A scale-down model of 4000-L cell culture process for inactivated foot-and-mouth disease vaccine production.

The anticipated increasing demand for inactivated foot-and-mouth (FMD) disease vaccine calls for its larger production capacity, while development of a large-scale process typically requires high running cost and has very limited experimental throughput at manufacturing scale. Thus, an economic scale-down model of representing a large-scale process becomes necessary and essential. In this study, we used a systematic approach to establish a scale-down model representing a 4000-L culture process for FMD vaccine production by suspension BHK-21 cells. In detail, we firstly compared hydrodynamic properties of three bioreactors (14-L, 800-L and 4000-L) under three different conditions (equivalent mixing time, equivalent shear stress and equivalent volumetric power). We figured out equivalent volumetric power (P/V) potentially as an appropriate scale-down strategy, since it resulted in comparable calculated hydrodynamic parameters among three bioreactors. Next, we used computational fluid dynamics (CFD) simulation to provide more details about hydrodynamic environments inside the bioreactors, which supports the reliability of this scale-down strategy. Finally, we compared cell growth, metabolites, vaccine productivity and product quality attributes during FMD vaccine production by BHK-21 cells and observed very close performances among three bioreactors, which once again demonstrates the robustness of this scale-down model. This scale-down strategy can be applied to study variations and critical quality attributes (CQAs) in the resultant production process based on quality by design (QbD) principles, aiming at further more efficient optimization of vaccine production.

Quality by Design-Driven Process Development of Cell Culture in Bioreactor for the Production of Foot-And-Mouth Veterinary Vaccine.

Quality by design (QbD) principle has been established as a guideline to emphasize the understanding of the relationship of product quality with process control. Vaccine product have characteristics of security and high efficiency, but it also has features such as complexity and rigorous regulatory for production. This case study describes an example of QbD-driven process development for manufacturing a veterinary vaccine produced with baby hamster kidney-21 cells. The study revealed that cell culture duration was the most significant factor affecting 50% tissue culture infectious doses (TCID50) and antigenic titer, and the factors of culture temperature and pH at infection phase exhibited less effect. Culture temperature at infection phase was the only significant factor for total protein. Through the Monte Carlo simulation, the design spaces of process parameters were determined. Meanwhile, the excellent and robust performance in manufacturing scale (4000-L) validated the effectiveness of this strategy. A reliable and robust multivariate process parameter range, that is, design space, was identified by this systematic approach. Our investigation presents a successful case of QbD principle, which encourages other researchers to combine the methodology into other biopharmaceutical manufacturing process.