Engineering AAV capsids for enhanced transduction of skeletal muscle

ABSTRACTWe are developing an improved adeno-associated virus (AAV)-based gene therapy vector that we call “enhanced AAV” or “eAAV” for short. eAAV is specifically designed for gene delivery to skeletal muscle tissue. Based on preliminary studies in mice we expect it will be approximately 100 times more effective than the recombinant AAVs (rAAV1 and rAAV8) used in recent clinical trials. This gain in efficiency should allow us to achieve far higher levels of therapeutic transgene products, either directly, due to increased transduction efficiency, or indirectly, by allowing us to use less vector and thereby reduce the likelihood of host immune responses to the transgene product.The aims of this grant are threefold. Aim 1 is to finalize the design of the eAAV product in cell culture and rodent studies. Aim 2 is to test the final eAAV product in nonhuman primates, and Aim 3 is to determine whether or not it poses any unique safety risks compared to other rAAV vectors. Aim 2 comprises the bulk of the project. Here we will compare eAAV to rAAV for its ability to express both alpha-1 antitrypsin (AAT) and the human immunodeficiency virus (HIV)-inhibitor eCD4 from skeletal muscle. Achieving therapeutic levels of AAT would allow for a permanent cure of genetic AAT-deficiency while achieving reliably high levels of eCD4 expression would enable a one-shot, potentially life-long treatment for HIV.PROJECT NARRATIVEWe are developing a prototype gene therapy vector called eAAV for use in skeletal muscle tissue. Over the course these experiments we will test eAAV for its ability to express therapeutic levels of the secreted proteins alpha-1 antitrypsin (AAT) and the HIV inhibitor eCD4, goals that previous gene therapy vectors have failed to achieve. Success would open up new avenues of therapy not only for AAT-deficiency and HIV but for a wide variety of other diseases as well.