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Virus removal filtration is a critical step in the manufacture of monoclonal antibody products, providing a robust size‐based removal of both enveloped and non‐enveloped viruses. Many monoclonal antibodies show very large reductions in filtrate flux during virus filtration, with the mechanisms governing this behavior and its dependence on the properties of the virus filter and antibody remaining largely unknown. Experiments were performed using the highly asymmetric Viresolve® Pro and the relatively homogeneous Pegasus™ SV4 virus filters using a highly purified monoclonal antibody. The filtrate flux for a 4 g/L antibody solution through the Viresolve® Pro decreased by about 10‐fold when the filter was oriented with the skin side down but by more than 1000‐fold when the asymmetric filter orientation was reversed and used with the skin side up. The very large flux decline observed with the skin side up could be eliminated by placing a large pore size prefilter directly on top of the virus filter; this improvement in filtrate flux was not seen when the prefilter was used inline or as a batch prefiltration step. The increase in flux due to the prefilter was not related to the removal of large protein aggregates or to an alteration in the extent of concentration polarization. Instead, the prefilter appears to transiently disrupt reversible associations of the antibodies caused by strong intermolecular attractions. These results provide important insights into the role of membrane morphology and antibody properties on the filtrate flux during virus filtration. [ABSTRACT FROM AUTHOR]

Virus filtration is a key component of the overall virus clearance strategy in the production of monoclonal antibodies. These virus filtration membranes also provide one of the most selective membrane separations ever demonstrated, with more than 95% recovery of the antibody product in the filtrate with more than 99.99% retention of even small parvovirus, despite the less than 2-fold difference in size between the virus and antibody. However, there is currently no quantitative data on the intrinsic sieving characteristics of commercially available virus filters. Experiments were performed with the Viresolve® Pro and Pegasus™ SV4 virus filters both with and without stirring to control the effects of concentration polarization. The actual sieving coefficient of a highly purified monoclonal antibody was less than 0.05 for both membranes, demonstrating that the high antibody recovery during typical virus filtration processes is a direct result of the high degree of concentration polarization in these systems. The intrinsic selectivity of the virus filter was in good agreement with predictions of available hydrodynamic models accounting for a log-normal pore size distribution. The actual sieving coefficient also decreased with increasing antibody concentration, consistent with available models for proteins with attractive interactions (negative values of the interaction parameter). These results provide important insights into the transport characteristics of virus filters and their effect on the performance of these virus filters in bioprocessing. Image 1 • Antibody retention evaluated for two commercial virus filters. • Transmission data analyzed by accounting for polarization effects. • Results show significant intrinsic antibody retention consistent with pore size. • High antibody yield during virus filtration directly due to polarization effects. • Actual sieving coefficient decreases with increasing antibody concentration. [ABSTRACT FROM AUTHOR]