Influenza Infects Lung Microvascular Endothelium Leading to Microvascular Leak: Role of Apoptosis and Claudin-5
(A) Viral titer increases over time as shown by TCID50 assay. This assay quantitates the ability of influenza to agglutinate red blood cells after viral replication (see Materials and Methods section for further details). The initial influenza dose was 25 HAU/100 000 cells. The control group had no cells, received the same influenza dose, and was analyzed at 24 hours. Results are representative of 3 experiments. (B) qPCR showing the fold change in viral RNA for the influenza A M1 protein (see Materials and Methods for primers) over time. Results are representative of 3 experiments. (C–D) Immunofluorescent images (C) and quantitation (D) showing the percentage of cells infected by influenza after 24 hours. Influenza was given at 40 HAU/100 000 cells. Nuclei are stained with DAPI and viral nucleoprotein is shown in green. Images are representative of 3 experiments; data are mean and standard error, *p<0.05 for flu vs. control (uninfected cells).