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Davies JP, Sivadas A, Keller KR, Roman BK, Wojcikiewicz RJH, Plate L. Expression of SARS-CoV-2 Nonstructural Proteins 3 and 4 Can Tune the Unfolded Protein Response in Cell Culture. J Proteome Res 2024; 23:356-367. [PMID: 38038604 PMCID: PMC11063930 DOI: 10.1021/acs.jproteome.3c00600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Coronaviruses (CoV), including SARS-CoV-2, modulate host proteostasis through the activation of stress-responsive signaling pathways such as the Unfolded Protein Response (UPR), which remedies misfolded protein accumulation by attenuating translation and increasing protein folding capacity. While CoV nonstructural proteins (nsps) are essential for infection, little is known about the role of nsps in modulating the UPR. We characterized the impact of overexpression of SARS-CoV-2 nsp4, a key driver of replication, on the UPR in cell culture using quantitative proteomics to sensitively detect pathway-wide upregulation of effector proteins. We find that nsp4 preferentially activates the ATF6 and PERK branches of the UPR. Previously, we found that an N-terminal truncation of nsp3 (nsp3.1) can suppress pharmacological ATF6 activation. To determine how nsp3.1 and nsp4 tune the UPR, their coexpression demonstrated that nsp3.1 suppresses nsp4-mediated PERK, but not ATF6 activation. Reanalysis of SARS-CoV-2 infection proteomics data revealed time-dependent activation of PERK targets early in infection, which subsequently fades. This temporal regulation suggests a role for nsp3 and nsp4 in tuning the PERK pathway to attenuate host translation beneficial for viral replication while avoiding later apoptotic signaling caused by chronic activation. This work furthers our understanding of CoV-host proteostasis interactions and highlights the power of proteomic methods for systems-level analysis of the UPR.
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Affiliation(s)
- Jonathan P Davies
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Athira Sivadas
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Katherine R Keller
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, New York 12310, United States
| | - Brynn K Roman
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Richard J H Wojcikiewicz
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, New York 12310, United States
| | - Lars Plate
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37240, United States
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2
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Barik S. Suppression of Innate Immunity by the Hepatitis C Virus (HCV): Revisiting the Specificity of Host-Virus Interactive Pathways. Int J Mol Sci 2023; 24:16100. [PMID: 38003289 PMCID: PMC10671098 DOI: 10.3390/ijms242216100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 10/31/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
The hepatitis C virus (HCV) is a major causative agent of hepatitis that may also lead to liver cancer and lymphomas. Chronic hepatitis C affects an estimated 2.4 million people in the USA alone. As the sole member of the genus Hepacivirus within the Flaviviridae family, HCV encodes a single-stranded positive-sense RNA genome that is translated into a single large polypeptide, which is then proteolytically processed to yield the individual viral proteins, all of which are necessary for optimal viral infection. However, cellular innate immunity, such as type-I interferon (IFN), promptly thwarts the replication of viruses and other pathogens, which forms the basis of the use of conjugated IFN-alpha in chronic hepatitis C management. As a countermeasure, HCV suppresses this form of immunity by enlisting diverse gene products, such as HCV protease(s), whose primary role is to process the large viral polyprotein into individual proteins of specific function. The exact number of HCV immune suppressors and the specificity and molecular mechanism of their action have remained unclear. Nonetheless, the evasion of host immunity promotes HCV pathogenesis, chronic infection, and carcinogenesis. Here, the known and putative HCV-encoded suppressors of innate immunity have been reviewed and analyzed, with a predominant emphasis on the molecular mechanisms. Clinically, the knowledge should aid in rational interventions and the management of HCV infection, particularly in chronic hepatitis.
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Affiliation(s)
- Sailen Barik
- EonBio, 3780 Pelham Drive, Mobile, AL 36619, USA
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3
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Denolly S, Guo H, Martens M, Płaszczyca A, Scaturro P, Prasad V, Kongmanas K, Punyadee N, Songjaeng A, Mairiang D, Pichlmair A, Avirutnan P, Bartenschlager R. Dengue virus NS1 secretion is regulated via importin-subunit β1 controlling expression of the chaperone GRp78 and targeted by the clinical drug ivermectin. mBio 2023; 14:e0144123. [PMID: 37702492 PMCID: PMC10653883 DOI: 10.1128/mbio.01441-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 07/10/2023] [Indexed: 09/14/2023] Open
Abstract
IMPORTANCE Dengue virus (DENV) is a major human pathogen that can cause hemorrhagic fever and shock syndrome. One important factor of DENV pathogenicity is non-structural protein 1 (NS1), a glycoprotein that is secreted from infected cells. Here we study the mode of action of the widely used drug ivermectin, used to treat parasitic infections and recently shown to lower NS1 blood levels in DENV-infected patients. We found that ivermectin blocks the nuclear transport of transcription factors required for the expression of chaperones that support the folding and secretion of glycoproteins, including NS1. Impairing nuclear transport of these transcription factors by ivermectin or depleting them from infected cells dampens NS1 folding and thus its secretion. These results reveal a novel mode of action of ivermectin that might apply to other flaviviruses as well.
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Affiliation(s)
- Solène Denolly
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, Heidelberg University, Medical Faculty Heidelberg, Heidelberg, Germany
| | - Hongbo Guo
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, Heidelberg University, Medical Faculty Heidelberg, Heidelberg, Germany
| | - Miriam Martens
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, Heidelberg University, Medical Faculty Heidelberg, Heidelberg, Germany
| | - Anna Płaszczyca
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, Heidelberg University, Medical Faculty Heidelberg, Heidelberg, Germany
| | - Pietro Scaturro
- Technical University of Munich, School of Medicine, Institute of Virology, Munich, Germany
- Leibniz Institute of Virology, Hamburg, Germany
| | - Vibhu Prasad
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, Heidelberg University, Medical Faculty Heidelberg, Heidelberg, Germany
| | - Kessiri Kongmanas
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Nuntaya Punyadee
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Adisak Songjaeng
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Dumrong Mairiang
- Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Molecular Biology of Dengue and Flaviviruses Research Team, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani, Thailand
| | - Andreas Pichlmair
- Technical University of Munich, School of Medicine, Institute of Virology, Munich, Germany
| | - Panisadee Avirutnan
- Division of Dengue Hemorrhagic Fever Research, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, Heidelberg University, Medical Faculty Heidelberg, Heidelberg, Germany
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Davies JP, Sivadas A, Keller KR, Wojcikiewicz RJ, Plate L. SARS-CoV-2 Nonstructural Proteins 3 and 4 tune the Unfolded Protein Response. bioRxiv 2023:2023.04.22.537917. [PMID: 37162862 PMCID: PMC10168236 DOI: 10.1101/2023.04.22.537917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Coronaviruses (CoV), including SARS-CoV-2, modulate host proteostasis through activation of stress-responsive signaling pathways such as the Unfolded Protein Response (UPR), which remedies misfolded protein accumulation by attenuating translation and increasing protein folding capacity. While CoV nonstructural proteins (nsps) are essential for infection, little is known about the role of nsps in modulating the UPR. We characterized the impact of SARS-CoV-2 nsp4, a key driver of replication, on the UPR using quantitative proteomics to sensitively detect pathway-wide upregulation of effector proteins. We find nsp4 preferentially activates the ATF6 and PERK branches of the UPR. Previously, we found an N-terminal truncation of nsp3 (nsp3.1) can suppress pharmacological ATF6 activation. To determine how nsp3.1 and nsp4 tune the UPR, their co-expression demonstrated that nsp3.1 suppresses nsp4-mediated PERK, but not ATF6 activation. Re-analysis of SARS-CoV-2 infection proteomics data revealed time-dependent activation of PERK targets early in infection, which subsequently fades. This temporal regulation suggests a role for nsp3 and nsp4 in tuning the PERK pathway to attenuate host translation beneficial for viral replication while avoiding later apoptotic signaling caused by chronic activation. This work furthers our understanding of CoV-host proteostasis interactions and highlights the power of proteomic methods for systems-level analysis of the UPR.
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Affiliation(s)
| | - Athira Sivadas
- Department of Biological Sciences, Vanderbilt University, Nashville, TN
| | | | | | - Lars Plate
- Department of Biological Sciences, Vanderbilt University, Nashville, TN
- Department of Chemistry, Vanderbilt University, Nashville, TN
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
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5
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Wu J, Zhao Y, Chen Q, Chen Y, Gu J, Mao L. Enterovirus A71 Promotes Exosome Secretion by the Nonstructural Protein 3A Interacting with Rab27a. Microbiol Spectr 2023; 11:e0344622. [PMID: 36790212 PMCID: PMC10101103 DOI: 10.1128/spectrum.03446-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 01/27/2023] [Indexed: 02/16/2023] Open
Abstract
Exosomes are small membrane-bound vesicles which are intraluminal vesicles (ILVs) secreted to the extracellular space after multivesicular bodies (MVBs) fuse with the plasma membrane. Although it is known that exosomes play a multitude of roles during viral infection, the mechanism that regulates their secretion during viral infection is unknown. Here, we found that enterovirus A71 (EV-A71) infection increased exosome secretion both in vivo and in vitro. Importantly, the expression of nonstructural protein 3A was sufficient to promote exosome secretion, while a mutation affecting the amino acid 18 position abrogated this effect, without changing the size of exosomes in vivo or in vitro. Transmission electron microscopy (TEM) analysis revealed that 3A decreases the number of MVBs and ILVs in vivo and in vitro, which suggested 3A may boost the fusion between MVBs and the plasma membrane. Furthermore, we demonstrated that an interaction between 3A and the small GTPase protein, Rab27a, protected Rab27a from ubiquitination, resulted in increasing exosome release. Data indicated a novel mechanism by which EV-A71 3A modifies exosome secretion during viral infection. IMPORTANCE Research has shown that viral infection impacts exosome secretion, but its regulation mechanisms remain poorly understood. Nonstructural protein 3A of EV-A71 interacts with many host factors and is involved in the remodeling of cellular membranes. In this investigation, we applied exogenous expression of 3A protein for exploring its regulation on exosome secretion and utilized immunoprecipitation combined with proteomics approaches to identify 3A-interacting factors. Our results demonstrate that 3A protein upregulates the release of the exosomes and that the 3A mutant strain of EV-A71 induce less exosome release compared with the EV-A71 wild type. Viral 3A protein interacts with the host factor Rab27a to prevent it from being ubiquitinated, which in turn improves exosome secretion both in vitro and in vivo. EV-A71 3A protein is a novel viral factor in the control of exosome production.
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Affiliation(s)
- Jing Wu
- Department of Laboratory Medicine, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, Jiangsu, China
| | - Yuxue Zhao
- Department of Laboratory Medicine, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, Jiangsu, China
| | - Qiaoqiao Chen
- Department of Laboratory Medicine, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, Jiangsu, China
| | - Yiwen Chen
- Department of Laboratory Medicine, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, Jiangsu, China
| | - Jiaqi Gu
- Department of Laboratory Medicine, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, Jiangsu, China
| | - Lingxiang Mao
- Department of Laboratory Medicine, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, Jiangsu, China
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Liang Q, Wan J, Liu H, Jia D, Chen Q, Wang A, Wei T. A plant nonenveloped double-stranded RNA virus activates and co-opts BNIP3-mediated mitophagy to promote persistent infection in its insect vector. Autophagy 2023; 19:616-631. [PMID: 35722949 PMCID: PMC9851205 DOI: 10.1080/15548627.2022.2091904] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Mitophagy that selectively eliminates damaged mitochondria is an essential mitochondrial quality control mechanism. Recently, mitophagy has been shown to be induced in host cells infected by a few animal viruses. Here, we report that southern rice black-streaked dwarf virus (SRBSDV), a plant nonenveloped double-stranded RNA virus, can also trigger mitophagy in its planthopper vector to prevent mitochondria-dependent apoptosis and promote persistent viral propagation. We find that the fibrillar structures constructed by the nonstructural protein P7-1 of SRBSDV directly target mitochondria via interaction with the mitophagy receptor BNIP3 (BCL2 interacting protein 3), and these mitochondria are then sequestered within autophagosomes to form mitophagosomes. Moreover, SRBSDV infection or P7-1 expression alone can promote BNIP3 dimerization on the mitochondria, and induce autophagy via the P7-1-ATG8 interaction. Furthermore, SRBSDV infection stimulates the phosphorylation of AMP-activated protein kinase (AMPK), resulting in BNIP3 phosphorylation via the AMPKα-BNIP3 interaction. Together, P7-1 induces BNIP3-mediated mitophagy by promoting the formation of phosphorylated BNIP3 dimers on the mitochondria. Silencing of ATG8, BNIP3, or AMPKα significantly reduces virus-induced mitophagy and viral propagation in insect vectors. These data suggest that in planthopper, SRBSDV-induced mitophagosomes are modified to accommodate virions and facilitate persistent viral propagation. In summary, our results demonstrate a previously unappreciated role of a viral protein in the induction of BNIP3-mediated mitophagy by bridging autophagosomes and mitochondria and reveal the functional importance of virus-induced mitophagy in maintaining persistent viral infection in insect vectors.Abbreviations: AMPK: AMP-activated protein kinase; ATG: autophagy related; BNIP3: BCL2 interacting protein 3; CASP3: caspase 3; dsRNA: double strand RNA; ER: endoplasmic reticulum; FITC: fluorescein isothiocyanate; FKBP8: FKBP prolyl isomerase 8; FUNDC1: FUN14 domain containing 1; GFP: green fluorescent protein; GST: glutathione S-transferase; padp: post-first access to diseased plants; Phos-tag: Phosphate-binding tag; PINK1: PTEN induced kinase 1; Sf9: Spodoptera frugiperda; SQSTM1: sequestosome 1; SRBSDV: southern rice black-streaked dwarf virus; STK11/LKB1: serine/threonine kinase 11; TOMM20: translocase of outer mitochondrial membrane 20; RBSDV: rice black-streaked dwarf virus; TUNEL: terminal deoxynucleotidyl dUTP nick end labeling; ULK1: unc-51 like autophagy activating kinase 1; VDAC1: voltage dependent anion channel 1.
