GFP Adeno-Associated Virus ( AAV2-GMN )

Adeno-associated virus (AAV) has been widely used as a vector for gene transfer to various tissues in vivo. Of the many serotypes available, only a few have been used experimentally, and each serotype exhibits unique tissue tropism characteristics determined by the receptors used for cell binding and transduction. Several AAV serotypes are effective in gene transfer to the central nervous system (CNS), and several (e.g., AAV9, rAAVrh.8, rAAVrh.10) exhibit robust brain delivery after intravenous injection. One approach to broaden tropism or retarget AAV to specific tissues of therapeutic interest is to modify the capsid surface by introducing peptides that bind to tissue-specific or tissue-enriched cell surface receptors.

Peptide-modified AAV2 vectors (AAV-GMN) contain capsid-displaying peptides that direct brain vascular targeting and transduction in vivo when delivered intravenously. AAV-GMN, but not AAV2, readily transduces the mouse brain endothelial cell line bEnd.3. The glycosaminoglycan chondroitin sulfate C is the primary receptor for AAV-GMN. Unlike AAV2, chondroitin sulfate expression is required for AAV-GMN cell transduction, and soluble chondroitin sulfate C can strongly inhibit AAV-GMN transduction of brain endothelial cells. Interestingly, AAV-GMN retains heparin binding properties, but its ability to transduce cells expressing heparin sulfate but not chondroitin sulfate is weaker than that of AAV2, suggesting that the peptide insertion has a negative impact on heparin-mediated transduction. When delivered directly, this modified virus can transduce multiple brain regions, so the potential of AAV-GMN as a therapeutic gene delivery vehicle for central nervous system diseases is not limited to the brain vascular endothelium.