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Mokhria RK, Bhardwaj JK, Sanghi AK. History, origin, transmission, genome structure, replication, epidemiology, pathogenesis, clinical features, diagnosis, and treatment of COVID-19: A review. World J Meta-Anal 2023; 11:266-276. [DOI: 10.13105/wjma.v11.i6.266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 07/15/2023] [Accepted: 07/25/2023] [Indexed: 09/13/2023] Open
Abstract
In December, 2019, pneumonia triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) surfaced in Wuhan, China. An acute respiratory illness named coronavirus disease 2019 (COVID-19) is caused by a new coronavirus designated as SARS-CoV-2. COVID-19 has surfaced as a major pandemic in the 21st century as yet. The entire world has been affected by this virus. World Health Organization proclaimed COVID-19 pandemic as a public health emergency of international concern on January 30, 2020. SARS-CoV-2 shares the same genome as coronavirus seen in bats. Therefore, bats might be its natural host of this virus. It primarily disseminates by means of the respiratory passage. Evidence revealed human-to-human transmission. Fever, cough, tiredness, and gastrointestinal illness are the manifestations in COVID-19-infected persons. Senior citizens are more vulnerable to infections which can lead to dangerous consequences. Various treatment strategies including antiviral therapies are accessible for the handling of this disease. In this review, we organized the most recent findings on COVID-19 history, origin, transmission, genome structure, replication, epidemiology, pathogenesis, clinical features, diagnosis, and treatment strategies.
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Affiliation(s)
- Rajesh Kumar Mokhria
- Department of School Education, Government Model Sanskriti Senior Secondary School, Chulkana, Panipat, 132101, Haryana, India
| | - Jitender Kumar Bhardwaj
- Reproductive Physiology Laboratory, Department of Zoology, Kurukshetra University, Kurukshetra 136119, Haryana, India
| | - Ashwani Kumar Sanghi
- School of Allied and Health Sciences, MVN University, Palwal 121102, Haryana, India
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Hmila I, Marnissi B, Kamali-Moghaddam M, Ghram A. Aptamer-Assisted Proximity Ligation Assay for Sensitive Detection of Infectious Bronchitis Coronavirus. Microbiol Spectr 2023; 11:e0208122. [PMID: 36651727 PMCID: PMC9927260 DOI: 10.1128/spectrum.02081-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 12/21/2022] [Indexed: 01/19/2023] Open
Abstract
Infectious bronchitis virus (IBV) is a coronavirus responsible for major health problems in the poultry industry. New virus strains continue to appear, causing large economic losses. To develop a rapid and accurate new quantitative assay for diagnosis of the virus without DNA extraction, we selected highly specific single-stranded DNA (ssDNA) aptamers with a high affinity to IBV, using the systematic evolution of ligands by exponential enrichment (SELEX) technology for aptamer screening, followed by high-throughput sequencing technology. Two of these aptamers, AptIBV5 and AptIBV2, were used to establish homogenous and solid-phase proximity ligation assays (PLAs). The developed assays were evaluated for their sensitivity and specificity using collected field samples and then compared to the newly developed sandwich enzyme-linked aptamer assay (ELAA) and reverse transcription-quantitative PCR (qRT-PCR), as the gold-standard method. The solid-phase PLA showed a lower limit of detection and a broader dynamic range than the two other assays. The developed technique may serve as an alternative assay for the diagnosis of IBV, with the potential to be extended to the detection of other important animal or human viruses. IMPORTANCE Infectious bronchitis virus (IBV) causes high morbidity and mortality and large economic losses in the poultry industry. The virus has the ability to genetically mutate into new IBV strains, causing devastating disease and outbreaks. To better monitor the emergence of this virus, the development of a rapid and highly sensitive diagnostic method should be implemented. For this, we generated aptamers with high affinity and specificity to the IBV in an ssDNA library. Using two high-affinity aptamers, we developed a sandwich ELAA and a very sensitive aptamer-based proximity ligation assay (PLA). The new assay showed high sensitivity and specificity and was used to detect IBV in farm samples. The PLA was compared to the newly developed sandwich ELAA and qRT-PCR, as the gold-standard technique.
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Affiliation(s)
- Issam Hmila
- Laboratory of Epidemiology and Veterinary Microbiology, Institute Pasteur of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Boutheina Marnissi
- Laboratory of Epidemiology and Veterinary Microbiology, Institute Pasteur of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Masood Kamali-Moghaddam
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
- Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Abdeljelil Ghram
- Laboratory of Epidemiology and Veterinary Microbiology, Institute Pasteur of Tunis, University of Tunis El Manar, Tunis, Tunisia
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Abstract
Coronavirus disease (COVID-19) is an infectious airborne viral pneumonia caused by a novel virus belonging to the family coronaviridae. On February 11, 2019, the Internal Committee on Taxonomy of Virus (ICTV) announced the name of the novel virus as "severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). One of the proteins present on its membrane i.e. the Spike protein is responsible for the attachment of the virus to the host. It spreads through the salivary droplets released when an infected person sneezes or coughs. The best way to slow down the disease is by protecting self by washing hands and using the disinfectant. Most of the infected people experience mild to moderate breathing issues. Serious illness might develop in people with underlying cardiovascular problems, diabetes and other immuno-compromised diseases. To date, there is no effective medicine available in the market which is effective in COVID-19. However, healthcare professionals are using ritonavir, flavipiravir, lopinavir, hydroxychloroquine and remdesivir. Along with the medicines, some countries are using convalescent plasma and mesenchymal stem cells for treatment. Till date, it has claimed millions of death worldwide. In this detailed review, we have discussed the structure of SARS-CoV-2, essential proteins, its lifecycle, transmission, symptoms, pathology, clinical features, diagnosis, prevention, treatment and epidemiology of the disease.
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Affiliation(s)
- Heena Rehman
- Department of Biochemistry, Jamia Hamdard, New Delhi, India
| | - Md Iftekhar Ahmad
- Department of Pharmaceutics, Shri Gopichand College of Pharmacy, Baghpat, India
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Mori Y, Fink C, Ichimura T, Sako K, Mori M, Lee NN, Aschauer P, Padmanabha Das KM, Hong S, Song M, Padera RF, Weins A, Lee LP, Nasr ML, Dekaban GA, Dikeakos JD, Bonventre JV. KIM-1/TIM-1 is a Receptor for SARS-CoV-2 in Lung and Kidney. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2022:2020.09.16.20190694. [PMID: 32995803 PMCID: PMC7523142 DOI: 10.1101/2020.09.16.20190694] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
SARS-CoV-2 precipitates respiratory distress by infection of airway epithelial cells and is often accompanied by acute kidney injury. We report that Kidney Injury Molecule-1/T cell immunoglobulin mucin domain 1 (KIM-1/TIM-1) is expressed in lung and kidney epithelial cells in COVID-19 patients and is a receptor for SARS-CoV-2. Human and mouse lung and kidney epithelial cells express KIM-1 and endocytose nanoparticles displaying the SARS-CoV-2 spike protein (virosomes). Uptake was inhibited by anti-KIM-1 antibodies and TW-37, a newly discovered inhibitor of KIM-1-mediated endocytosis. Enhanced KIM-1 expression by human kidney tubuloids increased uptake of virosomes. KIM-1 binds to the SARS-CoV-2 Spike protein in vitro . KIM-1 expressing cells, not expressing angiotensin-converting enzyme 2 (ACE2), are permissive to SARS-CoV-2 infection. Thus, KIM-1 is an alternative receptor to ACE2 for SARS-CoV-2. KIM-1 targeted therapeutics may prevent and/or treat COVID-19.
