CsA inhibited the influenza virus replication in MDCK cell line.

<p>A: Cytopathic effect assay of CsA on the influenza virus replication. Monolayers of MDCK cells on 96-well microwell plates were infected with influenza A/WSN/33 (MOI = 0.1). Infected cells were treated in duplicate with different concentrations of CsA (Control, 2.5 µg/ml, 5 µg/ml, 10 µg/ml) in DMEM with 2 µg/ml TPCK-treated trypsin, and the preparations were incubated at 37°C for another 36 h, after which the monolayers were stained with crystal violet (0.1% in 20% ethanol) and examined for cytopathic effect (CPE). Data are presented as the mean plusminus standard deviation (± SD) from three independent experiments. B: Plaque assay of the titer of viruses in the supernatant with different concentrations of CsA (0–10 µg/ml). Infected cells were treated in duplicate with different concentrations of CsA (0 µg/ml, 2.5 µg/ml, 5 µg/ml, 10 µg/ml) in DMEM with 2 µg/ml trypsin, and the preparations were incubated at 37°C for another 16 h, after which the titer of viruses in the supernatant was analyzed by plaque assay. Data are means ± SD of three separate experiments. C: The growth curves of influenza virus in MDCK cell line in the absence or presence of CsA (5 µg/ml).The cells were infected with influenza A/WSN/33 (MOI = 0.01) for 1 h. After being washed with PBS 3 times, the cells were cultured with fresh medium supplemented without or with CsA (5 µg/ml). At various times post-infection, viral titers in the supernatants were determined by plaque assay. Data are means ± SD of three separate experiments.