Fig. 5.

Catechin inhibited pandemic influenza A (H1N1) virus infection on A549 cells, as observed by immunofluorescence staining. (A) Cells only. (B) Extensive fluorescence was observed in virus-infected control. The quantitative of fluorescence foci was decreased in dose-dependent manner when cells treated with (C) 0.5 μg/mL, (D) 1 μg/mL, (E) 2.5 μg/mL, (F) 5 μg/mL and (G) 10 μg/mL of catechin. The green foci represented viral protein (marked by arrows) but not observed in control cells. Red fluorescence due to Evans blue staining shows the cells presented in each field of view under the Olympus fluorescence microscope at × 400 magnification. The scale bar in each panel represents 20 μM. The inhibition effect of the catechin was calculated at figure H. Asterisk (*) indicates significant difference (p < 0.05) compared to the virus infection control, respectively.