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Kishk SM, Kishk RM, Yassen ASA, Nafie MS, Nemr NA, ElMasry G, Al-Rejaie S, Simons C. Molecular Insights into Human Transmembrane Protease Serine-2 (TMPS2) Inhibitors against SARS-CoV2: Homology Modelling, Molecular Dynamics, and Docking Studies. Molecules 2020; 25:E5007. [PMID: 33137894 PMCID: PMC7663346 DOI: 10.3390/molecules25215007] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 10/23/2020] [Accepted: 10/24/2020] [Indexed: 02/08/2023] Open
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), which caused novel corona virus disease-2019 (COVID-19) pandemic, necessitated a global demand for studies related to genes and enzymes of SARS-CoV2. SARS-CoV2 infection depends on the host cell Angiotensin-Converting Enzyme-2 (ACE2) and Transmembrane Serine Protease-2 (TMPRSS2), where the virus uses ACE2 for entry and TMPRSS2 for S protein priming. The TMPRSS2 gene encodes a Transmembrane Protease Serine-2 protein (TMPS2) that belongs to the serine protease family. There is no crystal structure available for TMPS2, therefore, a homology model was required to establish a putative 3D structure for the enzyme. A homology model was constructed using SWISS-MODEL and evaluations were performed through Ramachandran plots, Verify 3D and Protein Statistical Analysis (ProSA). Molecular dynamics simulations were employed to investigate the stability of the constructed model. Docking of TMPS2 inhibitors, camostat, nafamostat, gabexate, and sivelestat, using Molecular Operating Environment (MOE) software, into the constructed model was performed and the protein-ligand complexes were subjected to MD simulations and computational binding affinity calculations. These in silico studies determined the tertiary structure of TMPS2 amino acid sequence and predicted how ligands bind to the model, which is important for drug development for the prevention and treatment of COVID-19.
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Affiliation(s)
- Safaa M. Kishk
- Pharmaceutical Medicinal Chemistry Department, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt
| | - Rania M. Kishk
- Microbiology and Immunology Department, Faculty of Medicine, Suez Canal University, Ismailia 41522, Egypt;
| | - Asmaa S. A. Yassen
- Pharmaceutical Organic Chemistry Department, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt;
| | - Mohamed S. Nafie
- Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt;
| | - Nader A. Nemr
- Endemic and Infectious Diseases Department, Faculty of Medicine, Suez Canal University, Ismailia 41522, Egypt;
| | - Gamal ElMasry
- Faculty of Agriculture, Suez Canal University, Ismailia 41522, Egypt;
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, Riyadh 11564, Saudi Arabia;
| | - Salim Al-Rejaie
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, Riyadh 11564, Saudi Arabia;
| | - Claire Simons
- School of Pharmacy & Pharmaceutical Sciences, Cardiff University, King Edward VII Avenue, Cardiff CF103NB, UK;
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SARS-CoV-2 Evolutionary Adaptation toward Host Entry and Recognition of Receptor O-Acetyl Sialylation in Virus-Host Interaction. Int J Mol Sci 2020; 21:ijms21124549. [PMID: 32604730 PMCID: PMC7352545 DOI: 10.3390/ijms21124549] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/15/2020] [Accepted: 06/22/2020] [Indexed: 02/06/2023] Open
Abstract
The recently emerged SARS-CoV-2 is the cause of the global health crisis of the coronavirus disease 2019 (COVID-19) pandemic. No evidence is yet available for CoV infection into hosts upon zoonotic disease outbreak, although the CoV epidemy resembles influenza viruses, which use sialic acid (SA). Currently, information on SARS-CoV-2 and its receptors is limited. O-acetylated SAs interact with the lectin-like spike glycoprotein of SARS CoV-2 for the initial attachment of viruses to enter into the host cells. SARS-CoV-2 hemagglutinin-esterase (HE) acts as the classical glycan-binding lectin and receptor-degrading enzyme. Most β-CoVs recognize 9-O-acetyl-SAs but switched to recognizing the 4-O-acetyl-SA form during evolution of CoVs. Type I HE is specific for the 9-O-Ac-SAs and type II HE is specific for 4-O-Ac-SAs. The SA-binding shift proceeds through quasi-synchronous adaptations of the SA-recognition sites of the lectin and esterase domains. The molecular switching of HE acquisition of 4-O-acetyl binding from 9-O-acetyl SA binding is caused by protein–carbohydrate interaction (PCI) or lectin–carbohydrate interaction (LCI). The HE gene was transmitted to a β-CoV lineage A progenitor by horizontal gene transfer from a 9-O-Ac-SA–specific HEF, as in influenza virus C/D. HE acquisition, and expansion takes place by cross-species transmission over HE evolution. This reflects viral evolutionary adaptation to host SA-containing glycans. Therefore, CoV HE receptor switching precedes virus evolution driven by the SA-glycan diversity of the hosts. The PCI or LCI stereochemistry potentiates the SA–ligand switch by a simple conformational shift of the lectin and esterase domains. Therefore, examination of new emerging viruses can lead to better understanding of virus evolution toward transitional host tropism. A clear example of HE gene transfer is found in the BCoV HE, which prefers 7,9-di-O-Ac-SAs, which is also known to be a target of the bovine torovirus HE. A more exciting case of such a switching event occurs in the murine CoVs, with the example of the β-CoV lineage A type binding with two different subtypes of the typical 9-O-Ac-SA (type I) and the exclusive 4-O-Ac-SA (type II) attachment factors. The protein structure data for type II HE also imply the virus switching to binding 4-O acetyl SA from 9-O acetyl SA. Principles of the protein–glycan interaction and PCI stereochemistry potentiate the SA–ligand switch via simple conformational shifts of the lectin and esterase domains. Thus, our understanding of natural adaptation can be specified to how carbohydrate/glycan-recognizing proteins/molecules contribute to virus evolution toward host tropism. Under the current circumstances where reliable antiviral therapeutics or vaccination tools are lacking, several trials are underway to examine viral agents. As expected, structural and non-structural proteins of SARS-CoV-2 are currently being targeted for viral therapeutic designation and development. However, the modern global society needs SARS-CoV-2 preventive and therapeutic drugs for infected patients. In this review, the structure and sialobiology of SARS-CoV-2 are discussed in order to encourage and activate public research on glycan-specific interaction-based drug creation in the near future.
