Researchers Develop Inline Virus Filtration Model for Bioprocessing

The bioprocessing industry is advancing towards continuous methods, prompting a need for improved validation of viral clearance. Researchers at Asahi Kasei Bioprocess America have introduced a small-scale inline virus spiking and mixing model that validates continuous chromatography and virus filtration systems without the use of a surge vessel. This innovation could significantly enhance efficiency and cost-effectiveness in bioprocessing.

In a recent statement, Ioana Pintescu, a research associate and lead author of the study, emphasized the model’s capability to define the “viral clearance capabilities of a virus filter undergoing continuous filtration.” The findings suggest potential for fully continuous bioprocessing, promising to save time and resources while improving operational flow.

The research team, which includes Julie Kozaili, PhD, and Daniel Strauss, PhD, director of R&D, successfully connected polishing chromatography with virus filtration to create a small-scale validation model. This model operated in a high-throughput environment for a continuous period of 72 hours, achieving a viral limit of detection at 0.73 log TCID50/mL, and demonstrated complete removal of porcine parvovirus (PPV) with a logarithmic reduction value (LRV) of 5.5 or greater.

Most existing virus filtration validation steps are tailored for batch processing, presenting challenges for continuous bioprocessing engineers. Continuous conditions introduce variations in product feed, which can increase system pressure, foul filters, and lead to fluctuations in pH, conductivity, and product concentration. While surge tanks can mitigate some of these issues, they also occupy valuable space and may limit operational flexibility.

To address these challenges, Pintescu and her colleagues examined worst-case scenarios and conducted runs that mirrored actual downstream processes for bovine serum albumin (BSA) and monoclonal antibody (mAb) production. Their connected chromatography-to-virus filtration model effectively processed both solutions without disruption or pressure fluctuations over the 72-hour duration.

Achieving these results entailed accommodating multiple operational parameters. The team established a maximum operating pressure of 0.3 megapascals (MPa) based on the specifications of the pump, column system, and virus filter. Flow rates were set at 0.3 mL/s for BSA filtrations and 0.165 mL/min for mAb filtrations. Despite gradual pressure increases throughout the experiment, the system maintained stability without encountering overpressure or backpressure issues.

The model’s performance was consistent across both spiked and non-spiked BSA and mAb runs, demonstrating complete viral clearance from starting virus load titers of 6.25 or 6.38 log TCID50/mL. “These results demonstrate that extended filtration run times and high throughput volumes posed no problem for the virus filter in this setup,” the researchers concluded, noting that every run achieved a PPV LRV greater than five.

Pintescu pointed out that while other R&D facilities can replicate this model, they must have the appropriate materials. Nevertheless, she acknowledged that further development is necessary to fully integrate virus filtration into continuous systems, particularly regarding the use or removal of surge tanks. Future optimization and design of new skid systems will be crucial for accommodating uninterrupted continuous feeds during downstream operations.

This innovative approach to virus filtration in continuous bioprocessing paves the way for enhanced operational efficiency and effectiveness in the biotechnology sector, signifying a noteworthy leap forward in the validation of viral clearance methods.