Fundamentals Of Viral Clearance Studies: Part 1: Selection Of A Viral Panel And An Appropriate Virus Spike

By Kathryn Martin Remington, Ph.D., Principal Scientist for Clearance Services, BioReliance

A viral clearance study is designed to experimentally demonstrate the virus reduction that could be achieved by selected steps in a biopharmaceutical manufacturing process in the unlikely event that process intermediates were to be contaminated by an infectious virus. The clearance study complements a testing program that screens for contaminating virus in source materials or product intermediate. 

A typical manufacturing process for a biopharmaceutical product, such as a monoclonal antibody or a recombinant protein, will contain steps that are dedicated to virus inactivation or removal. Low pH incubation or detergent treatment steps provide inactivation of enveloped viruses, while virus filtration steps can remove both enveloped and nonenveloped viruses. In addition, the manufacturing process is also likely to contain steps that purify the product, but which may have the potential to provide virus reduction. Chromatography steps are good examples of such steps. In a viral clearance study, several of process steps will be independently evaluated for their virus reduction potential by spiking virus into the pre-process step intermediate and measuring the amount of virus remaining after the process step. Individual spiking experiments are performed for each of a panel of viruses.