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Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2): An Emerging Zoonotic Respiratory Pathogen in Humans. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2020. [DOI: 10.22207/jpam.14.spl1.30] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two highly human pathogenic coronaviruses outbreak in the beginning of 21st century i.e. Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in 2002 and 2012 respectively caused high pathogenicity and fatality rates in human populations. Recently, a new coronavirus named as SARS-CoV-2 or nCoV-2019 was first reported in Wuhan, China in December 2019 which is responsible for an acute human respiratory illness referred as Coronavirus Disease (COVID-19), an ongoing pandemic. SARS-CoV-2 is the third known highly pathogenic virus affecting human population. This virus spread globally within few weeks of first identification and nearly 5.52 million confirmed cases with more than 3,47,000 deaths reported as of May 25, 2020. Till date, there are no specific anti-viral drugs, therapies or vaccines to contain and prevent this infectious pathogen outbreak. The global spread of this virus to over 210 countries resulted in both human and economic losses, highlighting the need for an immediate imperative research exploration on prophylactic and therapeutic measures. Current knowledge and understanding of the pathogenesis of similar coronavirus SARS-CoV and MERS-CoV might be helpful for the rapid development of treatment strategies to prevent the further spread of this virus. In this review, we recapitulate the topical understanding on the structure, pathogenesis and epidemiology of SARS-CoV-2 that has emerged as a major health concern worldwide.
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Isihak FA, Hamad MA, Mustafa NG. COVID-19: an updated review. RUSSIAN JOURNAL OF INFECTION AND IMMUNITY 2020. [DOI: 10.15789/2220-7619-cau-1443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
COVID-19 is a zoonotic disease that showed higher levels of transmissibility in humans. Coronavirus has the largest recognized genome (28–33 kb) of a positive-sense single stranded RNA. The genome composed of 5′-end, the translationable mRNA sequences for the key proteins; replicase, spike, envelop membrane, and nucleocapsid and 3′-end (polyA tail). This highly contagious virus may impair the immune system in the early phase of the disease, hence the symptoms of the disease appear very rapidly. Importantly until now, there is no efficient strategy for containing the disease. So, all the world scientists today are in a race against time to find a vaccine or treatment to COVID-19, which requires a deeper understanding.
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Parsons LM, Bouwman KM, Azurmendi H, de Vries RP, Cipollo JF, Verheije MH. Glycosylation of the viral attachment protein of avian coronavirus is essential for host cell and receptor binding. J Biol Chem 2019; 294:7797-7809. [PMID: 30902814 PMCID: PMC6514631 DOI: 10.1074/jbc.ra119.007532] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/01/2019] [Indexed: 12/16/2022] Open
Abstract
Avian coronaviruses, including infectious bronchitis virus (IBV), are important
respiratory pathogens of poultry. The heavily glycosylated IBV spike protein is
responsible for binding to host tissues. Glycosylation sites in the spike
protein are highly conserved across viral genotypes, suggesting an important
role for this modification in the virus life cycle. Here, we analyzed the
N-glycosylation of the receptor-binding domain (RBD) of IBV
strain M41 spike protein and assessed the role of this modification in host
receptor binding. Ten single Asn–to–Ala substitutions at the
predicted N-glycosylation sites of the M41–RBD were
evaluated along with two control Val–to–Ala substitutions. CD
analysis revealed that the secondary structure of all variants was retained
compared with the unmodified M41–RBD construct. Six of the 10
glycosylation variants lost binding to chicken trachea tissue and an
ELISA-presented α2,3-linked sialic acid oligosaccharide ligand.
LC/MSE glycomics analysis revealed that glycosylation sites have
specific proportions of N-glycan subtypes. Overall, the
glycosylation patterns of most variant RBDs were highly similar to those of the
unmodified M41–RBD construct. In silico docking
experiments with the recently published cryo-EM structure of the M41 IBV spike
protein and our glycosylation results revealed a potential ligand receptor site
that is ringed by four glycosylation sites that dramatically impact ligand
binding. Combined with the results of previous array studies, the glycosylation
and mutational analyses presented here suggest a unique glycosylation-dependent
binding modality for the M41 spike protein.
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Affiliation(s)
- Lisa M Parsons
- From the Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993
| | - Kim M Bouwman
- the Division of Pathology, Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands, and
| | - Hugo Azurmendi
- From the Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993
| | - Robert P de Vries
- the Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3512 JE Utrecht, The Netherlands
| | - John F Cipollo
- From the Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993,
| | - Monique H Verheije
- the Division of Pathology, Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands, and
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Li J, Helal ZH, Karch CP, Mishra N, Girshick T, Garmendia A, Burkhard P, Khan MI. A self-adjuvanted nanoparticle based vaccine against infectious bronchitis virus. PLoS One 2018; 13:e0203771. [PMID: 30216376 PMCID: PMC6138407 DOI: 10.1371/journal.pone.0203771] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 08/27/2018] [Indexed: 12/21/2022] Open
Abstract
Infectious bronchitis virus (IBV) affects poultry respiratory, renal and reproductive systems. Currently the efficacy of available live attenuated or killed vaccines against IBV has been challenged. We designed a novel IBV vaccine alternative using a highly innovative platform called Self-Assembling Protein Nanoparticle (SAPN). In this vaccine, B cell epitopes derived from the second heptad repeat (HR2) region of IBV spike proteins were repetitively presented in its native trimeric conformation. In addition, flagellin was co-displayed in the SAPN to achieve a self-adjuvanted effect. Three groups of chickens were immunized at four weeks of age with the vaccine prototype, IBV-Flagellin-SAPN, a negative-control construct Flagellin-SAPN or a buffer control. The immunized chickens were challenged with 5x104.7 EID50 IBV M41 strain. High antibody responses were detected in chickens immunized with IBV-Flagellin-SAPN. In ex vivo proliferation tests, peripheral mononuclear cells (PBMCs) derived from IBV-Flagellin-SAPN immunized chickens had a significantly higher stimulation index than that of PBMCs from chickens receiving Flagellin-SAPN. Chickens immunized with IBV-Flagellin-SAPN had a significant reduction of tracheal virus shedding and lesser tracheal lesion scores than did negative control chickens. The data demonstrated that the IBV-Flagellin-SAPN holds promise as a vaccine for IBV.
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Affiliation(s)
- Jianping Li
- Department of Pathobiology and Veterinary Science University of Connecticut, Storrs, CT, United States of America
| | - Zeinab H. Helal
- Department of Pathobiology and Veterinary Science University of Connecticut, Storrs, CT, United States of America
- Department of Microbiology and Immunology, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt
| | - Christopher P. Karch
- The Institute of Material Sciences, University of Connecticut, Storrs, CT, United States of America
| | - Neha Mishra
- Department of Pathobiology and Veterinary Science University of Connecticut, Storrs, CT, United States of America
| | - Theodore Girshick
- Charles River Laboratories, Avian vaccine services, North Franklin, CT, United States of America
| | - Antonio Garmendia
- Department of Pathobiology and Veterinary Science University of Connecticut, Storrs, CT, United States of America
| | - Peter Burkhard
- The Institute of Material Sciences, University of Connecticut, Storrs, CT, United States of America
- Department of Molecular Cell Biology, University of Connecticut, Storrs, CT, United States of America
- Alpha-O-Peptides AG, Riehen, Switzerland
| | - Mazhar I. Khan
- Department of Pathobiology and Veterinary Science University of Connecticut, Storrs, CT, United States of America
- * E-mail:
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Bayry J. Coronaviridae: Infectious Bronchitis Virus. EMERGING AND RE-EMERGING INFECTIOUS DISEASES OF LIVESTOCK 2017. [PMCID: PMC7122401 DOI: 10.1007/978-3-319-47426-7_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
Coronavirus particles serve three fundamentally important functions in infection. The virion provides the means to deliver the viral genome across the plasma membrane of a host cell. The virion is also a means of escape for newly synthesized genomes. Lastly, the virion is a durable vessel that protects the genome on its journey between cells. This review summarizes the available X-ray crystallography, NMR, and cryoelectron microscopy structural data for coronavirus structural proteins, and looks at the role of each of the major structural proteins in virus entry and assembly. The potential wider conservation of the nucleoprotein fold identified in the Arteriviridae and Coronaviridae families and a speculative model for the evolution of corona-like virus architecture are discussed.
