Secreted NS1 of Dengue Virus Attaches to the Surface of Cells via Interactions with Heparan Sulfate and Chondroitin Sulfate E

Panisadee Avirutnan,Michael S Diamond,Watchara Kasinrerk,Chunya Puttikhunt,Nuntaya Punyadee,John P Atkinson,Lijuan Zhang,Prida Malasit,Ananya Manuyakorn,Michael J Buchmeier

doi:10.1371/journal.ppat.0030183

Abstract

Dengue virus (DENV) nonstructural protein-1 (NS1) is a secreted glycoprotein that is absent from viral particles but accumulates in the supernatant and on the plasma membrane of cells during infection. Immune recognition of cell surface NS1 on endothelial cells has been hypothesized as a mechanism for the vascular leakage that occurs during severe DENV infection. However, it has remained unclear how NS1 becomes associated with the plasma membrane, as it contains no membrane-spanning sequence motif. Using flow cytometric and ELISA-based binding assays and mutant cell lines lacking selective glycosaminoglycans, we show that soluble NS1 binds back to the surface of uninfected cells primarily via interactions with heparan sulfate and chondroitin sulfate E. DENV NS1 binds directly to the surface of many types of epithelial and mesenchymal cells yet attaches poorly to most peripheral blood cells. Moreover, DENV NS1 preferentially binds to cultured human microvascular compared to aortic or umbilical cord vein endothelial cells. This binding specificity was confirmed in situ as DENV NS1 bound to lung and liver but not intestine or brain endothelium of mouse tissues. Differential binding of soluble NS1 by tissue endothelium and subsequent recognition by anti-NS1 antibodies could contribute to the selective vascular leakage syndrome that occurs during severe secondary DENV infection.

Highlights

Dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS) are severe and potentially fatal complications of infection by dengue virus (DENV), a mosquito-borne RNA virus of the Flaviviridae family
We demonstrate that soluble Dengue virus (DENV) nonstructural protein-1 (NS1) attaches to subsets of cells, including some but not all endothelial cells, primarily via an interaction with specific glycosaminoglycans
Our findings suggest that the selective vascular leakage that occurs in severe DENV infection may be related to the relative ability of endothelial cells in different tissues to bind soluble NS1 and to be targeted by cross-reactive anti-NS1 antibodies during secondary infection

Summary

Introduction

Dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS) are severe and potentially fatal complications of infection by dengue virus (DENV), a mosquito-borne RNA virus of the Flaviviridae family. DENV infects 25 to 100 million people per year, but the life-threatening complications primarily occur in school-age children [1]. Four serotypes of DENV exist, and DHF/DSS is commonly associated with secondary infection with a different virus serotype [2,3]. In the most severe cases, clinical deterioration is characterized by a rapid decline after several days of continuous high fever, thrombocytopenia, and selective vascular leakage at serosal sites [4]. The vascular leakage syndrome results in hemoconcentration, pleural effusions and ascites, and hypotension [4]. An effective strategy for disease prevention or treatment is currently lacking

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