Delivering genes across the blood-brain barrier: LY6A, a novel cellular receptor for AAV-PHP.B capsids.

Qin Huang,Isabelle G Tobey,Jonathan M Bloom,Tim Poterba,Alejandro B Balazs,Yujia Alina Chan,Ken Y Chan,Christine L Boutros,Cotton Seed,Benjamin E Deverman,Richard Daneman,Giovanni Di Pasquale

doi:10.1371/journal.pone.0225206

Abstract

The engineered AAV-PHP.B family of adeno-associated virus efficiently delivers genes throughout the mouse central nervous system. To guide their application across disease models, and to inspire the development of translational gene therapy vectors for targeting neurological diseases in humans, we sought to elucidate the host factors responsible for the CNS tropism of the AAV-PHP.B vectors. Leveraging CNS tropism differences across 13 mouse strains, we systematically determined a set of genetic variants that segregate with the permissivity phenotype, and rapidly identified LY6A as an essential receptor for the AAV-PHP.B vectors. Interfering with LY6A by CRISPR/Cas9-mediated Ly6a disruption or with blocking antibodies reduced transduction of mouse brain endothelial cells by AAV-PHP.eB, while ectopic expression of Ly6a increased AAV-PHP.eB transduction of HEK293T and CHO cells by 30-fold or more. Importantly, we demonstrate that this newly discovered mode of AAV binding and transduction can occur independently of other known AAV receptors. These findings illuminate the previously reported species- and strain-specific tropism characteristics of the AAV-PHP.B vectors and inform ongoing efforts to develop next-generation AAV vehicles for human CNS gene therapy.

Highlights

With the boom of gene replacement, knockdown, and editing technologies, the number of diseases that are potentially treatable by gene therapy is rapidly expanding
LY6A is essential for the central nervous system (CNS) tropism of the AAV-PHP.B capsids
Starting from millions of genetic variants comprised of singlenucleotide polymorphisms (SNPs) as well as insertions and deletions, we narrowed our analysis to variants predicted to affect expression, splicing, or protein coding regions

Summary

Introduction

With the boom of gene replacement, knockdown, and editing technologies, the number of diseases that are potentially treatable by gene therapy is rapidly expanding. AAV vectors are proving to be safe, versatile vehicles for in vivo gene therapy applications [1,2,3,4]. Delivery challenges impede the application of gene therapy, in the context of the brain, which is protected by the blood-brain barrier (BBB). To improve gene delivery across the central nervous system (CNS), our group and others have engineered AAV capsids using in vivo. LY6A is essential for the CNS tropism of the AAV-PHP.B capsids

Methods

Results

Conclusion