Use of bacteriophages as surrogates for mammalian viruses.

The threat of viral contamination is common to all processes using biological products of animal or human origin. Therefore, demonstration of virus clearance (i.e. validation of virus removal and/or inactivation steps) is of utmost importance to the biopharmaceutical industries. Ultimately, virus clearance studies should show that any virus removal/inactivation stage incorporated into the manufacturing process not only removes or inactivates known viruses that may be conceivably present (e.g. from cell banks and source materials), but also other viruses that may be introduced adventitiously (e.g. by addition of supplements downstream of the manufacturing process). In this paper, we outline the shared properties of mammalian viruses and similar sized bacteriophages, and factors that may influence the virus clearance process. We also present test data from filtration studies, showing similar titre reductions for both types of virus. We propose that well-characterised bacteriophage, such as PP7 and PR772 can be used as models for mammalian viruses if the virus removal mechanism is based on size exclusion.