title: Lack of humoral immune response to the tetracycline (Tet) activator in rats injected intracranially with Tet-off rAAV vectors.
abstract: The ability to safely control transgene expression from viral vectors is a long-term goal in the gene therapy field. We have previously reported tight regulation of GFP expression in rat brain using a self-regulating tet-off rAAV vector. The immune responses against tet regulatory elements observed by other groups in nonhuman primates after intramuscular injection of tet-on encoding vectors raise concerns about the clinical value of tet-regulated vectors. However, previous studies have not examined immune responses following injection of AAV vectors into brain. Therefore, rat striatum was injected with tet-off rAAV harboring a therapeutic gene for Parkinson's disease, either hAADC or hGDNF. The expression of each gene was tightly controlled by the tet-off regulatory system. Using an ELISA developed with purified GST-tTA protein, no detectable immunogenicity against tTA was observed in sera of rats that received an intrastriatal injection of either vector. In contrast, sera from rats intradermally injected with an adenovirus containing either tTA or rtTA, as positive controls, had readily detectable antibodies. These observations suggest that tet-off rAAV vectors do not elicit an immune response when injected into rat brain and that these may offer safer vectors for Parkinson's disease than vectors with constitutive expression.
authors.affiliation: Department of Pediatrics, Neurobiology Program, Children's Memorial Research Center, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Han
authors.forename: Q A
authors.initials: QA
authors.lastname: Chang
authors.forename: T
authors.initials: T
authors.lastname: Virag
authors.forename: N C
authors.initials: NC
authors.lastname: West
authors.forename: D
authors.initials: D
authors.lastname: George
authors.forename: M G
authors.initials: MG
authors.lastname: Castro
authors.forename: M C
authors.initials: MC
authors.lastname: Bohn
mesh_terms: D000818:Animals; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000235:genetics; D001479:Basal Ganglia / Q000276:immunology*; D000229:Dependovirus / Q000276:immunology*; D005786:Gene Expression Regulation; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000276:immunology*; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000235:genetics; D056724:Immunity, Humoral; D008297:Male; D010300:Parkinson Disease / Q000628:therapy*; D051381:Rats; D011916:Rats, Inbred F344; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D020218:Response Elements / Q000187:drug effects; D013752:Tetracycline / Q000494:pharmacology; D015534:Trans-Activators / Q000235:genetics / Q000276:immunology*; D019076:Transgenes / Q000187:drug effects
chemical_list: C495039:GDNF protein, human; D051100:Glial Cell Line-Derived Neurotrophic Factor; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D001142:Aromatic-L-Amino-Acid Decarboxylases; D013752:Tetracycline