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Affiliation(s)
- B W Neuman
- School of Biological Sciences, University of Reading, Reading, United Kingdom; College of STEM, Texas A&M University, Texarkana, Texarkana, TX, United States.
| | - M J Buchmeier
- University of California, Irvine, Irvine, CA, United States
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Yin L, Zeng Y, Wang W, Wei Y, Xue C, Cao Y. Immunogenicity and protective efficacy of recombinant fusion proteins containing spike protein of infectious bronchitis virus and hemagglutinin of H3N2 influenza virus in chickens. Virus Res 2016; 223:206-12. [PMID: 27497621 PMCID: PMC7114550 DOI: 10.1016/j.virusres.2016.07.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 07/09/2016] [Accepted: 07/29/2016] [Indexed: 02/03/2023]
Abstract
We generate fused S1 proteins with HA2 (rS1-HA2) or HA transmembrane domain and cytoplasmic tail (rS1-H3(TM)) of H3N2 influenza virus. The two recombinant fusion proteins rS1-HA2 and rS1-H3(TM) are superior to rS1 protein in terms of immunogenicity and protective efficacy. The strategy of fusing TMs or HA2 of HA proteins may provide a new strategy for development of high efficacy recombinant vaccine against IBV.
Infectious bronchitis (IB) is an acute and highly contagious viral respiratory disease of chickens and vaccination is the main method for disease control. The S1 protein, which contains several virus neutralization epitopes, is considered to be a target site of vaccine development. However, although protective immune responses could be induced by recombinant S1 protein, the protection rate in chickens was still low (<50%). Here, we generated fused S1 proteins with HA2 protein (rS1-HA2) or transmembrane domain and cytoplasmic tail (rS1-H3(TM)) from hemagglutinin of H3N2 influenza virus. After immunization, animals vaccinated with fusion proteins rS1-HA2 and rS1-H3(TM) demonstrated stronger robust humoral and cellular immune responses than that of rS1 and inactivated M41 vaccine. The protection rates of groups immunized with rS1-HA2 (87%) were significantly higher than the groups inoculated with rS1 (47%) and inactivated M41 vaccine (53%). And chickens injected with rS1-H3(TM) had similar level of protection (73%) comparing to chickens vaccinated with rS1 (47%) (P = 0.07). Our data suggest that S1 protein fused to the HA2 or TM proteins from hemagglutinin of H3N2 influenza virus may provide a new strategy for high efficacy recombinant vaccine development against IBV.
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Affiliation(s)
- Lijuan Yin
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China
| | - Yuyao Zeng
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China
| | - Wei Wang
- Linyi Institute for Food and Drug Control, Linyi, Shandong Province, PR China
| | - Ying Wei
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China
| | - Chunyi Xue
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China
| | - Yongchang Cao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China.
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Abstract
Members of the family Coronaviridae are evolutionarily related and play an important role in human and veterinary medicine. Taxonomic classification is based on the ultrastructure and morphogenesis of viral particles and on biochemical and molecular features. The family Coronaviridae belongs to the order Nidovirales, and is divided into two subfamilies: Coronavirinae and Torovirinae. The number of coronaviruses isolated from aquatic organisms is negligible; indeed, coronaviruses have only been identified in aquatic mammals, including harbor seal (genus Alphacoronavirus), bottlenose dolphin and beluga whale (genus Gammacoronavirus). White bream virus, isolated from the teleost Blicca bjoerkna (L.), is the type species of the genus Bafinivirus within the subfamily, Torovirinae.
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15
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Wickramasinghe INA, van Beurden SJ, Weerts EAWS, Verheije MH. The avian coronavirus spike protein. Virus Res 2014; 194:37-48. [PMID: 25451062 PMCID: PMC7114429 DOI: 10.1016/j.virusres.2014.10.009] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 10/06/2014] [Accepted: 10/07/2014] [Indexed: 02/07/2023]
Abstract
Avian coronaviruses of the genus Gammacoronavirus are represented by infectious bronchitis virus (IBV), the coronavirus of chicken. IBV causes a highly contagious disease affecting the respiratory tract and, depending on the strain, other tissues including the reproductive and urogenital tract. The control of IBV in the field is hampered by the many different strains circulating worldwide and the limited protection across strains due to serotype diversity. This diversity is believed to be due to the amino acid variation in the S1 domain of the major viral attachment protein spike. In the last years, much effort has been undertaken to address the role of the avian coronavirus spike protein in the various steps of the virus' live cycle. Various models have successfully been developed to elucidate the contribution of the spike in binding of the virus to cells, entry of cell culture cells and organ explants, and the in vivo tropism and pathogenesis. This review will give an overview of the literature on avian coronavirus spike proteins with particular focus on our recent studies on binding of recombinant soluble spike protein to chicken tissues. With this, we aim to summarize the current understanding on the avian coronavirus spike's contribution to host and tissue predilections, pathogenesis, as well as its role in therapeutic and protective interventions.
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Affiliation(s)
- I N Ambepitiya Wickramasinghe
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584CL Utrecht, The Netherlands
| | - S J van Beurden
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584CL Utrecht, The Netherlands
| | - E A W S Weerts
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584CL Utrecht, The Netherlands
| | - M H Verheije
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584CL Utrecht, The Netherlands.
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16
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Ribes JM, Ortego J, Ceriani J, Montava R, Enjuanes L, Buesa J. Transmissible gastroenteritis virus (TGEV)-based vectors with engineered murine tropism express the rotavirus VP7 protein and immunize mice against rotavirus. Virology 2010; 410:107-18. [PMID: 21094967 PMCID: PMC7111951 DOI: 10.1016/j.virol.2010.10.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 08/18/2010] [Accepted: 10/27/2010] [Indexed: 01/26/2023]
Abstract
A coronavirus vector based on the genome of the porcine transmissible gastroenteritis virus (TGEV) expressing the rotavirus VP7 protein was constructed to immunize and protect against rotavirus infections in a murine model. The tropism of this TGEV-derived vector was modified by replacing the spike S protein with the homologous protein from mouse hepatitis virus (MHV). The rotavirus gene encoding the VP7 protein was cloned into the coronavirus cDNA. BALB/c and STAT1-deficient mice were inoculated with the recombinant viral vector rTGEVS-MHV–VP7, which replicates in the intestine and spreads to other organs such as liver, spleen and lungs. TGEV-specific antibodies were detected in all the inoculated BALB/c mice, while rotavirus-specific antibodies were found only after immunization by the intraperitoneal route. Partial protection against rotavirus-induced diarrhea was achieved in suckling BALB/c mice born to dams immunized with the recombinant virus expressing VP7 when they were orally challenged with the homotypic rotavirus strain.
