Characterization of Interactions between Heparin/Glycosaminoglycan and Adeno-Associated Virus

Abstract

Adeno-associated virus (AAV) is a key candidate in the development of gene therapy. In this report, we used surface plasmon resonance spectroscopy to study the interaction between AAV and heparin and other glycosaminoglycans. Surface plasmon resonance results revealed that heparin binds to AAV with extremely high affinity. Solution competition studies shows that AAV binding to heparin is chain length dependent. AAV prefers to bind full chain heparin. All sulfo groups (especially N-sulfo and 6-O-sulfo groups) on heparin are important for the AAV- heparin interaction. Higher levels of sulfo group substitution in GAGs enhance their binding affinities. Atomic force microscopy was also performed to image AAV-2 complexed with heparin.

Differential Adeno-Associated Virus Serotype-Specific Interaction Patterns with Synthetic Heparins and Other Glycans

“…Previously pub- lished competition assays with short, size-fractionated heparins have shown only marginal inhibitory effects on AAV2 infection efficiencies (29). This is in line with the recent claim that a chain length of at least 13 would be needed to make full contact with the positively charged amino acids at the 3-fold symmetry axis on the capsid surface of AAV2 (38). The lack of AAV2 neutralization by heparin 7 could also be explained by lower affinity of AAV for pure synthetic heparins than for mixed natural heparin (Fig.…”

“…The variations in heparin binding specificities appear to reflect reported structural variations of AAV capsids and the relative positions of amino acids found to be critical for heparin binding (7,37). A recent publication using chemically modified natural heparin further supports the notion that AAV2 binds to 6-O-and N-sulfated HSPGs (38), and the loss of function of the well-studied AAV2 heparin binding site mutant (R585A/R588A) shows that HSPG binding is critical for cell entry (28). In contrast to the situation with AAV2, transduction with AAV3 was only partially inhibited by soluble heparins.…”

Hepatocyte Heparan Sulfate Is Required for Adeno-Associated Virus 2 but Dispensable for Adenovirus 5 Liver Transduction In Vivo

“…HS biosynthesis occurs by polymerization of alternating glucuronic acid and N-acetylglucosamine residues (12-14), catalyzed by an enzyme complex composed of EXT1 and EXT2 (15). EXT1 and EXT2 are essential molecules required for HS synthesis; cells lacking either molecule do not synthesize HS (16,49).AAV2 binds directly to cell surface HSPGs via an HS-binding motif on the virus capsid (3,17,18). AAV capsid modifications that alter the cluster of positive amino acids that constitute the HS binding motif abrogate liver transduction (3,19,20), suggesting that the ability of the capsid to bind to HS is critical for AAV2 liver transduction in vivo.…”

“…AAV2 binds directly to cell surface HSPGs via an HS-binding motif on the virus capsid (3,17,18). AAV capsid modifications that alter the cluster of positive amino acids that constitute the HS binding motif abrogate liver transduction (3,19,20), suggesting that the ability of the capsid to bind to HS is critical for AAV2 liver transduction in vivo.…”

Perspective on Adeno-Associated Virus Capsid Modification for Duchenne Muscular Dystrophy Gene Therapy

“…Defined structures for 11 naturally occurring or modified AAV serotype/variants have been resolved in recent years using X-ray crystallography and/or cryo-electron microscopy. These include 6 AAV-1 15 , AAV-2 [16][17][18][19][20][21][22] , AAV-3B 23, 24 , AAV-4 25, 26 , AAV-5 27-30 , AAV-6 31, 32 , AAV-7 33 , AAV-8 34-38 , AAV-9 39-41 , AAVrh32.33 42 , and AAV-DJ 43,44 . The structural information of these AAV capsids as well as their interaction with respective cellular receptor/co-receptors have provided the necessary framework to logically design tailored vectors.…”