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Affiliation(s)
- Qifu Liang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Vector-borne Virus Research Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Jiajia Wan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Vector-borne Virus Research Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Huan Liu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Vector-borne Virus Research Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Dongsheng Jia
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Vector-borne Virus Research Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Qian Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Vector-borne Virus Research Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Taiyun Wei
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Vector-borne Virus Research Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China,CONTACT Taiyun Wei State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Vector-borne Virus Research Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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7
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Saivish MV, Menezes GDL, da Costa VG, da Silva GCD, Marques RE, Nogueira ML, Silva RAD. Predicting Antigenic Peptides from Rocio Virus NS1 Protein for Immunodiagnostic Testing Using Immunoinformatics and Molecular Dynamics Simulation. Int J Mol Sci 2022; 23:7681. [PMID: 35887029 PMCID: PMC9322101 DOI: 10.3390/ijms23147681] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/02/2022] [Accepted: 07/06/2022] [Indexed: 12/10/2022] Open
Abstract
The mosquito-borne disease caused by the Rocio virus is a neglected threat, and new immune inputs for serological testing are urgently required for diagnosis in low-resource settings and epidemiological surveillance. We used in silico approaches to identify a specific antigenic peptide (p_ROCV2) in the NS1 protein of the Rocio virus that was theoretically predicted to be stable and exposed on its surface, where it demonstrated key properties allowing it to interact with antibodies. These findings related to the molecular dynamics of this peptide provide important insights for advancing diagnostic platforms and investigating therapeutic alternatives.
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Affiliation(s)
- Marielena Vogel Saivish
- Departamento de Doenças Dermatológicas, Infecciosas e Parasitárias, Faculdade de Medicina de São José do Rio Preto (FAMERP), São José do Rio Preto 15090-000, SP, Brazil; (M.V.S.); (G.C.D.d.S.)
- Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas 13083-100, SP, Brazil;
| | - Gabriela de Lima Menezes
- Núcleo Colaborativo de Biosistemas, Universidade Federal de Jataí, Jataí 75801-615, GO, Brazil;
- Bioinformatics Multidisciplinary Environment, Programa de Pós Graduação em Bioinformática, Universidade Federal do Rio Grande do Norte, Natal 59078-400, RN, Brazil
| | - Vivaldo Gomes da Costa
- Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP), São José do Rio Preto 15054-000, SP, Brazil;
| | - Gislaine Celestino Dutra da Silva
- Departamento de Doenças Dermatológicas, Infecciosas e Parasitárias, Faculdade de Medicina de São José do Rio Preto (FAMERP), São José do Rio Preto 15090-000, SP, Brazil; (M.V.S.); (G.C.D.d.S.)
| | - Rafael Elias Marques
- Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas 13083-100, SP, Brazil;
| | - Maurício Lacerda Nogueira
- Departamento de Doenças Dermatológicas, Infecciosas e Parasitárias, Faculdade de Medicina de São José do Rio Preto (FAMERP), São José do Rio Preto 15090-000, SP, Brazil; (M.V.S.); (G.C.D.d.S.)
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Abstract
The persistence of the coronavirus disease 2019 (COVID-19) pandemic has resulted in increasingly disruptive impacts, and it has become the most devastating challenge to global health in a century. The rapid emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants challenges the currently available therapeutics for clinical application. Nonstructural proteins (also known as replicase proteins) with versatile biological functions play central roles in viral replication and transcription inside the host cells, and they are the most conserved target proteins among the SARS-CoV-2 variants. Specifically, they constitute the replication-transcription complexes (RTCs) dominating the synthesis of viral RNA. Knowledge of themolecular mechanisms of nonstructural proteins and their assembly into RTCs will benefit the development of antivirals targeting them against existing or potentially emerging variants. In this review, we summarize current knowledge of the structures and functions of coronavirus nonstructural proteins as well as the assembly and functions of RTCs in the life cycle of the virus.
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Affiliation(s)
- Zhiyong Lou
- Ministry of Education Key Laboratory of Protein Science, School of Medicine, Tsinghua University, Beijing, China; ,
| | - Zihe Rao
- Ministry of Education Key Laboratory of Protein Science, School of Medicine, Tsinghua University, Beijing, China; , .,Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,School of Life Sciences, Tsinghua University, Beijing, China.,State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences and College of Pharmacy, Nankai University, Tianjin, China.,National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,Guangzhou Laboratory, Guangzhou, China
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9
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Mirabelli C, Jones MK, Young VL, Kolawole AO, Owusu I, Shan M, Abuaita B, Turula H, Trevino JG, Grigorova I, Lundy SK, Lyssiotis CA, Ward VK, Karst SM, Wobus CE. Human Norovirus Triggers Primary B Cell Immune Activation In Vitro. mBio 2022; 13:e0017522. [PMID: 35404121 PMCID: PMC9040803 DOI: 10.1128/mbio.00175-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/04/2022] [Indexed: 12/15/2022] Open
Abstract
Human norovirus (HNoV) is a global health and socioeconomic burden, estimated to infect every individual at least five times during their lifetime. The underlying mechanism for the potential lack of long-term immune protection from HNoV infections is not understood and prompted us to investigate HNoV susceptibility of primary human B cells and its functional impact. Primary B cells isolated from whole blood were infected with HNoV-positive stool samples and harvested at 3 days postinfection (dpi) to assess the viral RNA yield by reverse transcriptase quantitative PCR (RT-qPCR). A 3- to 18-fold increase in the HNoV RNA yield was observed in 50 to 60% of donors. Infection was further confirmed in B cells derived from splenic and lymph node biopsy specimens. Next, we characterized infection of whole-blood-derived B cells by flow cytometry in specific functional B cell subsets (naive CD27- IgD+, memory-switched CD27+ IgD-, memory-unswitched CD27+ IgD+, and double-negative CD27- IgD- cells). While the susceptibilities of the subsets were similar, changes in the B cell subset distribution upon infection were observed, which were also noted after treatment with HNoV virus-like particles and the predicted recombinant NS1 protein. Importantly, primary B cell stimulation with the predicted recombinant NS1 protein triggered B cell activation and induced metabolic changes. These data demonstrate that primary B cells are susceptible to HNoV infection and suggest that the NS1 protein can alter B cell activation and metabolism in vitro, which could have implications for viral pathogenesis and immune responses in vivo. IMPORTANCE Human norovirus (HNoV) is the most prevalent causative agent of gastroenteritis worldwide. Infection results in a self-limiting disease that can become chronic and severe in the immunocompromised, the elderly, and infants. There are currently no approved therapeutic and preventative strategies to limit the health and socioeconomic burdens associated with HNoV infections. Moreover, HNoV does not elicit lifelong immunity as repeat infections are common, presenting a challenge for vaccine development. Given the importance of B cells for humoral immunity, we investigated the susceptibility and impact of HNoV infection on human B cells. We found that HNoV replicates in human primary B cells derived from blood, spleen, and lymph node specimens, while the nonstructural protein NS1 can activate B cells. Because of the secreted nature of NS1, we put forward the hypothesis that HNoV infection can modulate bystander B cell function with potential impacts on systemic immune responses.
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Affiliation(s)
- Carmen Mirabelli
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Melissa K. Jones
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Microbiology and Cell Science, IFAS, University of Florida, Gainesville, Florida, USA
| | - Vivienne L. Young
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Abimbola O. Kolawole
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Irene Owusu
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
- West African Center for Cell Biology of Infectious Pathogens, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
| | - Mengrou Shan
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Basel Abuaita
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Holly Turula
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
- Graduate Program in Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jose G. Trevino
- Division of Surgical Oncology, Department of Surgery, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Irina Grigorova
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Steven K. Lundy
- Division of Rheumatology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Costas A. Lyssiotis
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Vernon K. Ward
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Stephanie M. Karst
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Christiane E. Wobus
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
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Barik S. Mechanisms of Viral Degradation of Cellular Signal Transducer and Activator of Transcription 2. Int J Mol Sci 2022; 23:ijms23010489. [PMID: 35008916 PMCID: PMC8745392 DOI: 10.3390/ijms23010489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/28/2021] [Accepted: 12/31/2021] [Indexed: 12/31/2022] Open
Abstract
Virus infection of eukaryotes triggers cellular innate immune response, a major arm of which is the type I interferon (IFN) family of cytokines. Binding of IFN to cell surface receptors triggers a signaling cascade in which the signal transducer and activator of transcription 2 (STAT2) plays a key role, ultimately leading to an antiviral state of the cell. In retaliation, many viruses counteract the immune response, often by the destruction and/or inactivation of STAT2, promoted by specific viral proteins that do not possess protease activities of their own. This review offers a summary of viral mechanisms of STAT2 subversion with emphasis on degradation. Some viruses also destroy STAT1, another major member of the STAT family, but most viruses are selective in targeting either STAT2 or STAT1. Interestingly, degradation of STAT2 by a few viruses requires the presence of both STAT proteins. Available evidence suggests a mechanism in which multiple sites and domains of STAT2 are required for engagement and degradation by a multi-subunit degradative complex, comprising viral and cellular proteins, including the ubiquitin–proteasomal system. However, the exact molecular nature of this complex and the alternative degradation mechanisms remain largely unknown, as critically presented here with prospective directions of future study.
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Affiliation(s)
- Sailen Barik
- EonBio, 3780 Pelham Drive, Mobile, AL 36619, USA
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11
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Ishida H, Murakami S, Kamiki H, Matsugo H, Katayama M, Sekine W, Ohira K, Takenaka-Uema A, Horimoto T. Construction of an Influenza D Virus with an Eight-Segmented Genome. Viruses 2021; 13:v13112166. [PMID: 34834971 PMCID: PMC8619389 DOI: 10.3390/v13112166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/22/2021] [Accepted: 10/25/2021] [Indexed: 11/16/2022] Open
Abstract
Influenza D virus (IDV) may cause the bovine respiratory disease complex, which is the most common and costly disease affecting the cattle industry. Previously, we revealed that eight segments could be actively packaged in its single virion, suggesting that IDV with the seven-segmented genome shows an agnostic genome packaging mechanism. Herein, we engineered an eight-segmented recombinant IDV in which the NS1 or NS2 genes were separated from NS segment into independent segments (NS1 or NS2 segments, respectively), leading to monocistronic translation of each NS protein. We constructed two plasmids: one for the viral RNA (vRNA)-synthesis of the NS1 segment with a silent mutation at the splicing acceptor site, which controls NS2 transcription in the NS segment; and another for the RNA synthesis of the NS2 segment, with deletion of the intron in the NS segment. These plasmids and six other vRNA-synthesis plasmids were used to fabricate an infectious eight-segmented IDV via reverse genetics. This system enables analysis of the functions of NS1 or NS2. We tested the requirement of the N-terminal overlapping region (NOR) in these proteins for viral infectivity. We rescued a virus with NOR-deleted NS2 protein, which displayed a growth rate equivalent to that of the eight-segmented virus with intact NS2. Thus, the NOR may not influence viral growth. In contrast, a virus with NOR-deleted NS1 protein could not be rescued. These results indicate that the eight-segmented rescue system of IDV may provide an alternative method to analyze viral proteins at the molecular level.
