Infection of Glial Cells by the Human Polyomavirus JC Is Mediated by an N-Linked Glycoprotein Containing Terminal α(2-6)-Linked Sialic Acids

Abstract

The human JC polyomavirus (JCV) is the etiologic agent of the fatal central nervous system (CNS) demyelinating disease progressive multifocal leukoencephalopathy (PML). PML typically occurs in immunosuppressed patients and is the direct result of JCV infection of oligodendrocytes. The initial event in infection of cells by JCV is attachment of the virus to receptors present on the surface of a susceptible cell. Our laboratory has been studying this critical event in the life cycle of JCV, and we have found that JCV binds to a limited number of cell surface receptors on human glial cells that are not shared by the related polyomavirus simian virus 40 (C. K. Liu, A. P. Hope, and W. J. Atwood, J. Neurovirol. 4:49–58, 1998). To further characterize specific JCV receptors on human glial cells, we tested specific neuraminidases, proteases, and phospholipases for the ability to inhibit JCV binding to and infection of glial cells. Several of the enzymes tested were capable of inhibiting virus binding to cells, but only neuraminidase was capable of inhibiting infection. The ability of neuraminidase to inhibit infection correlated with its ability to remove both α(2-3)- and α(2-6)-linked sialic acids from glial cells. A recombinant neuraminidase that specifically removes the α(2-3) linkage of sialic acid had no effect on virus binding or infection. A competition assay between virus and sialic acid-specific lectins that recognize either the α(2-3) or the α(2-6) linkage revealed that JCV preferentially interacts with α(2-6)-linked sialic acids on glial cells. Treatment of glial cells with tunicamycin, but not with benzylN-acetyl-α-d-galactosaminide, inhibited infection by JCV, indicating that the sialylated JCV receptor is an N-linked glycoprotein. As sialic acid containing glycoproteins play a fundamental role in mediating many virus-cell and cell-cell recognition processes, it will be of interest to determine what role these receptors play in the pathogenesis of PML.

Establishment of an immunoscreening system using recombinant VP1 protein for the isolation of a monoclonal antibody that blocks JC virus infection

“…In contrast, JCV enters host cells by receptor-mediated clathrin-dependent endocytosis [28]. Furthermore, it has been reported that JCV does not share receptor specificity with SV 40 on human glial cells, because anticlass I antibodies failed to inhibit JCV infection [6].…”

“…The cellular receptor molecule for JCV is unknown, but it has been reported to be an N-linked glycoprotein containing a2-6-linked sialic acids, based on the observation that a2-6-specific sialidase inhibits infection of glial cells by JCV. In addition, treatment of permissive cells with tunicamycin, which removes N-linked oligosaccharides, was shown to inhibit JCV infection in vitro [6]. These findings indicate that the interaction between the major structural protein VP1 and sialic acids is critical for JCV infectivity.…”

“…To evaluate the inhibitory effects on attachment and entry of VLPs, which have functions in cellular attachment and entry, similar to native JCV infection [2,6] into IMR-32 cells, the cells were pretreated in the presence of either 24D2 or the isotype control monoclonal antibody, and incubated with FITC-labeled VLPs. 24D2 completely inhibited cellular attachment and entry of FITC-VLPs in IMR-32 cells, while the isotype control antibody had no effect on attachment or entry (Fig.…”

The Polyomaviridae: Contributions of virus structure to our understanding of virus receptors and infectious entry

“…Both of the human polyomaviruses require sialic acid to infect cells. JCV can use either an α2,3or an α2,6-linked sialic acid to infect permissive glial cells (Dugan et al, 2007;Liu et al, 1998) and a ganglioside (GT1b) may also be involved (Komagome et al, 2002) (Table 1). BKV uses only the α2,3-linkage to infect cells (Dugan et al, 2005) (Table 1).…”

Infectious Demyelinating Diseases

“…Is JCV host cell restriction at the level of binding and entry or is it at the molecular level? The recent identiWcation of the speciWc cell surface receptor for JCV has provided some answers to these questions (Liu et al, 1998). The receptor, an a 2-6 linked sialic acid, is a commonly expressed ganglioside found on the surface of various cells.…”