Demonstration of nanofiltration-based virus safety for AAV manufacturing using model viruses

Virus safety for biopharmaceutical products has been a well-established concern for several decades. While various virus reduction steps have been identified and implemented for traditional plasma-derived and monoclonal antibody products, there are various challenges to achieving the same virus safety in emerging gene therapy products. Virus removal filtration, or nanofiltration, has proven difficult to implement for larger gene therapy modalities, though there is a regulatory expectation to incorporate this step for smaller modalities such as adeno-associated virus (AAV) vector products. Here, we demonstrate the applicability of a virus removal filter with a 35 nm mean pore size distribution for AAV processes based on filtrations with porcine parvovirus (PPV) as a model for AAV vector and simian virus 40 (SV40) as a model contaminant virus. Filtration runs were performed at low pressure and included a defined process pause, two manufacturing conditions known to potentially impact viral clearance. All filtrations demonstrated SV40 reduction to below the limit of detection and no detectable reduction in PPV, indicating robust removal of large contaminating viruses without impacting product yields for AAV products. Thus, virus removal filtration is appropriate for the removal of adventitious viruses in gene therapy product manufacturing. Virus removal filters have an established history of improving patient safety and should be included in the manufacture of advanced gene therapy products whenever possible.