scAAV4-GFP

Adeno-associated virus (AAV) is a widespread parvovirus with no known pathogenic mechanism in humans that is known to infect a variety of human tissues. Recombinant AAV viral vector systems contain less than 4% of the viral genome and have been shown to transduce a variety of cell types, including neurons and non-neuronal cells in the mammalian central nervous system (CNS) after direct injection into the brain. Conventional recombinant AAV vectors deliver a single-stranded DNA genome that must be converted to double-stranded DNA by host cell-mediated DNA synthesis for active expression. At high multiplicity of infection, hybridization of complementary DNA strands from different virions may also generate active double-stranded templates for expression. This requirement for double-stranded DNA formation has been shown to be a significant limiting factor for AAV vector transduction.

The recently developed self-complementary AAV (scAAV) vector system provides a valuable tool for AAV-mediated gene therapy studies of CNS diseases due to its high transduction efficiency. scAAV vectors are made with a replicating DNA construct that is less than half the length of the wtAAV genome, thus allowing the inverted repeat dimer molecule to be packaged but limiting the size of the transgene. The two halves of these molecules are complementary to each other and, once released from the capsid, base pair to form a double-stranded hairpin molecule. Because the kinetics of this reaction are first order with respect to the number of DNA molecules involved, the transduction efficiency (i.e., transducing units per genome-containing particle) is independent of the multiplicity of infection and host cell DNA synthesis.