1
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Lowery SA, Schuster N, Wong LYR, Carrillo T, Peters E, Odle A, Sariol A, Cesarz I, Li P, Perlman S. Mouse hepatitis virus JHMV I protein is required for maximal virulence. J Virol 2024:e0068024. [PMID: 39158347 DOI: 10.1128/jvi.00680-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Accepted: 07/04/2024] [Indexed: 08/20/2024] Open
Abstract
Betacoronaviruses encode a conserved accessory gene within the +1 open reading frame (ORF) of nucleocapsid called the internal N gene. This gene is referred to as "I" for mouse hepatitis virus (MHV), ORF9b for severe acute respiratory CoV (SARS-CoV) and SARS-CoV-2, and ORF8b for Middle East respiratory syndrome CoV (MERS-CoV). Previous studies have shown ORF8b and ORF9b have immunoevasive properties, while the only known information for MHV I is its localization within the virion of the hepatotropic/neurotropic A59 strain of MHV. Whether MHV I is an innate immune antagonist or has other functions has not been evaluated. In this report, we show that the I protein of the neurotropic JHM strain of MHV (JHMV) lacks a N terminal domain present in other MHV strains, has immunoevasive properties, and is a component of the virion. Genetic deletion of JHMV I (rJHMVIΔ57-137) resulted in a highly attenuated virus both in vitro and in vivo that displayed a post RNA replication/transcription defect that ultimately resulted in fewer infectious virions packaged compared with wild-type virus. This phenotype was only seen for rJHMVIΔ57-137, suggesting the structural changes predicted for A59 I altered its function, as genetic deletion of A59 I did not change viral replication or pathogenicity. Together, these data show that JHMV I both acts as a mild innate immune antagonist and aids in viral assembly and infectious virus production, and suggest that the internal N proteins from different betacoronaviruses have both common and virus strain-specific properties.IMPORTANCECoV accessory genes are largely studied in overexpression assays and have been identified as innate immune antagonists. However, functions identified after overexpression are often not confirmed in the infected animal host. Furthermore, some accessory proteins are components of the CoV virion, but their role in viral replication and release remains unclear. Here, we utilized reverse genetics to abrogate expression of a conserved CoV accessory gene, the internal N ("I") gene, of the neurotropic JHMV strain of MHV and found that loss of the I gene resulted in a post replication defect that reduced virion assembly and ultimately infectious virus production, while also increasing some inflammatory molecule expression. Thus, the JHMV I protein has roles in virion assembly that were previously underappreciated and in immunoevasion.
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Affiliation(s)
- Shea A Lowery
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Noah Schuster
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Lok-Yin Roy Wong
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Thomas Carrillo
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Erin Peters
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Abby Odle
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Alan Sariol
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Isabella Cesarz
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Pengfei Li
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Stanley Perlman
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, USA
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2
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Surya W, Queralt-Martin M, Mu Y, Aguilella VM, Torres J. SARS-CoV-2 accessory protein 7b forms homotetramers in detergent. Virol J 2022; 19:193. [PMID: 36414943 PMCID: PMC9680129 DOI: 10.1186/s12985-022-01920-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/04/2022] [Indexed: 11/23/2022] Open
Abstract
A global pandemic is underway caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 genome, like its predecessor SARS-CoV, contains open reading frames that encode accessory proteins involved in virus-host interactions active during infection and which likely contribute to pathogenesis. One of these accessory proteins is 7b, with only 44 (SARS-CoV) and 43 (SARS-CoV-2) residues. It has one predicted transmembrane domain fully conserved, which suggests a functional role, whereas most variability is contained in the predicted cytoplasmic C-terminus. In SARS-CoV, 7b protein is expressed in infected cells, and the transmembrane domain was necessary and sufficient for Golgi localization. Also, anti-p7b antibodies have been found in the sera of SARS-CoV convalescent patients. In the present study, we have investigated the hypothesis that SARS-2 7b protein forms oligomers with ion channel activity. We show that in both SARS viruses 7b is almost completely α-helical and has a single transmembrane domain. In SDS, 7b forms various oligomers, from monomers to tetramers, but only monomers when exposed to reductants. Combination of SDS gel electrophoresis and analytical ultracentrifugation (AUC) in both equilibrium and velocity modes suggests a dimer-tetramer equilibrium, but a monomer-dimer-tetramer equilibrium in the presence of reductant. This data suggests that although disulfide-linked dimers may be present, they are not essential to form tetramers. Inclusion of pentamers or higher oligomers in the SARS-2 7b model were detrimental to fit quality. Preliminary models of this association was generated with AlphaFold2, and two alternative models were exposed to a molecular dynamics simulation in presence of a model lipid membrane. However, neither of the two models provided any evident pathway for ions. To confirm this, SARS-2 p7b was studied using Planar Bilayer Electrophysiology. Addition of p7b to model membranes produced occasional membrane permeabilization, but this was not consistent with bona fide ion channels made of a tetrameric assembly of α-helices.
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Affiliation(s)
- Wahyu Surya
- grid.59025.3b0000 0001 2224 0361School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
| | - Maria Queralt-Martin
- grid.9612.c0000 0001 1957 9153Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12080 Castelló, Spain
| | - Yuguang Mu
- grid.59025.3b0000 0001 2224 0361School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
| | - Vicente M. Aguilella
- grid.9612.c0000 0001 1957 9153Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12080 Castelló, Spain
| | - Jaume Torres
- grid.59025.3b0000 0001 2224 0361School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
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3
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Kazmierski J, Friedmann K, Postmus D, Emanuel J, Fischer C, Jansen J, Richter A, Bosquillon de Jarcy L, Schüler C, Sohn M, Sauer S, Drosten C, Saliba A, Sander LE, Müller MA, Niemeyer D, Goffinet C. Nonproductive exposure of PBMCs to SARS-CoV-2 induces cell-intrinsic innate immune responses. Mol Syst Biol 2022; 18:e10961. [PMID: 35975552 PMCID: PMC9382356 DOI: 10.15252/msb.202210961] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 07/28/2022] [Accepted: 07/28/2022] [Indexed: 12/15/2022] Open
Abstract
Cell-intrinsic responses mounted in PBMCs during mild and severe COVID-19 differ quantitatively and qualitatively. Whether they are triggered by signals emitted by productively infected cells of the respiratory tract or result from physical interaction with virus particles remains unclear. Here, we analyzed susceptibility and expression profiles of PBMCs from healthy donors upon ex vivo exposure to SARS-CoV and SARS-CoV-2. In line with the absence of detectable ACE2 receptor expression, human PBMCs were refractory to productive infection. RT-PCR experiments and single-cell RNA sequencing revealed JAK/STAT-dependent induction of interferon-stimulated genes (ISGs) but not proinflammatory cytokines. This SARS-CoV-2-specific response was most pronounced in monocytes. SARS-CoV-2-RNA-positive monocytes displayed a lower ISG signature as compared to bystander cells of the identical culture. This suggests a preferential invasion of cells with a low ISG baseline profile or delivery of a SARS-CoV-2-specific sensing antagonist upon efficient particle internalization. Together, nonproductive physical interaction of PBMCs with SARS-CoV-2- and, to a much lesser extent, SARS-CoV particles stimulate JAK/STAT-dependent, monocyte-accentuated innate immune responses that resemble those detected in vivo in patients with mild COVID-19.
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Affiliation(s)
- Julia Kazmierski
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
- Berlin Institute of HealthBerlinGermany
| | - Kirstin Friedmann
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
| | - Dylan Postmus
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
- Berlin Institute of HealthBerlinGermany
| | - Jackson Emanuel
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
| | - Cornelius Fischer
- Scientific Genomics Platforms, Laboratory of Functional Genomics, Nutrigenomics and Systems BiologyMax Delbrück Center for Molecular MedicineBerlinGermany
| | - Jenny Jansen
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
- Berlin Institute of HealthBerlinGermany
| | - Anja Richter
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
| | - Laure Bosquillon de Jarcy
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
- Department of Infectious Diseases and Respiratory MedicineCharité ‐ Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt‐Universität zu Berlin, and Berlin Institute of Health (BIH)BerlinGermany
| | - Christiane Schüler
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
- Berlin Institute of HealthBerlinGermany
| | - Madlen Sohn
- Scientific Genomics Platforms, Laboratory of Functional Genomics, Nutrigenomics and Systems BiologyMax Delbrück Center for Molecular MedicineBerlinGermany
| | - Sascha Sauer
- Scientific Genomics Platforms, Laboratory of Functional Genomics, Nutrigenomics and Systems BiologyMax Delbrück Center for Molecular MedicineBerlinGermany
| | - Christian Drosten
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
- German Center for Infection Research, Associated Partner CharitéBerlinGermany
| | - Antoine‐Emmanuel Saliba
- Helmholtz Institute for RNA‐based Infection Research (HIRI)Helmholtz‐Center for Infection Research (HZI)WürzburgGermany
| | - Leif Erik Sander
- Department of Infectious Diseases and Respiratory MedicineCharité ‐ Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt‐Universität zu Berlin, and Berlin Institute of Health (BIH)BerlinGermany
| | - Marcel A Müller
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
- German Center for Infection Research, Associated Partner CharitéBerlinGermany
| | - Daniela Niemeyer
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
- German Center for Infection Research, Associated Partner CharitéBerlinGermany
| | - Christine Goffinet
- Institute of Virology, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlinGermany
- Berlin Institute of HealthBerlinGermany
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4
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Hall R, Guedán A, Yap MW, Young GR, Harvey R, Stoye JP, Bishop KN. SARS-CoV-2 ORF6 disrupts innate immune signalling by inhibiting cellular mRNA export. PLoS Pathog 2022; 18:e1010349. [PMID: 36007063 PMCID: PMC9451085 DOI: 10.1371/journal.ppat.1010349] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 09/07/2022] [Accepted: 07/21/2022] [Indexed: 11/18/2022] Open
Abstract
SARS-CoV-2 is a betacoronavirus and the etiological agent of COVID-19, a devastating infectious disease. Due to its far-reaching effect on human health, there is an urgent and growing need to understand the viral molecular biology of SARS-CoV-2 and its interaction with the host cell. SARS-CoV-2 encodes 9 predicted accessory proteins, which are presumed to be dispensable for in vitro replication, most likely having a role in modulating the host cell environment to aid viral replication. Here we show that the ORF6 accessory protein interacts with cellular Rae1 to inhibit cellular protein production by blocking mRNA export. We utilised cell fractionation coupled with mRNAseq to explore which cellular mRNA species are affected by ORF6 expression and show that ORF6 can inhibit the export of many mRNA including those encoding antiviral factors such as IRF1 and RIG-I. We also show that export of these mRNA is blocked in the context of SARS-CoV-2 infection. Together, our studies identify a novel mechanism by which SARS-CoV-2 can manipulate the host cell environment to supress antiviral responses, providing further understanding to the replication strategies of a virus that has caused an unprecedented global health crisis.
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Affiliation(s)
- Ross Hall
- Retroviral Replication Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Anabel Guedán
- Retroviral Replication Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Melvyn W. Yap
- Retroviral Replication Laboratory, The Francis Crick Institute, London, United Kingdom
| | - George R. Young
- Bioinformatics and Biostatistics STP, The Francis Crick Institute, London, United Kingdom
| | - Ruth Harvey
- World Influenza Centre, The Francis Crick Institute, London, United Kingdom
| | - Jonathan P. Stoye
- Retrovirus-Host Interactions Laboratory, The Francis Crick Institute, London, United Kingdom
- Department of Infectious Disease, Imperial College London, United Kingdom
| | - Kate N. Bishop
- Retroviral Replication Laboratory, The Francis Crick Institute, London, United Kingdom
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5
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Wong HT, Cheung V, Salamango DJ. Decoupling SARS-CoV-2 ORF6 localization and interferon antagonism. J Cell Sci 2022; 135:274474. [DOI: 10.1242/jcs.259666] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 02/15/2022] [Indexed: 11/20/2022] Open
Abstract
Like many pathogenic viruses, SARS-CoV-2 must overcome interferon (IFN)-mediated host defenses for infection establishment. To achieve this, SARS-CoV-2 deploys overlapping mechanisms to antagonize IFN production and signaling. The strongest IFN antagonist is the accessory protein ORF6, which localizes to multiple membranous compartments, including the nuclear envelope, where it directly binds nuclear pore components Nup98-Rae1 to inhibit nuclear translocation of activated STAT1/IRF3 transcription factors. However, this direct cause-and-effect relationship between ORF6 localization and IFN antagonism has yet to be explored experimentally. Here, we use extensive mutagenesis studies to define the structural determinants required for steady-state localization and demonstrate that mis-localized ORF6 variants still potently inhibit nuclear trafficking and IFN signaling. Additionally, expression of a peptide that mimics the ORF6/Nup98 interaction domain robustly blocked nuclear trafficking. Furthermore, pharmacologic and mutational approaches combined to suggest that ORF6 is likely a peripheral-membrane protein, opposed to being a transmembrane protein as previously speculated. Thus, ORF6 localization and IFN antagonism are independent activities, which raises the possibility that ORF6 may have additional functions within membrane networks to enhance virus replication.
