each quadrant are shown for each virus or for uninfected cells.