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12
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Hu Y, Ke P, Gao P, Zhang Y, Zhou L, Ge X, Guo X, Han J, Yang H. Identification of an Intramolecular Switch That Controls the Interaction of Helicase nsp10 with Membrane-Associated nsp12 of Porcine Reproductive and Respiratory Syndrome Virus. J Virol 2021; 95:e0051821. [PMID: 34076477 DOI: 10.1128/JVI.00518-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A critical step in replication of positive-stranded RNA viruses is the assembly of replication and transcription complexes (RTC). We have recently mapped the nonstructural protein (nsp) interaction network of porcine reproductive and respiratory syndrome virus (PRRSV) and provided evidence by truncation mutagenesis that the recruitment of viral core replicase enzymes (nsp9 and nsp10) to membrane proteins (nsp2, nsp3, nsp5, and nsp12) is subject to regulation. Here, we went further to discover an intramolecular switch within the helicase nsp10 that controls its interaction with the membrane-associated protein nsp12. Deletion of nsp10 linker region amino acids 124 to 133, connecting domain 1B to 1A, led to complete relocalization and colocalization in the cells coexpressing nsp12. Moreover, single-amino-acid substitutions (e.g., nsp10 E131A and I132A) were sufficient to enable the nsp10-nsp12 interaction. Further proof came from membrane floatation assays that revealed a clear movement of nsp10 mutants, but not wild-type nsp10, toward the top of sucrose gradients in the presence of nsp12. Interestingly, the same mutations were not able to activate the nsp10-nsp2/3 interaction, suggesting a differential requirement for conformation. Reverse genetics analysis showed that PRRSV mutants carrying the single substitutions were not viable and were defective in subgenomic RNA (sgRNA) accumulation. Together, our results provide strong evidence for a regulated interaction between nsp10 and nsp12 and suggest an essential role for an orchestrated RTC assembly in sgRNA synthesis. IMPORTANCE Assembly of replication and transcription complexes (RTC) is a limiting step for viral RNA synthesis. The PRRSV RTC macromolecular complexes are comprised of mainly viral nonstructural replicase proteins (nsps), but how they come together remains elusive. We previously showed that viral helicase nsp10 interacts nsp12 in a regulated manner by truncation mutagenesis. Here, we revealed that the interaction is controlled by single residues within the domain linker region of nsp10. Moreover, the activation mutations lead to defects in viral sgRNA synthesis. Our results provide important insight into the mechanisms of PRRSV RTC assembly and regulation of viral sgRNA synthesis.
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Pei J, Wagner ND, Zou AJ, Chatterjee S, Borek D, Cole AR, Kim PJ, Basler CF, Otwinowski Z, Gross ML, Amarasinghe GK, Leung DW. Structural basis for IFN antagonism by human respiratory syncytial virus nonstructural protein 2. Proc Natl Acad Sci U S A 2021; 118:e2020587118. [PMID: 33649232 PMCID: PMC7958447 DOI: 10.1073/pnas.2020587118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Human respiratory syncytial virus (RSV) nonstructural protein 2 (NS2) inhibits host interferon (IFN) responses stimulated by RSV infection by targeting early steps in the IFN-signaling pathway. But the molecular mechanisms related to how NS2 regulates these processes remain incompletely understood. To address this gap, here we solved the X-ray crystal structure of NS2. This structure revealed a unique fold that is distinct from other known viral IFN antagonists, including RSV NS1. We also show that NS2 directly interacts with an inactive conformation of the RIG-I-like receptors (RLRs) RIG-I and MDA5. NS2 binding prevents RLR ubiquitination, a process critical for prolonged activation of downstream signaling. Structural analysis, including by hydrogen-deuterium exchange coupled to mass spectrometry, revealed that the N terminus of NS2 is essential for binding to the RIG-I caspase activation and recruitment domains. N-terminal mutations significantly diminish RIG-I interactions and result in increased IFNβ messenger RNA levels. Collectively, our studies uncover a previously unappreciated regulatory mechanism by which NS2 further modulates host responses and define an approach for targeting host responses.
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Affiliation(s)
- Jingjing Pei
- John T. Milliken Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110
| | - Nicole D Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63110
| | - Angela J Zou
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110
| | - Srirupa Chatterjee
- John T. Milliken Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110
| | - Dominika Borek
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Aidan R Cole
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110
| | - Preston J Kim
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110
| | - Christopher F Basler
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303
| | - Zbyszek Otwinowski
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63110
| | - Gaya K Amarasinghe
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110
| | - Daisy W Leung
- John T. Milliken Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110;
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110
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Kim NE, Kim DK, Song YJ. SARS-CoV-2 Nonstructural Proteins 1 and 13 Suppress Caspase-1 and the NLRP3 Inflammasome Activation. Microorganisms 2021; 9:microorganisms9030494. [PMID: 33652815 PMCID: PMC7996899 DOI: 10.3390/microorganisms9030494] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/21/2021] [Accepted: 02/22/2021] [Indexed: 02/07/2023] Open
Abstract
Viral infection-induced activation of inflammasome complexes has both positive and negative effects on the host. Proper activation of inflammasome complexes induces down-stream effector mechanisms that inhibit viral replication and promote viral clearance, whereas dysregulated activation has detrimental effects on the host. Coronaviruses, including SARS-CoV and MERS-CoV, encode viroporins that activate the NLRP3 inflammasome, and the severity of coronavirus disease is associated with the inflammasome activation. Although the NLRP3 inflammasome activation is implicated in the pathogenesis of coronaviruses, these viruses must evade inflammasome-mediated antiviral immune responses to establish primary replication. Screening of a complementary DNA (cDNA) library encoding 28 SARS-CoV-2 open reading frames (ORFs) showed that two nonstructural proteins (NSPs), NSP1 and NSP13, inhibited caspase-1-mediated IL-1β activation. NSP1 amino acid residues involved in host translation shutoff and NSP13 domains responsible for helicase activity were associated with caspase-1 inhibition. In THP-1 cells, both NSP1 and NSP13 significantly reduced NLRP3-inflammasome-induced caspase-1 activity and IL-1β secretion. These findings indicate that SARS-CoV-2 NSP1 and NSP13 are potent antagonists of the NLRP3 inflammasome.
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Affiliation(s)
- Na-Eun Kim
- Department of Life Science, Gachon University, Seongnam-Si, Gyeonggi-do 13120, Korea;
| | - Dae-Kyum Kim
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada;
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E1, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
- Center for Personalized Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14203, USA
| | - Yoon-Jae Song
- Department of Life Science, Gachon University, Seongnam-Si, Gyeonggi-do 13120, Korea;
- Correspondence:
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15
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Gallo G, Caignard G, Badonnel K, Chevreux G, Terrier S, Szemiel A, Roman-Sosa G, Binder F, Gu Q, Da Silva Filipe A, Ulrich RG, Kohl A, Vitour D, Tordo N, Ermonval M. Interactions of Viral Proteins from Pathogenic and Low or Non-Pathogenic Orthohantaviruses with Human Type I Interferon Signaling. Viruses 2021; 13:140. [PMID: 33478127 PMCID: PMC7835746 DOI: 10.3390/v13010140] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/12/2021] [Accepted: 01/16/2021] [Indexed: 12/13/2022] Open
Abstract
Rodent-borne orthohantaviruses are asymptomatic in their natural reservoir, but they can cause severe diseases in humans. Although an exacerbated immune response relates to hantaviral pathologies, orthohantaviruses have to antagonize the antiviral interferon (IFN) response to successfully propagate in infected cells. We studied interactions of structural and nonstructural (NSs) proteins of pathogenic Puumala (PUUV), low-pathogenic Tula (TULV), and non-pathogenic Prospect Hill (PHV) viruses, with human type I and III IFN (IFN-I and IFN-III) pathways. The NSs proteins of all three viruses inhibited the RIG-I-activated IFNβ promoter, while only the glycoprotein precursor (GPC) of PUUV, or its cleavage product Gn/Gc, and the nucleocapsid (N) of TULV inhibited it. Moreover, the GPC of both PUUV and TULV antagonized the promoter of IFN-stimulated responsive elements (ISRE). Different viral proteins could thus contribute to inhibition of IFNβ response in a viral context. While PUUV and TULV strains replicated similarly, whether expressing entire or truncated NSs proteins, only PUUV encoding a wild type NSs protein led to late IFN expression and activation of IFN-stimulated genes (ISG). This, together with the identification of particular domains of NSs proteins and different biological processes that are associated with cellular proteins in complex with NSs proteins, suggested that the activation of IFN-I is probably not the only antiviral pathway to be counteracted by orthohantaviruses and that NSs proteins could have multiple inhibitory functions.
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Affiliation(s)
- Giulia Gallo
- Unité des Stratégies Antivirales, Institut Pasteur, 75015 Paris, France; (G.G.); (N.T.)
- Ecole Doctorale Complexité du Vivant, Sorbonne Université, 75006 Paris, France
| | - Grégory Caignard
- UMR 1161 Virologie, Anses-INRAE-EnvA, 94700 Maisons-Alfort, France; (G.C.); (D.V.)
| | - Karine Badonnel
- BREED, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France;
| | - Guillaume Chevreux
- Institut Jacques Monod, CNRS UMR 7592, ProteoSeine Mass Spectrometry Plateform, Université de Paris, 75013 Paris, France; (G.C.); (S.T.)
| | - Samuel Terrier
- Institut Jacques Monod, CNRS UMR 7592, ProteoSeine Mass Spectrometry Plateform, Université de Paris, 75013 Paris, France; (G.C.); (S.T.)
| | - Agnieszka Szemiel
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK; (A.S.); (Q.G.); (A.D.S.F.); (A.K.)
| | | | - Florian Binder
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, 17493 Greifswald-Insel Riems, Germany; (F.B.); (R.G.U.)
| | - Quan Gu
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK; (A.S.); (Q.G.); (A.D.S.F.); (A.K.)
| | - Ana Da Silva Filipe
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK; (A.S.); (Q.G.); (A.D.S.F.); (A.K.)
| | - Rainer G. Ulrich
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, 17493 Greifswald-Insel Riems, Germany; (F.B.); (R.G.U.)
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK; (A.S.); (Q.G.); (A.D.S.F.); (A.K.)
| | - Damien Vitour
- UMR 1161 Virologie, Anses-INRAE-EnvA, 94700 Maisons-Alfort, France; (G.C.); (D.V.)
| | - Noël Tordo
- Unité des Stratégies Antivirales, Institut Pasteur, 75015 Paris, France; (G.G.); (N.T.)
- Institut Pasteur de Guinée, BP 4416 Conakry, Guinea
| | - Myriam Ermonval
- Unité des Stratégies Antivirales, Institut Pasteur, 75015 Paris, France; (G.G.); (N.T.)
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16
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Abstract
Enteric symptomology seen in early-stage severe acute respiratory syndrome (SARS)-2003 and COVID-19 is evidence of virus replication occurring in the intestine, liver and pancreas. Aberrant lipid metabolism in morbidly obese individuals adversely affects the COVID-19 immune response and increases disease severity. Such observations are in line with the importance of lipid metabolism in COVID-19, and point to the gut as a site for intervention as well as a therapeutic target in treating the disease. Formation of complex lipid membranes and palmitoylation of coronavirus proteins are essential during viral replication and assembly. Inhibition of fatty acid synthase (FASN) and restoration of lipid catabolism by activation of AMP-activated protein kinase (AMPK) impede replication of coronaviruses closely related to SARS-coronavirus-2 (CoV-2). In vitro findings and clinical data reveal that the FASN inhibitor, orlistat, and the AMPK activator, metformin, may inhibit coronavirus replication and reduce systemic inflammation to restore immune homeostasis. Such observations, along with the known mechanisms of action for these types of drugs, suggest that targeting fatty acid lipid metabolism could directly inhibit virus replication while positively impacting the patient's response to COVID-19.
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Moghaddam P, Zahmatkesh A, Bagheri M, Mahravani H. Are Epitopic Sites of 3AB and 3D Nonstructural Proteins Sufficient for Detection of Foot and Mouth Disease? Viral Immunol 2020; 34:79-85. [PMID: 33296262 DOI: 10.1089/vim.2020.0144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An efficient method for detection of foot and mouth disease (FMD) and, particularly, differentiation of vaccinated from infected animals is the use of nonstructural (NS) proteins as antigens in Enzyme-Linked Immunosorbent Assay (ELISA) Kits. In this study, only epitopic regions of 3AB and 3D NS proteins were used for recombinant protein production, as a cost-effective method instead of peptide synthesis, for application in in-house ELISA diagnostic kits. Specific primers were designed according to the antigenic regions of 3AB (C-terminus of 3A and the whole 3B) and 3D (N-terminus) proteins, and the polymerase chain reaction (PCR) amplification was performed. Purified amplicons were cloned into pET21a (+) vectors and then transformed into Escherichia coli (BL21). Thereafter, bacteria were induced with 1 mM isopropyl β-d-1-thiogalactopyranoside (IPTG) for expression of antigenic proteins. Antigenic 3AB protein was expressed in soluble form, but 3D protein was extracted from the bacterial lysate. Protein expression was confirmed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analyses. An indirect ELISA was developed for each protein, and the diagnostic sensitivity and specificity were determined. The 3AB-ELISA showed higher sensitivity and specificity than 3D-ELISA (95.24% and 100%, compared with 90.48% and 88.71%, respectively). The epitopic 3AB-ELISA developed here can be used for detection and differentiation of FMD infected from vaccinated animals, but the epitopic 3D-ELISA showed lower efficiency in screening for FMD status.
