Poster abstracts

Poster number 66 submitted by Adam Davis

Genetic modification of AAV9 mediating enhanced transduction of motor neurons.

Adam S. Davis (Biophysics, The Ohio State University), Thais Federici, Ph.D. (Department of Neurosurgery, Emory University School of Medicine), Nicholas M. Boulis, M.D. (Departmetn of Neurosurgery, Emory University School of Medicine), William C. Ray, Ph.D. (Biophyics, The Ohio State University), Jeffrey S. Bartlett, Ph.D. (Biophysics, The Ohio State University), K. Reed Clark (Department of Pediatrics, The Ohio State University School of Medicine)

Abstract:
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease. A small percentage of cases involve a genetic component and are categorized as familial ALS, while the remainder of cases exhibit no obvious genetic component and are thusly categorized as sporadic ALS. To date, the FDA has approved a single marginally effective treatment; however, several therapeutic neuro-protective factors have demonstrated significant potential in animal models. Because direct injection of these therapeutic agents is both invasive and transient, a viral vector capable of targeted and prolonged neuro-protective factor expression would be an ideal method of administration.
Methods: Adeno-associated virus (AAV) has been broadly examined as a gene therapy vector. It is non-pathogenic in humans and exhibits prolonged gene expression. Previous studies have shown that AAV tolerates short linear peptide inserts into its capsid proteins at several specific locations. We have previously identified a 12 amino acid peptide, tet1, which binds the motor neuron axon membrane specific receptor Gt1b. Further we have successfully incorporated tet1 into the capsid proteins of AAV serotype 1 (AAV1) increasing its specificity for motor neurons while simultaneously decreasing its specificity for non-Gt1b expressing cells in vitro. Previous studies have indicated that AAV serotype 9 (AAV9) is capable of crossing the blood brain barrier (BBB) after intravenous (IV) administration. The transduction profile of AAV9 after endothelial transcytosis remains a debate; however, it has been hypothesized that AAV9 preferentially transduces astrocytes in a receptor-mediated fashion. Because the crystal structure of AAV9 remains unpublished, we will determine the structurally homologous amino acids in AAV1 to determine the capsid location for tet1 insertion. We will incorporate tet1 into AAV9 via PCR mutagenesis and assess its efficacy for increasing motor neuron specificity in the context of AAV9.

Keywords: AAV9, motor neuron, ALS