Inhibition of influenza A virus in different cellular models. Experimental values of half-maximal inhibitory concentration (IC50), half-maximal toxic concentration (TC50) and selectivity index (SI) of berberine (BBR) versus influenza A virus replication in different cell lines. A549: adenocarcinoma human alveolar basal epithelial cells; MDCK: Madin–Darby canine kidney cells; LET1: lung epithelial type I cell line; HAE: human airway epithelial cells. For HAE cultures no TC50 and SI values were measured (indicated as “-“).