Widespread Correction of Lysosomal Storage in the Mucopolysaccharidosis Type VII Mouse Brain with a Herpes Simplex Virus Type 1 Vector Expressing β-Glucuronidase

Abstract

We have inoculated a herpes simplex virus type 1 (HSV-1) vector into a variety of sites in the mouse brain and assayed the regions of latency and expression of a beta-glucuronidase (GUSB) cDNA from the latency-associated transcript promoter. Injection sites used were somatosensory cortex, visual cortex, striatum, dorsal hippocampus, and CSF spaces. Latent vector was detected in regions at a distance from the respective injection sites, consistent with axonal transport of vector. Regions of GUSB activity varied by injection site and included cerebral cortex, striatum, thalamus, hypothalamus, substantia nigra, hippocampus, midbrain, pons, medulla, cerebellum, and spinal cord. After a single injection, GUSB enzymatic activity reached wild-type levels in several brain regions. GUSB was found in some areas without any detectable vector, indicative of axonal transport of GUSB enzyme. GUSB-deficient mice, which have the lysosomal storage disease mucopolysaccharidosis (MPS) VII, have lysosomal storage lesions in cells throughout the brain. Adult MPS VII mice treated by injection of vector into a single site on each side of the brain had correction of storage lesions in a large volume of brain. The potential for long-term, widespread correction of lysosomal storage diseases with HSV-1 vectors is discussed.