Orthobunyavirus ultrastructure and the curious tripodal glycoprotein spike

Bowden, T.A., Bitto, D., McLees, A., Yeromonahos, C., Elliott, R.M. and Huiskonen, J.T. (2013) Orthobunyavirus ultrastructure and the curious tripodal glycoprotein spike. PLoS Pathogens, 9(5), e1003374. (doi: 10.1371/journal.ppat.1003374)

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Abstract

The genus <i>Orthobunyavirus</i> within the family <i>Bunyaviridae</i> constitutes an expanding group of emerging viruses, which threaten human and animal health. Despite the medical importance, little is known about orthobunyavirus structure, a prerequisite for understanding virus assembly and entry. Here, using electron cryo-tomography, we report the ultrastructure of Bunyamwera virus, the prototypic member of this genus. Whilst Bunyamwera virions are pleomorphic in shape, they display a locally ordered lattice of glycoprotein spikes. Each spike protrudes 18 nm from the viral membrane and becomes disordered upon introduction to an acidic environment. Using sub-tomogram averaging, we derived a three-dimensional model of the trimeric pre-fusion glycoprotein spike to 3-nm resolution. The glycoprotein spike consists mainly of the putative class-II fusion glycoprotein and exhibits a unique tripod-like arrangement. Protein–protein contacts between neighbouring spikes occur at membrane-proximal regions and intra-spike contacts at membrane-distal regions. This trimeric assembly deviates from previously observed fusion glycoprotein arrangements, suggesting a greater than anticipated repertoire of viral fusion glycoprotein oligomerization. Our study provides evidence of a pH-dependent conformational change that occurs during orthobunyaviral entry into host cells and a blueprint for the structure of this group of emerging pathogens.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Elliott, Professor Richard
Authors: Bowden, T.A., Bitto, D., McLees, A., Yeromonahos, C., Elliott, R.M., and Huiskonen, J.T.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:PLoS Pathogens
Publisher:Public Library of Science
ISSN:1553-7374
ISSN (Online):1553-7374
Copyright Holders:Copyright © 2013 The Authors
First Published:First published in PLoS ONE 9(5):e1003374
Publisher Policy:Reproduced under a Creative Commons License

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