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Saadi F, Pal D, Sarma JD. Spike Glycoprotein Is Central to Coronavirus Pathogenesis-Parallel Between m-CoV and SARS-CoV-2. Ann Neurosci 2021; 28:201-218. [PMID: 35341224 PMCID: PMC8948335 DOI: 10.1177/09727531211023755] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 03/24/2021] [Indexed: 01/04/2023] Open
Abstract
Coronaviruses (CoVs) are single-stranded, polyadenylated, enveloped RNA of positive polarity with a unique potential to alter host tropism. This has been exceptionally demonstrated by the emergence of deadly virus outbreaks of the past: Severe Acute Respiratory Syndrome (SARS-CoV) in 2003 and Middle East Respiratory Syndrome (MERS-CoV) in 2012. The 2019 outbreak by the new cross-species transmission of SARS-CoV-2 has put the world on alert. CoV infection is triggered by receptor recognition, membrane fusion, and successive viral entry mediated by the surface Spike (S) glycoprotein. S protein is one of the major antigenic determinants and the target for neutralizing antibodies. It is a valuable target in antiviral therapies because of its central role in cell-cell fusion, viral antigen spread, and host immune responses leading to immunopathogenesis. The receptor-binding domain of S protein has received greater attention as it initiates host attachment and contains major antigenic determinants. However, investigating the therapeutic potential of fusion peptide as a part of the fusion core complex assembled by the heptad repeats 1 and 2 (HR1 and HR2) is also warranted. Along with receptor attachment and entry, fusion mechanisms should also be explored for designing inhibitors as a therapeutic intervention. In this article, we review the S protein function and its role in mediating membrane fusion, spread, tropism, and its associated pathogenesis with notable therapeutic strategies focusing on results obtained from studies on a murine β-Coronavirus (m-CoV) and its associated disease process.
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Affiliation(s)
- Fareeha Saadi
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, Kolkata, West Bengal, India
| | - Debnath Pal
- Department of Computational and Data Sciences, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Jayasri Das Sarma
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, Kolkata, West Bengal, India
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Taherizadeh M, Tabibzadeh A, Panahi M, Safarnezhad Tameshkel F, Golahdooz M, Karbalaie Niya MH. An Introduction to SARS Coronavirus 2; Comparative Analysis with MERS and SARS Coronaviruses: A Brief Review. IRANIAN JOURNAL OF PUBLIC HEALTH 2020; 49:30-37. [PMID: 34268203 PMCID: PMC8266008 DOI: 10.18502/ijph.v49is1.3667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 03/26/2020] [Indexed: 12/15/2022]
Abstract
Since the 1970 the replication and pathogenesis mechanism of different coronaviruses have been studded.. In 2002-2003, SARS (Severe Acute Respiratory Syndrome coronavirus) in China emerged which resulted in 8098 cases and 774 deaths. About 10 years later in 2012, the MERS (Middle East Respiratory Syndrome coronavirus) spread in Middle Eastern countries and leads to infection in 2465 cases. In Dec 2019, another acute respiratory disease caused by a novel coronavirus named SARS-2 emerged in Wuhan, China. The virus is assumed to be mainly transmitted by respiratory droplets. Travels and communications leads to high prevalence of COVID-19 (Coronavirus Disease 2019) in the world, and currently in Iran. The current review was conducted to compare the virus structure, genome organization, virus life cycle, pathogenesis and prediction the future of COVID-19.