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Affiliation(s)
- Parvin Moghaddam
- Department of Cell and Molecular Biology, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran
| | - Azadeh Zahmatkesh
- Department of Genomics and Genetic Engineering, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - Masoumeh Bagheri
- Department of Genomics and Genetic Engineering, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - Homayoon Mahravani
- Foot and Mouth Disease Reference Laboratory, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
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Park SY, Lee JM, Kim AY, Park SH, Kim JS, Kim H, Park JW, Park JH, Ko YJ, Park CK. Application of Heparin Affinity Chromatography to Produce a Differential Vaccine without Eliciting Antibodies against the Nonstructural Proteins of the Serotype O Foot-and-Mouth Disease Viruses. Viruses 2020; 12:v12121405. [PMID: 33297420 PMCID: PMC7762290 DOI: 10.3390/v12121405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/30/2020] [Accepted: 12/03/2020] [Indexed: 11/16/2022] Open
Abstract
Although polyethylene glycol (PEG) application is the most widely used method in removing nonstructural proteins (NSPs) for foot-and-mouth disease (FMD) vaccine production, some NSPs remaining in the antigen could elicit antibodies against these proteins after repeated vaccinations in livestock. Therefore, the purpose of this study was to purify the FMD virus (FMDV) via affinity chromatography using a heparin ligand to remove most proteins, including NSPs. Chromatography showed an intact virus (146S) particle recovery of 70% or more for three different strains of serotype O FMDV (two locally isolated strains and one genetically modified strain). The experimental vaccine made with antigens eluted via heparin affinity chromatography elicited virus-neutralizing antibodies against homologous viruses but did not induce antibodies against NSPs even after five immunizations in goats; this indicated that the NSPs were effectively removed from the vaccine antigen. This method can then be used to produce a higher-quality vaccine compared with PEG application in terms of the purity of the FMD vaccine. Therefore, this result would be an important groundwork for advanced FMD vaccine manufacturing in the near future.
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Affiliation(s)
- Sun Young Park
- Animal and Plant Quarantine Agency, 177 Hyeoksin-8-ro, Gimcheon-si 39660, Gyeongsangbuk-do, Korea; (S.Y.P.); (J.-M.L.); (A.-Y.K.); (S.H.P.); (J.-S.K.); (H.K.); (J.-W.P.); (J.-H.P.)
- Animal Disease Intervention Center, College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Gyeongsangbuk-do, Korea
| | - Jung-Min Lee
- Animal and Plant Quarantine Agency, 177 Hyeoksin-8-ro, Gimcheon-si 39660, Gyeongsangbuk-do, Korea; (S.Y.P.); (J.-M.L.); (A.-Y.K.); (S.H.P.); (J.-S.K.); (H.K.); (J.-W.P.); (J.-H.P.)
| | - Ah-Young Kim
- Animal and Plant Quarantine Agency, 177 Hyeoksin-8-ro, Gimcheon-si 39660, Gyeongsangbuk-do, Korea; (S.Y.P.); (J.-M.L.); (A.-Y.K.); (S.H.P.); (J.-S.K.); (H.K.); (J.-W.P.); (J.-H.P.)
| | - Sang Hyun Park
- Animal and Plant Quarantine Agency, 177 Hyeoksin-8-ro, Gimcheon-si 39660, Gyeongsangbuk-do, Korea; (S.Y.P.); (J.-M.L.); (A.-Y.K.); (S.H.P.); (J.-S.K.); (H.K.); (J.-W.P.); (J.-H.P.)
| | - Jae-Seok Kim
- Animal and Plant Quarantine Agency, 177 Hyeoksin-8-ro, Gimcheon-si 39660, Gyeongsangbuk-do, Korea; (S.Y.P.); (J.-M.L.); (A.-Y.K.); (S.H.P.); (J.-S.K.); (H.K.); (J.-W.P.); (J.-H.P.)
| | - Hyejin Kim
- Animal and Plant Quarantine Agency, 177 Hyeoksin-8-ro, Gimcheon-si 39660, Gyeongsangbuk-do, Korea; (S.Y.P.); (J.-M.L.); (A.-Y.K.); (S.H.P.); (J.-S.K.); (H.K.); (J.-W.P.); (J.-H.P.)
- Animal Disease Intervention Center, College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Gyeongsangbuk-do, Korea
| | - Jung-Won Park
- Animal and Plant Quarantine Agency, 177 Hyeoksin-8-ro, Gimcheon-si 39660, Gyeongsangbuk-do, Korea; (S.Y.P.); (J.-M.L.); (A.-Y.K.); (S.H.P.); (J.-S.K.); (H.K.); (J.-W.P.); (J.-H.P.)
| | - Jong-Hyeon Park
- Animal and Plant Quarantine Agency, 177 Hyeoksin-8-ro, Gimcheon-si 39660, Gyeongsangbuk-do, Korea; (S.Y.P.); (J.-M.L.); (A.-Y.K.); (S.H.P.); (J.-S.K.); (H.K.); (J.-W.P.); (J.-H.P.)
| | - Young-Joon Ko
- Animal and Plant Quarantine Agency, 177 Hyeoksin-8-ro, Gimcheon-si 39660, Gyeongsangbuk-do, Korea; (S.Y.P.); (J.-M.L.); (A.-Y.K.); (S.H.P.); (J.-S.K.); (H.K.); (J.-W.P.); (J.-H.P.)
- Correspondence: (Y.-J.K.); (C.-K.P.); Tel.: +82-5491-209-08 (Y.-J.K.); +82-5395-059-73 (C.-K.P.)
| | - Choi-Kyu Park
- Animal Disease Intervention Center, College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Gyeongsangbuk-do, Korea
- Correspondence: (Y.-J.K.); (C.-K.P.); Tel.: +82-5491-209-08 (Y.-J.K.); +82-5395-059-73 (C.-K.P.)
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Arora R, Liew CW, Soh TS, Otoo DA, Seh CC, Yue K, Nilar S, Wang G, Yokokawa F, Noble CG, Chen YL, Shi PY, Lescar J, Smith TM, Benson TE, Lim SP. Two RNA Tunnel Inhibitors Bind in Highly Conserved Sites in Dengue Virus NS5 Polymerase: Structural and Functional Studies. J Virol 2020; 94:e01130-20. [PMID: 32907977 DOI: 10.1128/JVI.01130-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 08/29/2020] [Indexed: 11/20/2022] Open
Abstract
Dengue virus (DENV) NS5 RNA-dependent RNA polymerase (RdRp), an important drug target, synthesizes viral RNA and is essential for viral replication. While a number of allosteric inhibitors have been reported for hepatitis C virus RdRp, few have been described for DENV RdRp. Following a diverse compound screening campaign and a rigorous hit-to-lead flowchart combining biochemical and biophysical approaches, two DENV RdRp nonnucleoside inhibitors were identified and characterized. These inhibitors show low- to high-micromolar inhibition in DENV RNA polymerization and cell-based assays. X-ray crystallography reveals that they bind in the enzyme RNA template tunnel. One compound (NITD-434) induced an allosteric pocket at the junction of the fingers and palm subdomains by displacing residue V603 in motif B. Binding of another compound (NITD-640) ordered the fingers loop preceding the F motif, close to the RNA template entrance. Most of the amino acid residues that interacted with these compounds are highly conserved in flaviviruses. Both sites are important for polymerase de novo initiation and elongation activities and essential for viral replication. This work provides evidence that the RNA tunnel in DENV RdRp offers interesting target sites for inhibition.IMPORTANCE Dengue virus (DENV), an important arthropod-transmitted human pathogen that causes a spectrum of diseases, has spread dramatically worldwide in recent years. Despite extensive efforts, the only commercial vaccine does not provide adequate protection to naive individuals. DENV NS5 polymerase is a promising drug target, as exemplified by the development of successful commercial drugs against hepatitis C virus (HCV) polymerase and HIV-1 reverse transcriptase. High-throughput screening of compound libraries against this enzyme enabled the discovery of inhibitors that induced binding sites in the RNA template channel. Characterizations by biochemical, biophysical, and reverse genetics approaches provide a better understanding of the biological relevance of these allosteric sites and the way forward to design more-potent inhibitors.
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He L, Liu W, Li J. [Overview of novel coronavirus infection and replication]. Sheng Wu Gong Cheng Xue Bao 2020; 36:1961-1969. [PMID: 33169562 DOI: 10.13345/j.cjb.200318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Coronaviruses are a type of positive-sense single-stranded RNA virus with envelope and widely exist in nature to cause respiratory infectious diseases. The novel coronavirus is a new outbreak virus that is susceptible to all people. Up to now, the disease has been widely spread in the world and poses a great threat to public health. In this review, the genomic features, key proteins, host infection and replication of coronaviruses and novel coronaviruses are reviewed in order to provide theoretical basis for the study of the pathogenic mechanism of virus infection on host cells and to provide basic support for the development of specific antiviral drugs.
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Affiliation(s)
- Lihong He
- Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenjun Liu
- Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Li
- Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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21
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Ogando NS, Zevenhoven-Dobbe JC, van der Meer Y, Bredenbeek PJ, Posthuma CC, Snijder EJ. The Enzymatic Activity of the nsp14 Exoribonuclease Is Critical for Replication of MERS-CoV and SARS-CoV-2. J Virol 2020; 94:e01246-20. [PMID: 32938769 PMCID: PMC7654266 DOI: 10.1128/jvi.01246-20] [Citation(s) in RCA: 155] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 09/09/2020] [Indexed: 02/08/2023] Open
Abstract
Coronaviruses (CoVs) stand out for their large RNA genome and complex RNA-synthesizing machinery comprising 16 nonstructural proteins (nsps). The bifunctional nsp14 contains 3'-to-5' exoribonuclease (ExoN) and guanine-N7-methyltransferase (N7-MTase) domains. While the latter presumably supports mRNA capping, ExoN is thought to mediate proofreading during genome replication. In line with such a role, ExoN knockout mutants of mouse hepatitis virus (MHV) and severe acute respiratory syndrome coronavirus (SARS-CoV) were previously reported to have crippled but viable hypermutation phenotypes. Remarkably, using reverse genetics, a large set of corresponding ExoN knockout mutations has now been found to be lethal for another betacoronavirus, Middle East respiratory syndrome coronavirus (MERS-CoV). For 13 mutants, viral progeny could not be recovered, unless-as happened occasionally-reversion had first occurred. Only a single mutant was viable, likely because its E191D substitution is highly conservative. Remarkably, a SARS-CoV-2 ExoN knockout mutant was found to be unable to replicate, resembling observations previously made for alpha- and gammacoronaviruses, but starkly contrasting with the documented phenotype of ExoN knockout mutants of the closely related SARS-CoV. Subsequently, we established in vitro assays with purified recombinant MERS-CoV nsp14 to monitor its ExoN and N7-MTase activities. All ExoN knockout mutations that proved lethal in reverse genetics were found to severely decrease ExoN activity while not affecting N7-MTase activity. Our study strongly suggests that CoV nsp14 ExoN has an additional function, which apparently is critical for primary viral RNA synthesis and thus differs from the proofreading function that, based on previous MHV and SARS-CoV studies, was proposed to boost longer-term replication fidelity.IMPORTANCE The bifunctional nsp14 subunit of the coronavirus replicase contains 3'-to-5' exoribonuclease (ExoN) and guanine-N7-methyltransferase domains. For the betacoronaviruses MHV and SARS-CoV, ExoN was reported to promote the fidelity of genome replication, presumably by mediating a form of proofreading. For these viruses, ExoN knockout mutants are viable while displaying an increased mutation frequency. Strikingly, we have now established that the equivalent ExoN knockout mutants of two other betacoronaviruses, MERS-CoV and SARS-CoV-2, are nonviable, suggesting an additional and critical ExoN function in their replication. This is remarkable in light of the very limited genetic distance between SARS-CoV and SARS-CoV-2, which is highlighted, for example, by 95% amino acid sequence identity in their nsp14 sequences. For (recombinant) MERS-CoV nsp14, both its enzymatic activities were evaluated using newly developed in vitro assays that can be used to characterize these key replicative enzymes in more detail and explore their potential as target for antiviral drug development.
