title: Long-term preservation of cone photoreceptors and restoration of cone function by gene therapy in the guanylate cyclase-1 knockout (GC1KO) mouse.
abstract: OBJECTIVE
  The authors previously showed that subretinal delivery of AAV5 vectors containing murine guanylate cyclase-1 (GC1) cDNA driven by either photoreceptor-specific (hGRK1) or ubiquitous (smCBA) promoters was capable of restoring cone-mediated function and visual behavior and preserving cone photoreceptors in the GC1 knockout (GC1KO) mouse for 3 months. Here, the authors compared therapy conferred by the aforementioned vectors to that achieved with the highly efficient capsid tyrosine mutant AAV8(Y733F) and asked whether long-term therapy is achievable in this model.
  
  
  METHODS
  AAV5-hGRK1-mGC1, AAV5-smCBA-mGC1, or AAV8(Y733F)-hGRK1-mGC1 was delivered subretinally to GC1KO mice between postnatal day (P)14 and P25. Retinal function was assayed by electroretinography. Localization of AAV-mediated GC1 expression and cone survival were assayed with immunohistochemistry, and the spread of vector genomes beyond the retina was quantified by PCR of optic nerve and brain tissue.
  
  
  RESULTS
  Cone function was restored with all vectors tested, with AAV8(Y733F) being the most efficient. Electroretinographic responses were clearly measurable out to 1 year after treatment. AAV-mediated expression of GC1 was found exclusively in photoreceptors out to 15 months after injection. Cones were preserved for at least 11 months after treatment. AAV5- and AAV8(733)-delivered vector genomes were recovered primarily from optic nerve of the treated eye and, in only instance, from brain (1 of 20 samples).
  
  
  CONCLUSIONS
  The authors demonstrate for the first time that long-term therapy (∼1 year) is achievable in a mammalian model of GC1 deficiency. These data provide additional justification for the development of an AAV-based gene therapy vector for the clinical treatment of Leber congenital amaurosis-1.
authors.affiliation: Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Sanford L
authors.initials: SL
authors.lastname: Boye
authors.forename: Thomas
authors.initials: T
authors.lastname: Conlon
authors.forename: Kirsten
authors.initials: K
authors.lastname: Erger
authors.forename: Renee
authors.initials: R
authors.lastname: Ryals
authors.forename: Andy
authors.initials: A
authors.lastname: Neeley
authors.forename: Travis
authors.initials: T
authors.lastname: Cossette
authors.forename: Jijing
authors.initials: J
authors.lastname: Pang
authors.forename: Frank M
authors.initials: FM
authors.lastname: Dyka
authors.forename: William W
authors.initials: WW
authors.lastname: Hauswirth
authors.forename: Shannon E
authors.initials: SE
authors.lastname: Boye
mesh_terms: D000818:Animals; D002470:Cell Survival; D000229:Dependovirus / Q000235:genetics*; D004195:Disease Models, Animal; D004596:Electroretinography; D005260:Female; D051606:G-Protein-Coupled Receptor Kinase 1 / Q000235:genetics; D015316:Genetic Therapy; D005822:Genetic Vectors; D006162:Guanylate Cyclase / Q000235:genetics*; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics; D056965:Injections, Intraocular; D057130:Leber Congenital Amaurosis / Q000235:genetics / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics*; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C515337:Gnat2 protein, mouse; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C110715:guanylate cyclase 1; D051606:G-Protein-Coupled Receptor Kinase 1; C496764:GRK1 protein, human; D020962:Heterotrimeric GTP-Binding Proteins; D006162:Guanylate Cyclase