A Plant Extract of Ribes nigrum folium Possesses Anti-Influenza Virus Activity In Vitro and In Vivo by Preventing Virus Entry to Host Cells

A549 cells were left untreated or treated with the indicated amounts of LADANIA067 before and during infection with the influenza virus strains A/FPV/Bratislava/79 (FPV) (H7N7) (8 h: MOI = 0.1; 24 h: MOI = 0.01) (A), A/NRW/173/09, an pandemic swine-origin-IAV (SO-IAV) (H1N1pan) (8 h: MOI = 1.5; 24 h: MOI = 0.5) (B) or A/Puerto Rico/8/34 (PR8) (H1N1) (MOI = 0.01) (C). In (C) cells were left untreated or treated with the indicated amounts (left panel) or 50 µg/ml of LADANIA067 before and during infection. (A–C) The virus was pretreated with LADANIA067 as well. Supernatants were assayed for progeny virus particles at the times indicated. Data represent means ±SD of 4 biological samples. Statistical significance was assessed by students t-test (*p<0.05, **p<0.01, ***p<0.001).