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Affiliation(s)
- Natacha S Ogando
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jessika C Zevenhoven-Dobbe
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Yvonne van der Meer
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Peter J Bredenbeek
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Clara C Posthuma
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Eric J Snijder
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
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Rahman SK, Kerviel A, Mohl BP, He Y, Zhou ZH, Roy P. A Calcium Sensor Discovered in Bluetongue Virus Nonstructural Protein 2 Is Critical for Virus Replication. J Virol 2020; 94:e01099-20. [PMID: 32759321 DOI: 10.1128/JVI.01099-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/29/2020] [Indexed: 12/20/2022] Open
Abstract
After entering the host cells, viruses use cellular host factors to ensure a successful virus replication process. For replication in infected cells, members of the Reoviridae family form inclusion body-like structures known as viral inclusion bodies (VIB) or viral factories. Bluetongue virus (BTV) forms VIBs in infected cells through nonstructural protein 2 (NS2), a phosphoprotein. An important regulatory factor critical for VIB formation is phosphorylation of NS2. In our study, we discovered a characteristic calcium-binding EF-hand-like motif in NS2 and found that the calcium binding preferentially affects phosphorylation level of the NS2 and has a role in regulating VIB assembly. Many viruses use specific viral proteins to bind calcium ions (Ca2+) for stability or to modify host cell pathways; however, to date, no Ca2+ binding protein has been reported in bluetongue virus (BTV), the causative agent of bluetongue disease in livestock. Here, using a comprehensive bioinformatics screening, we identified a putative EF-hand-like Ca2+ binding motif in the carboxyl terminal region of BTV nonstructural phosphoprotein 2 (NS2). Subsequently, using a recombinant NS2, we demonstrated that NS2 binds Ca2+ efficiently and that Ca2+ binding was perturbed when the Asp and Glu residues in the motif were substituted by alanine. Using circular dichroism analysis, we found that Ca2+ binding by NS2 triggered a helix-to-coil secondary structure transition. Further, cryo-electron microscopy in the presence of Ca2+ revealed that NS2 forms helical oligomers which, when aligned with the N-terminal domain crystal structure, suggest an N-terminal domain that wraps around the C-terminal domain in the oligomer. Further, an in vitro kinase assay demonstrated that Ca2+ enhanced the phosphorylation of NS2 significantly. Importantly, mutations introduced at the Ca2+ binding site in the viral genome by reverse genetics failed to allow recovery of viable virus, and the NS2 phosphorylation level and assembly of viral inclusion bodies (VIBs) were reduced. Together, our data suggest that NS2 is a dedicated Ca2+ binding protein and that calcium sensing acts as a trigger for VIB assembly, which in turn facilitates virus replication and assembly. IMPORTANCE After entering the host cells, viruses use cellular host factors to ensure a successful virus replication process. For replication in infected cells, members of the Reoviridae family form inclusion body-like structures known as viral inclusion bodies (VIB) or viral factories. Bluetongue virus (BTV) forms VIBs in infected cells through nonstructural protein 2 (NS2), a phosphoprotein. An important regulatory factor critical for VIB formation is phosphorylation of NS2. In our study, we discovered a characteristic calcium-binding EF-hand-like motif in NS2 and found that the calcium binding preferentially affects phosphorylation level of the NS2 and has a role in regulating VIB assembly.
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Min YQ, Shi C, Yao T, Feng K, Mo Q, Deng F, Wang H, Ning YJ. The Nonstructural Protein of Guertu Virus Disrupts Host Defenses by Blocking Antiviral Interferon Induction and Action. ACS Infect Dis 2020; 6:857-870. [PMID: 32167734 DOI: 10.1021/acsinfecdis.9b00492] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Guertu virus (GTV) is a potentially highly pathogenic bunyavirus newly isolated in China, which is genetically related to the severe fever with thrombocytopenia syndrome virus (SFTSV) and Heartland virus (HRTV), two other emerging life-threatening bunyaviruses. Previous studies suggested that SFTSV and HRTV antagonize the interferon (IFN) system by targeting antiviral signaling proteins in different ways. However, whether and how GTV counteracts the host innate immunity are unclear. Here, we found that GTV strongly inhibits both IFN induction and action through its nonstructural protein (NSs). Different from the NSs of SFTSV and HRTV, GTV NSs (G-NSs) induced the formation of two distinctive cytoplasmic structures, compact inclusion bodies (IBs) and extended filamentous structures (FSs). Protein interaction and colocalization analyses demonstrated that G-NSs interacts with TBK1 (TANK binding kinase-1, the pivotal kinase for IFN induction) and STAT2 (signal transducer and activator of transcription 2, the essential transcription factor for IFN action) and irreversibly sequesters the host proteins into the viral IBs and FSs. Consistently, G-NSs thus inhibited phosphorylation/activation and nuclear translocation of IFN-regulatory factor 3 (IRF3, the substrate of TBK1), diminishing the IFN induction. Furthermore, G-NSs sequestration of STAT2 blocked phosphorylation/activation and nuclear translocation of STAT2, disabling IFN action and host antiviral state establishment. Collectively, this study shows the robust subversion of the two phases of the IFN antiviral system by GTV and unravels the respective molecular mechanisms, exhibiting some notable differences from those employed by SFTSV and HRTV, providing insights into the virus-host interactions and pathogenesis, and probably also benefiting the prevention and treatment of the related infectious diseases in the future.
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Affiliation(s)
- Yuan-Qin Min
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Chen Shi
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- The University of Chinese Academy of Sciences, Beijing 101408, China
| | - Ting Yao
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- The University of Chinese Academy of Sciences, Beijing 101408, China
| | - Kuan Feng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- The University of Chinese Academy of Sciences, Beijing 101408, China
| | - Qiong Mo
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- The University of Chinese Academy of Sciences, Beijing 101408, China
| | - Fei Deng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Hualin Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Yun-Jia Ning
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
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24
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Kandeel M, Ibrahim A, Fayez M, Al-Nazawi M. From SARS and MERS CoVs to SARS-CoV-2: Moving toward more biased codon usage in viral structural and nonstructural genes. J Med Virol 2020; 92:660-666. [PMID: 32159237 PMCID: PMC7228358 DOI: 10.1002/jmv.25754] [Citation(s) in RCA: 122] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 03/09/2020] [Indexed: 12/11/2022]
Abstract
Background Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is an emerging disease with fatal outcomes. In this study, a fundamental knowledge gap question is to be resolved by evaluating the differences in biological and pathogenic aspects of SARS‐CoV‐2 and the changes in SARS‐CoV‐2 in comparison with the two prior major COV epidemics, SARS and Middle East respiratory syndrome (MERS) coronaviruses. Methods The genome composition, nucleotide analysis, codon usage indices, relative synonymous codons usage, and effective number of codons (ENc) were analyzed in the four structural genes; Spike (S), Envelope (E), membrane (M), and Nucleocapsid (N) genes, and two of the most important nonstructural genes comprising RNA‐dependent RNA polymerase and main protease (Mpro) of SARS‐CoV‐2, Beta‐CoV from pangolins, bat SARS, MERS, and SARS CoVs. Results SARS‐CoV‐2 prefers pyrimidine rich codons to purines. Most high‐frequency codons were ending with A or T, while the low frequency and rare codons were ending with G or C. SARS‐CoV‐2 structural proteins showed 5 to 20 lower ENc values, compared with SARS, bat SARS, and MERS CoVs. This implies higher codon bias and higher gene expression efficiency of SARS‐CoV‐2 structural proteins. SARS‐CoV‐2 encoded the highest number of over‐biased and negatively biased codons. Pangolin Beta‐CoV showed little differences with SARS‐CoV‐2 ENc values, compared with SARS, bat SARS, and MERS CoV. Conclusion Extreme bias and lower ENc values of SARS‐CoV‐2, especially in Spike, Envelope, and Mpro genes, are suggestive for higher gene expression efficiency, compared with SARS, bat SARS, and MERS CoVs.
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Affiliation(s)
- Mahmoud Kandeel
- Department of Biomedical Sciences, College of Veterinary Medicine, King Faisal University, Al-hofuf, Egypt.,Department of Pharmacology, Faculty of Veterinary Medicine, Kafrelshikh University, Kafrelshikh, Egypt
| | - Abdelazim Ibrahim
- Department of Pathology, College of Veterinary Medicine, King Faisal University, Al-hofuf, Saudi Arabia.,Department of Pathology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
| | - Mahmoud Fayez
- Al Ahsa Veterinary Diagnostic Laboratory, Ministry of Agriculture, Al-Ahsa, Kingdom of Saudi Arabia.,Veterinary Serum and Vaccine Institute, Cairo, Egypt
| | - Mohammed Al-Nazawi
- Department of Biomedical Sciences, College of Veterinary Medicine, King Faisal University, Al-hofuf, Egypt
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25
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Choi Y, Jiang Z, Shin WJ, Jung JU. Severe Fever with Thrombocytopenia Syndrome Virus NSs Interacts with TRIM21 To Activate the p62-Keap1-Nrf2 Pathway. J Virol 2020; 94:e01684-19. [PMID: 31852783 DOI: 10.1128/JVI.01684-19] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 12/10/2019] [Indexed: 12/28/2022] Open
Abstract
Nuclear factor erythroid 2-related factor 2 (Nrf2) dissociates from its inhibitor, Keap1, upon stress signals and subsequently induces an antioxidant response that critically controls the viral life cycle and pathogenesis. Besides intracellular Fc receptor function, tripartite motif 21 (TRIM21) E3 ligase plays an essential role in the p62-Keap1-Nrf2 axis pathway for redox homeostasis. Specifically, TRIM21-mediated p62 ubiquitination abrogates p62 oligomerization and sequestration activity and negatively regulates the Keap1-Nrf2-mediated antioxidant response. A number of viruses target the Nrf2-mediated antioxidant response to generate an optimal environment for their life cycle. Here we report that a nonstructural protein (NSs) of severe fever with thrombocytopenia syndrome virus (SFTSV) interacts with and inhibits TRIM21 to activate the Nrf2 antioxidant signal pathway. Mass spectrometry identified TRIM21 to be a binding protein for NSs. NSs bound to the carboxyl-terminal SPRY subdomain of TRIM21, enhancing p62 stability and oligomerization. This facilitated p62-mediated Keap1 sequestration and ultimately increased Nrf2-mediated transcriptional activation of antioxidant genes, including those for heme oxygenase 1, NAD(P)H quinone oxidoreductase 1, and CD36. Mutational analysis found that the NSs-A46 mutant, which no longer interacted with TRIM21, was unable to increase Nrf2-mediated transcriptional activation. Functionally, the NS wild type (WT), but not the NSs-A46 mutant, increased the surface expression of the CD36 scavenger receptor, resulting in an increase in phagocytosis and lipid uptake. A combination of reverse genetics and assays with Ifnar -/- mouse models revealed that while the SFTSV-A46 mutant replicated similarly to wild-type SFTSV (SFTSV-WT), it showed weaker pathogenic activity than SFTSV-WT. These data suggest that the activation of the p62-Keap1-Nrf2 antioxidant response induced by the NSs-TRIM21 interaction contributes to the development of an optimal environment for the SFTSV life cycle and efficient pathogenesis.IMPORTANCE Tick-borne diseases have become a growing threat to public health. SFTSV, listed by the World Health Organization as a prioritized pathogen, is an emerging phlebovirus, and fatality rates among those infected with this virus are high. Infected Haemaphysalis longicornis ticks are the major source of human SFTSV infection. In particular, the recent spread of this tick to over 12 states in the United States has increased the potential for outbreaks of this disease beyond Far East Asia. Due to the lack of therapies and vaccines against SFTSV infection, there is a pressing need to understand SFTSV pathogenesis. As the Nrf2-mediated antioxidant response affects viral life cycles, a number of viruses deregulate Nrf2 pathways. Here we demonstrate that the SFTSV NSs inhibits the TRIM21 function to upregulate the p62-Keap1-Nrf2 antioxidant pathway for efficient viral pathogenesis. This study not only demonstrates the critical role of SFTSV NSs in viral pathogenesis but also suggests potential future therapeutic approaches to treat SFTSV-infected patients.
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El Sahili A, Soh TS, Schiltz J, Gharbi-Ayachi A, Seh CC, Shi PY, Lim SP, Lescar J. NS5 from Dengue Virus Serotype 2 Can Adopt a Conformation Analogous to That of Its Zika Virus and Japanese Encephalitis Virus Homologues. J Virol 2019; 94:e01294-19. [PMID: 31597763 DOI: 10.1128/JVI.01294-19] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 09/30/2019] [Indexed: 01/07/2023] Open
Abstract
Flavivirus nonstructural protein 5 (NS5) contains an N-terminal methyltransferase (MTase) domain and a C-terminal polymerase (RNA-dependent RNA polymerase [RdRp]) domain fused through a 9-amino-acid linker. While the individual NS5 domains are structurally conserved, in the full-length protein, their relative orientations fall into two classes: the NS5 proteins from Japanese encephalitis virus (JEV) and Zika virus (ZIKV) adopt one conformation, while the NS5 protein from dengue virus serotype 3 (DENV3) adopts another. Here, we report a crystallographic structure of NS5 from DENV2 in a conformation similar to the extended one seen in JEV and ZIKV NS5 crystal structures. Replacement of the DENV2 NS5 linker with DENV1, DENV3, DENV4, JEV, and ZIKV NS5 linkers had modest or minimal effects on in vitro DENV2 MTase and RdRp activities. Heterotypic DENV NS5 linkers attenuated DENV2 replicon growth in cells, while the JEV and ZIKV NS5 linkers abolished replication. Thus, the JEV and ZIKV linkers likely hindered essential DENV2 NS5 interactions with other viral or host proteins within the virus replicative complex. Overall, this work sheds light on the dynamics of the multifunctional flavivirus NS5 protein and its interdomain linker. Targeting the NS5 linker is a possible strategy for producing attenuated flavivirus strains for vaccine design.IMPORTANCE Flaviviruses include important human pathogens, such as dengue virus and Zika virus. NS5 is a nonstructural protein essential for flavivirus RNA replication with dual MTase and RdRp enzyme activities and thus constitutes a major drug target. Insights into NS5 structure, dynamics, and evolution should inform the development of antiviral inhibitors and vaccine design. We found that NS5 from DENV2 can adopt a conformation resembling that of NS5 from JEV and ZIKV. Replacement of the DENV2 NS5 linker with the JEV and ZIKV NS5 linkers abolished DENV2 replication in cells, without significantly impacting in vitro DENV2 NS5 enzymatic activities. We propose that heterotypic flavivirus NS5 linkers impede DENV2 NS5 protein-protein interactions that are essential for virus replication.
