Interaction of E2 Glycoprotein with Heparan Sulfate Is Crucial for Cellular Infection of Sindbis Virus

Wuyang Zhu,Lihua Wang,Yiliang Yang,Yun Feng,Juan Jia,Shihong Fu,Guodong Liang,Ying He,Jin-Ping Li,Bradley S Schneider

doi:10.1371/journal.pone.0009656

Abstract

Cell culture-adapted strains of Sindbis virus (SINV) initially attach to cells by the ability to interact with heparan sulfate (HS) through selective mutation for positively charged amino acid (aa) scattered in E2 glycoprotein (W. B. Klimstra, K. D. Ryman, and R. E. Johnston, J. Virol. 72: 7357–7366, 1998). Here we have further confirmed that interaction of E2 protein with HS is crucial for cellular infection of SINV based on the reverse genetic system of XJ-160 virus, a Sindbis-like virus (SINLV). Both SINV YN87448 and SINLV XJ-160 displayed similar infectivity on BHK-21, Vero, or C6/36 cells, but XJ-160 failed to infect mouse embryonic fibroblast (MEF) cells. The molecular mechanisms underlying the selective infectivity of XJ-160 were approached by substituting the E1, E2, or both genes of XJ-160 with that of YN87448, and the chimeric virus was denominated as XJ-160/E1, XJ-160/E2, or XJ-160/E1E2, respectively. In contrast to the parental XJ-160, all chimeric viruses became infectious to wild-type MEF cells (MEF-wt). While MEF-Ext −/− cells, producing shortened HS chains, were resistant not only to XJ-160, but also to YN87448 as well as the chimeric viruses, indicating that the inability of XJ-160 to infect MEF-wt cells likely due to its incompetent discrimination of cellular HS. Treatment with heparin or HS-degrading enzyme resulted in a substantial decrease in plaque formation by YN87448, XJ-160/E2, and XJ-160/E1E2, but had marginal effect on XJ-160 and XJ-160/E1, suggesting that E2 glycoprotein from YN87448 plays a more important role than does E1 in mediating cellular HS-related cell infection. In addition, the peptide containing 145–150 aa from E2 gene of YN87448 specifically bound to heparin, while the corresponding peptide from the E2 gene of XJ-160 essentially showed no binding to heparin. As a new dataset, these results clearly confirm an essential role of E2 glycoprotein, especially the domain of 145–150 aa, in SINV cellular infection through the interaction with HS.

Highlights

IntroductionSingle-strand RNA viruses, belonging to the genus of Alphavirus in the family Togaviridae that has more than 30 members [1]
Sindbis viruses are enveloped, single-strand RNA viruses, belonging to the genus of Alphavirus in the family Togaviridae that has more than 30 members [1]
These findings demonstrated that both Sindbis virus (SINV) YN87448 and Sindbis-like virus (SINLV) XJ-160 exhibited a similar infectivity and growth capacity in either mammalian cells or mosquito cells, such as BHK-21, Vero, and C6/36 cells

Summary

Introduction

Single-strand RNA viruses, belonging to the genus of Alphavirus in the family Togaviridae that has more than 30 members [1]. Other wild-type alphaviruses, such as VEEV, Semliki Forest virus (SFV) and Ross River virus (RRV), were shown HS-binding phenotype of infection during tissue culture [5,7,8]. Previous investigations on the SINVHS interaction indicate that HS-dependent phenotype has a selective advantage through the adaptive mutation for positively charged animo acid (aa) during tissue culture. Nontissue culture adapted SINV infect host cells by a HS-independent mechanism, while several of adaptive mutations for positively charged aa scattered in E2 gene have been found to increase viral infectivity by enhancing the binding or attachment to HS on the surface of the cell surface [5,18,19]. HS-binding phenotype could have implications for SINV virulence [19,20,21,22]

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