Purification of recombinant adeno-associated virus type 8 vectors by ion exchange chromatography generates clinical grade vector stock

Recombinant vectors based on the recently isolated AAV serotype 8 (rAAV-8) shows great promise for gene therapy, particularly for disorders affecting the liver. Transition of this vector system to the clinic, however, is limited by the lack of an efficient scaleable purification method. In this report, we describe a simple method for purification of rAAV-8 vector particles based on ion exchange chromatography that generates vector stocks with greater than 90% purity. The average yield of purified rAAV-8 from five different vector preparation was 41%. Electron microscopy of these purified stocks revealed typical icosohedral virions with less than 10% empty particles. Liver targeted delivery of ion-exchange purified rAAV-8 vector encoding the human factor IX (hFIX) gene, resulted in plasma hFIX levels approaching 30% of normal in immunocompetent mice, which is 20-fold higher than observed with an equivalent number of rAAV-5 ion exchange purified vector particles. The method takes less then 5 h to process and purify rAAV-8 vector from producer cells and represents a significant advance on the CsCl density centrifugation technique in current use for purification of rAAV-8 vector systems and will likely facilitate the transition of the rAAV-8 vector system to the clinic.