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27
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Feng K, Deng F, Hu Z, Wang H, Ning YJ. Heartland virus antagonizes type I and III interferon antiviral signaling by inhibiting phosphorylation and nuclear translocation of STAT2 and STAT1. J Biol Chem 2019; 294:9503-9517. [PMID: 31040183 DOI: 10.1074/jbc.ra118.006563] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 04/17/2019] [Indexed: 01/30/2023] Open
Abstract
Heartland virus (HRTV) is a pathogenic phlebovirus recently identified in the United States and related to severe fever with thrombocytopenia syndrome virus (SFTSV) emerging in Asia. We previously reported that SFTSV disrupts host antiviral responses directed by interferons (IFNs) and their downstream regulators, signal transducer and activator of transcription (STAT) proteins. However, whether HRTV infection antagonizes the IFN-STAT signaling axis remains unclear. Here, we show that, similar to SFTSV, HRTV also inhibits IFN-α- and IFN-λ-mediated antiviral responses. As expected, the nonstructural protein (NSs) of HRTV (HNSs) robustly antagonized both type I and III IFN signaling. Protein interaction analyses revealed that a common component downstream of type I and III IFN signaling, STAT2, is the target of HNSs. Of note, the DNA-binding and linker domains of STAT2 were required for an efficient HNSs-STAT2 interaction. Unlike the NSs of SFTSV (SNSs), which blocks both STAT2 and STAT1 nuclear accumulation, HNSs specifically blocked IFN-triggered nuclear translocation only of STAT2. However, upon HRTV infection, IFN-induced nuclear translocation of both STAT2 and STAT1 was suppressed, suggesting that STAT1 is an additional HRTV target for IFN antagonism. Consistently, despite HNSs inhibiting phosphorylation only of STAT2 and not STAT1, HRTV infection diminished both STAT2 and STAT1 phosphorylation. These results suggest that HRTV antagonizes IFN antiviral signaling by dampening both STAT2 and STAT1 activities. We propose that HNSs-specific targeting of STAT2 likely plays an important role but is not all of the "tactics" of HRTV in its immune evasion.
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Affiliation(s)
- Kuan Feng
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and.,the University of Chinese Academy of Sciences, Beijing 101408, China
| | - Fei Deng
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Zhihong Hu
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Hualin Wang
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Yun-Jia Ning
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
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28
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Roulin PS, Murer LP, Greber UF. A Single Point Mutation in the Rhinovirus 2B Protein Reduces the Requirement for Phosphatidylinositol 4-Kinase Class III Beta in Viral Replication. J Virol 2018; 92:e01462-18. [PMID: 30209171 DOI: 10.1128/JVI.01462-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 08/31/2018] [Indexed: 01/31/2023] Open
Abstract
Rhinoviruses (RVs) replicate on cytoplasmic membranes derived from the Golgi apparatus. They encode membrane-targeted proteins 2B, 2C, and 3A, which control trafficking and lipid composition of the replication membrane. The virus recruits host factors for replication, such as phosphatidylinositol 4 (PI4)-kinase 3beta (PI4K3b), which boosts PI4-phosphate (PI4P) levels and drives lipid countercurrent exchange of PI4P against cholesterol at endoplasmic reticulum-Golgi membrane contact sites through the lipid shuttling protein oxysterol binding protein 1 (OSBP1). We identified a PI4K3b inhibitor-resistant RV-A16 variant with a single point mutation in the conserved 2B protein near the cytosolic carboxy terminus, isoleucine 92 to threonine (termed 2B[I92T]). The mutation did not confer resistance to cholesterol-sequestering compounds or OSBP1 inhibition, suggesting invariant dependency on the PI4P/cholesterol lipid countercurrents. In the presence of PI4K3b inhibitor, Golgi reorganization and PI4P lipid induction occurred in RV-A16 2B[I92] but not in wild-type infection. The knockout of PI4K3b abolished the replication of both the 2B[I92T] mutant and the wild type. Doxycycline-inducible expression of PI4K3b in PI4K3b knockout cells efficiently rescued the 2B[I92T] mutant and, less effectively, wild-type virus infection. Ectopic expression of 2B[I92T] or 2B was less efficient than that of 3A in recruiting PI4K3b to perinuclear membranes, suggesting a supportive rather than decisive role of 2B in recruiting PI4K3b. The data suggest that 2B tunes the recruitment of PI4K3b to the replication membrane and allows the virus to adapt to cells with low levels of PI4K3b while still maintaining the PI4P/cholesterol countercurrent for establishing Golgi-derived RV replication membranes.IMPORTANCE Human rhinoviruses (RVs) are the major cause of the common cold worldwide. They cause asthmatic exacerbations and chronic obstructive pulmonary disease. Despite recent advances, the development of antivirals and vaccines has proven difficult due to the high number and variability of RV types. The identification of critical host factors and their interactions with viral proteins and membrane lipids for the establishment of viral replication is a basis for drug development strategies. Our findings here shed new light on the interactions between nonstructural viral membrane proteins and class III phosphatidylinositol 4 kinases from the host and highlight the importance of phosphatidylinositol 4 phosphate for RV replication.
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29
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Fukai K, Nishi T, Shimada N, Morioka K, Yamada M, Yoshida K, Yamakawa M. Comparative evaluation of two ELISA kits for detecting antibodies to a nonstructural protein of foot-and-mouth disease virus using serum samples collected from naturally and experimentally infected cows. J Vet Med Sci 2018; 80:1624-1630. [PMID: 30135332 PMCID: PMC6207510 DOI: 10.1292/jvms.17-0662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
When foot-and-mouth disease (FMD) occurs and a “vaccination-to-live” policy is adopted in
a country, the country must perform serological surveillance of a nonstructural protein
(NSP) of FMD virus. The NCPanaftosa kit is the only kit for detecting antibodies to NSPs
that is officially recognized as the reference regent by the World Organization for Animal
Health; however, it is only used in South American countries. In this study, the
specificity and sensitivity of the NCPanaftosa kit were compared with those of the
PrioCHECK kit sold by an international company. Results in this study suggest that the
PrioCHECK kit performs similarly to the NCPanaftosa kit in detecting antibodies to the NSP
in the cattle population.
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Affiliation(s)
- Katsuhiko Fukai
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-honcho, Kodaira, Tokyo 187-0022, Japan
| | - Tatsuya Nishi
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-honcho, Kodaira, Tokyo 187-0022, Japan
| | - Nobuaki Shimada
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-honcho, Kodaira, Tokyo 187-0022, Japan
| | - Kazuki Morioka
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-honcho, Kodaira, Tokyo 187-0022, Japan
| | - Manabu Yamada
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-honcho, Kodaira, Tokyo 187-0022, Japan
| | - Kazuo Yoshida
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-honcho, Kodaira, Tokyo 187-0022, Japan
| | - Makoto Yamakawa
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-honcho, Kodaira, Tokyo 187-0022, Japan
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Abu Bakar F, Ng LFP. Nonstructural Proteins of Alphavirus-Potential Targets for Drug Development. Viruses 2018; 10:E71. [PMID: 29425115 DOI: 10.3390/v10020071] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 02/02/2018] [Accepted: 02/06/2018] [Indexed: 12/31/2022] Open
Abstract
Alphaviruses are enveloped, positive single-stranded RNA viruses, typically transmitted by arthropods. They often cause arthralgia or encephalitic diseases in infected humans and there is currently no targeted antiviral treatment available. The re-emergence of alphaviruses in Asia, Europe, and the Americas over the last decade, including chikungunya and o'nyong'nyong viruses, have intensified the search for selective inhibitors. In this review, we highlight key molecular determinants within the alphavirus replication complex that have been identified as viral targets, focusing on their structure and functionality in viral dissemination. We also summarize recent structural data of these viral targets and discuss how these could serve as templates to facilitate structure-based drug design and development of small molecule inhibitors.
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Pietilä MK, Albulescu IC, Hemert MJV, Ahola T. Polyprotein Processing as a Determinant for in Vitro Activity of Semliki Forest Virus Replicase. Viruses 2017; 9:v9100292. [PMID: 28991178 PMCID: PMC5691643 DOI: 10.3390/v9100292] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 09/29/2017] [Accepted: 10/03/2017] [Indexed: 12/11/2022] Open
Abstract
Semliki Forest virus (SFV) is an arthropod-borne alphavirus that induces membrane invaginations (spherules) in host cells. These harbor the viral replication complexes (RC) that synthesize viral RNA. Alphaviruses have four replicase or nonstructural proteins (nsPs), nsP1-4, expressed as polyprotein P1234. An early RC, which synthesizes minus-strand RNA, is formed by the polyprotein P123 and the polymerase nsP4. Further proteolytic cleavage results in a late RC consisting of nsP1-4 and synthesizing plus strands. Here, we show that only the late RCs are highly active in RNA synthesis in vitro. Furthermore, we demonstrate that active RCs can be isolated from both virus-infected cells and cells transfected with the wild-type replicase in combination with a plasmid expressing a template RNA. When an uncleavable polyprotein P123 and polymerase nsP4 were expressed together with a template, high levels of minus-strand RNA were produced in cells, but RCs isolated from these cells were hardly active in vitro. Furthermore, we observed that the uncleavable polyprotein P123 and polymerase nsP4, which have previously been shown to form spherules even in the absence of the template, did not replicate an exogenous template. Consequently, we hypothesize that the replicase proteins were sequestered in spherules and were no longer able to recruit a template.
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Affiliation(s)
- Maija K Pietilä
- Department of Food and Environmental Sciences, University of Helsinki, Viikinkaari 9 PO Box 56, 00014 Helsinki, Finland.
| | - Irina C Albulescu
- Department of Medical Microbiology, Leiden University Medical Center PO Box 9600, 2300 RC, Leiden, The Netherlands.
| | - Martijn J van Hemert
- Department of Medical Microbiology, Leiden University Medical Center PO Box 9600, 2300 RC, Leiden, The Netherlands.
| | - Tero Ahola
- Department of Food and Environmental Sciences, University of Helsinki, Viikinkaari 9 PO Box 56, 00014 Helsinki, Finland.
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Ning YJ, Feng K, Min YQ, Deng F, Hu Z, Wang H. Heartland virus NSs protein disrupts host defenses by blocking the TBK1 kinase-IRF3 transcription factor interaction and signaling required for interferon induction. J Biol Chem 2017; 292:16722-16733. [PMID: 28848048 DOI: 10.1074/jbc.m117.805127] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/21/2017] [Indexed: 12/19/2022] Open
Abstract
Heartland virus (HRTV) is a pathogenic phlebovirus related to the severe fever with thrombocytopenia syndrome virus (SFTSV), another phlebovirus causing life-threatening disease in humans. Previous findings have suggested that SFTSV can antagonize the host interferon (IFN) system via viral nonstructural protein (NSs)-mediated sequestration of antiviral signaling proteins into NSs-induced inclusion bodies. However, whether and how HRTV counteracts the host innate immunity is unknown. Here, we report that HRTV NSs (HNSs) also antagonizes IFN and cytokine induction and bolsters viral replication, although no noticeable inclusion body formation was observed in HNSs-expressing cells. Furthermore, HNSs inhibited the virus-triggered activation of IFN-β promoter by specifically targeting the IFN-stimulated response element but not the NF-κB response element. Consistently, HNSs blocked the phosphorylation and nuclear translocation of IFN regulatory factor 3 (IRF3, an IFN-stimulated response element-activating transcription factor). Reporter gene assays next showed that HNSs blockades the antiviral signaling mediated by RIG-I-like receptors likely at the level of TANK-binding kinase 1 (TBK1). Indeed, HNSs strongly interacts with TBK1 as indicated by confocal microscopy and pulldown analyses, and we also noted that the scaffold dimerization domain of TBK1 is required for the TBK1-HNSs interaction. Finally, pulldown assays demonstrated that HNSs expression dose-dependently diminishes a TBK1-IRF3 interaction, further explaining the mechanism for HNSs function. Collectively, these data suggest that HNSs, an antagonist of host innate immunity, interacts with TBK1 and thereby hinders the association of TBK1 with its substrate IRF3, thus blocking IRF3 activation and transcriptional induction of the cellular antiviral responses.
