Separation of empty and full AAV8 capsids was achieved during their elution from a weak anion exchanger with an ascending pH gradient at low conductivity. Experimental data suggest elution was mediated by loss of positive charge from the exchanger. The method produced a full capsid peak with fewer empty capsids than elution of a strong anion exchanger with a salt gradient. Elution of the weak exchanger by sodium chloride gradients or by pH gradients in the presence of sodium chloride gave inferior separation performance. Pre-elution of empty capsids with a pH step allowed full capsids to be eluted by salt without compromising separation. Loading at intermediate pH prevented empty capsid binding and enabled step elution of full capsids in a physiological buffer environment.
Tag: <span>anion exchange chromatography</span>
Cancer is one of the leading causes of death worldwide, and the second leading cause of death in Cuba. To address this serious health problem, some research has involved suppressing tumor growth by inhibiting the angiogenesis process using several molecules including antibodies. A divalent version of antibody fragments, the CIGB-598a, with a molecular weight between 100 and 110 kDa, has been expressed in CHO cells specific for a novel epitope of the human vascular endothelium growth factor (VEGF). This material has been generated at the Center for Genetic Engineering and Biotechnology to support cancer research efforts. As in other studies involving the purification of recombinant molecules, CIGB-598a exhibited a high degree of aggregation in the CHO cell culture supernatant. This required the design of a downstream process capable of removing high levels of aggregates to obtain a highly pure target molecule for use in preclinical studies and human applications further down the road. We have developed a suitable downstream method based on the combination of three chromatography processes: affinity, cation-exchange, and anion-exchange that recover a relatively low level of CIGB-598a, but at a level of high purity (greater than 95 %) with fewer aggregates (below 1%)…