Lack of humoral immune response to the tetracycline (Tet) activator in rats injected intracranially with Tet-off rAAV vectors

• Published in: Gene therapy Vol. 17; no. 5; pp. 616 - 625
• Main Authors: Han, Y, Chang, Q A, Virag, T, West, N C, George, D, Castro, M G, Bohn, M C
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-05-2010; Nature Publishing Group
• Subjects: 631/250/2152/2153; 631/326/596/2561; 631/378/1689/1718; 631/61/201; Adeno-associated virus; Adenovirus; Adenoviruses; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Antibiotics; Applied cell therapy and gene therapy; Aromatic-L-Amino-Acid Decarboxylases - genetics; Basal Ganglia - immunology; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Biotechnology; Care and treatment; Cell Biology; Dependovirus - immunology; Enzyme-linked immunosorbent assay; Expression vectors; Fundamental and applied biological sciences. Psychology; Gene Expression; Gene Expression Regulation; Gene Therapy; Genetic aspects; Genetic Therapy; Genetic Vectors - immunology; Glial Cell Line-Derived Neurotrophic Factor - genetics; Health aspects; Health. Pharmaceutical industry; Human Genetics; Immune response; Immune response (humoral); Immune system; Immunity, Humoral; Immunogenicity; Industrial applications and implications. Economical aspects; Injection; Male; Medical sciences; Movement disorders; Nanotechnology; Neostriatum; Neurodegenerative diseases; original-article; Parkinson Disease - therapy; Parkinson's disease; Primates; Rats; Rats, Inbred F344; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - immunology; Regulatory sequences; Response Elements - drug effects; Rodents; Tetracycline - pharmacology; Trans-Activators - genetics; Trans-Activators - immunology; Transfusions. Complications. Transfusion reactions. Cell and gene therapy; Transgenes - drug effects; United States; tTA; gene therapy; regulated gene expression; rtTA; Parkinson's disease; viral vectors; Nervous system diseases; Immune response; Rat; Recombinant virus; Rodentia; Parkinson disease; Gene expression; Cerebral disorder; Tetracycline; Vertebrata; Mammalia; Central nervous system disease; Degenerative disease; Gene therapy; Vector; Humoral immunity; Extrapyramidal syndrome
• ISSN: 0969-7128; 1476-5462
• DOI: 10.1038/gt.2010.6

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.