Investigation of the colloidal stability of adeno-associated viral vectors and how it influences their chromatographic purification

Adeno-associated viruses (AAVs) are among the most investigated vectors for gene therapies. However, they are associated to great manufacturing complexities, due to their poor colloidal stability. Indeed, the aggregation during their chromatographic purification determines the loss of valuable product. At the same time, the colloidal stability of AAVs and the reversibility of their aggregation is poorly studied in the literature. To cover this gap, we systematically investigated the role of pH and of different cations and anions of the Hofmeister series on the colloidal stability of AAV2, and how this impacts their chromatographic purification. The anions investigated were (Formula presented.), (Formula presented.), and (Formula presented.), while the cations were (Formula presented.), (Formula presented.) and (Formula presented.). The volume fraction of primary particles tracked by dynamic light scattering increases with respect to aggregates when increasing the medium ionic strength, with the anions having a more beneficial impact on the colloidal stability. The cation demonstrating the most effective stabilizing effect was (Formula presented.), extensively employed in biopharmaceutical purification processes, while the most effective anion was (Formula presented.), commonly used in the purification of nucleic acids. This study was demonstrated to have direct implications in increasing the AAV recovery from chromatographic purifications, with the potential of decreasing their manufacturing costs.