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Affiliation(s)
| | - Alireza Tabibzadeh
- Department of Virology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Mahshid Panahi
- Gastrointestinal and Liver Diseases Research Center, Iran University of Medical Sciences, Tehran, Iran
| | | | - Mahsa Golahdooz
- Department of Virology, Pasteur Institute of Iran, Tehran, Iran
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Belouzard S, Millet JK, Licitra BN, Whittaker GR. Mechanisms of coronavirus cell entry mediated by the viral spike protein. Viruses 2012; 4:1011-33. [PMID: 22816037 PMCID: PMC3397359 DOI: 10.3390/v4061011] [Citation(s) in RCA: 878] [Impact Index Per Article: 73.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 06/13/2012] [Accepted: 06/14/2012] [Indexed: 12/12/2022] Open
Abstract
Coronaviruses are enveloped positive-stranded RNA viruses that replicate in the cytoplasm. To deliver their nucleocapsid into the host cell, they rely on the fusion of their envelope with the host cell membrane. The spike glycoprotein (S) mediates virus entry and is a primary determinant of cell tropism and pathogenesis. It is classified as a class I fusion protein, and is responsible for binding to the receptor on the host cell as well as mediating the fusion of host and viral membranes—A process driven by major conformational changes of the S protein. This review discusses coronavirus entry mechanisms focusing on the different triggers used by coronaviruses to initiate the conformational change of the S protein: receptor binding, low pH exposure and proteolytic activation. We also highlight commonalities between coronavirus S proteins and other class I viral fusion proteins, as well as distinctive features that confer distinct tropism, pathogenicity and host interspecies transmission characteristics to coronaviruses.
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Affiliation(s)
- Sandrine Belouzard
- Center for Infection and Immunity of Lille, CNRS UMR8204, INSERM U1019, Institut Pasteur de Lille, Université Lille Nord de France, 59000 Lille, France;
| | - Jean K. Millet
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA; (J.K.M.); (B.N.L.)
| | - Beth N. Licitra
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA; (J.K.M.); (B.N.L.)
| | - Gary R. Whittaker
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA; (J.K.M.); (B.N.L.)
- Author to whom correspondence should be addressed; ; Tel.: +1-607-253-4021; Fax: +1-607-253-3384
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Eifart P, Ludwig K, Böttcher C, de Haan CAM, Rottier PJM, Korte T, Herrmann A. Role of endocytosis and low pH in murine hepatitis virus strain A59 cell entry. J Virol 2007; 81:10758-68. [PMID: 17626088 PMCID: PMC2045462 DOI: 10.1128/jvi.00725-07] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infection by the coronavirus mouse hepatitis virus strain A59 (MHV-A59) requires the release of the viral genome by fusion with the respective target membrane of the host cell. Fusion is mediated by the viral S protein. Here, the entry pathway of MHV-A59 into murine fibroblast cells was studied by independent approaches. Infection of cells assessed by plaque reduction assay was strongly inhibited by lysosomotropic compounds and substances that interfere with clathrin-dependent endocytosis, suggesting that MHV-A59 is taken up via endocytosis and delivered to acidic endosomal compartments. Infection was only slightly reduced in the presence of substances inhibiting proteases of endosomal compartments, precluding that the endocytic uptake is required to activate the fusion potential of the S protein by its cleavage. Fluorescence confocal microscopy of labeled MHV-A59 confirmed that virus is taken up via endocytosis. Bright labeling of intracellular compartments suggests their fusion with the viral envelope. No fusion with the plasma membrane was observed at neutral pH conditions. However, when virus was bound to cells and the pH was lowered to 5.0, we observed a strong labeling of the plasma membrane. Electron microscopy revealed low pH triggered conformational alterations of the S ectodomain. Very likely, these alterations are irreversible because low-pH treatment of viruses in the absence of target membranes caused an irreversible loss of the fusion activity. The results imply that endocytosis plays a major role in MHV-A59 infection and the acidic pH of the endosomal compartment triggers a conformational change of the S protein mediating fusion.
