Time of addition of BPR1P0034. (A) MDCK cells were inoculated with influenza A/WSN/33 virus at MOI = 5. BPR1P0034 was added at the indicated times. Viral infection was performed between --1 h and 0 h. (B) After each incubation period, the test medium containing 1 μM of compound was removed and the cells were incubated with fresh medium until 10 h postinfection. The supernatant was collected and viral yield was determined by plaque assay. This is a representative result of two independent experiments.