VIRAL INACTIVATION
UV-C Irradiation: A New Viral Inactivation Method for Biopharmaceuticals
Kate Bergmann, PhD
Viral Safety and Viral Clearance Manager Eurofins Lancaster Laboratories
Submitted: 08/27/2014 Accepted for Publication: 09/02/2014 Introduction
Viral contamination events have occurred in a number of production processes over the last 20 years. In most cases, the source was either proven or suspected to be a raw material component. Most of the contamination events have occurred with non-enveloped viruses, which lack an outer lipid envelope.
Testing for virus in raw materials, starting materials, or in the unprocessed bulk product can assist in ensuring that the product will be free of detectable viral contamination. However, some viruses may not be detected in the assays, and therefore the risk of virus contamination cannot be fully controlled by testing alone.
Viral Clearance Studies
Viral clearance studies play a crucial role in assuring that biopharmaceutical products made in animal cells are free of virus that could potentially contaminate the product.
In viral clearance studies,
selected steps in the product’s purification process are deliberately spiked with selected viruses, and the ability of the step to remove and/or inactivate the virus is evaluated. A clearance factor for the entire process can be calculated for each virus by adding results from all of the steps tested. Results of viral clearance studies demonstrate that undetected viruses that may contaminate the unprocessed bulk can be effectively cleared from the product during the purification process.
Mechanisms of Viral Clearance
Katherine Bergmann, PhD, is manager of Viral Safety and Viral Clearance Services at
Eurofins Lancaster Laboratories. She has extensive experience in cell line characterization, lot release testing and viral/TSE clearance validation and has
numerous publications and presentations in the field. She has performed biomedical research in protein chemistry, cell biology and virology at
Georgetown University, Scripps Research Institute and Rockefeller University. She received a PhD from Brown University and a AB degree from
Mount Holyoke College. Dr. Bergmann served on the PDA task force on Preparation of Virus Spikes Used for Virus Clearance Studies.
Purification process steps can act in two different ways: by separating the virus from the product stream (termed removal steps), and by inactivating the virus so that it is no longer infectious (inactivation steps). Some steps may act in both ways. Inactivation steps, such as low pH, detergent, or irradiation, are important contributors to the total clearance obtained, and regulatory agencies expect to see at least one effective inactivation step in a purification process. However, non- enveloped viruses are significantly more difficult to inactivate than enveloped viruses. Of particular interest is Murine Minute Virus (MMV), which has been detected as a viral contaminant of CHO cells. Most purification processes have no inactivation step that is effective for MMV.
Viral Inactivation Using UV-C Irradiation
Although UV-C irradiation has been used for water treatment for a number of years, its use with biopharmaceutical products is fairly new, and there is limited information available on its effectiveness in inactivating viruses. UV-C irradiation is performed with monochromatic light at 254 nm, which targets nucleic acids preferentially over proteins. We have evaluated this technology for its effectiveness with viruses from seven different families (Table 1). The instrument used in these studies was a GMP-compliant lab scale UV-C irradiation system. In this instrument, the solution is pumped through a helical reactor coil that surrounds the UV bulb. The UV dosage is controlled by the light intensity and the flow rate.
12 American Pharmaceutical Review | Biopharmaceutical Supplement 2014
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