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Affiliation(s)
- Hoi Tong Wong
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, 11794, USA
| | - Victoria Cheung
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, 1194, USA
| | - Daniel J. Salamango
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, 11794, USA
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6
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Chazal N. Coronavirus, the King Who Wanted More Than a Crown: From Common to the Highly Pathogenic SARS-CoV-2, Is the Key in the Accessory Genes? Front Microbiol 2021; 12:682603. [PMID: 34335504 PMCID: PMC8317507 DOI: 10.3389/fmicb.2021.682603] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/22/2021] [Indexed: 12/14/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), that emerged in late 2019, is the etiologic agent of the current "coronavirus disease 2019" (COVID-19) pandemic, which has serious health implications and a significant global economic impact. Of the seven human coronaviruses, all of which have a zoonotic origin, the pandemic SARS-CoV-2, is the third emerging coronavirus, in the 21st century, highly pathogenic to the human population. Previous human coronavirus outbreaks (SARS-CoV-1 and MERS-CoV) have already provided several valuable information on some of the common molecular and cellular mechanisms of coronavirus infections as well as their origin. However, to meet the new challenge caused by the SARS-CoV-2, a detailed understanding of the biological specificities, as well as knowledge of the origin are crucial to provide information on viral pathogenicity, transmission and epidemiology, and to enable strategies for therapeutic interventions and drug discovery. Therefore, in this review, we summarize the current advances in SARS-CoV-2 knowledges, in light of pre-existing information of other recently emerging coronaviruses. We depict the specificity of the immune response of wild bats and discuss current knowledge of the genetic diversity of bat-hosted coronaviruses that promotes viral genome expansion (accessory gene acquisition). In addition, we describe the basic virology of coronaviruses with a special focus SARS-CoV-2. Finally, we highlight, in detail, the current knowledge of genes and accessory proteins which we postulate to be the major keys to promote virus adaptation to specific hosts (bat and human), to contribute to the suppression of immune responses, as well as to pathogenicity.
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Affiliation(s)
- Nathalie Chazal
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS, Montpellier, France
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7
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Gorkhali R, Koirala P, Rijal S, Mainali A, Baral A, Bhattarai HK. Structure and Function of Major SARS-CoV-2 and SARS-CoV Proteins. Bioinform Biol Insights 2021; 15:11779322211025876. [PMID: 34220199 PMCID: PMC8221690 DOI: 10.1177/11779322211025876] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 05/25/2021] [Indexed: 01/20/2023] Open
Abstract
SARS-CoV-2 virus, the causative agent of COVID-19 pandemic, has a genomic organization consisting of 16 nonstructural proteins (nsps), 4 structural proteins, and 9 accessory proteins. Relative of SARS-CoV-2, SARS-CoV, has genomic organization, which is very similar. In this article, the function and structure of the proteins of SARS-CoV-2 and SARS-CoV are described in great detail. The nsps are expressed as a single or two polyproteins, which are then cleaved into individual proteins using two proteases of the virus, a chymotrypsin-like protease and a papain-like protease. The released proteins serve as centers of virus replication and transcription. Some of these nsps modulate the host’s translation and immune systems, while others help the virus evade the host immune system. Some of the nsps help form replication-transcription complex at double-membrane vesicles. Others, including one RNA-dependent RNA polymerase and one exonuclease, help in the polymerization of newly synthesized RNA of the virus and help minimize the mutation rate by proofreading. After synthesis of the viral RNA, it gets capped. The capping consists of adding GMP and a methylation mark, called cap 0 and additionally adding a methyl group to the terminal ribose called cap1. Capping is accomplished with the help of a helicase, which also helps remove a phosphate, two methyltransferases, and a scaffolding factor. Among the structural proteins, S protein forms the receptor of the virus, which latches on the angiotensin-converting enzyme 2 receptor of the host and N protein binds and protects the genomic RNA of the virus. The accessory proteins found in these viruses are small proteins with immune modulatory roles. Besides functions of these proteins, solved X-ray and cryogenic electron microscopy structures related to the function of the proteins along with comparisons to other coronavirus homologs have been described in the article. Finally, the rate of mutation of SARS-CoV-2 residues of the proteome during the 2020 pandemic has been described. Some proteins are mutated more often than other proteins, but the significance of these mutation rates is not fully understood.
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Affiliation(s)
- Ritesh Gorkhali
- Department of Biotechnology, Kathmandu University, Dhulikhel, Nepal
| | | | - Sadikshya Rijal
- Department of Biotechnology, Kathmandu University, Dhulikhel, Nepal
| | - Ashmita Mainali
- Department of Biotechnology, Kathmandu University, Dhulikhel, Nepal
| | - Adesh Baral
- Department of Biotechnology, Kathmandu University, Dhulikhel, Nepal
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8
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Barik S. Systematizing the genomic order and relatedness in the open reading frames (ORFs) of the coronaviruses. INFECTION GENETICS AND EVOLUTION 2021; 92:104858. [PMID: 33848683 PMCID: PMC8053407 DOI: 10.1016/j.meegid.2021.104858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 04/05/2021] [Accepted: 04/07/2021] [Indexed: 11/16/2022]
Abstract
The coronaviruses (CoVs), including SARS-CoV-2, the agent of the ongoing deadly CoVID-19 pandemic (Coronavirus disease-2019), represent a highly complex and diverse class of RNA viruses with large genomes, complex gene repertoire, and intricate transcriptional and translational mechanisms. The 3′-terminal one-third of the genome encodes four structural proteins, namely spike, envelope, membrane, and nucleocapsid, interspersed with genes for accessory proteins that are largely nonstructural and called ‘open reading frame’ (ORF) proteins with alphanumerical designations, but not in a consistent or sequential order. Here, I report a comparative study of these ORF proteins, mainly encoded in two gene clusters, i.e. between the Spike and the Envelope genes, and between the Membrane and the Nucleocapsid genes. For brevity and focus, a greater emphasis was placed on the first cluster, collectively designated as the ‘orf3 region’ for ease of referral. Overall, an apparently diverse set of ORFs, such as ORF3a, ORF3b, ORF3c, ORF3d, ORF4 and ORF5, but not necessarily numbered in that order on all CoV genomes, were analyzed along with other ORFs. Unexpectedly, the gene order or naming of the ORFs were never fully conserved even within the members of one Genus. These studies also unraveled hitherto unrecognized orf genes in alternative translational frames, encoding potentially novel polypeptides as well as some that are highly similar to known ORFs. Finally, several options of an inclusive and systematic numbering are proposed not only for the orf3 region but also for the other orf genes in the viral genome in an effort to regularize the apparently confusing names and orders. Regardless of the ultimate acceptability of one system over the others, this treatise is hoped to initiate an informed discourse in this area.
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9
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Prates ET, Garvin MR, Pavicic M, Jones P, Shah M, Demerdash O, Amos BK, Geiger A, Jacobson D. Potential Pathogenicity Determinants Identified from Structural Proteomics of SARS-CoV and SARS-CoV-2. Mol Biol Evol 2021; 38:702-715. [PMID: 32941612 PMCID: PMC7543629 DOI: 10.1093/molbev/msaa231] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Despite SARS-CoV and SARS-CoV-2 being equipped with highly similar protein arsenals, the corresponding zoonoses have spread among humans at extremely different rates. The specific characteristics of these viruses that led to such distinct outcomes remain unclear. Here, we apply proteome-wide comparative structural analysis aiming to identify the unique molecular elements in the SARS-CoV-2 proteome that may explain the differing consequences. By combining protein modeling and molecular dynamics simulations, we suggest nonconservative substitutions in functional regions of the spike glycoprotein (S), nsp1, and nsp3 that are contributing to differences in virulence. Particularly, we explain why the substitutions at the receptor-binding domain of S affect the structure–dynamics behavior in complexes with putative host receptors. Conservation of functional protein regions within the two taxa is also noteworthy. We suggest that the highly conserved main protease, nsp5, of SARS-CoV and SARS-CoV-2 is part of their mechanism of circumventing the host interferon antiviral response. Overall, most substitutions occur on the protein surfaces and may be modulating their antigenic properties and interactions with other macromolecules. Our results imply that the striking difference in the pervasiveness of SARS-CoV-2 and SARS-CoV among humans seems to significantly derive from molecular features that modulate the efficiency of viral particles in entering the host cells and blocking the host immune response.
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Affiliation(s)
- Erica T Prates
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN.,National Virtual Biotechnology Laboratory, US Department of Energy, TN
| | - Michael R Garvin
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN.,National Virtual Biotechnology Laboratory, US Department of Energy, TN
| | - Mirko Pavicic
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN.,National Virtual Biotechnology Laboratory, US Department of Energy, TN
| | - Piet Jones
- National Virtual Biotechnology Laboratory, US Department of Energy, TN.,The Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee Knoxville, Knoxville, TN
| | - Manesh Shah
- Genome Science and Technology, The University of Tennessee Knoxville, Knoxville, TN
| | - Omar Demerdash
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN
| | - B Kirtley Amos
- Department of Horticulture, N-318 Ag Sciences Center, University of Kentucky, Lexington, KY
| | - Armin Geiger
- National Virtual Biotechnology Laboratory, US Department of Energy, TN.,The Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee Knoxville, Knoxville, TN
| | - Daniel Jacobson
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN.,National Virtual Biotechnology Laboratory, US Department of Energy, TN.,The Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee Knoxville, Knoxville, TN.,Genome Science and Technology, The University of Tennessee Knoxville, Knoxville, TN.,Department of Psychology, The University of Tennessee Knoxville, Knoxville, TN
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10
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Chugh RM, Bhanja P, Norris A, Saha S. Experimental Models to Study COVID-19 Effect in Stem Cells. Cells 2021; 10:E91. [PMID: 33430424 PMCID: PMC7827246 DOI: 10.3390/cells10010091] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 12/30/2020] [Accepted: 01/06/2021] [Indexed: 12/18/2022] Open
Abstract
The new strain of coronavirus (severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2)) emerged in 2019 and hence is often referred to as coronavirus disease 2019 (COVID-19). This disease causes hypoxic respiratory failure and acute respiratory distress syndrome (ARDS), and is considered as the cause of a global pandemic. Very limited reports in addition to ex vivo model systems are available to understand the mechanism of action of this virus, which can be used for testing of any drug efficacy against virus infectivity. COVID-19 induces tissue stem cell loss, resulting inhibition of epithelial repair followed by inflammatory fibrotic consequences. Development of clinically relevant models is important to examine the impact of the COVID-19 virus in tissue stem cells among different organs. In this review, we discuss ex vivo experimental models available to study the effect of COVID-19 on tissue stem cells.
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Affiliation(s)
- Rishi Man Chugh
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS 66160, USA; (R.M.C.); (P.B.)
| | - Payel Bhanja
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS 66160, USA; (R.M.C.); (P.B.)
| | - Andrew Norris
- BCN Bio Sciences, Pasadena, CA 91107, USA;
- David Geffen School of Medicine at University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Subhrajit Saha
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS 66160, USA; (R.M.C.); (P.B.)
