Knockout of Pro-Apoptotic BAX and BAK1 Genes in HEK293T Cells Enhances Adeno-Associated Virus (AAV) Production: AAV2 and AAV9

Abstract

Increasing demand for adeno-associated virus (AAV) used in gene therapy highlights the need to enhance AAV production. When intracellular AAV2 and extracellular AAV9 were produced in HEK293T cells using the triple transfection method, apoptosis occurred during the AAV production. To mitigate apoptosis induced by AAV production, the pro-apoptotic BAX/BAK1 genes were knocked out in HEK293T cells. BAX/BAK1 knockout (BBKO) in HEK293T cells significantly increased the production of both AAV2 and AAV9. For AAV2, BBKO increased the genome titer of AAV2 by 55% without negatively affecting the proportion of unwanted empty capsids generated during AAV production. Empty capsid ratios were determined based on viral genome and capsid titers and confirmed via transmission electron microscopy (TEM). Likewise, for AAV9, BBKO increased the genome titer of AAV9 by 66% without negatively affecting the proportion of empty capsids. Additionally, as assessed using a transduction assay, BBKO increased the functional titers of AAV2 and AAV9 by 30% and 46%, respectively. Therefore, BBKO increased AAV production, while maintaining full capsid ratio and infectivity. Taken together, BBKO proved to be an efficient method for enhancing AAV production in HEK293T cells for both AAV2 and AAV9.