545. Strong Cortico-Spinal Transduction After AAV5 Delivery into the Central Nervous System of Nonhuman Primates

Widespread distribution of gene products at clinically relevant levels throughout the central nervous system (CNS) without involving peripheral organs is still a challenge. Previous work demonstrated that infusion of adeno-associated virus (AAV) serotypes 9 (AAV9) and 7 (AAV7) into the cerebrospinal fluid (CSF) via cisterna magna of nonhuman primates (NHP) resulted in widespread transduction throughout cortex and spinal cord. Adeno-associated virus serotype 5 (AAV5) is also a potential candidate for CNS gene therapy when delivered into brain parenchyma but its performance in CSF has not been described. In the present work, we compared transduction patterns after CSF and parenchymal delivery of AAV5-GFP. For CSF delivery, we injected various doses of AAV5 (1E+14, 1E+13 and 1E+12 vg/mL) into CSF via lumbar routes in naive NHP and studied vector distribution and cellular transduction 4 weeks after CSF delivery. We found a dose-dependent increase in transduction with strong levels of cell transduction and distribution throughout cortex and along the spinal cord at the highest doses and no signal in the low-dose group. These results suggest a dose threshold when delivering into CSF, most likely due to a dilution of the viral particles. Both astrocytes and neurons were transduced by AAV5 when infused either in CSF or directly into brain parenchyma.Parenchymal delivery of AAV5-GFP was analyzed 8 weeks after surgery. Interestingly, when infused into the thalamus and the contralateral putamen, AAV5 resulted in higher levels of expression in cortical and subcortical structures than those observed in high-dose CSF animals. Surprisingly, thalamic injection directed spinal cord transduction throughout the cortico-bulbar axis. These results suggest not only that smaller volumes of AAV5 infused directly into the thalamus can result in robust and widespread cellular transduction in the brain but also to spinal cord. Our results confirm AAV5 as a powerful viral vector for gene transfer in the CNS and underscore its translational potential for treating neurological disorders of the brain and spinal cord.