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
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11
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Garvin MR, T Prates E, Pavicic M, Jones P, Amos BK, Geiger A, Shah MB, Streich J, Felipe Machado Gazolla JG, Kainer D, Cliff A, Romero J, Keith N, Brown JB, Jacobson D. Potentially adaptive SARS-CoV-2 mutations discovered with novel spatiotemporal and explainable AI models. Genome Biol 2020; 21:304. [PMID: 33357233 PMCID: PMC7756312 DOI: 10.1186/s13059-020-02191-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/29/2020] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND A mechanistic understanding of the spread of SARS-CoV-2 and diligent tracking of ongoing mutagenesis are of key importance to plan robust strategies for confining its transmission. Large numbers of available sequences and their dates of transmission provide an unprecedented opportunity to analyze evolutionary adaptation in novel ways. Addition of high-resolution structural information can reveal the functional basis of these processes at the molecular level. Integrated systems biology-directed analyses of these data layers afford valuable insights to build a global understanding of the COVID-19 pandemic. RESULTS Here we identify globally distributed haplotypes from 15,789 SARS-CoV-2 genomes and model their success based on their duration, dispersal, and frequency in the host population. Our models identify mutations that are likely compensatory adaptive changes that allowed for rapid expansion of the virus. Functional predictions from structural analyses indicate that, contrary to previous reports, the Asp614Gly mutation in the spike glycoprotein (S) likely reduced transmission and the subsequent Pro323Leu mutation in the RNA-dependent RNA polymerase led to the precipitous spread of the virus. Our model also suggests that two mutations in the nsp13 helicase allowed for the adaptation of the virus to the Pacific Northwest of the USA. Finally, our explainable artificial intelligence algorithm identified a mutational hotspot in the sequence of S that also displays a signature of positive selection and may have implications for tissue or cell-specific expression of the virus. CONCLUSIONS These results provide valuable insights for the development of drugs and surveillance strategies to combat the current and future pandemics.
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Affiliation(s)
- Michael R Garvin
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
| | - Erica T Prates
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
| | - Mirko Pavicic
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
| | - Piet Jones
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
- The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee Knoxville, Knoxville, TN, USA
| | - B Kirtley Amos
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
- Department of Horticulture, N-318 Ag Sciences Center, University of Kentucky, Lexington, KY, USA
| | - Armin Geiger
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
- The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Manesh B Shah
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
| | - Jared Streich
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
| | | | - David Kainer
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
| | - Ashley Cliff
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
- The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Jonathon Romero
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA
- The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Nathan Keith
- Lawrence Berkeley National Laboratory, Environmental Genomics & Systems Biology, Berkeley, CA, USA
| | - James B Brown
- Lawrence Berkeley National Laboratory, Environmental Genomics & Systems Biology, Berkeley, CA, USA
| | - Daniel Jacobson
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, USA.
- The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee Knoxville, Knoxville, TN, USA.
- Department of Psychology, University of Tennessee Knoxville, Knoxville, TN, USA.
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12
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Matsuyama T, Kubli SP, Yoshinaga SK, Pfeffer K, Mak TW. An aberrant STAT pathway is central to COVID-19. Cell Death Differ 2020. [PMID: 33037393 DOI: 10.1038/s41418‐020‐00633‐7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
COVID-19 is caused by SARS-CoV-2 infection and characterized by diverse clinical symptoms. Type I interferon (IFN-I) production is impaired and severe cases lead to ARDS and widespread coagulopathy. We propose that COVID-19 pathophysiology is initiated by SARS-CoV-2 gene products, the NSP1 and ORF6 proteins, leading to a catastrophic cascade of failures. These viral components induce signal transducer and activator of transcription 1 (STAT1) dysfunction and compensatory hyperactivation of STAT3. In SARS-CoV-2-infected cells, a positive feedback loop established between STAT3 and plasminogen activator inhibitor-1 (PAI-1) may lead to an escalating cycle of activation in common with the interdependent signaling networks affected in COVID-19. Specifically, PAI-1 upregulation leads to coagulopathy characterized by intravascular thrombi. Overproduced PAI-1 binds to TLR4 on macrophages, inducing the secretion of proinflammatory cytokines and chemokines. The recruitment and subsequent activation of innate immune cells within an infected lung drives the destruction of lung architecture, which leads to the infection of regional endothelial cells and produces a hypoxic environment that further stimulates PAI-1 production. Acute lung injury also activates EGFR and leads to the phosphorylation of STAT3. COVID-19 patients' autopsies frequently exhibit diffuse alveolar damage (DAD) and increased hyaluronan (HA) production which also leads to higher levels of PAI-1. COVID-19 risk factors are consistent with this scenario, as PAI-1 levels are increased in hypertension, obesity, diabetes, cardiovascular diseases, and old age. We discuss the possibility of using various approved drugs, or drugs currently in clinical development, to treat COVID-19. This perspective suggests to enhance STAT1 activity and/or inhibit STAT3 functions for COVID-19 treatment. This might derail the escalating STAT3/PAI-1 cycle central to COVID-19.
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Affiliation(s)
- Toshifumi Matsuyama
- Department of Pathology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Shawn P Kubli
- Princess Margaret Cancer Centre, University Health Network, 610 University Avenue, Toronto, ON, M5G 2M9, Canada
| | | | - Klaus Pfeffer
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tak W Mak
- Princess Margaret Cancer Centre, University Health Network, 610 University Avenue, Toronto, ON, M5G 2M9, Canada. .,Department of Medical Biophysics and Department of Immunology, University of Toronto, 101 College Street, Toronto, ON, M5G 1L7, Canada. .,Department of Medicine, University of Hong Kong, Pok Fu Lam, 999077, Hong Kong.
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13
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An aberrant STAT pathway is central to COVID-19. Cell Death Differ 2020; 27:3209-3225. [PMID: 33037393 PMCID: PMC7545020 DOI: 10.1038/s41418-020-00633-7] [Citation(s) in RCA: 198] [Impact Index Per Article: 49.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 09/20/2020] [Accepted: 09/24/2020] [Indexed: 02/07/2023] Open
Abstract
COVID-19 is caused by SARS-CoV-2 infection and characterized by diverse clinical symptoms. Type I interferon (IFN-I) production is impaired and severe cases lead to ARDS and widespread coagulopathy. We propose that COVID-19 pathophysiology is initiated by SARS-CoV-2 gene products, the NSP1 and ORF6 proteins, leading to a catastrophic cascade of failures. These viral components induce signal transducer and activator of transcription 1 (STAT1) dysfunction and compensatory hyperactivation of STAT3. In SARS-CoV-2-infected cells, a positive feedback loop established between STAT3 and plasminogen activator inhibitor-1 (PAI-1) may lead to an escalating cycle of activation in common with the interdependent signaling networks affected in COVID-19. Specifically, PAI-1 upregulation leads to coagulopathy characterized by intravascular thrombi. Overproduced PAI-1 binds to TLR4 on macrophages, inducing the secretion of proinflammatory cytokines and chemokines. The recruitment and subsequent activation of innate immune cells within an infected lung drives the destruction of lung architecture, which leads to the infection of regional endothelial cells and produces a hypoxic environment that further stimulates PAI-1 production. Acute lung injury also activates EGFR and leads to the phosphorylation of STAT3. COVID-19 patients' autopsies frequently exhibit diffuse alveolar damage (DAD) and increased hyaluronan (HA) production which also leads to higher levels of PAI-1. COVID-19 risk factors are consistent with this scenario, as PAI-1 levels are increased in hypertension, obesity, diabetes, cardiovascular diseases, and old age. We discuss the possibility of using various approved drugs, or drugs currently in clinical development, to treat COVID-19. This perspective suggests to enhance STAT1 activity and/or inhibit STAT3 functions for COVID-19 treatment. This might derail the escalating STAT3/PAI-1 cycle central to COVID-19.
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14
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Patel CN, Kumar SP, Pandya HA, Rawal RM. Identification of potential inhibitors of coronavirus hemagglutinin-esterase using molecular docking, molecular dynamics simulation and binding free energy calculation. Mol Divers 2020; 25:421-433. [PMID: 32996011 PMCID: PMC7524381 DOI: 10.1007/s11030-020-10135-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/18/2020] [Indexed: 02/07/2023]
Abstract
Abstract The pandemic outbreak of the Corona viral infection has become a critical global health issue. Biophysical and structural evidence shows that spike protein possesses a high binding affinity towards host angiotensin-converting enzyme 2 and viral hemagglutinin-acetylesterase (HE) glycoprotein receptor. We selected HE as a target in this study to identify potential inhibitors using a combination of various computational approaches such as molecular docking, ADMET analysis, dynamics simulations and binding free energy calculations. Virtual screening of NPACT compounds identified 3,4,5-Trihydroxy-1,8-bis[(2R,3R)-3,5,7-trihydroxy-3,4-dihydro-2H-chromen-2-yl]benzo[7]annulen-6-one, Silymarin, Withanolide D, Spirosolane and Oridonin as potential HE inhibitors with better binding energy. Furthermore, molecular dynamics simulations for 100 ns time scale revealed that most of the key HE contacts were retained throughout the simulations trajectories. Binding free energy calculations using MM/PBSA approach ranked the top-five potential NPACT compounds which can act as effective HE inhibitors. Graphic abstract ![]()
Electronic supplementary material The online version of this article (10.1007/s11030-020-10135-w) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chirag N Patel
- Department of Botany, Bioinformatics, and Climate Change Impacts Management, University School of Sciences, Gujarat University, Ahmedabad, 380009, India
| | - Sivakumar Prasanth Kumar
- Department of Life Sciences, University School of Sciences, Gujarat University, Ahmedabad, 380009, India
| | - Himanshu A Pandya
- Department of Botany, Bioinformatics, and Climate Change Impacts Management, University School of Sciences, Gujarat University, Ahmedabad, 380009, India
| | - Rakesh M Rawal
- Department of Life Sciences, University School of Sciences, Gujarat University, Ahmedabad, 380009, India.
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15
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Koonpaew S, Teeravechyan S, Frantz PN, Chailangkarn T, Jongkaewwattana A. PEDV and PDCoV Pathogenesis: The Interplay Between Host Innate Immune Responses and Porcine Enteric Coronaviruses. Front Vet Sci 2019; 6:34. [PMID: 30854373 PMCID: PMC6395401 DOI: 10.3389/fvets.2019.00034] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 01/28/2019] [Indexed: 12/24/2022] Open
Abstract
Enteropathogenic porcine epidemic diarrhea virus (PEDV) and porcine deltacoronavirus (PDCoV), members of the coronavirus family, account for the majority of lethal watery diarrhea in neonatal pigs in the past decade. These two viruses pose significant economic and public health burdens, even as both continue to emerge and reemerge worldwide. The ability to evade, circumvent or subvert the host’s first line of defense, namely the innate immune system, is the key determinant for pathogen virulence, survival, and the establishment of successful infection. Unfortunately, we have only started to unravel the underlying viral mechanisms used to manipulate host innate immune responses. In this review, we gather current knowledge concerning the interplay between these viruses and components of host innate immunity, focusing on type I interferon induction and signaling in particular, and the mechanisms by which virus-encoded gene products antagonize and subvert host innate immune responses. Finally, we provide some perspectives on the advantages gained from a better understanding of host-pathogen interactions. This includes their implications for the future development of PEDV and PDCoV vaccines and how we can further our knowledge of the molecular mechanisms underlying virus pathogenesis, virulence, and host coevolution.