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Affiliation(s)
- Yun-Jia Ning
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Kuan Feng
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuan-Qin Min
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Fei Deng
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Zhihong Hu
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Hualin Wang
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
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Brennan B, Rezelj VV, Elliott RM. Mapping of Transcription Termination within the S Segment of SFTS Phlebovirus Facilitated Generation of NSs Deletant Viruses. J Virol 2017; 91:e00743-17. [PMID: 28592543 DOI: 10.1128/JVI.00743-17] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 05/31/2017] [Indexed: 12/15/2022] Open
Abstract
SFTS phlebovirus (SFTSV) is an emerging tick-borne bunyavirus that was first reported in China in 2009. Here we report the generation of a recombinant SFTSV (rHB29NSsKO) that cannot express the viral nonstructural protein (NSs) upon infection of cells in culture. We show that rHB29NSsKO replication kinetics are greater in interferon (IFN)-incompetent cells and that the virus is unable to suppress IFN induced in response to viral replication. The data confirm for the first time in the context of virus infection that NSs acts as a virally encoded IFN antagonist and that NSs is dispensable for virus replication. Using 3' rapid amplification of cDNA ends (RACE), we mapped the 3' end of the N and NSs mRNAs, showing that the mRNAs terminate within the coding region of the opposite open reading frame. We show that the 3' end of the N mRNA terminates upstream of a 5'-GCCAGCC-3' motif present in the viral genomic RNA. With this knowledge, and using virus-like particles, we could demonstrate that the last 36 nucleotides of the NSs open reading frame (ORF) were needed to ensure the efficient termination of the N mRNA and were required for recombinant virus rescue. We demonstrate that it is possible to recover viruses lacking NSs (expressing just a 12-amino-acid NSs peptide or encoding enhanced green fluorescent protein [eGFP]) or an NSs-eGFP fusion protein in the NSs locus. This opens the possibility for further studies of NSs and potentially the design of attenuated viruses for vaccination studies.IMPORTANCE SFTS phlebovirus (SFTSV) and related tick-borne viruses have emerged globally since 2009. SFTSV has been shown to cause severe disease in humans. For bunyaviruses, it has been well documented that the nonstructural protein (NSs) enables the virus to counteract the human innate antiviral defenses and that NSs is one of the major determinants of virulence in infection. Therefore, the use of reverse genetics systems to engineer viruses lacking NSs is an attractive strategy to rationally attenuate bunyaviruses. Here we report the generation of several recombinant SFTS viruses that cannot express the NSs protein or have the NSs open reading frame replaced with a reporter gene. These viruses cannot antagonize the mammalian interferon (IFN) response mounted to virus infection. The generation of NSs-lacking viruses was achieved by mapping the transcriptional termination of two S-segment-derived subgenomic mRNAs, which revealed that transcription termination occurs upstream of a 5'-GCCAGCC-3' motif present in the virus genomic S RNA.
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Rezelj VV, Li P, Chaudhary V, Elliott RM, Jin DY, Brennan B. Differential Antagonism of Human Innate Immune Responses by Tick-Borne Phlebovirus Nonstructural Proteins. mSphere 2017; 2:e00234-17. [PMID: 28680969 DOI: 10.1128/mSphere.00234-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 06/05/2017] [Indexed: 12/24/2022] Open
Abstract
In recent years, several newly discovered tick-borne viruses causing a wide spectrum of diseases in humans have been ascribed to the Phlebovirus genus of the Bunyaviridae family. The nonstructural protein (NSs) of bunyaviruses is the main virulence factor and interferon (IFN) antagonist. We studied the molecular mechanisms of IFN antagonism employed by the NSs proteins of human apathogenic Uukuniemi virus (UUKV) and those of Heartland virus (HRTV) and severe fever with thrombocytopenia syndrome virus (SFTSV), both of which cause severe disease. Using reporter assays, we found that UUKV NSs weakly inhibited the activation of the beta interferon (IFN-β) promoter and response elements. UUKV NSs weakly antagonized human IFN-β promoter activation through a novel interaction with mitochondrial antiviral-signaling protein (MAVS), confirmed by coimmunoprecipitation and confocal microscopy studies. HRTV NSs efficiently antagonized both IFN-β promoter activation and type I IFN signaling pathways through interactions with TBK1, preventing its phosphorylation. HRTV NSs exhibited diffused cytoplasmic localization. This is in comparison to the inclusion bodies formed by SFTSV NSs. HRTV NSs also efficiently interacted with STAT2 and impaired IFN-β-induced phosphorylation but did not affect STAT1 or its translocation to the nucleus. Our results suggest that a weak interaction between STAT1 and HRTV or SFTSV NSs may explain their inability to block type II IFN signaling efficiently, thus enabling the activation of proinflammatory responses that lead to severe disease. Our findings offer insights into how pathogenicity may be linked to the capacity of NSs proteins to block the innate immune system and illustrate the plethora of viral immune evasion strategies utilized by emerging phleboviruses. IMPORTANCE Since 2011, there has been a large expansion in the number of emerging tick-borne viruses that have been assigned to the Phlebovirus genus. Heartland virus (HRTV) and SFTS virus (SFTSV) were found to cause severe disease in humans, unlike other documented tick-borne phleboviruses such as Uukuniemi virus (UUKV). Phleboviruses encode nonstructural proteins (NSs) that enable them to counteract the human innate antiviral defenses. We assessed how these proteins interacted with the innate immune system. We found that UUKV NSs engaged with innate immune factors only weakly, at one early step. However, the viruses that cause more severe disease efficiently disabled the antiviral response by targeting multiple components at several stages across the innate immune induction and signaling pathways. Our results suggest a correlation between the efficiency of the virus protein/host interaction and severity of disease.
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Hammond RG, Tan X, Johnson MA. SARS-unique fold in the Rousettus bat coronavirus HKU9. Protein Sci 2017; 26:1726-1737. [PMID: 28580734 PMCID: PMC5563143 DOI: 10.1002/pro.3208] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/26/2017] [Accepted: 05/26/2017] [Indexed: 12/28/2022]
Abstract
The coronavirus nonstructural protein 3 (nsp3) is a multifunctional protein that comprises multiple structural domains. This protein assists viral polyprotein cleavage, host immune interference, and may play other roles in genome replication or transcription. Here, we report the solution NMR structure of a protein from the “SARS‐unique region” of the bat coronavirus HKU9. The protein contains a frataxin fold or double‐wing motif, which is an α + β fold that is associated with protein/protein interactions, DNA binding, and metal ion binding. High structural similarity to the human severe acute respiratory syndrome (SARS) coronavirus nsp3 is present. A possible functional site that is conserved among some betacoronaviruses has been identified using bioinformatics and biochemical analyses. This structure provides strong experimental support for the recent proposal advanced by us and others that the “SARS‐unique” region is not unique to the human SARS virus, but is conserved among several different phylogenetic groups of coronaviruses and provides essential functions. PDB Code(s): 5UTV
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Affiliation(s)
- Robert G Hammond
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama, 35294
| | - Xuan Tan
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama, 35294
| | - Margaret A Johnson
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama, 35294
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Abstract
Human enterovirus 71 (EV-A71) is one of the main etiological agents of hand, foot, and mouth disease (HFMD), which has been prevalent mainly in the Asia-Pacific region in the past several decades. The nonstructural proteins of EV-A71 will be expressed significantly during viral replication in host cells after EV-A71 infection. For the determination of the antibodies response against nonstructural proteins of EV-A71, in this study, the complete 2ABC, 3ABC, and 3D proteins were expressed in Escherichia coli and were then studied for their immunoreactivity by immunoblot assay and indirect enzyme-linked immunosorbent assay (ELISA), respectively. Three His-tagged fusion proteins were expressed effectively in E. coli, which were in agreement with the expected molecular mass. The results from immunoblot assay and indirect ELISA showed that all three purified fusion proteins can react with IgG antibodies from EV-A71-infected patients, but can hardly be recognized by IgG antibodies derived from mice or rabbits immunized by inactivated EV-A71 virus particles. The IgG antibody response against nonstructural proteins of EV-A71 is associated with viral infection or replication, which indicate that these nonstructural proteins could be used as candidate antigen for early diagnosis of EV-A71 infection, or to distinguish the EV-A71-specific antibodies after viral infection from inactivated vaccine immunization.
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Affiliation(s)
- Xuyan Chen
- 1 Department of Laboratory Medicine, School of Medicine, Shaoxing University , Shaoxing, Zhejiang, People's Republic of China
| | - Bo Qin
- 2 Clinical Laboratory Center , Shaoxing People's Hospital, Shaoxing, Zhejiang, People's Republic of China
| | - Min Shi
- 1 Department of Laboratory Medicine, School of Medicine, Shaoxing University , Shaoxing, Zhejiang, People's Republic of China
| | - Longying Zhu
- 1 Department of Laboratory Medicine, School of Medicine, Shaoxing University , Shaoxing, Zhejiang, People's Republic of China
| | - Menglin Sun
- 1 Department of Laboratory Medicine, School of Medicine, Shaoxing University , Shaoxing, Zhejiang, People's Republic of China
| | - Xufeng Liu
- 1 Department of Laboratory Medicine, School of Medicine, Shaoxing University , Shaoxing, Zhejiang, People's Republic of China
| | - Jianhua Zhang
- 1 Department of Laboratory Medicine, School of Medicine, Shaoxing University , Shaoxing, Zhejiang, People's Republic of China
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Matheus S, Boukhari R, Labeau B, Ernault V, Bremand L, Kazanji M, Rousset D. Specificity of Dengue NS1 Antigen in Differential Diagnosis of Dengue and Zika Virus Infection. Emerg Infect Dis 2016; 22:1691-3. [PMID: 27347853 PMCID: PMC4994358 DOI: 10.3201/eid2209.160725] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Abraham A, Savithri HS. A novel viral RNA helicase with an independent translation enhancement activity. FEBS Lett 2016; 590:1187-99. [PMID: 27001161 DOI: 10.1002/1873-3468.12145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/04/2016] [Accepted: 03/07/2016] [Indexed: 11/12/2022]
Abstract
RNA helicases have not been identified among negative sense RNA viruses. In this study, it is shown that Nonstructural protein (NSs) of Groundnut bud necrosis virus (GBNV) acts as a Mg(2+) - and ATP-dependent bipolar RNA helicase. Biophysical and biochemical analysis of the deletion mutants (NΔ124 NSs, CΔ80 NSs) revealed that both the N- and C-terminal residues are required for substrate binding, oligomerization and helicase activity, but are dispensable for ATPase activity. Interestingly, NSs could enhance the translation of RNA (~ 10-fold) independent of its helicase activity. This is the first report of a RNA helicase from negative strand RNA viruses.
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Affiliation(s)
- Ambily Abraham
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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Reddy VRAP, Theuns S, Roukaerts IDM, Zeller M, Matthijnssens J, Nauwynck HJ. Genetic Characterization of the Belgian Nephropathogenic Infectious Bronchitis Virus (NIBV) Reference Strain B1648. Viruses 2015; 7:4488-506. [PMID: 26262637 PMCID: PMC4576188 DOI: 10.3390/v7082827] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 07/24/2015] [Accepted: 08/03/2015] [Indexed: 12/21/2022] Open
Abstract
The virulent nephropathogenic infectious bronchitis virus (NIBV) strain B1648 was first isolated in 1984, in Flanders, Belgium. Despite intensive vaccination, B1648 and its variants are still circulating in Europe and North Africa. Here, the full-length genome of this Belgian NIBV reference strain was determined by next generation sequencing (NGS) to understand its evolutionary relationship with other IBV strains, and to identify possible genetic factors that may be associated with the nephropathogenicity. Thirteen open reading frames (ORFs) were predicted in the B1648 strain (5′UTR-1a-1b-S-3a-3b-E-M-4b-4c-5a-5b-N-6b-3′UTR). ORFs 4b, 4c and 6b, which have been rarely reported in literature, were present in B1648 and most of the other IBV complete genomes. According to phylogenetic analysis of the full-length genome, replicase transcriptase complex, spike protein, partial S1 gene and M protein, B1648 strain clustered with the non-Massachusetts type strains NGA/A116E7/2006, UKr 27-11, QX-like ITA/90254/2005, QX-like CK/SWE/0658946/10, TN20/00, RF-27/99, RF/06/2007 and SLO/266/05. Based on the partial S1 fragment, B1648 clustered with the strains TN20/00, RF-27/99, RF/06/2007 and SLO/266/05 and, further designated as B1648 genotype. The full-length genome of B1648 shared the highest sequence homology with UKr 27-11, Gray, JMK, and NGA/A116E7/2006 (91.2% to 91.6%) and was least related with the reference Beaudette and Massachusetts strains (89.7%). Nucleotide and amino acid sequence analyses indicated that B1648 strain may have played an important role in the evolution of IBV in Europe and North Africa. Further, the nephropathogenicity determinants might be located on the 1a, spike, M and accessory proteins (3a, 3b, 4b, 4c, 5a, 5b and 6b). Overall, strain B1648 is distinct from all the strains reported so far in Europe and other parts of the world.
