Establishing time-point of infection (TOI) for ΔNS1 H1N1 Influenza virus production in Vero cells cultured on microcarriers with EX-CELL Vero SFM. (A) Growth curve of Vero cells cultivated using 250 ml spinner flasks with 3 g/l Cytodex 1 microcarriers. Cells were infected at day 5, day 6 and day 7 as depicted, by transferring 5 ml of the culture to each well on suspension 6-well plates. (B) Virus titre was measured at 48 hours post-infection for all TOI. Each bar represents the mean of the virus titres yielded from two runs using MOI of 0.001. The error bars indicate the standard deviation of the two runs.