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Affiliation(s)
- Surapong Koonpaew
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathumthani, Thailand
| | - Samaporn Teeravechyan
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathumthani, Thailand
| | - Phanramphoei Namprachan Frantz
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathumthani, Thailand
| | - Thanathom Chailangkarn
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathumthani, Thailand
| | - Anan Jongkaewwattana
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathumthani, Thailand
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16
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Porcine Deltacoronavirus Accessory Protein NS6 Antagonizes Interferon Beta Production by Interfering with the Binding of RIG-I/MDA5 to Double-Stranded RNA. J Virol 2018; 92:JVI.00712-18. [PMID: 29769346 DOI: 10.1128/jvi.00712-18] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 05/11/2018] [Indexed: 12/12/2022] Open
Abstract
Porcine deltacoronavirus (PDCoV) has recently emerged as an enteric pathogen that can cause serious vomiting and diarrhea in suckling piglets. The first outbreak of PDCoV occurred in the United States in 2014 and was followed by reports of PDCoV in South Korea, China, Thailand, Lao People's Democratic Republic, and Vietnam, leading to economic losses for pig farms and posing a considerable threat to the swine industry worldwide. Our previous studies have shown that PDCoV encodes three accessory proteins, NS6, NS7, and NS7a, but the functions of these proteins in viral replication, pathogenesis, and immune regulation remain unclear. Here, we found that ectopic expression of accessory protein NS6 significantly inhibits Sendai virus-induced interferon beta (IFN-β) production as well as the activation of transcription factors IRF3 and NF-κB. Interestingly, NS6 does not impede the IFN-β promoter activation mediated via key molecules in the RIG-I-like receptor (RLR) signaling pathway, specifically RIG-I, MDA5, and their downstream molecules MAVS, TBK1, IKKε, and IRF3. Further analyses revealed that NS6 is not an RNA-binding protein; however, it interacts with RIG-I/MDA5. This interaction attenuates the binding of double-stranded RNA by RIG-I/MDA5, resulting in the reduction of RLR-mediated IFN-β production. Taken together, our results demonstrate that ectopic expression of NS6 antagonizes IFN-β production by interfering with the binding of RIG-I/MDA5 to double-stranded RNA, revealing a new strategy employed by PDCoV accessory proteins to counteract the host innate antiviral immune response.IMPORTANCE Coronavirus accessory proteins are species specific, and they perform multiple functions in viral pathogenicity and immunity, such as acting as IFN antagonists and cell death inducers. Our previous studies have shown that PDCoV encodes three accessory proteins. Here, we demonstrated for the first time that PDCoV accessory protein NS6 antagonizes IFN-β production by interacting with RIG-I and MDA5 to impede their association with double-stranded RNA. This is an efficient strategy of antagonizing type I IFN production by disrupting the binding of host pattern recognition receptors (PRRs) and pathogen-associated molecular patterns (PAMPs). These findings deepen our understanding of the function of accessory protein NS6, and they may direct us toward novel therapeutic targets and lead to the development of more effective vaccines against PDCoV infection.
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Agrawal AS, Tao X, Algaissi A, Garron T, Narayanan K, Peng BH, Couch RB, Tseng CTK. Immunization with inactivated Middle East Respiratory Syndrome coronavirus vaccine leads to lung immunopathology on challenge with live virus. Hum Vaccin Immunother 2016. [PMID: 27269431 DOI: 10.1080/21645515.2016.11776881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2023] Open
Abstract
To determine if a hypersensitive-type lung pathology might occur when mice were given an inactivated MERS-CoV vaccine and challenged with infectious virus as was seen with SARS-CoV vaccines, we prepared and vaccinated mice with an inactivated MERS-CoV vaccine. Neutralizing antibody was induced by vaccine with and without adjuvant and lung virus was reduced in vaccinated mice after challenge. Lung mononuclear infiltrates occurred in all groups after virus challenge but with increased infiltrates that contained eosinophils and increases in the eosinophil promoting IL-5 and IL-13 cytokines only in the vaccine groups. Inactivated MERS-CoV vaccine appears to carry a hypersensitive-type lung pathology risk from MERS-CoV infection that is similar to that found with inactivated SARS-CoV vaccines from SARS-CoV infection.
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Affiliation(s)
- Anurodh Shankar Agrawal
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
| | - Xinrong Tao
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
| | - Abdullah Algaissi
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
- e Department of Medical Laboratories Technology , College of Applied Medical Sciences, Jazan University , Jazan , Saudi Arabia
| | - Tania Garron
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
| | - Krishna Narayanan
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
| | - Bi-Hung Peng
- b Pathology, University of Texas Medical Branch , Galveston , TX , USA
| | - Robert B Couch
- c Internal Medicine, Division of Infectious Disease, University of Texas Medical Branch , Galveston , TX , USA
| | - Chien-Te K Tseng
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
- d Center for Biodefense and Emerging Infectious Disease, University of Texas Medical Branch , Galveston , TX , USA
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18
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Agrawal AS, Tao X, Algaissi A, Garron T, Narayanan K, Peng BH, Couch RB, Tseng CTK. Immunization with inactivated Middle East Respiratory Syndrome coronavirus vaccine leads to lung immunopathology on challenge with live virus. Hum Vaccin Immunother 2016; 12:2351-6. [PMID: 27269431 PMCID: PMC5027702 DOI: 10.1080/21645515.2016.1177688] [Citation(s) in RCA: 173] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
To determine if a hypersensitive-type lung pathology might occur when mice were given an inactivated MERS-CoV vaccine and challenged with infectious virus as was seen with SARS-CoV vaccines, we prepared and vaccinated mice with an inactivated MERS-CoV vaccine. Neutralizing antibody was induced by vaccine with and without adjuvant and lung virus was reduced in vaccinated mice after challenge. Lung mononuclear infiltrates occurred in all groups after virus challenge but with increased infiltrates that contained eosinophils and increases in the eosinophil promoting IL-5 and IL-13 cytokines only in the vaccine groups. Inactivated MERS-CoV vaccine appears to carry a hypersensitive-type lung pathology risk from MERS-CoV infection that is similar to that found with inactivated SARS-CoV vaccines from SARS-CoV infection.
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Affiliation(s)
- Anurodh Shankar Agrawal
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
| | - Xinrong Tao
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
| | - Abdullah Algaissi
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA.,e Department of Medical Laboratories Technology , College of Applied Medical Sciences, Jazan University , Jazan , Saudi Arabia
| | - Tania Garron
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
| | - Krishna Narayanan
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA
| | - Bi-Hung Peng
- b Pathology, University of Texas Medical Branch , Galveston , TX , USA
| | - Robert B Couch
- c Internal Medicine, Division of Infectious Disease, University of Texas Medical Branch , Galveston , TX , USA
| | - Chien-Te K Tseng
- a Departments of Microbiology and Immunology , University of Texas Medical Branch , Galveston , TX , USA.,d Center for Biodefense and Emerging Infectious Disease, University of Texas Medical Branch , Galveston , TX , USA
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Jimenez-Guardeño JM, Regla-Nava JA, Nieto-Torres JL, DeDiego ML, Castaño-Rodriguez C, Fernandez-Delgado R, Perlman S, Enjuanes L. Identification of the Mechanisms Causing Reversion to Virulence in an Attenuated SARS-CoV for the Design of a Genetically Stable Vaccine. PLoS Pathog 2015; 11:e1005215. [PMID: 26513244 PMCID: PMC4626112 DOI: 10.1371/journal.ppat.1005215] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 09/18/2015] [Indexed: 12/15/2022] Open
Abstract
A SARS-CoV lacking the full-length E gene (SARS-CoV-∆E) was attenuated and an effective vaccine. Here, we show that this mutant virus regained fitness after serial passages in cell culture or in vivo, resulting in the partial duplication of the membrane gene or in the insertion of a new sequence in gene 8a, respectively. The chimeric proteins generated in cell culture increased virus fitness in vitro but remained attenuated in mice. In contrast, during SARS-CoV-∆E passage in mice, the virus incorporated a mutated variant of 8a protein, resulting in reversion to a virulent phenotype. When the full-length E protein was deleted or its PDZ-binding motif (PBM) was mutated, the revertant viruses either incorporated a novel chimeric protein with a PBM or restored the sequence of the PBM on the E protein, respectively. Similarly, after passage in mice, SARS-CoV-∆E protein 8a mutated, to now encode a PBM, and also regained virulence. These data indicated that the virus requires a PBM on a transmembrane protein to compensate for removal of this motif from the E protein. To increase the genetic stability of the vaccine candidate, we introduced small attenuating deletions in E gene that did not affect the endogenous PBM, preventing the incorporation of novel chimeric proteins in the virus genome. In addition, to increase vaccine biosafety, we introduced additional attenuating mutations into the nsp1 protein. Deletions in the carboxy-terminal region of nsp1 protein led to higher host interferon responses and virus attenuation. Recombinant viruses including attenuating mutations in E and nsp1 genes maintained their attenuation after passage in vitro and in vivo. Further, these viruses fully protected mice against challenge with the lethal parental virus, and are therefore safe and stable vaccine candidates for protection against SARS-CoV. Zoonotic coronaviruses, including SARS-CoV, Middle East respiratory syndrome (MERS-CoV), porcine epidemic diarrhea virus (PEDV) and swine delta coronavirus (SDCoV) have recently emerged causing high morbidity and mortality in human or piglets. No fully protective therapy is still available for these CoVs. Therefore, the development of efficient vaccines is a high priority. Live attenuated vaccines are considered most effective compared to other types of vaccines, as they induce a long-lived, balanced immune response. However, safety is the main concern of this type of vaccines because attenuated viruses can eventually revert to a virulent phenotype. Therefore, an essential feature of any live attenuated vaccine candidate is its stability. In addition, introduction of several safety guards is advisable to increase vaccine safety. In this manuscript, we analyzed the mechanisms by which an attenuated SARS-CoV reverted to a virulent phenotype and describe the introduction of attenuating deletions that maintained virus stability. The virus, engineered with two safety guards, provided full protection against challenge with a lethal SARS-CoV. Understanding the molecular mechanisms leading to pathogenicity and the in vivo evaluation of vaccine genetic stability contributed to a rational design of a promising SARS-CoV vaccine.
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Affiliation(s)
- Jose M. Jimenez-Guardeño
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Campus Universidad Autónoma de Madrid, Madrid, Spain
| | - Jose A. Regla-Nava
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Campus Universidad Autónoma de Madrid, Madrid, Spain
| | - Jose L. Nieto-Torres
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Campus Universidad Autónoma de Madrid, Madrid, Spain
| | - Marta L. DeDiego
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Campus Universidad Autónoma de Madrid, Madrid, Spain
| | - Carlos Castaño-Rodriguez
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Campus Universidad Autónoma de Madrid, Madrid, Spain
| | - Raul Fernandez-Delgado
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Campus Universidad Autónoma de Madrid, Madrid, Spain
| | - Stanley Perlman
- Department of Microbiology, University of Iowa, Iowa City, Iowa, United States of America
| | - Luis Enjuanes
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Campus Universidad Autónoma de Madrid, Madrid, Spain
- * E-mail:
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20
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DeDiego ML, Nieto-Torres JL, Jimenez-Guardeño JM, Regla-Nava JA, Castaño-Rodriguez C, Fernandez-Delgado R, Usera F, Enjuanes L. Coronavirus virulence genes with main focus on SARS-CoV envelope gene. Virus Res 2014; 194:124-37. [PMID: 25093995 PMCID: PMC4261026 DOI: 10.1016/j.virusres.2014.07.024] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 07/21/2014] [Accepted: 07/24/2014] [Indexed: 12/20/2022]
Abstract
Coronavirus (CoV) infection is usually detected by cellular sensors, which trigger the activation of the innate immune system. Nevertheless, CoVs have evolved viral proteins that target different signaling pathways to counteract innate immune responses. Some CoV proteins act as antagonists of interferon (IFN) by inhibiting IFN production or signaling, aspects that are briefly addressed in this review. After CoV infection, potent cytokines relevant in controlling virus infections and priming adaptive immune responses are also generated. However, an uncontrolled induction of these proinflammatory cytokines can lead to pathogenesis and disease severity as described for SARS-CoV and MERS-CoV. The cellular pathways mediated by interferon regulatory factor (IRF)-3 and -7, activating transcription factor (ATF)-2/jun, activator protein (AP)-1, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and nuclear factor of activated T cells (NF-AT), are the main drivers of the inflammatory response triggered after viral infections, with NF-κB pathway the most frequently activated. Key CoV proteins involved in the regulation of these pathways and the proinflammatory immune response are revisited in this manuscript. It has been shown that the envelope (E) protein plays a variable role in CoV morphogenesis, depending on the CoV genus, being absolutely essential in some cases (genus α CoVs such as TGEV, and genus β CoVs such as MERS-CoV), but not in others (genus β CoVs such as MHV or SARS-CoV). A comprehensive accumulation of data has shown that the relatively small E protein elicits a strong influence on the interaction of SARS-CoV with the host. In fact, after infection with viruses in which this protein has been deleted, increased cellular stress and unfolded protein responses, apoptosis, and augmented host immune responses were observed. In contrast, the presence of E protein activated a pathogenic inflammatory response that may cause death in animal models and in humans. The modification or deletion of different motifs within E protein, including the transmembrane domain that harbors an ion channel activity, small sequences within the middle region of the carboxy-terminus of E protein, and its most carboxy-terminal end, which contains a PDZ domain-binding motif (PBM), is sufficient to attenuate the virus. Interestingly, a comprehensive collection of SARS-CoVs in which these motifs have been modified elicited full and long-term protection even in old mice, making those deletion mutants promising vaccine candidates. These data indicate that despite its small size, E protein drastically influences the replication of CoVs and their pathogenicity. Although E protein is not essential for CoV genome replication or subgenomic mRNA synthesis, it affects virus morphogenesis, budding, assembly, intracellular trafficking, and virulence. In fact, E protein is responsible in a significant proportion of the inflammasome activation and the associated inflammation elicited by SARS-CoV in the lung parenchyma. This exacerbated inflammation causes edema accumulation leading to acute respiratory distress syndrome (ARDS) and, frequently, to the death of infected animal models or human patients.
