A New Scalable Method for the Purification of Recombinant Adenovirus Vectors

Abstract

Recombinant adenovirus vectors continue to be the preferred vectors for many types of gene therapy. However, issues regarding production and safety as well as the development of a scalable process for these vectors remain a challenge. Additionally, any process must address the well-documented immune and toxicologic responses to these vectors. Some alternatives to classic CsCl-gradient purification based on column chromatography have been developed, but these first-generation processes are still limited in potential application. We report the development of a tandem column chromatography process incorporating two resins; anion-exchange and PolyFlo^® (Puresyn, Inc., Malvern, PA). PolyFlo is used in a novel manner as a polishing step to remove additional host and viral proteins not removed by the anion-exchange capture step. By using the β-galactosidase reporter vector, H5.CMV-lacZ, the purity of the product is improved compared to the same vector purified by 2× CsCl or anion-exchange alone as determined by high-performance liquid chromatography (HPLC), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE; silver stain), Western analysis, electron microscopy, and particle:infectious (VP:IU) unit ratio. The recovery over the entire process is significantly better than 2× CsCl and higher than other first-generation tandem chromatography processes. This new process is reproducible and scalable to 10¹⁵ input viral particles per run. Furthermore, the purified adenovirus product remains intact after multiple freeze/thaw cycles and is stable at 4°C, -20°C, and -75°C. The process described here permits purification of adenovirus particles at a high concentration at large scale without centrifugation.