Arbidol not only prevented the cytopathic effect ( CPE ) of CVB 5 , as demonstrated in an MTT colorimetric assay , when added during or after viral infection , with a 50 % inhibitory concentration ( IC 50 ) from 2 . 66 to 6 . 62 lg / ml , but it also decreased the CVB 5 - RNA level in infected host cells , as shown in