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Affiliation(s)
- Juan Manuel Ribes
- Department of Microbiology and Ecology, School of Medicine, University of Valencia, Avda. Blasco Ibáñez, 17, 46010 Valencia, Spain
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17
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Caron LF. Etiology and immunology of infectious bronchitis virus. BRAZILIAN JOURNAL OF POULTRY SCIENCE 2010. [DOI: 10.1590/s1516-635x2010000200007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Madu IG, Belouzard S, Whittaker GR. SARS-coronavirus spike S2 domain flanked by cysteine residues C822 and C833 is important for activation of membrane fusion. Virology 2009; 393:265-71. [PMID: 19717178 PMCID: PMC3594805 DOI: 10.1016/j.virol.2009.07.038] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 05/27/2009] [Accepted: 07/30/2009] [Indexed: 01/04/2023]
Abstract
The S2 domain of the coronavirus spike (S) protein is known to be responsible for mediating membrane fusion. In addition to a well-recognized cleavage site at the S1–S2 boundary, a second proteolytic cleavage site has been identified in the severe acute respiratory syndrome coronavirus (SARS-CoV) S2 domain (R797). C-terminal to this S2 cleavage site is a conserved region flanked by cysteine residues C822 and C833. Here, we investigated the importance of this well conserved region for SARS-CoV S-mediated fusion activation. We show that the residues between C822–C833 are well conserved across all coronaviruses. Mutagenic analysis of SARS-CoV S, combined with cell–cell fusion and pseudotyped virion infectivity assays, showed a critical role for the core-conserved residues C822, D830, L831, and C833. Based on available predictive models, we propose that the conserved domain flanked by cysteines 822 and 833 forms a loop structure that interacts with components of the SARS-CoV S trimer to control the activation of membrane fusion.
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Affiliation(s)
- Ikenna G Madu
- C4127 Veterinary Medical Center, Department of Microbiology and Immunology, Cornell University, Ithaca NY 14853, USA
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19
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Two-step conformational changes in a coronavirus envelope glycoprotein mediated by receptor binding and proteolysis. J Virol 2009; 83:11133-41. [PMID: 19706706 DOI: 10.1128/jvi.00959-09] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The coronaviruses mouse hepatitis virus type 2 (MHV-2) and severe acute respiratory syndrome coronavirus (SARS-CoV) utilize proteases to enter host cells. Upon receptor binding, the spike (S) proteins of both viruses are activated for membrane fusion by proteases, such as trypsin, present in the environment, facilitating virus entry from the cell surface. In contrast, in the absence of extracellular proteases, these viruses can enter cells via an endosomal pathway and utilize endosomal cathepsins for S protein activation. We demonstrate that the MHV-2 S protein uses multistep conformational changes for membrane fusion. After interaction with a soluble form of the MHV receptor (CEACAM1a), the metastable form of S protein is converted to a stable trimer, as revealed by mildly denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Liposome-binding assays indicate that the receptor-bound virions are associated with the target membrane through hydrophobic interactions. The exposure of receptor-bound S protein to trypsin or cathepsin L (CPL) induces the formation of six-helix bundles (6HB), the final conformation. This trypsin- or CPL-mediated conversion to 6HB can be blocked by a heptad repeat peptide known to block the formation of 6HB. Although trypsin treatment enabled receptor-bound MHV-2 to enter from the cell surface, CPL failed to do so. Interestingly, consecutive treatment with CPL and then chlorpromazine enabled a portion of the virus to enter from cell surface. These results suggest that trypsin suffices for the induction of membrane fusion of receptor-primed S protein, but an additional unidentified cellular factor is required to trigger membrane fusion by CPL.
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20
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Aromatic amino acids in the juxtamembrane domain of severe acute respiratory syndrome coronavirus spike glycoprotein are important for receptor-dependent virus entry and cell-cell fusion. J Virol 2008; 82:2883-94. [PMID: 18199653 DOI: 10.1128/jvi.01805-07] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus (SARS-CoV) spike glycoprotein (S) is a class I viral fusion protein that binds to its receptor glycoprotein, human angiotensin converting enzyme 2 (hACE2), and mediates virus entry and cell-cell fusion. The juxtamembrane domain (JMD) of S is an aromatic amino acid-rich region proximal to the transmembrane domain that is highly conserved in all coronaviruses. Alanine substitutions for one or two of the six aromatic residues in the JMD did not alter the surface expression of the SARS-CoV S proteins with a deletion of the C-terminal 19 amino acids (S Delta19) or reduce binding to soluble human ACE2 (hACE2). However, hACE2-dependent entry of trypsin-treated retrovirus pseudotyped viruses expressing JMD mutant S Delta19 proteins was greatly reduced. Single alanine substitutions for aromatic residues reduced entry to 10 to 60% of the wild-type level. The greatest reduction was caused by residues nearest the transmembrane domain. Four double alanine substitutions reduced entry to 5 to 10% of the wild-type level. Rapid hACE2-dependent S-mediated cell-cell fusion was reduced to 60 to 70% of the wild-type level for all single alanine substitutions and the Y1188A/Y1191A protein. S Delta19 proteins with other double alanine substitutions reduced cell-cell fusion further, from 40% to less than 20% of wild-type levels. The aromatic amino acids in the JMD of the SARS-CoV S glycoprotein play critical roles in receptor-dependent virus-cell and cell-cell fusion. Because the JMD is so highly conserved in all coronavirus S proteins, it is a potential target for development of drugs that may inhibit virus entry and/or cell-cell fusion mediated by S proteins of all coronaviruses.
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21
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Ortego J, Ceriani JE, Patiño C, Plana J, Enjuanes L. Absence of E protein arrests transmissible gastroenteritis coronavirus maturation in the secretory pathway. Virology 2007; 368:296-308. [PMID: 17692883 PMCID: PMC7103363 DOI: 10.1016/j.virol.2007.05.032] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 04/17/2007] [Accepted: 05/14/2007] [Indexed: 12/24/2022]
Abstract
A recombinant transmissible gastroenteritis coronavirus (rTGEV) in which E gene was deleted (rTGEV-ΔE) has been engineered. This deletion mutant only grows in cells expressing E protein (E+ cells) indicating that E was an essential gene for TGEV replication. Electron microscopy studies of rTGEV-ΔE infected BHK-pAPN-E− cells showed that only immature intracellular virions were assembled. These virions were non-infectious and not secreted to the extracellular medium in BHK-pAPN-E− cells. RNA and protein composition analysis by RNase-gold and immunoelectron microscopy showed that rTGEV-ΔE virions contained RNA and also all the structural TGEV proteins, except the deleted E protein. Nevertheless, full virion maturation was blocked. Studies of the rTGEV-ΔE subcellular localization by confocal and immunoelectron microscopy in infected E− cells showed that in the absence of E protein virus trafficking was arrested in the intermediate compartment. Therefore, the absence of E protein in TGEV resulted in two actions, a blockade of virus trafficking in the membranes of the secretory pathway, and prevention of full virus maturation.
