Amino acid substitutions in the E2 glycoprotein of Sindbis-like virus XJ-160 confer the ability to undergo heparan sulfate-dependent infection of mouse embryonic fibroblasts

Wuyang Zhu,Jinping Li,Guodong Liang,Shihong Fu,Ying He

doi:10.1186/1743-422x-7-225

Abstract

We have recently demonstrated an essential role of the domain of 145-150 amino acid in the E2 glycoprotein of Sindbis virus in the interaction with cellular heparan sulfate (HS) and in the infection of mouse embryonic fibroblasts (MEF) cells. In this study, we constructed and characterized the mutants of Sindbis-like virus XJ-160 in which Tyr-146 and/or Asn-149 in the E2 glycoprotein had been substituted with His and Arg, respectively. Unlike parental virus XJ-160, mutants with either or both substitutions were able to infect wild-type mouse embryonic fibroblasts (MEF-wt) or MEF-Epi-/- cells which produce mutant HS. Significantly more infectious particles were released from MEF-wt than from MEF-Epi-/- cells. The mutant virus with both substitutions release was inhibited by pre-incubation of virus with heparin or pre-treatment of BHK-21 cells with HS-degrading enzyme. Both XJ-160 and the mutant viruses retained substantial neurovirulence in suckling mice. Our findings provide further support to the importance of positively charged residues in the HS-binding site of E2 in mediating Sindbis virus infection of MEF cells.

Highlights

We have recently demonstrated an essential role of the domain of 145-150 amino acid in the E2 glycoprotein of Sindbis virus in the interaction with cellular heparan sulfate (HS) and in the infection of mouse embryonic fibroblasts (MEF) cells
Based on the divergence of nucleotide sequencing and biological characteristics, Sindbis virus can be divided into two groups, SINV and Sindbis-like virus (SINLV) [3]
SINV YN87448 and SINLV XJ-160 were isolated from a pool of Anopheles mosquitoes collected in Xinjiang and from a female patient with fever in Yunnan, China [4,5]

Summary

Introduction

We have recently demonstrated an essential role of the domain of 145-150 amino acid in the E2 glycoprotein of Sindbis virus in the interaction with cellular heparan sulfate (HS) and in the infection of mouse embryonic fibroblasts (MEF) cells. * Correspondence: gdliang@hotmail.com 1State Key Laboratory for Infectious Disease Prevention and Control (SKLID), Institute for Viral Disease Control and Prevention, China CDC, Beijing, China Full list of author information is available at the end of the article of a wide range of invertebrate and vertebrate cells. The results of immunofluorescence assay (IFA) and plaque assay indicated that XJ-160 virus was capable of assembling infectious particles in spite of different site-directed mutation at residue E2-146 or residue E2-149, and that all the mutant viruses displayed plaque morphologies similar to those formed by XJ-160, the mutants seem to form bigger plaques (Additional file 1, Figure 1).

Results

Conclusion