GFP Adeno-Associated Virus ( A588-RGD4C )

AAV vectors can effectively transduce a wide variety of cells. However, it has recently been determined that low levels of heparan sulfate proteoglycan (HSPG)-mediated vector binding limit AAV transduction of several important gene therapy target cells. Other yet-to-be-characterized cell types may similarly lack sufficient levels of HSPGs to allow efficient gene transduction. The dramatic increase in transduction of cells lacking HSPGs shown here suggests that genetically engineered targeted AAV vectors may be successfully used to expand the range of tissues amenable to effective AAV-mediated gene therapy. Studies have shown that genetic integration of RGD-containing sequences into the AAV2 capsid protein can extend tropism to previously impermissible cell types. The crystal core structure of AAV2 is a β-barrel motif composed of antiparallel β sheets and interspersed loop domains. The largest of these loops is located between β sheets G and H (the GH loop) and contains most of the sites that have proven to be amenable to manipulation. The optimal site for epitope insertion appears to define a subdomain within this loop based on surface exposure and local structural flexibility. RGD-modified viral particles can directly interact with purified integrin αvβ3. Furthermore, these modified AAV particles are able to bind to integrin receptors on the surface of appropriate target cells and exploit this interaction for cellular entry, supporting the concept that enhanced transgene expression efficiency is due to more efficient primary interactions between virus and target cells and specific targeting through alternative cellular receptors.