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Affiliation(s)
- Javier Ortego
- Centro Nacional de Biotecnología, CSIC, Department of Molecular and Cell Biology, Campus Universidad Autónoma, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Juan E. Ceriani
- Fort-Dodge Veterinaria, Department of Research and Development, Girona, Spain
| | - Cristina Patiño
- Centro Nacional de Biotecnología, CSIC, Macromolecular Structure, Campus Universidad Autónoma, Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Juan Plana
- Fort-Dodge Veterinaria, Department of Research and Development, Girona, Spain
| | - Luis Enjuanes
- Centro Nacional de Biotecnología, CSIC, Department of Molecular and Cell Biology, Campus Universidad Autónoma, Darwin 3, Cantoblanco, 28049 Madrid, Spain
- Corresponding author. Fax: +34 915854915.
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22
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Versteeg GA, van de Nes PS, Bredenbeek PJ, Spaan WJM. The coronavirus spike protein induces endoplasmic reticulum stress and upregulation of intracellular chemokine mRNA concentrations. J Virol 2007; 81:10981-90. [PMID: 17670839 PMCID: PMC2045536 DOI: 10.1128/jvi.01033-07] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Murine hepatitis virus (MHV) and severe acute respiratory syndrome (SARS) coronavirus (CoV) are two of the best-studied representatives of the family Coronaviridae. During CoV infection, numerous cytokines and chemokines are induced in vitro and in vivo. Human interleukin 8 and its mouse functional counterpart, CXCL2, are early-expressed chemokines. Here we show that SARS-CoV and MHV induce endoplasmic reticulum (ER) stress and Cxcl2 mRNA transcription during infection in vitro. Expression of the viral spike protein significantly induced ER stress and Cxcl2 mRNA upregulation, while expression of the other structural genes did not. Additional experiments with UV-inactivated virus, cell-cell fusion-blocking antibodies, and an MHV mutant with a defect in spike protein maturation demonstrated that spike-host interactions in the ER are responsible for the induction of ER stress and subsequent Cxcl2 mRNA transcription. Despite significant increases in levels of Cxcl2 mRNA and functional nucleus-to-cytoplasm RNA transport, no CXCL2 protein was released into the medium from MHV-infected cells. Yet Sendai virus-infected cells showed substantial Cxcl2 mRNA induction and a simultaneous increase in levels of secreted CXCL2 protein. Our results demonstrate that expression of CoV spike proteins induces ER stress, which could subsequently trigger innate immune responses. However, at that point in infection, translation of host mRNA is already severely reduced in infected cells, preventing the synthesis of CXCL2 and ER stress proteins despite their increased mRNA concentrations.
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Affiliation(s)
- Gijs A Versteeg
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, LUMC E4-P, P.O. Box 9600, 2300 RC Leiden, The Netherlands
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23
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Rinninger A, Richet C, Pons A, Kohla G, Schauer R, Bauer HC, Zanetta JP, Vlasak R. Localisation and distribution of O-acetylated N-acetylneuraminic acids, the endogenous substrates of the hemagglutinin-esterases of murine coronaviruses, in mouse tissue. Glycoconj J 2006; 23:73-84. [PMID: 16575524 PMCID: PMC7088067 DOI: 10.1007/s10719-006-5439-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Infections by mouse hepatitis viruses result in disease of the liver, the gastrointestinal tract, respiratory tract, and the central nervous system. Coronaviruses related to mouse hepatitis virus express a hemagglutinin-esterase surface glycoprotein, which specifically hydrolyses either 5-N-acetyl-4-O-acetyl neuraminic acid (Neu4,5Ac2) or 5-N-acetyl-9-O-acetyl neuraminic acid (Neu5,9Ac2). Moreover, these sialic acids represent potential cellular receptor determinants for murine coronaviruses. Until now, the distribution of these sialic acids in mouse brain was not thoroughly investigated. Particularly Neu4,5Ac2 was not yet found in mouse brain. Using a sensitive method of gas chromatography coupled to mass spectrometry in the electron impact mode of ionization this manuscript demonstrates the occurrence of 13 different sialic acids varying in their alkyl and acyl substituents in mouse tissues including 5-N-acetyl-4-O-acetyl-9-O-lactyl-neuraminic acid (Neu4,5Ac29Lt), 5-N-acetyl-9-O-lactyl-neuraminic acid (Neu5Ac9Lt), 5-N-acetyl-8-O-methyl-neuraminic acid (Neu5Ac8Me) and the 1,7-lactone (Neu5Ac1,7L) of neuraminic acid. Neu4,5Ac2, relatively abundant in the gut, was present as a minor compound in all tissues, including liver, olfactory lobe, telencephalon, metencephalon and hippocampus. Neu5,9Ac2 was also found in these tissues, except in the liver. It is suggested that these sialic acids represent the endogenous substrate and receptor determinants for murine coronaviruses.
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Affiliation(s)
- Andreas Rinninger
- Applied Biotechnology, Departments of Cell Biology and Organismic Biology, University Salzburg, A-5020 Salzburg, Austria
| | | | - Alexandre Pons
- CNRS Unité Mixte de Recherche 8576, Laboratoire de Glycobiologie Structurale et Fonctionnelle, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Guido Kohla
- Biochemisches Institut, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
| | - Roland Schauer
- Biochemisches Institut, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
| | - Hans-Christian Bauer
- Applied Biotechnology, Departments of Cell Biology and Organismic Biology, University Salzburg, A-5020 Salzburg, Austria
| | - Jean-Pierre Zanetta
- CNRS Unité Mixte de Recherche 8576, Laboratoire de Glycobiologie Structurale et Fonctionnelle, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Reinhard Vlasak
- Applied Biotechnology, Departments of Cell Biology and Organismic Biology, University Salzburg, A-5020 Salzburg, Austria
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24
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Tangudu C, Olivares H, Netland J, Perlman S, Gallagher T. Severe acute respiratory syndrome coronavirus protein 6 accelerates murine coronavirus infections. J Virol 2006; 81:1220-9. [PMID: 17108045 PMCID: PMC1797517 DOI: 10.1128/jvi.01515-06] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One or more of the unique 3'-proximal open reading frames (ORFs) of the severe acute respiratory syndrome (SARS) coronavirus may encode determinants of virus virulence. A prime candidate is ORF6, which encodes a 63-amino-acid membrane-associated peptide that can dramatically increase the lethality of an otherwise attenuated JHM strain of murine coronavirus (L. Pewe, H. Zhou, J. Netland, C. Tangudu, H. Olivares, L. Shi, D. Look, T. Gallagher, and S. Perlman, J. Virol. 79:11335-11342, 2005). To discern virulence mechanisms, we compared the in vitro growth properties of rJ.6, a recombinant JHM expressing the SARS peptide, with isogenic rJ.6-KO, which has an inactive ORF containing a mutated initiation codon and a termination codon at internal position 27. The rJ.6 infections proceeded rapidly, secreting progeny about 1.5 h earlier than rJ.6-KO infections did. The rJ.6 infections were also set apart by early viral protein accumulation and by robust expansion via syncytia, a characteristic feature of JHM virus dissemination. We found no evidence for protein 6 operating at the virus entry or assembly stage, as virions from either infection were indistinguishable. Rather, protein 6 appeared to operate by fostering viral RNA and protein synthesis, as RNA quantifications by reverse transcription-quantitative PCR revealed viral RNA levels in the rJ.6 cultures that were five to eight times higher than those lacking protein 6. Furthermore, protein 6 coimmunoprecipitated with viral RNAs and colocalized on cytoplasmic vesicles with replicating viral RNAs. The SARS coronavirus encodes a novel membrane protein 6 that can accelerate replication of a related mouse virus, a property that may explain its ability to increase in vivo virus virulence.
