title: Hepatitis A virus and the origins of picornaviruses.
abstract: Hepatitis A virus (HAV) remains enigmatic, despite 1.4 million cases worldwide annually. It differs radically from other picornaviruses, existing in an enveloped form and being unusually stable, both genetically and physically, but has proved difficult to study. Here we report high-resolution X-ray structures for the mature virus and the empty particle. The structures of the two particles are indistinguishable, apart from some disorder on the inside of the empty particle. The full virus contains the small viral protein VP4, whereas the empty particle harbours only the uncleaved precursor, VP0. The smooth particle surface is devoid of depressions that might correspond to receptor-binding sites. Peptide scanning data extend the previously reported VP3 antigenic site, while structure-based predictions suggest further epitopes. HAV contains no pocket factor and can withstand remarkably high temperature and low pH, and empty particles are even more robust than full particles. The virus probably uncoats via a novel mechanism, being assembled differently to other picornaviruses. It utilizes a VP2 'domain swap' characteristic of insect picorna-like viruses, and structure-based phylogenetic analysis places HAV between typical picornaviruses and the insect viruses. The enigmatic properties of HAV may reflect its position as a link between 'modern' picornaviruses and the more 'primitive' precursor insect viruses; for instance, HAV retains the ability to move from cell-to-cell by transcytosis.
authors.affiliation: National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China.
authors.forename: Xiangxi
authors.initials: X
authors.lastname: Wang
authors.affiliation: Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford, UK.
authors.forename: Jingshan
authors.initials: J
authors.lastname: Ren
authors.affiliation: National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China.|Sinovac Biotech Co., Ltd., Beijing, 100085, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Gao
authors.affiliation: National Institutes for Food and Drug Control, No. 2, TiantanXili, Beijing 100050, China.
authors.forename: Zhongyu
authors.initials: Z
authors.lastname: Hu
authors.affiliation: National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Sun
authors.affiliation: National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Li
authors.affiliation: Institute of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Rowlands
authors.affiliation: Sinovac Biotech Co., Ltd., Beijing, 100085, China.
authors.forename: Weidong
authors.initials: W
authors.lastname: Yin
authors.affiliation: National Institutes for Food and Drug Control, No. 2, TiantanXili, Beijing 100050, China.
authors.forename: Junzhi
authors.initials: J
authors.lastname: Wang
authors.affiliation: Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford, UK.|Diamond Light Sources, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
authors.forename: David I
authors.initials: DI
authors.lastname: Stuart
authors.affiliation: National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China.|Laboratory of Structural Biology, School of Medicine, Tsinghua University, Beijing, 100084, China.
authors.forename: Zihe
authors.initials: Z
authors.lastname: Rao
authors.affiliation: Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford, UK.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Fry
mesh_terms: D000818:Animals; D002213:Capsid / Q000737:chemistry; D036022:Capsid Proteins / Q000737:chemistry; D018360:Crystallography, X-Ray; D019143:Evolution, Molecular; D030041:Hepatitis A virus / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007313:Insecta / Q000821:virology; D008958:Models, Molecular; D010802:Phylogeny; D010849:Picornaviridae / Q000737:chemistry*; D057900:Transcytosis; D014771:Virion / Q000737:chemistry; D053586:Virus Internalization
chemical_list: D036022:Capsid Proteins