FIG 2.

The host cellular protein A5 is translocated to the cell surface. (A) A549 cells were either left uninfected or infected with IAV A/WSN/33 virus (MOI of 1). At 24 hpi, cellular A5 or viral HA proteins were visualized by immunofluorescence microscopy, using anti-A5 and anti-HA specific antibodies, respectively. The nuclei were stained with DAPI (4′,6′-diamidino-2-phenylindole), and the merged images are shown (original magnification, ×189). The results are representative of two independent experiments. Please note the presence of A5 labeling in the cytoplasm in uninfected cells, which is largely absent in the infected ones (arrows) but rather detected at the plasma membrane (stars). (B) A549 cells were either left uninfected or infected with A/WSN/33 virus (MOI of 10). At 24 hpi, flow cytometry analysis was performed using an anti-A5 antibody (closed histograms) or an isotype control (open histograms). Labeling of A5 was performed either on unpermeabilized cells, showing cell surface A5 proteins, or on permeabilized cells, showing total A5 proteins (left panel). Quantification of the mean fluorescence intensity of A5 expression ± the SD from five independent experiments is shown on the right panel. *, P < 0.05 (NI versus WSN).