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Affiliation(s)
- Chandra Tangudu
- Department of Microbiology and Immunology, Loyola University Medical Center, 2160 South First Avenue, Maywood, IL 60153, USA
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25
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Neuman BW, Adair BD, Yoshioka C, Quispe JD, Orca G, Kuhn P, Milligan RA, Yeager M, Buchmeier MJ. Supramolecular architecture of severe acute respiratory syndrome coronavirus revealed by electron cryomicroscopy. J Virol 2006; 80:7918-28. [PMID: 16873249 PMCID: PMC1563832 DOI: 10.1128/jvi.00645-06] [Citation(s) in RCA: 260] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Coronavirus particles are enveloped and pleomorphic and are thus refractory to crystallization and symmetry-assisted reconstruction. A novel methodology of single-particle image analysis was applied to selected virus features to obtain a detailed model of the oligomeric state and spatial relationships among viral structural proteins. Two-dimensional images of the S, M, and N structural proteins of severe acute respiratory syndrome coronavirus and two other coronaviruses were refined to a resolution of approximately 4 nm. Proteins near the viral membrane were arranged in overlapping lattices surrounding a disordered core. Trimeric glycoprotein spikes were in register with four underlying ribonucleoprotein densities. However, the spikes were dispensable for ribonucleoprotein lattice formation. The ribonucleoprotein particles displayed coiled shapes when released from the viral membrane. Our results contribute to the understanding of the assembly pathway used by coronaviruses and other pleomorphic viruses and provide the first detailed view of coronavirus ultrastructure.
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Affiliation(s)
- Benjamin W Neuman
- Department of Molecular and Integrative Neuroscience, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA.
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26
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de Haan CAM, Te Lintelo E, Li Z, Raaben M, Wurdinger T, Bosch BJ, Rottier PJM. Cooperative involvement of the S1 and S2 subunits of the murine coronavirus spike protein in receptor binding and extended host range. J Virol 2006; 80:10909-18. [PMID: 16956938 PMCID: PMC1642182 DOI: 10.1128/jvi.00950-06] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
To study the process of spike (S)-receptor interaction during coronavirus entry, we evaluated the contributions of mutations in different regions of the murine hepatitis virus (MHV) S protein to natural receptor murine carcinoembryonic antigen-related cell adhesion molecule 1a (CEACAM1a) dependence and to the acquisition of extended host range. Extended-host-range variants of MHV strain A59 were previously obtained from persistently infected cells (J. H. Schickli, B. D. Zelus, D. E. Wentworth, S. G. Sawicki, and K. V. Holmes, J. Virol. 71:9499-9504, 1997). These variant viruses contain several mutations in the S protein that confer to the viruses the ability to enter cells in a heparan sulfate-dependent manner (C. A. de Haan, Z. Li, E. te Lintelo, B. J. Bosch, B. J. Haijema, and P. J. M. Rottier, J. Virol. 79:14451-14456, 2005). While the parental MHV-A59 is fully dependent on murine CEACAM1a for its entry, viruses carrying the variant mutations in the amino-terminal part of their S protein had become dependent on both CEACAM1a and heparan sulfate. Substitutions in a restricted, downstream part of the S protein encompassing heptad repeat region 1 (HR1) and putative fusion peptide (FP) did not alter the CEACAM1a dependence. However, when the mutations in both parts of the S protein were combined, the resulting viruses became independent of CEACAM1a and acquired the extended host range. In addition, these viruses showed a decreased binding to and inhibition by soluble CEACAM1a. The observations suggest that the amino-terminal region of the S protein, including the receptor-binding domain, and a region in the central part of the S protein containing HR1 and FP, i.e., regions far apart in the linear sequence, communicate and may even interact physically in the higher-order structure of the spike.
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Affiliation(s)
- Cornelis A M de Haan
- Virology Division, Department of Infectious Diseases and Immunology, Yalelaan 1, 3584 CL Utrecht, The Netherlands.
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27
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Hwang WC, Lin Y, Santelli E, Sui J, Jaroszewski L, Stec B, Farzan M, Marasco WA, Liddington RC. Structural basis of neutralization by a human anti-severe acute respiratory syndrome spike protein antibody, 80R. J Biol Chem 2006; 281:34610-6. [PMID: 16954221 PMCID: PMC7981188 DOI: 10.1074/jbc.m603275200] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Severe acute respiratory syndrome (SARS) is a newly emerged infectious disease that caused pandemic spread in 2003. The etiological agent of SARS is a novel coronavirus (SARS-CoV). The coronaviral surface spike protein S is a type I transmembrane glycoprotein that mediates initial host binding via the cell surface receptor angiotensin-converting enzyme 2 (ACE2), as well as the subsequent membrane fusion events required for cell entry. Here we report the crystal structure of the S1 receptor binding domain (RBD) in complex with a neutralizing antibody, 80R, at 2.3 Å resolution, as well as the structure of the uncomplexed S1 RBD at 2.2 Å resolution. We show that the 80R-binding epitope on the S1 RBD overlaps very closely with the ACE2-binding site, providing a rationale for the strong binding and broad neutralizing ability of the antibody. We provide a structural basis for the differential effects of certain mutations in the spike protein on 80R versus ACE2 binding, including escape mutants, which should facilitate the design of immunotherapeutics to treat a future SARS outbreak. We further show that the RBD of S1 forms dimers via an extensive interface that is disrupted in receptor- and antibody-bound crystal structures, and we propose a role for the dimer in virus stability and infectivity.
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Affiliation(s)
- William C Hwang
- Infectious and Inflammatory Disease Center, Burnham Institute for Medical Research, La Jolla, California 92037, USA
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28
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Abstract
Coronaviruses are large, enveloped RNA viruses of both medical and veterinary importance. Interest in this viral family has intensified in the past few years as a result of the identification of a newly emerged coronavirus as the causative agent of severe acute respiratory syndrome (SARS). At the molecular level, coronaviruses employ a variety of unusual strategies to accomplish a complex program of gene expression. Coronavirus replication entails ribosome frameshifting during genome translation, the synthesis of both genomic and multiple subgenomic RNA species, and the assembly of progeny virions by a pathway that is unique among enveloped RNA viruses. Progress in the investigation of these processes has been enhanced by the development of reverse genetic systems, an advance that was heretofore obstructed by the enormous size of the coronavirus genome. This review summarizes both classical and contemporary discoveries in the study of the molecular biology of these infectious agents, with particular emphasis on the nature and recognition of viral receptors, viral RNA synthesis, and the molecular interactions governing virion assembly.