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Affiliation(s)
- Patricia Eifart
- Institut für Biologie/Biophysik, Humboldt-Universität zu Berlin, Invalidenstr. 42, D-10115 Berlin, Germany
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Liu C, Feng Y, Gao F, Zhang Q, Wang M. Characterization of HCoV-229E fusion core: implications for structure basis of coronavirus membrane fusion. Biochem Biophys Res Commun 2006; 345:1108-15. [PMID: 16714001 PMCID: PMC7092883 DOI: 10.1016/j.bbrc.2006.04.141] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Accepted: 04/18/2006] [Indexed: 11/01/2022]
Abstract
Human coronavirus 229E (HCoV-229E), a member of group I coronaviruses, has been identified as one of the major viral agents causing respiratory tract diseases in humans for nearly 40 years. However, the detailed molecular mechanism of the membrane fusion mediated by the spike (S) protein of HCoV-229E remains elusive. Here, we report, for the first time, a rationally designed fusion core of HCoV-229E (HR1-SGGRGG-HR2), which was in vitro produced in GST prokaryotic expression system. Multiple lines of experimental data including gel-filtration, chemical cross-linking, and circular diagram (CD) demonstrated that the HCoV-229E fusion core possesses the typical properties of the trimer of coiled-coil heterodimer (six alpha-helix bundle). 3D structure modeling presents its most-likely structure, similar to those of coronaviruses that have been well-documented. Collectively, HCoV-229E S protein belongs to the type I fusion protein, which is characterized by the existence of two heptad-repeat regions (HR1 and HR2), furthermore, the available knowledge concerning HCoV-229E fusion core may make it possible to design small molecule or polypeptide drugs targeting the membrane fusion, a crucial step of HCoV-229E infection.
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Affiliation(s)
- Cheng Liu
- College of Veterinary Medicine, China Agricultural University, Beijing 100094, PR China
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Ma G, Feng Y, Gao F, Wang J, Liu C, Li Y. Biochemical and biophysical characterization of the transmissible gastroenteritis coronavirus fusion core. Biochem Biophys Res Commun 2005; 337:1301-7. [PMID: 16236266 PMCID: PMC7092864 DOI: 10.1016/j.bbrc.2005.09.189] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2005] [Accepted: 09/30/2005] [Indexed: 11/25/2022]
Abstract
Transmissible gastroenteritis coronavirus (TGEV) is one of the most destructive agents, responsible for the enteric infections that are lethal for suckling piglets, causing enormous economic loss to the porcine fostering industry every year. Although it has been known that TGEV spiker protein is essential for the viral entry for many years, the detail knowledge of the TGEV fusion protein core is still very limited. Here, we report that TGEV fusion core (HR1-SGGRGG-HR2), in vitro expressed in GST prokaryotic expression system, shares the typical properties of the trimer of coiled-coil heterodimer (six α-helix bundle), which has been confirmed by a combined series of biochemical and biophysical evidences including size exclusion chromatography (gel-filtration), chemical crossing, and circular diagram. The 3D homologous structure model presents its most likely structure, extremely similar to those of the coronaviruses documented. Taken together, TGEV spiker protein belongs to the class I fusion protein, characterized by the existence of two heptad-repeat (HR) regions, HR1 and HR2, and the present knowledge about the truncated TGEV fusion protein core may facilitate in the design of the small molecule or polypeptide drugs targeting the membrane fusion between TGEV and its host.
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Affiliation(s)
- Guangpeng Ma
- Department of Preventive Veterinary, College of Veterinary Medicine, Northeast Agriculture University, 150030 Harbin, PR China
| | - Youjun Feng
- Laboratory of Molecular Immunology and Molecular Virology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, PR China
- Graduate School of the Chinese Academy of Sciences, PR China
| | - Feng Gao
- Laboratory of Molecular Immunology and Molecular Virology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, PR China
- China Agricultural University, Beijing 100094, PR China
| | - Jinzi Wang
- China Agricultural University, Beijing 100094, PR China
| | - Cheng Liu
- China Agricultural University, Beijing 100094, PR China
| | - Yijing Li
- Department of Preventive Veterinary, College of Veterinary Medicine, Northeast Agriculture University, 150030 Harbin, PR China
- Corresponding author. Fax: +86 0451 5113336.
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