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Affiliation(s)
- Marta L DeDiego
- Department of Molecular and Cell Biology, National Center of Biotechnology (CNB-CSIC), Campus Universidad Autonoma de Madrid, Madrid, Spain
| | - Jose L Nieto-Torres
- Department of Molecular and Cell Biology, National Center of Biotechnology (CNB-CSIC), Campus Universidad Autonoma de Madrid, Madrid, Spain
| | - Jose M Jimenez-Guardeño
- Department of Molecular and Cell Biology, National Center of Biotechnology (CNB-CSIC), Campus Universidad Autonoma de Madrid, Madrid, Spain
| | - Jose A Regla-Nava
- Department of Molecular and Cell Biology, National Center of Biotechnology (CNB-CSIC), Campus Universidad Autonoma de Madrid, Madrid, Spain
| | - Carlos Castaño-Rodriguez
- Department of Molecular and Cell Biology, National Center of Biotechnology (CNB-CSIC), Campus Universidad Autonoma de Madrid, Madrid, Spain
| | - Raul Fernandez-Delgado
- Department of Molecular and Cell Biology, National Center of Biotechnology (CNB-CSIC), Campus Universidad Autonoma de Madrid, Madrid, Spain
| | - Fernando Usera
- Department of Biosafety, National Center of Biotechnology (CNB-CSIC), Campus Universidad Autonoma de Madrid, Madrid, Spain
| | - Luis Enjuanes
- Department of Molecular and Cell Biology, National Center of Biotechnology (CNB-CSIC), Campus Universidad Autonoma de Madrid, Madrid, Spain.
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21
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Narayanan K, Ramirez SI, Lokugamage KG, Makino S. Coronavirus nonstructural protein 1: Common and distinct functions in the regulation of host and viral gene expression. Virus Res 2014; 202:89-100. [PMID: 25432065 PMCID: PMC4444399 DOI: 10.1016/j.virusres.2014.11.019] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 01/16/2023]
Abstract
Novel strategies to inhibit host gene expression by coronavirus nonstructural protein 1. Summarizes the conserved and divergent functions of Alpha and Betacoronavirus nsp1. Provides a mechanistic insight into the unique properties of SARS coronavirus nsp1.
The recent emergence of two highly pathogenic human coronaviruses (CoVs), severe acute respiratory syndrome CoV and Middle East respiratory syndrome CoV, has ignited a strong interest in the identification of viral factors that determine the virulence and pathogenesis of CoVs. The nonstructural protein 1 (nsp1) of CoVs has attracted considerable attention in this regard as a potential virulence factor and a target for CoV vaccine development because of accumulating evidence that point to its role in the downregulation of host innate immune responses to CoV infection. Studies have revealed both functional conservation and mechanistic divergence among the nsp1 of different mammalian CoVs in perturbing host gene expression and antiviral responses. This review summarizes the current knowledge about the biological functions of CoV nsp1 that provides an insight into the novel strategies utilized by this viral protein to modulate host and viral gene expression during CoV infection.
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Affiliation(s)
- Krishna Narayanan
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, TX 77555-1019, United States.
| | - Sydney I Ramirez
- Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX 77555-1019, United States.
| | - Kumari G Lokugamage
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, TX 77555-1019, United States.
| | - Shinji Makino
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, TX 77555-1019, United States.
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22
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Liu DX, Fung TS, Chong KKL, Shukla A, Hilgenfeld R. Accessory proteins of SARS-CoV and other coronaviruses. Antiviral Res 2014; 109:97-109. [PMID: 24995382 PMCID: PMC7113789 DOI: 10.1016/j.antiviral.2014.06.013] [Citation(s) in RCA: 292] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 06/17/2014] [Accepted: 06/23/2014] [Indexed: 01/21/2023]
Abstract
The huge RNA genome of SARS coronavirus comprises a number of open reading frames that code for a total of eight accessory proteins. Although none of these are essential for virus replication, some appear to have a role in virus pathogenesis. Notably, some SARS-CoV accessory proteins have been shown to modulate the interferon signaling pathways and the production of pro-inflammatory cytokines. The structural information on these proteins is also limited, with only two (p7a and p9b) having their structures determined by X-ray crystallography. This review makes an attempt to summarize the published knowledge on SARS-CoV accessory proteins, with an emphasis on their involvement in virus-host interaction. The accessory proteins of other coronaviruses are also briefly discussed. This paper forms part of a series of invited articles in Antiviral Research on "From SARS to MERS: 10 years of research on highly pathogenic human coronaviruses" (see Introduction by Hilgenfeld and Peiris (2013)).
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Affiliation(s)
- Ding Xiang Liu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
| | - To Sing Fung
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Kelvin Kian-Long Chong
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Aditi Shukla
- Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany; German Center for Infection Research (DZIF), University of Lübeck, Germany
| | - Rolf Hilgenfeld
- Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany; German Center for Infection Research (DZIF), University of Lübeck, Germany
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23
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McBride R, Fielding BC. The role of severe acute respiratory syndrome (SARS)-coronavirus accessory proteins in virus pathogenesis. Viruses 2012. [PMID: 23202509 PMCID: PMC3509677 DOI: 10.3390/v4112902] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
A respiratory disease caused by a novel coronavirus, termed the severe acute respiratory syndrome coronavirus (SARS-CoV), was first reported in China in late 2002. The subsequent efficient human-to-human transmission of this virus eventually affected more than 30 countries worldwide, resulting in a mortality rate of ~10% of infected individuals. The spread of the virus was ultimately controlled by isolation of infected individuals and there has been no infections reported since April 2004. However, the natural reservoir of the virus was never identified and it is not known if this virus will re-emerge and, therefore, research on this virus continues. The SARS-CoV genome is about 30 kb in length and is predicted to contain 14 functional open reading frames (ORFs). The genome encodes for proteins that are homologous to known coronavirus proteins, such as the replicase proteins (ORFs 1a and 1b) and the four major structural proteins: nucleocapsid (N), spike (S), membrane (M) and envelope (E). SARS-CoV also encodes for eight unique proteins, called accessory proteins, with no known homologues. This review will summarize the current knowledge on SARS-CoV accessory proteins and will include: (i) expression and processing; (ii) the effects on cellular processes; and (iii) functional studies.
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Affiliation(s)
- Ruth McBride
- Anatomy Cluster, Department of Medical Biosciences, Faculty of Natural Sciences, University of the Western Cape, Private Bag X17, Modderdam Road, Bellville, Western Cape, 7535, South Africa;
| | - Burtram C. Fielding
- Molecular Biology and Virology Laboratory, Department of Medical Biosciences, Faculty of Natural Sciences, University of the Western Cape, Private Bag X17, Modderdam Road, Bellville, Western Cape, 7535, South Africa
- Author to whom correspondence should be addressed; ; Tel.: +27-21-959-3620; Fax: +27-21-959-3125
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24
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Verdiá-Báguena C, Nieto-Torres JL, Alcaraz A, DeDiego ML, Torres J, Aguilella VM, Enjuanes L. Coronavirus E protein forms ion channels with functionally and structurally-involved membrane lipids. Virology 2012; 432:485-94. [PMID: 22832120 PMCID: PMC3438407 DOI: 10.1016/j.virol.2012.07.005] [Citation(s) in RCA: 144] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 06/06/2012] [Accepted: 07/06/2012] [Indexed: 12/28/2022]
Abstract
Coronavirus (CoV) envelope (E) protein ion channel activity was determined in channels formed in planar lipid bilayers by peptides representing either the transmembrane domain of severe acute respiratory syndrome CoV (SARS-CoV) E protein, or the full-length E protein. Both of them formed a voltage independent ion conductive pore with symmetric ion transport properties. Mutations N15A and V25F located in the transmembrane domain prevented the ion conductivity. E protein derived channels showed no cation preference in non-charged lipid membranes, whereas they behaved as pores with mild cation selectivity in negatively-charged lipid membranes. The ion conductance was also controlled by the lipid composition of the membrane. Lipid charge also regulated the selectivity of a HCoV-229E E protein derived peptide. These results suggested that the lipids are functionally involved in E protein ion channel activity, forming a protein-lipid pore, a novel concept for CoV E protein ion channel entity.
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Affiliation(s)
- Carmina Verdiá-Báguena
- Department of Physics, Laboratory of Molecular Biophysics, Universitat Jaume I, 12071 Castellón, Spain
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25
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Calvo E, DeDiego ML, García P, López JA, Pérez-Breña P, Falcón A. Severe acute respiratory syndrome coronavirus accessory proteins 6 and 9b interact in vivo. Virus Res 2012; 169:282-8. [PMID: 22820404 PMCID: PMC7114373 DOI: 10.1016/j.virusres.2012.07.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 07/11/2012] [Accepted: 07/12/2012] [Indexed: 12/15/2022]
Abstract
The 3'proximal one-third of the severe acute respiratory syndrome coronavirus (SARS-CoV) genome encodes the structural proteins and eight accessory proteins, including 3a, 3b, 6, 7a, 7b, 8a, 8b and 9b, varying in length from 39 to 274aa which do not share significant homology with viral proteins of known coronaviruses. The SARS-CoV protein 6 is 63 amino acids in length and has been previously involved in virus pathogenicity and replication. To further analyze this functions, the interaction of SARS-CoV protein 6 with other viral and/or cellular factors has been analyzed during SARS-CoV infective cycle. Protein 6 immunoprecipitation from extracts of SARS-CoV infected cells and mass spectrometry analysis revealed an interaction of viral proteins 6 and 9b in biologically relevant conditions. This interaction has been reinforced by co-localization of both proteins in the cytoplasm of SARS-CoV infected cells.
