APOPercentage apoptosis assay was used to confirm the progression of apoptotic events in influenza A virus infected macrophages (Fig. 3B) . No apoptotic cells were detected from control samples or influenza A virus infected samples at 6 h post-infection. At 12 h after the infection 19% of the cells were apoptotic, and at 18 h after the infection already 73% of the cells were apoptotic demonstrating the rapid progression of apoptosis at later timepoints.