Effective Separation Of Full And Empty Adeno-Associated Virus Capsids By Anion Exchange

Adeno-associated vector (AAV) is now established as the primary viral vector for gene therapy applications. It is essential to optimize the polishing step of your AAV process for the separation of full capsids from empty capsids for each serotype, which leads to improved viral genome (VG) recovery and a purity of full capsids.

We have developed a protocol for anion exchange with Capto™ Q chromatography resin, which allows near-complete separation of full and empty capsids for multiple recombinant serotypes (rAAV2, rAAV5, rAAV8, and rAAV9). Previously, we have shown how Capto™ Q ImpRes chromatography resin can achieve VG recovery of approximately 60% to 70% and full capsid enrichment to between approximately 40% and 60%.

To further improve full capsid recovery and purity, we will show how Capto™ Q resin with dextran surface extenders, magnesium chloride (MgCl₂), and the elution salt type (especially for rAAV9) significantly enhance separation. Finally, we found that using Capto™ Q, a single protocol with sodium acetate in the elution buffer, and a step-elution approach greatly improved VG yields and full capsid purity to approximately 80% and above for all the serotypes tested.