Fig 7.

HPAI H5N1 (A/turkey/Turkey/1/05) and USSR H1N1 (A/USSR/77) virus-infected pig respiratory epithelial cells showed greater reductions in cell viability than the corresponding human cells. (A) HPAI H5N1 virus-infected (MOI of 1.0) human and pig respiratory epithelial cells labeled with propidium iodide were sorted by flow cytometry to determine the proportion of hypodiploid (sub-G₁) cells as an indication of cells undergoing nuclear fragmentation. A more severe nuclear fragmentation of pig cells was observed at 48 h infection. Data shown are the means of data from biological replicates. (B and C) Proliferation MTS assays (Promega) were performed on human and pig cells infected for 24 h with HPAI H5N1 virus (B) and USSR H1N1 virus (C) at a range of MOIs, to assess metabolic reductase activity as an indicator of cell viability. At an MOI of 10 for both viruses, much fewer viable pig cells than human cells were detected. Data shown are means of data from four biological replicates. Error bars indicate standard errors of the means. OD, optical density.