Fig. 3

Pelargonium extract affects various steps of the replication cycle of influenza virus A/Hong Kong/68. We performed plaque reduction assays with influenza virus A/Hong Kong/68 and pelargonium extract (50 μg/mL) in MDCK cells. Zanamivir (1 μM) was included as reference inhibitor. We added pelargonium extract or zanamivir to MDCK cells and/or influenza virus A/Hong Kong/68 at different times before virus infection (pretreatment of cells or virus; at 37 °C for 1 h), during virus adsorption (at 4 °C for 2 h), after virus adsorption (at 37 °C for about 72 in the agar overlay), and during as well as after adsorption. After an incubation at 37 °C for 72 h and crystal violet staining, we counted the plaques over a light box. The mean plaque number of three mock-treated virus controls was set to 100%. The bars indicate the mean and standard deviation of the percent plaque reduction by pelargonium extract and zanamivir compared to the mock-treated virus control. Means and standard deviations of three independent experiments are shown