Influenza Infects Lung Microvascular Endothelium Leading to Microvascular Leak: Role of Apoptosis and Claudin-5
(A) Influenza irradiated with ultraviolet light (UV flu) cannot replicate. Influenza (40 HAU/100 000 cells) was irradiated with UV light for 10 minutes before viral titer was measured using the TCID50 assay as in Figure 1A. Results are representative of 2 experiments. (B) Viral proteins are expressed in endothelial cells infected with UV-irradiated influenza. Influenza was given at an MOI of 8 for 12 hours. Nuclei are stained with DAPI and viral nucleoprotein is shown in green. Images are representative of 2 experiments. Immunofluorescent images (C) and quantitation (D) showing the ratio of nuclear to cytosolic p65, a measure of NFκB activation, in cells infected by influenza after 12 hours. Influenza was given at an MOI of 8. Arrows indicate infected cells, while asterisks denote their nuclei. P65 is shown in green. Infected cells were identified by immunofluorescence for influenza viral protein M1 (not shown). Images are representative of 4 experiments; data are mean and standard error, *p<0.05 for live flu and UV flu vs. control (uninfected cells).