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Affiliation(s)
- Enrique Calvo
- Unidad de Proteómica, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
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26
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DeDiego ML, Nieto-Torres JL, Jiménez-Guardeño JM, Regla-Nava JA, Alvarez E, Oliveros JC, Zhao J, Fett C, Perlman S, Enjuanes L. Severe acute respiratory syndrome coronavirus envelope protein regulates cell stress response and apoptosis. PLoS Pathog 2011; 7:e1002315. [PMID: 22028656 PMCID: PMC3197621 DOI: 10.1371/journal.ppat.1002315] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 08/29/2011] [Indexed: 12/21/2022] Open
Abstract
Severe acute respiratory syndrome virus (SARS-CoV) that lacks the envelope (E) gene (rSARS-CoV-ΔE) is attenuated in vivo. To identify factors that contribute to rSARS-CoV-ΔE attenuation, gene expression in cells infected by SARS-CoV with or without E gene was compared. Twenty-five stress response genes were preferentially upregulated during infection in the absence of the E gene. In addition, genes involved in signal transduction, transcription, cell metabolism, immunoregulation, inflammation, apoptosis and cell cycle and differentiation were differentially regulated in cells infected with rSARS-CoV with or without the E gene. Administration of E protein in trans reduced the stress response in cells infected with rSARS-CoV-ΔE or with respiratory syncytial virus, or treated with drugs, such as tunicamycin and thapsigargin that elicit cell stress by different mechanisms. In addition, SARS-CoV E protein down-regulated the signaling pathway inositol-requiring enzyme 1 (IRE-1) of the unfolded protein response, but not the PKR-like ER kinase (PERK) or activating transcription factor 6 (ATF-6) pathways, and reduced cell apoptosis. Overall, the activation of the IRE-1 pathway was not able to restore cell homeostasis, and apoptosis was induced probably as a measure to protect the host by limiting virus production and dissemination. The expression of proinflammatory cytokines was reduced in rSARS-CoV-ΔE-infected cells compared to rSARS-CoV-infected cells, suggesting that the increase in stress responses and the reduction of inflammation in the absence of the E gene contributed to the attenuation of rSARS-CoV-ΔE. To identify potential mechanisms mediating the in vivo attenuation of SARS-CoV lacking the E gene (rSARS-CoV-ΔE), the effect of the presence of the E gene on host gene expression was studied. In rSARS-CoV-ΔE-infected cells, the expression of at least 25 stress response genes was preferentially upregulated, compared to cells infected with rSARS-CoV. E protein supplied in trans reversed the increase in stress response genes observed in cells infected with rSARS-CoV-ΔE or with respiratory syncytial virus, and by treatment with drugs causing stress by different mechanisms. Furthermore, in the presence of the E protein a subset (IRE-1 pathway), but not two others (PERK and ATF-6), of the unfolded protein response was also reduced. Nevertheless, the activation of the unfolded protein response to control cell homeostasis was not sufficient to alleviate cell stress, and an increase in cell apoptosis in cells infected with the virus lacking E protein was observed. This apoptotic response was probably induced to protect the host by limiting virus production and dissemination. In cells infected with rSARS-CoV-ΔE, genes associated with the proinflammatory pathway were down-regulated compared to cells infected with virus expressing E protein, supporting the idea that a reduction in inflammation was also relevant in the attenuation of the virus deletion mutant.
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Affiliation(s)
- Marta L DeDiego
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Campus Universidad Autónoma de Madrid, Madrid, Spain
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27
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Nieto-Torres JL, Dediego ML, Alvarez E, Jiménez-Guardeño JM, Regla-Nava JA, Llorente M, Kremer L, Shuo S, Enjuanes L. Subcellular location and topology of severe acute respiratory syndrome coronavirus envelope protein. Virology 2011; 415:69-82. [PMID: 21524776 PMCID: PMC4726981 DOI: 10.1016/j.virol.2011.03.029] [Citation(s) in RCA: 172] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 03/10/2011] [Accepted: 03/31/2011] [Indexed: 11/28/2022]
Abstract
Severe acute respiratory syndrome (SARS) coronavirus (CoV) envelope (E) protein is a transmembrane protein. Several subcellular locations and topological conformations of E protein have been proposed. To identify the correct ones, polyclonal and monoclonal antibodies specific for the amino or the carboxy terminus of E protein, respectively, were generated. E protein was mainly found in the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) of cells transfected with a plasmid encoding E protein or infected with SARS-CoV. No evidence of E protein presence in the plasma membrane was found by using immunofluorescence, immunoelectron microscopy and cell surface protein labeling. In addition, measurement of plasma membrane voltage gated ion channel activity by whole-cell patch clamp suggested that E protein was not present in the plasma membrane. A topological conformation in which SARS-CoV E protein amino terminus is oriented towards the lumen of intracellular membranes and carboxy terminus faces cell cytoplasm is proposed.
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Affiliation(s)
- Jose L Nieto-Torres
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain
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28
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Dormitzer PR, Mandl CW, Rappuoli R. Recombinant Live Vaccines to Protect Against the Severe Acute Respiratory Syndrome Coronavirus. REPLICATING VACCINES 2011. [PMCID: PMC7123558 DOI: 10.1007/978-3-0346-0277-8_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The severe acute respiratory syndrome (SARS) coronavirus (CoV) was identified as the etiological agent of an acute respiratory disease causing atypical pneumonia and diarrhea with high mortality. Different types of SARS-CoV vaccines, including nonreplicative and vectored vaccines, have been developed. Administration of these vaccines to animal model systems has shown promise for the generation of efficacious and safe vaccines. Nevertheless, the identification of side effects, preferentially in the elderly animal models, indicates the need to develop novel vaccines that should be tested in improved animal model systems. Live attenuated viruses have generally proven to be the most effective vaccines against viral infections. A limited number of SARS-CoV attenuating modifications have been described, including mutations, and partial or complete gene deletions affecting the replicase, like the nonstructural proteins (nsp1 or nsp2), or the structural genes, and drastic changes in the sequences that regulate the expression of viral subgenomic mRNAs. A promising vaccine candidate developed in our laboratory was based on deletion of the envelope E gene alone, or in combination with the removal of six additional genes nonessential for virus replication. Viruses lacking E protein were attenuated, grew in the lung, and provided homologous and heterologous protection. Improvements of this vaccine candidate have been directed toward increasing virus titers using the power of viruses with mutator phenotypes, while maintaining the attenuated phenotype. The safety of the live SARS-CoV vaccines is being increased by the insertion of complementary modifications in genes nsp1, nsp2, and 3a, by gene scrambling to prevent the rescue of a virulent phenotype by recombination or remodeling of vaccine genomes based on codon deoptimization using synthetic biology. The newly generated vaccine candidates are very promising, but need to be evaluated in animal model systems that include young and aged animals.
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Affiliation(s)
- Philip R. Dormitzer
- Novartis Vaccines & Diagnostics, Sydney St. 45, Cambridge, 02139 Massachusetts USA
| | - Christian W. Mandl
- Novartis Vaccines & Diagnostics, Inc., Massachusetts Ave. 350, Cambridge, 02139 Massachusetts USA
| | - Rino Rappuoli
- Novartis Vaccines & Diagnostics S.r.l., Via Fiorentina 1, Siena, 53100 Italy
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29
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Keng CT, Akerström S, Leung CSW, Poon LLM, Peiris JSM, Mirazimi A, Tan YJ. SARS coronavirus 8b reduces viral replication by down-regulating E via an ubiquitin-independent proteasome pathway. Microbes Infect 2010; 13:179-88. [PMID: 21035562 PMCID: PMC7110893 DOI: 10.1016/j.micinf.2010.10.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 10/19/2010] [Accepted: 10/21/2010] [Indexed: 12/27/2022]
Abstract
The severe acute respiratory syndrome coronavirus (SARS-CoV) 8b protein, which is not expressed by other known coronaviruses, can down-regulate the envelope (E) protein via a proteasome-dependent pathway. Here, we showed that the down-regulation of E is not dependent on the lysine residues on 8b and the reduction of polyubiquitination of E mutants is not correlated with their down-regulation by 8b, suggesting an ubiquitin-independent proteasome pathway is involved. A time-course study revealed that 8b was expressed at late-stages of SARS-CoV infection. By using Vero E6 cells stably expressing green fluorescence protein-tagged 8b, ectopic expression of 8b was shown to significantly reduce the production of progeny virus and down-regulate E expression. Taken together, these results suggest that 8b negatively modulates virus replication by down-regulating E via an ubiquitin-independent proteasome pathway.
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Affiliation(s)
- Choong-Tat Keng
- Collaborative Anti-Viral Research Group, Institute of Molecular and Cell Biology, Singapore
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30
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Alvarez E, DeDiego ML, Nieto-Torres JL, Jiménez-Guardeño JM, Marcos-Villar L, Enjuanes L. The envelope protein of severe acute respiratory syndrome coronavirus interacts with the non-structural protein 3 and is ubiquitinated. Virology 2010; 402:281-91. [PMID: 20409569 PMCID: PMC7119183 DOI: 10.1016/j.virol.2010.03.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 01/05/2010] [Accepted: 03/06/2010] [Indexed: 02/02/2023]
Abstract
To analyze the proteins interacting with the severe acute respiratory syndrome coronavirus (SARS-CoV) envelope (E) protein, a SARS-CoV was engineered including two tags associated to the E protein. Using this virus, complexes of SARS-CoV E and other proteins were purified using a tandem affinity purification system. Several viral and cell proteins including spike, membrane, non-structural protein 3 (nsp3), dynein heavy chain, fatty acid synthase and transmembrane protein 43 bound E protein. In the present work, we focused on the binding of E protein to nsp3 in infected cells and cell-free systems. This interaction was mediated by the N-terminal acidic domain of nsp3. Moreover, nsp3 and E protein colocalized during the infection. It was shown that E protein was ubiquitinated in vitro and in cell culture, suggesting that the interaction between nsp3 and E protein may play a role in the E protein ubiquitination status and therefore on its turnover.
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Affiliation(s)
- Enrique Alvarez
- Centro Nacional de Biotecnología (CNB), CSIC, Darwin 3, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain
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31
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The N-terminal region of severe acute respiratory syndrome coronavirus protein 6 induces membrane rearrangement and enhances virus replication. J Virol 2010; 84:3542-51. [PMID: 20106914 DOI: 10.1128/jvi.02570-09] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus (SARS-CoV) accessory protein 6 (p6) is a 63-amino-acid multifunctional Golgi-endoplasmic reticulum (ER) membrane-associated protein, with roles in enhancing virus replication and in evading the innate immune response to infection by inhibiting STAT1 (signal transducer and activator of transcription factor 1) translocation to the nucleus. Here, we demonstrate that p6 has an N-terminal region-cytoplasm-C-terminal region-cytoplasm configuration with residues 2 to 37 likely membrane embedded. Expression of p6, or of its N-terminal 41-amino-acid region, in the absence of other viral proteins, induced the formation of membranous structures, some of which were similar to double membrane vesicles involved in virus replication. Consistent with a role in virus replication, p6 partially colocalized with nonstructural protein 3 (nsp3), a marker for virus replication complexes. Further, while the C-terminal region is required for preventing STAT1 translocation to the nucleus, our results also indicated that the N-terminal 18 amino acids were necessary for maximal inhibition. Collectively, these results support the notion that p6 is a two-domain protein, although the function of each is not completely independent of the other.
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32
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Modulation of Host Cell Death by SARS Coronavirus Proteins. MOLECULAR BIOLOGY OF THE SARS-CORONAVIRUS 2010. [PMCID: PMC7176189 DOI: 10.1007/978-3-642-03683-5_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Both types of cell death, namely necrosis and apoptosis, are found in organs of SARS coronavirus (CoV) infected patients. The gastrointestinal tract, however, although also a target for SARS-CoV replication, is obviously not affected by cell death mechanisms. Such differences in cell death induction are paralleled by in-vitro studies. In a colon-derived cell line (Caco-2), proapoptotic proteins were down- and antiapoptotic proteins were upregulated during SARS-CoV infection. By contrast, in SARS-CoV infected Vero E6 cells, apoptosis was induced via the p38 MAPK and caspase dependent pathways. Both apoptotic pathways, although mostly the intrinsic signal transduction, can be targeted by structural as well as accessory proteins of SARS-CoV. The fact that all structural and most of the accessory proteins of SARS-CoV are implicated in apoptotic scenarios indicates the fundamental role of apoptosis in the SARS-CoV life cycle. Interestingly, at least for the nucleocapsid protein of SARS-CoV, a cell-type specific manipulation of apoptosis was confirmed.
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33
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A single tyrosine in the severe acute respiratory syndrome coronavirus membrane protein cytoplasmic tail is important for efficient interaction with spike protein. J Virol 2009; 84:1891-901. [PMID: 20007283 DOI: 10.1128/jvi.02458-09] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus (SARS-CoV) encodes 3 major envelope proteins: spike (S), membrane (M), and envelope (E). Previous work identified a dibasic endoplasmic reticulum retrieval signal in the cytoplasmic tail of SARS-CoV S that promotes efficient interaction with SARS-CoV M. The dibasic signal was shown to be important for concentrating S near the virus assembly site rather than for direct interaction with M. Here, we investigated the sequence requirements of the SARS-CoV M protein that are necessary for interaction with SARS-CoV S. The SARS-CoV M tail was shown to be necessary for S localization in the Golgi region when the proteins were exogenously coexpressed in cells. This was specific, since SARS-CoV M did not retain an unrelated glycoprotein in the Golgi. Importantly, we found that an essential tyrosine residue in the SARS-CoV M cytoplasmic tail, Y(195), was important for S-M interaction. When Y(195) was mutated to alanine, M(Y195A) no longer retained S intracellularly at the Golgi. Unlike wild-type M, M(Y195A) did not reduce the amount of SARS-CoV S carbohydrate processing or surface levels when the two proteins were coexpressed. Mutating Y(195) also disrupted SARS-CoV S-M interaction in vitro. These results suggest that Y(195) is necessary for efficient SARS-CoV S-M interaction and, thus, has a significant involvement in assembly of infectious virus.
