ARVO 2016 Annual Meeting Abstracts 141 Gene Therapy Sunday, May 01, 2016 1:30 PM–3:15 PM Exhibit/Poster Hall Poster Session Program #/Board # Range: 754–787/C0043–C0076 Organizing Section: Physiology/Pharmacology Program Number: 754 Poster Board Number: C0043 Presentation Time: 1:30 PM–3:15 PM Rescue of a mutant T8993G ATP6 mouse model of NARP and MILS with Mito-Targeted AAV9 Containing Normal ATP6 Huijun Yuan1, 2, Hong Yu1, 3, John Guy1, 2. 1Bascom Palmer Eye Institute, Miami, FL; 2University of Miami Miler School of Medicine, MIAMI, FL; 3University of Miami Miler School of Medicine, Miami, FL. Purpose: To develop gene therapy for the rescue of neurogenic ataxia & retinitis pigmentosa (NARP) and maternally inherited Leigh syndrome (MILS). Methods: To rescue the NARP & MILS mouse model, the human normal ATP6 gene was fused in frame with a FLAG epitope (ATP6FLAG) followed by the mitochondrial encoded mCherry and under the mitochondrial heavy strand promoter. Visual function was monitored using serial flash and pattern electroretinography (PERG). Motor function was evaluated by Rota-Rod testing. Human ATP6 DNA fragments were amplified and sequenced from A6M mouse mitochondria DNA. To rescue A6M mice, mito-targeted AAV9 was generated by modified VP2 with cox8. 10ul of mito-AAV9/ATP6 (1.85e+12 vg/ml) were respectively injected into 3 month old A6M (n=10) and around 18 month old (later stage) A6M mice (n=10) with a genotype and phenotype of T8993G NARP and MILS, and untreated A6M mice (n=10) of same conditions as controls. Results: After injection of mito-AAV9ATP6 rescue vector, treated A6M mice (n=10) showed 100% survival for one year compared to 30% survival of untreated A6M mice. PERG amplitudes of treated A6M mice was increased to 19.6 uV after six month compared to 11.3 uV for untreated A6M mice (P=0.0001). Confocal laser scanning ophthalmoscopy (CLSO) showed mCherry of treated A6M mice expressed 5 times higher compared to untreated A6M mouse (P