Pooled Screens Identify GPR108 and TM9SF2 as Host Cell Factors Critical for AAV Transduction

Adeno-associated virus (AAV) has been used extensively as a vector for gene therapy. Despite its widespread use, the mechanisms by which AAV enters the cell and is trafficked to the nucleus are poorly understood. In this study, we performed two pooled, genome-wide screens to identify positive and negative factors modulating AAV2 transduction. Genome-wide libraries directed against all human genes with four designs per gene or eight designs per gene were transduced into U-2 OS cells. These pools were transduced with AAV2 encoding EGFP and sorted based on the intensity of EGFP expression. Analysis of enriched and depleted barcodes in the sorted samples identified several genes that putatively decreased AAV2 transduction. A subset of screen hits was validated in flow cytometry and imaging studies. In addition to KIAA0319L (AAVR), we confirmed the role of two genes, GPR108 and TM9SF2, in mediating viral transduction in eight different AAV serotypes. Interestingly, GPR108 displayed serotype selectivity and was not required for AAV5 transduction. Follow-up studies suggested that GPR108 localized primarily to the Golgi, where it may interact with AAV and play a critical role in mediating virus escape or trafficking. Cumulatively, these results expand our understanding of the process of AAV transduction in different cell types and serotypes.