3.6 Process Performance and Product Quality of AEX Run with Quaternary Ammonium Salt
As there is typically a tradeoff between full-rAAV enhancement and rAAV genome (full capsid) recovery in AEX chromatography, the effectiveness of TEA-Ac was assessed by plotting the percentage of full-rAAV (determined by AUC assay) in the AEX elution pool as a function of the AEX-step genome recovery (calculated based on genome copy determined by qPCR) for a total of 8 runs. As shown in Figure 5 , two linear regressions were generated corresponding to either TEA-Ac containing runs (R2=0.75) or non-TEA-Ac containing runs (R2=0.79), respectively. The slopes of the two regression lines are similar, indicating that the tradeoff rate between full-rAAV percentage to genome recovery is TEA-Ac independent. However, the intercepts of the two regression lines are quite different, projecting TEA-Ac containing runs has ~50% more genome yield than that of non-TEA-Ac containing runs under same full-rAAV percentage. Taken together, TEA-Ac demonstrated its effectiveness in AEX preparative process operation through not only better chromatographic peak separation, but also enhanced process performance and product quality, holding the promise for future implementation in scale-up AEX operation.