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Affiliation(s)
- Vishwanatha R A P Reddy
- Laboratory of Virology, Department of Virology, Parasitology and Immunology,Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
| | - Sebastiaan Theuns
- Laboratory of Virology, Department of Virology, Parasitology and Immunology,Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
| | - Inge D M Roukaerts
- Laboratory of Virology, Department of Virology, Parasitology and Immunology,Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
| | - Mark Zeller
- Rega Institute for Medical Research, Laboratory of Clinical Virology, Department of Microbiologyand Immunology, KU Leuven-University of Leuven, Minderbroedersstraat 10, BE-3000 Leuven, Belgium.
| | - Jelle Matthijnssens
- Rega Institute for Medical Research, Laboratory of Clinical Virology, Department of Microbiologyand Immunology, KU Leuven-University of Leuven, Minderbroedersstraat 10, BE-3000 Leuven, Belgium.
- Rega Institute for Medical Research, Laboratory of Viral Metagenomics, Department ofMicrobiology and Immunology, KU Leuven-University of Leuven, Minderbroedersstraat 10, BE-3000 Leuven, Belgium.
| | - Hans J Nauwynck
- Laboratory of Virology, Department of Virology, Parasitology and Immunology,Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
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Chen TH, Lee F, Lin YL, Pan CH, Shih CN, Tseng CH, Tsai HJ. Development of a multiplex Luminex assay for detecting swine antibodies to structural and nonstructural proteins of foot-and-mouth disease virus in Taiwan. J Microbiol Immunol Infect 2014; 49:196-207. [PMID: 25074628 DOI: 10.1016/j.jmii.2014.05.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 04/28/2014] [Accepted: 05/01/2014] [Indexed: 11/16/2022]
Abstract
BACKGROUND/PURPOSE(S) Foot-and-mouth disease (FMD) and swine vesicular disease (SVD) are serious vesicular diseases that have devastated swine populations throughout the world. The aim of this study was to develop a multianalyte profiling (xMAP) Luminex assay for the differential detection of antibodies to the FMD virus of structural proteins (SP) and nonstructural proteins (NSP). METHODS After the xMAP was optimized, it detected antibodies to SP-VP1 and NSP-3ABC of the FMD virus in a single serum sample. These tests were also compared with 3ABC polypeptide blocking enzyme-linked immunosorbent assay (ELISA) and virus neutralization test (VNT) methods for the differential diagnosis and assessment of immune status, respectively. RESULTS To detect SP antibodies in 661 sera from infected naïve pigs and vaccinated pigs, the diagnostic sensitivity (DSn) and diagnostic specificity (DSp) of the xMAP were 90.0-98.7% and 93.0-96.5%, respectively. To detect NSP antibodies, the DSn was 90% and the DSp ranged from 93.3% to 99.1%. The xMAP can detect the immune response to SP and NSP as early as 4 days postinfection and 8 days postinfection, respectively. Furthermore, the SP and NSP antibodies in all 15 vaccinated but unprotected pigs were detected by xMAP. A comparison of SP and NSP antibodies detected in the sera of the infected samples indicated that the results from the xMAP had a high positive correlation with results from the VNT and a 3ABC polypeptide blocking ELISA assay. However, simultaneous quantitation detected that xMAP had no relationship with the VNT. Furthermore, the specificity was 93.3-94.9% with 3ABC polypeptide blocking ELISA for the FMDV-NSP antibody. CONCLUSION The results indicated that xMAP has the potential to detect antibodies to FMDV-SP-VP1 and NSP-3ABC and to distinguish FMDV-infected pigs from pigs infected with the swine vesicular disease virus.
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Affiliation(s)
- Tsu-Han Chen
- Animal Health Research Institute, New Taipei City, Taiwan; Graduate Institute of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | - Fan Lee
- Animal Health Research Institute, New Taipei City, Taiwan
| | - Yeou-Liang Lin
- Animal Health Research Institute, New Taipei City, Taiwan
| | - Chu-Hsiang Pan
- Animal Health Research Institute, New Taipei City, Taiwan
| | - Chia-Ni Shih
- Animal Health Research Institute, New Taipei City, Taiwan
| | | | - Hsiang-Jung Tsai
- Animal Health Research Institute, New Taipei City, Taiwan; Graduate Institute of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan.
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41
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Keane SC, Giedroc DP. ¹H, ¹³C, ¹⁵N resonance assignments of murine hepatitis virus nonstructural protein 3a. Biomol NMR Assign 2014; 8:15-17. [PMID: 23135776 PMCID: PMC3587040 DOI: 10.1007/s12104-012-9443-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 10/31/2012] [Indexed: 06/01/2023]
Abstract
Nonstructural protein (nsp) 3 is the largest of 16 nsps translated from the murine hepatitis virus (MHV) genome. The N-terminal most domain of nsp3, nsp3a, has been identified by reverse genetics as a likely binding partner of MHV nucleocapsid protein. Here we report the backbone and side chain resonance assignments of MHV nsp3a (residues 1-114).
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Affiliation(s)
- Sarah C. Keane
- Department of Chemistry, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN 47405-7102 USA
| | - David P. Giedroc
- Department of Chemistry, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN 47405-7102 USA
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Yan S, Wu G. Possibility of cross-species/subtype reassortments in influenza A viruses: an analysis of nonstructural protein variations. Virulence 2013; 4:716-25. [PMID: 24104702 DOI: 10.4161/viru.26612] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The reassortment of genetic segments from different host species and from different subtypes of influenza A viruses occurs frequently, which may generate new strains causing flu epidemic or pandemic. However, the underlined mechanisms of reassortment were less addressed from the viewpoint of protein variations. Recently, we used the amino-acid pair predictability as an indicator to convert eight types of influenza A virus proteins into predictable portion of amino-acid pairs, and then applied the models I and II ANOVA to estimate their differences in terms of subtypes and host species. In order to get a full picture, 2729 and 1063 non-structural 1 and 2 proteins of influenza A viruses were analyzed in this study. The results are consistent with those obtained from hemagglutinin, neuraminidase, nucleoprotein, polymerase acidic protein, polymerase basic proteins 1 and 2, and matrix proteins 1 and 2, indicating that inter-species/subtypes variations are smaller than intra-species/subtype ones. Our findings provide statistical evidence that can partially explains why cross-subtype mutation and cross-species infection easily occur during co-infecting of different strains.
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Affiliation(s)
- Shaomin Yan
- State Key Laboratory of Non-food Biomass Enzyme Technology; National Engineering Research Center for Non-food Biorefinery; Guangxi Key Laboratory of Biorefinery; Guangxi Academy of Sciences; Guangxi, PR China
| | - Guang Wu
- State Key Laboratory of Non-food Biomass Enzyme Technology; National Engineering Research Center for Non-food Biorefinery; Guangxi Key Laboratory of Biorefinery; Guangxi Academy of Sciences; Guangxi, PR China
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Jin X, Chen Y, Sun Y, Zeng C, Wang Y, Tao J, Wu A, Yu X, Zhang Z, Tian J, Guo D. Characterization of the guanine-N7 methyltransferase activity of coronavirus nsp14 on nucleotide GTP. Virus Res 2013; 176:45-52. [PMID: 23702198 PMCID: PMC7114466 DOI: 10.1016/j.virusres.2013.05.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 05/04/2013] [Accepted: 05/06/2013] [Indexed: 11/22/2022]
Abstract
We found SARS-CoV nsp14 could methylate GTP and dGTP. Critical residues of nsp14 essential for the activity on GTP were identified. m7GTP or nsp14 could interfere with protein translation.
Most eukaryotic viruses that replicate in the cytoplasm, including coronaviruses, have evolved strategies to cap their RNAs. In our previous work, the nonstructural protein (nsp) 14 of severe acute respiratory syndrome coronavirus (SARS-CoV) was identified as a cap (guanine-N7)-methyltransferase (N7-MTase). In this study, we found that GTP, dGTP as well as cap analogs GpppG, GpppA and m7GpppG could be methylated by SARS-CoV nsp14. In contrast, the nsp14 could not modify ATP, CTP, UTP, dATP, dCTP, dUTP or cap analog m7GpppA. Critical residues of nsp14 essential for the methyltransferase activity on GTP were identified, which include F73, R84, W86, R310, D331, G333, P335, Y368, C414, and C416. We further showed that the methyltransferase activity of GTP was universal for nsp14 of other coronaviruses. Moreover, the accumulation of m7GTP or presence of protein nsp14 could interfere with protein translation of cellular mRNAs. Altogether, the results revealed a new enzymatic activity of coronavirus nsp14.
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Affiliation(s)
- Xu Jin
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
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Lorenz IC. The Hepatitis C Virus Nonstructural Protein 2 (NS2): An Up-and-Coming Antiviral Drug Target. Viruses 2010; 2:1635-46. [PMID: 21994698 DOI: 10.3390/v2081635] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 08/03/2010] [Accepted: 08/04/2010] [Indexed: 01/31/2023] Open
Abstract
Infection with Hepatitis C Virus (HCV) continues to be a major global health problem. To overcome the limitations of current therapies using interferon-α in combination with ribavirin, there is a need to develop drugs that specifically block viral proteins. Highly efficient protease and polymerase inhibitors are currently undergoing clinical testing and will become available in the next few years. However, with resistance mutations emerging quickly, additional enzymatic activities or functions of HCV have to be targeted by novel compounds. One candidate molecule is the nonstructural protein 2 (NS2), which contains a proteolytic activity that is essential for viral RNA replication. In addition, NS2 is crucial for the assembly of progeny virions and modulates various cellular processes that interfere with viral replication. This review describes the functions of NS2 in the life cycle of HCV and highlights potential antiviral strategies involving NS2.
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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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Serrano P, Johnson MA, Chatterjee A, Pedrini B, Wüthrich K. NMR assignment of the nonstructural protein nsp3(1066-1181) from SARS-CoV. Biomol NMR Assign 2008; 2:135-138. [PMID: 19636888 PMCID: PMC2776825 DOI: 10.1007/s12104-008-9104-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Accepted: 07/01/2008] [Indexed: 05/28/2023]
Abstract
Sequence-specific NMR assignments of the globular core comprising the residues 1066-1181 within the non-structural protein nsp3e from the SARS coronavirus have been obtained using triple-resonance NMR experiments with the uniformly [(13)C, (15)N]-labeled protein. The backbone and side chain assignments are nearly complete, providing the basis for the ongoing NMR structure determination. A preliminary identification of regular secondary structures has been derived from the (13)C chemical shifts.
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Affiliation(s)
- Pedro Serrano
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
| | - Margaret A. Johnson
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
| | - Amarnath Chatterjee
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
| | - Bill Pedrini
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
| | - Kurt Wüthrich
- Department of Molecular Biology and Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
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Chatterjee A, Johnson MA, Serrano P, Pedrini B, Wüthrich K. NMR assignment of the domain 513-651 from the SARS-CoV nonstructural protein nsp3. Biomol NMR Assign 2007; 1:191-194. [PMID: 19636862 PMCID: PMC7090708 DOI: 10.1007/s12104-007-9052-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2007] [Accepted: 09/21/2007] [Indexed: 05/28/2023]
Abstract
Sequence-specific NMR assignments of an internal domain of the protein nsp3, nsp3(513-651), which is a part of the SARS coronavirus (SARS-CoV) replicase polyprotein, have been determined, using triple-resonance NMR experiments with the uniformly [(13)C,(15)N]-labeled protein. The complete assignments (>99%) provide the basis for the ongoing three-dimensional structure determination.
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Affiliation(s)
- Amarnath Chatterjee
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
| | - Margaret A. Johnson
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
| | - Pedro Serrano
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
| | - Bill Pedrini
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
| | - Kurt Wüthrich
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, La Jolla, CA 92037 USA
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Affiliation(s)
- M. S. Almeida
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037 USA
| | - M. A. Johnson
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037 USA
| | - K. Wüthrich
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037 USA
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Affiliation(s)
- Stanley Perlman
- Department of Pediatrics, University of Iowa, 52242 Iowa City, IA USA
| | - Kathryn V. Holmes
- Department of Microbiology, University of Colorado Health Sciences Center at Fitzsimons, 80045-8333 Aurora, CO USA
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Serrano P, Almeida MS, Johnson & MA, Wüthrich K. NMR assignment of the protein nsp3a from SARS-CoV. J Biomol NMR 2006; 36 Suppl 1:45. [PMID: 16799860 PMCID: PMC7087748 DOI: 10.1007/s10858-006-9017-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Accepted: 04/11/2006] [Indexed: 05/10/2023]
Affiliation(s)
- P. Serrano
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - M. S. Almeida
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - M. A. Johnson &
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - K. Wüthrich
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
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