Transduction of striatum and cortex tissues by adeno-associated viral vectors produced by herpes simplex virus- and baculovirus-based methods

Recombinant adeno-associated virus (AAV) vectors can be engineered to carry genetic material encoding therapeutic gene products that have demonstrated significant clinical promise. These viral vectors are typically produced in mammalian cells by the transient transfection of two or three plasmids encoding the AAV rep and cap genes, the adenovirus helper gene, and a gene of interest. Although this method can produce high-quality AAV vectors when used with multiple purification protocols, one critical limitation is the difficulty in scaling-up manufacturing, which poses a significant hurdle to the broad clinical utilization of AAV vectors. To address this challenge, recombinant herpes simplex virus type I (rHSV-1)- and recombinant baculovirus (rBac)-based methods have been established recently. These methods are more amenable to large-scale production of AAV vectors than methods using the transient transfection of mammalian cells. To investigate potential applications of AAV vectors produced by rHSV-1- or rBac-based platforms, the in vivo transduction of rHSV-1- or rBac-produced AAV serotype 2 (AAV2) vectors within the rat brain were examined by comparing them with vectors generated by the conventional transfection method. Injection of rHSV-1- or rBac-produced AAV vectors into rat striatum and cortex tissues revealed no differences in cellular tropism (i.e., predominantly neuronal targeting) or anteroposterior spread compared with AAV2 vectors produced by transient transfection. This report represents a step towards validating AAV vectors produced by the rHSV-1- and the rBac-based systems as promising tools, especially for delivering therapeutic molecules to the central nervous system.