Supernatant is discarded and pellet resuspended in protein-free media. Ultracentrifugation: Virus in culture supernatant is pelleted by high-speed centrifugation. Virus is eluted using protein-free, high-salt buffer. Q-Membrane Chromatography: Crude preparation is passed through an anion-exchange membrane adsorber, which binds the virus. After several days, culture supernatants are collected and clarified. MVM PREPARATION METHODS Crude: 324K cells are infected with MVM. We subsequently reflected upon the challenges encountered in an effort to understand and prevent them in the future.

This success was made possible by cooperation among the drug producer, filter manufacturer, and contract testing laboratory specialists. Fortunately, despite initial difficulties, throughput and virus removal targets were ultimately met thanks to implementation of a flexible spiking strategy.

Here, we recount a virus clearance study in which challenges arose because of unpredicted hydraulic consequences of virus spiking. The purpose of a clearance study is to accurately represent manufacturing, and this goal is subverted when virus spike impurities cause fouling that is not representative of the full-scale process. Moreover, the presence of undefined impurities in a virus spike casts doubt on the integrity of a scaled-down model. Spike-induced fouling may prevent achievement of throughput targets, resulting in studies being deemed unsuccessful even though virus reduction was satisfactory.

Studies suggest that such filter membrane fouling is generally caused by impurities present in virus stocks rather than virus particles themselves ( 1, 2, 3, 4, 5, 6). Unfortunately, in reality the virus spike frequently has detrimental effects on filter hydraulic performance, resulting in decreased fluid flow. Ideally, during a scaled-down study, adding virus to a drug process solution does not perturb filtration, and a spiked process fluid flows across a filter at the same rate (or pressure) as does unspiked material.

Spike performance