Fig. 3

The time-of-addition assay. MDCK cells were prepared in a 24-well plate and then adsorbed with virus (A/PR/8/34, 0.01 MOI) for 2 h at 4 °C. Then, the cells were washed and MEM was added to the cells. Fr 14 was added 2 h prior to the infection (-2 h) or at the same time as the virus infection (0 h) and at the indicated time points post-infection (2 h, 4 h, 6 h, 8 h). Following incubation for 10 h, the supernatants were collected, and infectious titres were determined by CPE assay