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34
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Lal SK, Xu K, Sun B. SARS Accessory Proteins ORF3a and 9b and Their Functional Analysis. MOLECULAR BIOLOGY OF THE SARS-CORONAVIRUS 2009. [PMCID: PMC7123986 DOI: 10.1007/978-3-642-03683-5_11] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The SARS coronavirus (CoV) positive-stranded RNA viral genome encodes 14 open reading frames (ORFs), eight of which encode proteins termed as “accessory proteins.” These proteins help the virus infect the host and promote virulence. In this chapter we describe some of our latest investigations into the structure and function of two such accessory proteins: ORF3a and 9b. The ORF3a accessory protein is the largest accessory protein in SARS-CoV and is a unique membrane protein consisting of three transmembrane domains. It colocalizes on the cell membrane and host Golgi networks and may be involved in ion channel formation during infection. Similarly the ORF9b accessory protein is 98 amino acids, associates with the spike and nucleocapsid proteins and has unusual membrane binding properties. In this chapter we have suggested possible new roles for these two accessory proteins which may in the long run contain answers to many unanswered questions and also give us new ideas for drugs and vaccine design.
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Affiliation(s)
- Sunil K. Lal
- Engineering & Biotechnology, International Centre for Genetic, Aruna Asaf Ali Marg, New Delhi, 110067 India
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35
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Abstract
Coronavirus genomes are single-stranded positive-sense RNA that are transcribed into a nested set of 3′ coterminal subgenomic RNAs for gene expression. Members of the Coronaviridae express canonical polymerase genes, as well as structural genes, including S, E, M, and N, but also express a highly divergent set of accessory genes whose open reading frames are interspersed among the structural genes within the 3′ one-third of the viral genome. The accessory genes are thought to contain “luxury” functions that are often not required for in-vitro virus replication. The severe acute respiratory syndrome coronavirus (SARS-CoV) expresses eight such accessory genes (ORF3a, -3b, -6, -7a, -7b, -8a, -8b, and -9b), the most of any known coronavirus. This chapter will review our current knowledge of expression, structure, and function of each of the SARS-CoV accessory genes.
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Affiliation(s)
- Sunil K. Lal
- Engineering & Biotechnology, International Centre for Genetic, Aruna Asaf Ali Marg, New Delhi, 110067 India
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36
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Abstract
Coronaviruses are positive strand RNA viruses that cause disease in humans, and domestic and companion animals. They are most notorious for causing severe acute respiratory syndrome (SARS) outbreaks in 2002–2003. All coronaviruses follow the same basic strategy of replication. All coronaviruses encode 15 or 16 replicase related proteins, 4 or 5 structural proteins and 1–8 group-specific or accessory proteins. Many of the replicase proteins are assembled into replication machinery in double-membrane vesicles (DMVs) and on a reticular network of membranes that are derived from the endoplasmic reticulum. Coronaviruses are readily transmitted across species. This phenomenon was illustrated when the SARS-coronavirus crossed species from bats to intermediate hosts, such as palm civets, and then to humans. It also explains the large number of species, including humans, that are infected with viruses closely related to bovine coronavirus. In many coronavirus infections, disease severity increases during virus clearance, suggesting that the host immune response is both protective and pathogenic. Furthermore, inhibition of specific aspects of the immune response results in less severe disease and less tissue destruction, without diminishing the kinetics of virus clearance. Like all successful viruses, coronaviruses have evolved both passive and active mechanisms to evade the interferon response. Replication in DMVs may contribute to passive evasion of the innate immune response by making double-stranded RNA inaccessible to cellular sensors.
Coronaviruses gained prominence during the SARS outbreaks of 2002–2003, but there are many different coronaviruses that infect humans and animals. Perlman and Netland describe the biology of the coronaviruses, including their replication, host immune response and interspecies transmission. Although coronaviruses were first identified nearly 60 years ago, they only received notoriety in 2003 when one of their members was identified as the aetiological agent of severe acute respiratory syndrome. Previously these viruses were known to be important agents of respiratory and enteric infections of domestic and companion animals and to cause approximately 15% of all cases of the common cold. This Review focuses on recent advances in our understanding of the mechanisms of coronavirus replication, interactions with the host immune response and disease pathogenesis. It also highlights the recent identification of numerous novel coronaviruses and the propensity of this virus family to cross species barriers.
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Affiliation(s)
- Stanley Perlman
- Department of Microbiology and Interdisciplinary Program in Immunology, University of Iowa, Iowa City, 52242, USA.
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Molecular determinants for subcellular localization of the severe acute respiratory syndrome coronavirus open reading frame 3b protein. J Virol 2009; 83:6631-40. [PMID: 19403678 DOI: 10.1128/jvi.00367-09] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Viruses such as hepatitis C and the severe acute respiratory syndrome coronavirus (SARS-CoV) encode proteins that are distributed between mitochondria and the nucleus, but little is known about the factors that control partitioning between these sites. SARS-CoV encodes a unique accessory gene called open reading frame (ORF) 3b that, like other unique accessory genes in SARS-CoV, likely contributes to viral pathogenicity. The ORF 3b protein is 154 amino acids and is predicted to express from the second ORF in subgenomic RNA3. In this report, we have characterized the molecular components that regulate intracellular localization of the ORF 3b protein. We demonstrate unique shuttling behavior of ORF 3b, whereby the protein initially accumulates in the nucleus and subsequently translocates to mitochondria. Following nuclear localization, ORF 3b traffics to the outer membrane of mitochondria via a predicted amphipathic alpha-helix. Additionally, ORF 3b contains a consensus nuclear export sequence, and we demonstrate that nuclear export and thus mitochondrial translocation are dependent on a leptomycin B-sensitive nuclear export mechanism. We further show that ORF 3b inhibits induction of type I interferon induced by retinoic acid-induced gene 1 and the mitochondrial antiviral signaling protein. Our observations provide insights into the cellular localization of ORF 3b that may enhance our understanding of the mechanisms by which ORF 3b contributes to SARS-CoV pathogenesis. The findings reported here reveal that for multilocalized proteins, consideration of the spatiotemporal distribution may be crucial for understanding viral protein behavior and function.
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Xu K, Zheng BJ, Zeng R, Lu W, Lin YP, Xue L, Li L, Yang LL, Xu C, Dai J, Wang F, Li Q, Dong QX, Yang RF, Wu JR, Sun B. Severe acute respiratory syndrome coronavirus accessory protein 9b is a virion-associated protein. Virology 2009; 388:279-85. [PMID: 19394665 PMCID: PMC7103405 DOI: 10.1016/j.virol.2009.03.032] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 02/10/2009] [Accepted: 03/26/2009] [Indexed: 12/28/2022]
Abstract
Eight accessory proteins have been identified in severe acute respiratory syndrome-associated coronavirus (SARS-CoV). They are believed to play roles in the viral life cycle and may contribute to the pathogenesis and virulence. ORF9b as one of these accessory proteins is located in subgenomic mRNA9 and encodes a 98 amino acid protein. However, whether 9b protein is a structural component of SARS-CoV particles remains unknown. In this study, we demonstrate that 9b protein is translated from bicistronic mRNA9 via leaky ribosome scanning and it is incorporated into both virus-like particles (VLPs) and purified SARS-CoV virions. Further analysis shows that sufficient incorporation of 9b protein into VLPs is dependent upon the co-expression of E and M proteins, but not upon the presence of either S or N protein. Our data indicate that 9b protein of SARS-CoV is another virion-associated accessory protein. This finding will lead to a better understanding of the properties of the SARS-CoV 9b protein.
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Affiliation(s)
- Ke Xu
- Laboratory of Molecular Virology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai Institutes of Biological Sciences, 225 South Chongqing Road, Shanghai 200025, China
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Severe acute respiratory syndrome coronavirus protein 6 is required for optimal replication. J Virol 2008; 83:2368-73. [PMID: 19091867 DOI: 10.1128/jvi.02371-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus (SARS-CoV) encodes several accessory proteins of unknown function. One of these proteins, protein 6 (p6), which is encoded by ORF6, enhances virus replication when introduced into a heterologous murine coronavirus (mouse hepatitis virus [MHV]) but is not essential for optimal SARS-CoV replication after infection at a relatively high multiplicity of infection (MOI). Here, we reconcile these apparently conflicting results by showing that p6 enhances SARS-CoV replication to nearly the same extent as when expressed in the context of MHV if cells are infected at a low MOI and accelerates disease in mice transgenic for the human SARS-CoV receptor.
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Frieman M, Baric R. Mechanisms of severe acute respiratory syndrome pathogenesis and innate immunomodulation. Microbiol Mol Biol Rev 2008; 72:672-85, Table of Contents. [PMID: 19052324 PMCID: PMC2593566 DOI: 10.1128/mmbr.00015-08] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The modulation of the immune response is a common practice of many highly pathogenic viruses. The emergence of the highly pathogenic coronavirus severe acute respiratory virus (SARS-CoV) serves as a robust model system to elucidate the virus-host interactions that mediate severe end-stage lung disease in humans and animals. Coronaviruses encode the largest positive-sense RNA genome of approximately 30 kb, encode a variety of replicase and accessory open reading frames that are structurally unique, and encode novel enzymatic functions among RNA viruses. These viruses have broad or specific host ranges, suggesting the possibility of novel strategies for targeting and regulating host innate immune responses following virus infection. Using SARS-CoV as a model, we review the current literature on the ability of coronaviruses to interact with and modify the host intracellular environment during infection. These studies are revealing a rich set of novel viral proteins that engage, modify, and/or disrupt host cell signaling and nuclear import machinery for the benefit of virus replication.
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Affiliation(s)
- Matthew Frieman
- University of North Carolina, 210 McGaveran-Greenberg Hall, CB 7435, Chapel Hill, NC 27599, USA
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Pan J, Peng X, Gao Y, Li Z, Lu X, Chen Y, Ishaq M, Liu D, DeDiego ML, Enjuanes L, Guo D. Genome-wide analysis of protein-protein interactions and involvement of viral proteins in SARS-CoV replication. PLoS One 2008; 3:e3299. [PMID: 18827877 PMCID: PMC2553179 DOI: 10.1371/journal.pone.0003299] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Accepted: 09/09/2008] [Indexed: 02/05/2023] Open
Abstract
Analyses of viral protein-protein interactions are an important step to understand viral protein functions and their underlying molecular mechanisms. In this study, we adopted a mammalian two-hybrid system to screen the genome-wide intraviral protein-protein interactions of SARS coronavirus (SARS-CoV) and therefrom revealed a number of novel interactions which could be partly confirmed by in vitro biochemical assays. Three pairs of the interactions identified were detected in both directions: non-structural protein (nsp) 10 and nsp14, nsp10 and nsp16, and nsp7 and nsp8. The interactions between the multifunctional nsp10 and nsp14 or nsp16, which are the unique proteins found in the members of Nidovirales with large RNA genomes including coronaviruses and toroviruses, may have important implication for the mechanisms of replication/transcription complex assembly and functions of these viruses. Using a SARS-CoV replicon expressing a luciferase reporter under the control of a transcription regulating sequence, it has been shown that several viral proteins (N, X and SUD domains of nsp3, and nsp12) provided in trans stimulated the replicon reporter activity, indicating that these proteins may regulate coronavirus replication and transcription. Collectively, our findings provide a basis and platform for further characterization of the functions and mechanisms of coronavirus proteins.
