CAG-ChR2-YFP AAV (Serotype 8)

Adeno-associated virus (AAV) is a non-enveloped parvovirus with a single-stranded DNA genome of approximately 4.7 kb that is a common backbone for recombinant viral vectors. AAV is non-pathogenic, has relatively low immunogenicity, and AAV vectors can be produced in large quantities with high purity. AAV is able to transduce post-mitotic cells for long periods of time, with gene expression observed for more than 6 years in primates. These factors have led to the widespread use of AAV vectors in the nervous system, where they can transduce targeted brain regions locally via stereotactic injection, diffusely transduce large brain volumes via intraventricular or intravenous administration, or transfer genes into primary cultures of neurons and glial cells. A large number of evolutionarily diverse AAV serotypes have been identified. When compared directly after brain injection, these serotypes exhibit different neuronal cell tropisms, transduction intensities, and gene expression profiles. While some serotypes transduce only within the normal range of diffusion, others also transduce cells at considerable distances from the injection site. This distal transduction results from axonal transport of the intact vector, either by uptake in the axon terminal, retrograde transport to the cell body, and subsequent transduction, or by uptake in projection neurons, anterograde transport along axonal projections, secretion from the axon terminal, and transduction in second-order neurons.