Leveraging host-cell modulators of adeno-associated vector transduction to tailor viral biodistribution

Clinical successes in gene therapy using adeno-associated vectors (AAVs) are offering a hopeful path toward the correction of several monogenic disorders. At its core, AAV gene delivery relies on multiple interactions between the capsid or vector genome and numerous host-cell factors, a complex process that remains incompletely understood. Whether different serotypes similarly hijack the intracellular machinery in a cell, and whether these processes are necessarily conserved across species, are not known. To identify host factors enabling or preventing transduction across species or serotypes, CRISPR-Cas9 whole-genome knockdown screens were conducted in mouse (AML12) and human (HuH-7) cell lines before transduction with AAV2 or AAV9. Key common entry factors (AAVR, GPR108) were confirmed, with many other serotype- and/or species-specific host-cell modulators identified. Interestingly, while serotype-specific differences were observed for successful transduction of a specific cell line, species-specific divergences were even more striking when comparing results across murine and human cells for the same serotype. Leveraging these data, we developed a novel approach to detarget liver transduction by transiently downregulating the expression of key entry factors in this tissue using GalNac-small interfering RNAs (siRNAs) prior to AAV9 administration. Such manipulation not only blunted hepatic transduction but also redirected the vector to other transduction-permissive tissues.