Facing the Challenges in Vaccine Upstream Bioprocessing * rAAV Production in Suspension CAP GT® Cells in BioBLU® 3c and 10c Single-Use Vessels Scale-up strategy The scientists optimized the agitation speed during process development. Scale-up was based on similar power input at both scales. The agitation speed of the BioBLU 3c vessel with a 2 L working volume was set to 200 rpm (corresponding to a tip speed of 0.69 m/s); for the BioBLU 10c with a 10 L working volume, it was 175 rpm (corresponding to a tip speed of 0.84 m/s). This results in comparable power inputs of around 62 W/m³ at both scales. Analytics The bioprocess engineers determined the viable cell density and cell viability offline using a NucleoCounter® NC-3000™ (ChemoMetec®, Denmark). They analyzed the transfection efficiency by measuring GFP fluorescence with a NucleoCounter NC-3000. Productivity was measured by quantification of the viral genome titer by qPCR. Results The researchers compared the performance of the initial shake-flask process with bioprocess 27 | GENengnews.com Figure 3. Cell growth and viability. performance at working volumes of 2 L and 10 L. They conducted the same production process in two duplicate runs runs at the 2 L scale (2 L rAAV A and rAAV B) and two duplicate runs at the 10 L scale (10 L rAAV A and rAAV B). For the two duplicate runs at 2 L and 10 L, the bioprocess engineers plotted the viable cell density and viability over time (Figure 3). Similar growth patterns were achieved. The viable cell density at the point of transfection was similar to the original shake flask process (data not shown). Post transfection at 72 h, viability dropped in a similar manner in all runs. This was expected, as virus production is cytotoxic. The DO control was very tight at both scales,http://www.GENengnews.com