NEURON-SPECIFIC TRANSDUCTION IN THE RAT SEPTOHIPPOCAMPAL OR NIGROSTRIATAL PATHWAY BY RECOMBINANT ADENOASSOCIATED VIRUS VECTORS

Viral vector-mediated gene transfer in brain can provide a means for g ene therapy and functional studies. However, robust and persistent tra nsgene expression in specific populations of the adult brain has been difficult to achieve. In an attempt to produce localized and persisten t transduction in rat brain, we compared recombinant adeno-associated virus (rAAV) vectors incorporating either the immediate early cytomega lovirus (CMV) promoter or the neuron-specific enolase (NSE) promoter. Transduction in hippocampus resulting from the NSE promoter-containing construct was more efficient and persistent than that resulting from the CMV promoter-containing construct. Most hippocampal cells transduc ed with the NSE promoter had multipolar neuron morphology. Neurons wit h glutamatergic morphology were transduced weakly. In order to produce a local supply of neurotrophic factor to cells that degenerate under certain disease and experimental conditions, the NSE promoter was util ized to drive expression of brain-derived neurotrophic: factor (BDNF) in medial septum or substantia nigra. In this construct, the NSE promo ter drives dicistronic expression of BDNF and an enhanced version of g reen fluorescent protein (GFP). We estimated 3000-15,000 GFP-positive cells per injection of rAAV into septum or substantia nigra, a transdu ction ratio of 5-20 infectious virus particles per transduced cell. Th is frequency may be sufficient for trophic factor gene therapy as well as for investigating specific protein function in ''topical (i.e., lo calized) transgenic'' animals produced by rAAV. (C) 1998 Academic Pres s.