title: Systemic Gene Transfer of a Hexosaminidase Variant Using an scAAV9.47 Vector Corrects GM2 Gangliosidosis in Sandhoff Mice.
abstract: GM2 gangliosidosis is a group of neurodegenerative diseases caused by β-hexosaminidase A (HexA) enzyme deficiency. There is currently no cure. HexA is composed of two similar, nonidentical subunits, α and β, which must interact with the GM2 activator protein (GM2AP), a substrate-specific cofactor, to hydrolyze GM2 ganglioside. Mutations in either subunit or the activator can result in the accumulation of GM2 ganglioside within neurons throughout the central nervous system. The resulting neuronal cell death induces the primary symptoms of the disease: motor impairment, seizures, and sensory impairments. This study assesses the long-term effects of gene transfer in a Sandhoff (β-subunit knockout) mouse model. The study utilized a modified human β-hexosaminidase α-subunit (μ-subunit) that contains critical sequences from the β-subunit that enables formation of a stable homodimer (HexM) and interaction with GM2AP to hydrolyze GM2 ganglioside. We investigated a self-complementary adeno-associated viral (scAAV) vector expressing HexM, through intravenous injections of the neonatal mice. We monitored one cohort for 8 weeks and another cohort long-term for survival benefit, behavioral, biochemical, and molecular analyses. Untreated Sandhoff disease (SD) control mice reached a humane endpoint at approximately 15 weeks, whereas treated mice had a median survival age of 40 weeks, an approximate 2.5-fold survival advantage. On behavioral tests, the treated mice outperformed their knockout age-matched controls and perform similarly to the heterozygous controls. Through the enzymatic and GM2 ganglioside analyses, we observed a significant decrease in the GM2 ganglioside level, even though the enzyme levels were not significantly increased. Molecular analyses revealed a global distribution of the vector between brain and spinal cord regions. In conclusion, the neonatal delivery of a novel viral vector expressing the human HexM enzyme is effective in ameliorating the SD mouse phenotype for long-term. Our data could have implications not only for treatment of SD but also for Tay-Sachs disease (α-subunit deficiency) and similar brain disorders.
authors.affiliation: 1 Centre for Neuroscience Studies, Queen's University , Kingston, Ontario, Canada .
authors.forename: Karlaina J L
authors.initials: KJ
authors.lastname: Osmon
authors.affiliation: 2 Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario, Canada .
authors.forename: Evan
authors.initials: E
authors.lastname: Woodley
authors.affiliation: 3 Medical Genetics/Departments of Pediatrics, Queen's University , Kingston, Ontario, Canada .
authors.forename: Patrick
authors.initials: P
authors.lastname: Thompson
authors.affiliation: 3 Medical Genetics/Departments of Pediatrics, Queen's University , Kingston, Ontario, Canada .
authors.forename: Katalina
authors.initials: K
authors.lastname: Ong
authors.affiliation: 4 Gene Therapy Center, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: Subha
authors.initials: S
authors.lastname: Karumuthil-Melethil
authors.affiliation: 5 New Hope Research Foundation , North Oaks, Minnesota.
authors.forename: John G
authors.initials: JG
authors.lastname: Keimel
authors.affiliation: 6 Department of Microbiology, University of Manitoba , Winnipeg, Manitoba, Canada .
authors.forename: Brian L
authors.initials: BL
authors.lastname: Mark
authors.affiliation: 7 Genetics and Genome Biology, SickKids, Toronto, Ontario, Canada .|8 Department of Laboratory Medicine and Pathology, University of Toronto , Toronto, Ontario, Canada .
authors.forename: Don
authors.initials: D
authors.lastname: Mahuran
authors.affiliation: 4 Gene Therapy Center, University of North Carolina , Chapel Hill, North Carolina.|9 Department of Ophthalmology, University of North Carolina , Chapel Hill, North Carolina.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Gray
authors.affiliation: 1 Centre for Neuroscience Studies, Queen's University , Kingston, Ontario, Canada .|2 Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario, Canada .|3 Medical Genetics/Departments of Pediatrics, Queen's University , Kingston, Ontario, Canada .
authors.forename: Jagdeep S
authors.initials: JS
authors.lastname: Walia
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D000229:Dependovirus / Q000235:genetics*; D004195:Disease Models, Animal; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000008:administration & dosage*; D006596:Hexosaminidases / Q000235:genetics*; D051379:Mice; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D012497:Sandhoff Disease / Q000201:enzymology / Q000235:genetics / Q000628:therapy*
chemical_list: D006596:Hexosaminidases