Effect on the infectivity of HRV-4 particles. Approximately twofold quantities of the IC50 values of ellagic acid (EA) and ribavirin (RN) were applied. Human rhinovirus-4 (HRV-4) particles were incubated with 50 μg/mL EA and 100 μg/mL RN for 1 h at 4°C. Afterwards, HeLa cells were incubated with treated or untreated virus for 1 h at 37°C. Unbound virus was removed by washing the wells, and infection was continued by cultivating cells in fresh medium with or without test compound at 37°C. After 2 days, inhibition was evaluated by SRB method and expressed as the inhibition rate. Each bar represents the mean ± SD of triplicate samples of three independent experiments. ***Significant at P < 0.001, according to a Student’s t-test.