AAVmyo and MyoAAV as promising vectors to deliver gene therapy in two mouse models of vacuolar myopathy

Topic:

Translational Research

Poster Number: 330

Author(s):

Lan Weiss, PhD., University of California, Irvine, CA, Hai Zhang, PhD, University of California, Irvine, CA, Alyaa Shmara, MD., University of California, Irvine, CA, Philip Farahat, University of California Irvine, Barbara Tedesco, PhD, University of Milan, Italy, Victoria Boock, University of California, Irvine, CA, Ginny Wu, University of California, Irvine, CA, Salma Metwaly, University of California, Irvine, CA, Villalta Armando, PhD, University of California, Irvine, CA, Angelo Poletti, PhD, University of Milan, Italy, Xiangmin Xu, PhD., University of California, Irvine, CA, Virginia Kimonis, MD., University of California, Irvine, CA

Genetically modified adeno-associated virus (AAV)-mediated gene therapies are increasingly common for use in clinical trials; a few of them have been approved for patient treatments by the Food and Drug Administration (FDA). These viral vectors are designed to target the genetic root cause of the disease through gene replacement and/or genome editing. Recently myotropic AAV variants AAVMYO and MyoAAV have emerged as promising vectors to deliver gene payloads to muscle tissue. Our goal is to develop a safe and effective, allele-independent gene therapy approach for degenerative vacuolar myopathies using these new variants. We designed different vectors including AAVmyo-CAG-EGFP, MyoAAV2A-pAM-CAG-TdTomato, MyoAAV4A-pAM-CAG-TdTomato, and compared with AAV9-CAG-EGFP as a control vector. They were tested at the doses at 1e12 and 4 e12 vector genome (vg) via systemic delivery in C57BL6 wild type, and VCP R155H/+ and Hspb8 c515/+ myopathy transgenic mice. After three weeks post treatment mouse organs and blood samples were collected and analyzed to determine toxicity and muscle tropism efficiency. GFP/ TdTomato expression was convincingly higher in both doses of AAVmyo and MyoAAV compared to AAV9 in various skeletal and cardiac muscles. We observed the induction MyoAAV 4A-specific T cells in Hspb8 c515/+ mice. However, there were no signs of inflammation of myofibers on H&E staining. Our preliminary studies indicated better muscle tropism and less liver tropism with AAVMYO and MyoAAV deeming it safer and muscle specific for gene targeting. This leads to a promising next step of targeting the mutant alleles and replacing them with WT VCP or Hspb8 in the mouse models. Success in these studies holds promise for treatment of these vacuolar myopathies and related diseases in patients.