Robust clarification for adeno-associated virus vectors via depth filtration

The bioprocessing industry widely embraces depth filtration for cell culture clarification of recombinant proteins produced in mammalian cell lines; however, Adeno-Associated Virus (AAV) processes present a unique harvest challenge due to a potential lysis step and the surface characteristics of the target product. While efficient at removing cell debris and other insoluble impurities, many depth filters are optimized for adsorption of soluble impurities for monoclonal antibody process streams, where target products are relatively high concentration and have a slight net positive surface charge. Since AAV have slightly acidic isoelectric points, these viruses may interact with positively charged adsorptive depth filters at typical harvest pH ranges. Process development, therefore, requires thorough screening and investigation of depth filters prior to selection for AAV clarification. In light of these concerns, MilliporeSigma reviewed internal data to understand trends of depth filter performance for clarification of AAV from SF9 and HEK293 cell lines; additionally, a controlled screening experiment confirmed findings from data mining activities. This body of work presents the results from these two investigations, which suggest Millistak+® depth filters to be a robust solution for clarification of multiple AAV serotypes from SF9 and HEK293 cell cultures. Additionally, the study demonstrates scalability from bench scale to process scale, giving confidence for implementation in cGMP. Robust performance, ease of use in manufacturing, and scalability make depth filtration an ideal selection for clarification of AAV.