Effect of protein fouling on filtrate flux and virus breakthrough behaviors during virus filtration process.

Virus filtration process is used to ensure viral safety in the biopharmaceutical downstream processes with high virus removal capacity (i.e., >4 log10 ). However, it is still constrained by protein fouling, which results in reduced filtration capacity and possible virus breakthrough. This study investigated the effects of protein fouling on filtrate flux and virus breakthrough using commercial membranes that had different symmetricity, nominal pore size, and pore size gradients. Flux decay tendency due to protein fouling was influenced by hydrodynamic drag force and protein concentration. As the results of prediction with the classical fouling model, standard blocking was suitable for most virus filters. Undesired virus breakthrough was observed in the membranes having relatively a large pore diameter of the retentive region. The study found that elevated levels of protein solution reduced virus removal performance. However, the impact of prefouled membranes was minimal. These findings shed light on the factors that influence protein fouling during the virus filtration process of biopharmaceutical production.

Virus inactivation using an electrically conducting virus filter in biopharmaceutical manufacturing process.

Biopharmaceutical manufacturing processes using mammalian cells or plasma carry the risk of viral contamination. To mitigate these risks, it is essential to ensure viral clearance during the downstream process. Virus-retentive filters are used for size-based virus filtration, offering robust viral removal of more than 99.99%. However, virus breakthroughs have also been reported during virus filtration under certain conditions. In addition, these virus-retentive filters are disposable to ensure the safety of bioproducts, leading to significant costs and environmental concerns. In this study, innovative electrically conducting virus filters were fabricated using free-standing carbon veils (CV) and used to achieve additional virus inactivation after filtration. The viruses were captured in a CV-assisted virus filter, which was electrically heated using direct current to inactivate the viruses. This electrically conducting virus filter can inactivate viruses and can be reused up to five times. These results demonstrate that electrical conduction through electrical conducting damaged the phage capsid and eliminated the RNA genome, leading to bacteriophage inactivation. Moreover, it was confirmed that the electrically conducting virus filter could be reused up to five times without any changes to its physical or chemical structure. This study contributes to the reduction of process costs and environmental impacts by enabling the reuse of virus filters and enhancing the safety of the virus filtration process by preventing undesired virus breakthroughs.

Protein loss during membrane processes in biopharmaceutical manufacturing.

Maximizing product yield in biopharmaceutical manufacturing processes is a critical factor in determining the overall cost of goods, especially given the high value of these biological products. However, there has been relatively limited research on the quantitative analysis of protein losses due to adsorption and fouling during the different membrane filtration processes employed in typical downstream operations. This study aims to provide a comprehensive analysis of protein loss in the range of membrane systems used in downstream processing including clarification, virus removal filtration, ultrafiltration/diafiltration for formulation, and final sterile filtration, all using commercially available membranes with three model proteins (bovine serum albumin, human serum albumin, and immunoglobulin G). The correlation between protein loss and various parameters (i.e., protein type, protein concentration, throughput, membrane morphology, and protein removal mechanism) was also investigated. This study provides important insights into the nature of protein loss during membrane processes as well as a methodology for quantifying protein yield loss in bioprocesses.