Membrane-Associated Heparan Sulfate Proteoglycan Is a Receptor for Adeno-Associated Virus Type 2 Virions

TLDR

AAV infects a wide range of mammalian and avian species, yet the initial cellular events of infection remain poorly understood, and the virus is being developed as a gene‑therapy vector. The authors aimed to identify the cellular receptor for AAV‑2 to aid in virus purification and inform its therapeutic use. They used defined mutant CHO cell lines and biochemical assays to show that heparan sulfate proteoglycans mediate AAV attachment and infection. Their results demonstrate that heparan sulfate proteoglycans are essential for AAV‑2 binding and entry, as shown by heparin inhibition, loss of attachment after enzymatic removal of heparan, and impaired infection in HSPG‑deficient cells, thereby establishing HSPG as the viral receptor and explaining AAV’s broad host range.

Abstract

ABSTRACT The human parvovirus adeno-associated virus (AAV) infects a broad range of cell types, including human, nonhuman primate, canine, murine, and avian. Although little is known about the initial events of virus infection, AAV is currently being developed as a vector for human gene therapy. Using defined mutant CHO cell lines and standard biochemical assays, we demonstrate that heparan sulfate proteoglycans mediate both AAV attachment to and infection of target cells. Competition experiments using heparin, a soluble receptor analog, demonstrated dose-dependent inhibition of AAV attachment and infection. Enzymatic removal of heparan but not chondroitin sulfate moieties from the cell surface greatly reduced AAV attachment and infectivity. Finally, mutant cell lines that do not produce heparan sulfate proteoglycans were significantly impaired for both AAV binding and infection. This is the first report that proteoglycan has a role in cellular attachment of a parvovirus. Together, these results demonstrate that membrane-associated heparan sulfate proteoglycan serves as the viral receptor for AAV type 2, and provide an explanation for the broad host range of AAV. Identification of heparan sulfate proteoglycan as a viral receptor should facilitate development of new reagents for virus purification and provide critical information on the use of AAV as a gene therapy vector.