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Affiliation(s)
- Ji'An Pan
- State Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Xiaoxue Peng
- State Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Yajing Gao
- State Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Zhilin Li
- State Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Xiaolu Lu
- State Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Yingzhao Chen
- State Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Musarat Ishaq
- State Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Dan Liu
- State Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Marta L. DeDiego
- Centro Nacional de Biotecnología, CSIC, Department of Molecular and Cell Biology, Campus Universidad Autónoma, Madrid, Spain
| | - Luis Enjuanes
- Centro Nacional de Biotecnología, CSIC, Department of Molecular and Cell Biology, Campus Universidad Autónoma, Madrid, Spain
| | - Deyin Guo
- State Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
- * E-mail:
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The transmembrane domain of the severe acute respiratory syndrome coronavirus ORF7b protein is necessary and sufficient for its retention in the Golgi complex. J Virol 2008; 82:9477-91. [PMID: 18632859 DOI: 10.1128/jvi.00784-08] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus (SARS-CoV) ORF7b (also called 7b) protein is an integral membrane protein that is translated from a bicistronic open reading frame encoded within subgenomic RNA 7. When expressed independently or during virus infection, ORF7b accumulates in the Golgi compartment, colocalizing with both cis- and trans-Golgi markers. To identify the domains of this protein that are responsible for Golgi localization, we have generated a set of mutant proteins and analyzed their subcellular localizations by indirect immunofluorescence confocal microscopy. The N- and C-terminal sequences are dispensable, but the ORF7b transmembrane domain (TMD) is essential for Golgi compartment localization. When the TMD of human CD4 was replaced with the ORF7b TMD, the resulting chimeric protein localized to the Golgi complex. Scanning alanine mutagenesis identified two regions in the carboxy-terminal portion of the TMD that eliminated the Golgi complex localization of the chimeric CD4 proteins or ORF7b protein. Collectively, these data demonstrate that the Golgi complex retention signal of the ORF7b protein resides solely within the TMD.
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Dediego ML, Pewe L, Alvarez E, Rejas MT, Perlman S, Enjuanes L. Pathogenicity of severe acute respiratory coronavirus deletion mutants in hACE-2 transgenic mice. Virology 2008; 376:379-89. [PMID: 18452964 PMCID: PMC2810402 DOI: 10.1016/j.virol.2008.03.005] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 02/21/2008] [Accepted: 03/10/2008] [Indexed: 02/07/2023]
Abstract
Recombinant severe acute respiratory virus (SARS-CoV) variants lacking the group specific genes 6, 7a, 7b, 8a, 8b and 9b (rSARS-CoV-Delta[6-9b]), the structural gene E (rSARS-CoV-DeltaE), and a combination of both sets of genes (rSARS-CoV-Delta[E,6-9b]) have been generated. All these viruses were rescued in monkey (Vero E6) cells and were also infectious for human (Huh-7, Huh7.5.1 and CaCo-2) cell lines and for transgenic (Tg) mice expressing the SARS-CoV receptor human angiotensin converting enzyme-2 (hACE-2), indicating that none of these proteins is essential for the viral cycle. Furthermore, in Vero E6 cells, all the viruses showed the formation of particles with the same morphology as the wt virus, indicating that these proteins do not have a high impact in the final morphology of the virions. Nevertheless, in the absence of E protein, release of virus particles efficacy was reduced. Viruses lacking E protein grew about 100-fold lower than the wt virus in lungs of Tg infected mice but did not grow in the brains of the same animals, in contrast to the rSARS-CoV-Delta[6-9b] virus, which grew almost as well as the wt in both tissues. Viruses lacking E protein were highly attenuated in the highly sensitive hACE-2 Tg mice, in contrast to the minimal rSARS-CoV-Delta[6-9b] and wt viruses. These data indicate that E gene might be a virulence factor influencing replication level, tissue tropism and pathogenicity of SARS-CoV, suggesting that DeltaE attenuated viruses are promising vaccine candidates.
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Affiliation(s)
- Marta L Dediego
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CSIC), Campus Universidad Autónoma, Darwin 3, Cantoblanco, 28049 Madrid, Spain
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Severe acute respiratory syndrome coronavirus protein 6 accelerates murine hepatitis virus infections by more than one mechanism. J Virol 2008; 82:7212-22. [PMID: 18448520 DOI: 10.1128/jvi.02406-07] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus (SARS-CoV) encodes numerous accessory proteins whose importance in the natural infection process is currently unclear. One of these accessory proteins is set apart by its function in the context of a related murine hepatitis virus (MHV) infection. SARS-CoV protein 6 increases MHV neurovirulence and accelerates MHV infection kinetics in tissue culture. Protein 6 also blocks nuclear import of macromolecules from the cytoplasm, a process known to involve its C-terminal residues interacting with cellular importins. In this study, protein 6 was expressed from plasmid DNAs and accumulated in cells prior to infection by wild-type MHV. Output of MHV progeny was significantly increased by preexisting protein 6. Protein 6 with C-terminal deletion mutations no longer interfered with nuclear import processes but still retained much of the capacity to augment MHV infections. However, some virus growth-enhancing activity could be ascribed to the C-terminal end of protein 6. To determine whether this augmentation provided by the C terminus was derived from interference with nuclear import, we evaluated the virus-modulating effects of small interfering RNAs (siRNAs) directed against importin-beta mRNAs, which down-regulated classical nuclear import pathways. The siRNAs did indeed prime cells for enhanced MHV infection. Our findings indicated that protein 6-mediated nuclear import blocks augmented MHV infections but is clearly not the only way that this accessory protein operates to create a milieu conducive to robust virus growth. Thus, the SARS-CoV protein 6 accelerates MHV infections by more than one mechanism.
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45
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Proteomics analysis unravels the functional repertoire of coronavirus nonstructural protein 3. J Virol 2008; 82:5279-94. [PMID: 18367524 DOI: 10.1128/jvi.02631-07] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Severe acute respiratory syndrome (SARS) coronavirus infection and growth are dependent on initiating signaling and enzyme actions upon viral entry into the host cell. Proteins packaged during virus assembly may subsequently form the first line of attack and host manipulation upon infection. A complete characterization of virion components is therefore important to understanding the dynamics of early stages of infection. Mass spectrometry and kinase profiling techniques identified nearly 200 incorporated host and viral proteins. We used published interaction data to identify hubs of connectivity with potential significance for virion formation. Surprisingly, the hub with the most potential connections was not the viral M protein but the nonstructural protein 3 (nsp3), which is one of the novel virion components identified by mass spectrometry. Based on new experimental data and a bioinformatics analysis across the Coronaviridae, we propose a higher-resolution functional domain architecture for nsp3 that determines the interaction capacity of this protein. Using recombinant protein domains expressed in Escherichia coli, we identified two additional RNA-binding domains of nsp3. One of these domains is located within the previously described SARS-unique domain, and there is a nucleic acid chaperone-like domain located immediately downstream of the papain-like proteinase domain. We also identified a novel cysteine-coordinated metal ion-binding domain. Analyses of interdomain interactions and provisional functional annotation of the remaining, so-far-uncharacterized domains are presented. Overall, the ensemble of data surveyed here paint a more complete picture of nsp3 as a conserved component of the viral protein processing machinery, which is intimately associated with viral RNA in its role as a virion component.
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Narayanan K, Huang C, Makino S. SARS coronavirus accessory proteins. Virus Res 2007; 133:113-21. [PMID: 18045721 PMCID: PMC2720074 DOI: 10.1016/j.virusres.2007.10.009] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 09/12/2007] [Accepted: 10/10/2007] [Indexed: 12/19/2022]
Abstract
The emergence of the severe acute respiratory syndrome coronavirus (SARS-CoV) has led to a renewed interest in studying the role of accessory proteins in regulating coronavirus infections in the natural host. A significant body of evidence has accumulated in the area of SARS-CoV and host interactions that indicate that the accessory proteins might play an important role in modulating the host response to virus infection and thereby, contribute to pathogenesis. In this review, we have compiled the current knowledge about SARS-CoV accessory proteins, obtained from studies in cell culture systems, reverse genetics and animal models, to shed some light into the possible role of these proteins in the propagation and virulence of SARS-CoV in its natural host. We conclude by providing some questions for future studies that will greatly advance our knowledge about the biological significance and contributions of the accessory proteins in the development of SARS in humans.
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Affiliation(s)
- Krishna Narayanan
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, TX 77555-1019, United States.
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Netland J, Ferraro D, Pewe L, Olivares H, Gallagher T, Perlman S. Enhancement of murine coronavirus replication by severe acute respiratory syndrome coronavirus protein 6 requires the N-terminal hydrophobic region but not C-terminal sorting motifs. J Virol 2007; 81:11520-5. [PMID: 17670827 PMCID: PMC2045524 DOI: 10.1128/jvi.01308-07] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus encodes several accessory proteins of unknown function. We previously showed that one such protein, encoded by ORF6, enhanced the growth of mouse hepatitis virus in tissue culture cells and in mice. Protein 6 consists of an N-terminal hydrophobic peptide and a C-terminal region containing intracellular protein sorting motifs. Herein, we show that mutation of the hydrophobic region but not the sorting motifs affected the ability of protein 6 to enhance virus growth. Collectively, these results support the notion that the 6 protein interacts with membrane-bound viral replication or assembly machinery to directly enhance virus replication and virulence in animals.
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Affiliation(s)
- Jason Netland
- Department of Microbiology, University of Iowa, BSB 3-712, Iowa City, IA 52242, USA
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Frieman M, Yount B, Heise M, Kopecky-Bromberg SA, Palese P, Baric RS. Severe acute respiratory syndrome coronavirus ORF6 antagonizes STAT1 function by sequestering nuclear import factors on the rough endoplasmic reticulum/Golgi membrane. J Virol 2007; 81:9812-24. [PMID: 17596301 PMCID: PMC2045396 DOI: 10.1128/jvi.01012-07] [Citation(s) in RCA: 410] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The host innate immune response is an important deterrent of severe viral infection in humans and animals. Nuclear import factors function as key gatekeepers that regulate the transport of innate immune regulatory cargo to the nucleus of cells to activate the antiviral response. Using severe acute respiratory syndrome coronavirus (SARS-CoV) as a model, we demonstrate that SARS-COV ORF6 protein is localized to the endoplasmic reticulum (ER)/Golgi membrane in infected cells, where it binds to and disrupts nuclear import complex formation by tethering karyopherin alpha 2 and karyopherin beta 1 to the membrane. Retention of import factors at the ER/Golgi membrane leads to a loss of STAT1 transport into the nucleus in response to interferon signaling, thus blocking the expression of STAT1-activated genes that establish an antiviral state. We mapped the region of ORF6, which binds karyopherin alpha 2, to the C terminus of ORF6 and show that mutations in the C terminus no longer bind karyopherin alpha 2 or block the nuclear import of STAT1. We also show that N-terminal deletions of karyopherin alpha 2 that no longer bind to karyopherin beta 1 still retain ORF6 binding activity but no longer block STAT1 nuclear import. Recombinant SARS-CoV lacking ORF6 did not tether karyopherin alpha 2 to the ER/Golgi membrane and allowed the import of the STAT1 complex into the nucleus. We discuss the likely implications of these data on SARS-CoV replication and pathogenesis.
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Affiliation(s)
- Matthew Frieman
- Department of Epidemiology, School of Public Health, University of North Carolina at Chapel Hill, 3304 Hooker Research Center, Chapel Hill, NC 27599-7435, USA
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49
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Abstract
The emergence of the highly pathogenic SARS coronavirus (SARS-CoV) has reignited interest in coronavirus biology and pathogenesis. An emerging theme in coronavirus pathogenesis is that the interaction between specific viral genes and the host immune system, specifically the innate immune system, functions as a key determinant in regulating virulence and disease outcomes. Using SARS-CoV as a model, we will review the current knowledge of the interplay between coronavirus infection and the host innate immune system in vivo, and then discuss the mechanisms by which specific gene products antagonize the host innate immune response in cell culture models. Our data suggests that the SARS-CoV uses specific strategies to evade and antagonize the sensing and signaling arms of the interferon pathway. We summarize by identifying future points of consideration that will contribute greatly to our understanding of the molecular mechanisms governing coronavirus pathogenesis and virulence, and the development of severe disease in humans and animals.
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Affiliation(s)
- Matthew Frieman
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States.
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