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Affiliation(s)
- Paul S Masters
- Wadsworth Center, New York State Department of Health, Albany, 12201, USA
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29
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Supramolecular architecture of severe acute respiratory syndrome coronavirus revealed by electron cryomicroscopy. J Virol 2006. [PMID: 16873249 DOI: 10.1128/jvi.00645‐06] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Coronavirus particles are enveloped and pleomorphic and are thus refractory to crystallization and symmetry-assisted reconstruction. A novel methodology of single-particle image analysis was applied to selected virus features to obtain a detailed model of the oligomeric state and spatial relationships among viral structural proteins. Two-dimensional images of the S, M, and N structural proteins of severe acute respiratory syndrome coronavirus and two other coronaviruses were refined to a resolution of approximately 4 nm. Proteins near the viral membrane were arranged in overlapping lattices surrounding a disordered core. Trimeric glycoprotein spikes were in register with four underlying ribonucleoprotein densities. However, the spikes were dispensable for ribonucleoprotein lattice formation. The ribonucleoprotein particles displayed coiled shapes when released from the viral membrane. Our results contribute to the understanding of the assembly pathway used by coronaviruses and other pleomorphic viruses and provide the first detailed view of coronavirus ultrastructure.
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30
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Chu VC, McElroy LJ, Chu V, Bauman BE, Whittaker GR. The avian coronavirus infectious bronchitis virus undergoes direct low-pH-dependent fusion activation during entry into host cells. J Virol 2006; 80:3180-8. [PMID: 16537586 PMCID: PMC1440383 DOI: 10.1128/jvi.80.7.3180-3188.2006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Coronaviruses are the causative agents of respiratory disease in humans and animals, including severe acute respiratory syndrome. Fusion of coronaviruses is generally thought to occur at neutral pH, although there is also evidence for a role of acidic endosomes during entry of a variety of coronaviruses. Therefore, the molecular basis of coronavirus fusion during entry into host cells remains incompletely defined. Here, we examined coronavirus-cell fusion and entry employing the avian coronavirus infectious bronchitis virus (IBV). Virus entry into cells was inhibited by acidotropic bases and by other inhibitors of pH-dependent endocytosis. We carried out fluorescence-dequenching fusion assays of R18-labeled virions and show that for IBV, coronavirus-cell fusion occurs in a low-pH-dependent manner, with a half-maximal rate of fusion occurring at pH 5.5. Fusion was reduced, but still occurred, at lower temperatures (20 degrees C). We observed no effect of inhibitors of endosomal proteases on the fusion event. These data are the first direct measure of virus-cell fusion for any coronavirus and demonstrate that the coronavirus IBV employs a direct, low-pH-dependent virus-cell fusion activation reaction. We further show that IBV was not inactivated, and fusion was unaffected, by prior exposure to pH 5.0 buffer. Virions also showed evidence of reversible conformational changes in their surface proteins, indicating that aspects of the fusion reaction may be reversible in nature.
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Affiliation(s)
- Victor C Chu
- Dept. of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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31
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de Haan CAM, Li Z, te Lintelo E, Bosch BJ, Haijema BJ, Rottier PJM. Murine coronavirus with an extended host range uses heparan sulfate as an entry receptor. J Virol 2006; 79:14451-6. [PMID: 16254381 PMCID: PMC1280238 DOI: 10.1128/jvi.79.22.14451-14456.2005] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Only a relatively few mutations in its spike protein allow the murine coronavirus to switch from a murine-restricted tropism to an extended host range by being passaged in vitro. One such virus that we studied had acquired two putative heparan sulfate-binding sites while preserving another site in the furin-cleavage motif. The adaptation of the virus through the use of heparan sulfate as an attachment/entry receptor was demonstrated by increased heparin binding as well as by inhibition of infection through treatment of cells and the virus with heparinase and heparin, respectively.
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Affiliation(s)
- Cornelis A M de Haan
- Virology Division, Department of Infectious Diseases and Immunology, Yalelaan 1, 3584CL Utrecht, The Netherlands.
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32
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Abstract
This chapter describes the interactions between the different structural components of the viruses and discusses their relevance for the process of virion formation. Two key factors determine the efficiency of the assembly process: intracellular transport and molecular interactions. Many viruses have evolved elaborate strategies to ensure the swift and accurate delivery of the virion components to the cellular compartment(s) where they must meet and form (sub) structures. Assembly of viruses starts in the nucleus by the encapsidation of viral DNA, using cytoplasmically synthesized capsid proteins; nucleocapsids then migrate to the cytosol, by budding at the inner nuclear membrane followed by deenvelopment, to pick up the tegument proteins.
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Affiliation(s)
- Cornelis A M de Haan
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
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33
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Tang T, Wu MP, Chen S, Hou M, Hong M, Pan F, Yu H, Chen J, Yao C, Wang AH. Biochemical and immunological studies of nucleocapsid proteins of severe acute respiratory syndrome and 229E human coronaviruses. Proteomics 2005; 5:925-37. [PMID: 15759315 PMCID: PMC7167620 DOI: 10.1002/pmic.200401204] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Severe acute respiratory syndrome (SARS) is a serious health threat and its early diagnosis is important for infection control and potential treatment of the disease. Diagnostic tools require rapid and accurate methods, of which a capture ELISA method may be useful. Toward this goal, we have prepared and characterized soluble full‐length nucleocapsid proteins (N protein) from SARS and 229E human coronaviruses. N proteins form oligomers, mostly as dimers at low concentration. These two N proteins degrade rapidly upon storage and the major degraded N protein is the C‐terminal fragment of amino acid (aa) 169–422. Taken together with other data, we suggest that N protein is a two‐domain protein, with the N‐terminal aa 50–150 as the RNA‐binding domain and the C‐terminal aa 169–422 as the dimerization domain. Polyclonal antibodies against the SARS N protein have been produced and the strong binding sites of the anti‐nucleocapsid protein (NP) antibodies produced were mapped to aa 1–20, aa 150–170 and aa 390–410. These sites are generally consistent with those mapped by sera obtained from SARS patients. The SARS anti‐NP antibody was able to clearly detect SARS virus grown in Vero E6 cells and did not cross‐react with the NP from the human coronavirus 229E. We have predicted several antigenic sites (15–20 amino acids) of S, M and N proteins and produced antibodies against those peptides, some of which could be recognized by sera obtained from SARS patients. Antibodies against the NP peptides could detect the cognate N protein clearly. Further refinement of these antibodies, particularly large‐scale production of monoclonal antibodies, could lead to the development of useful diagnostic kits for diseases associated with SARS and other human coronaviruses.
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MESH Headings
- Amino Acid Sequence
- Amino Acids/chemistry
- Animals
- Antibodies, Viral/chemistry
- Antigens/chemistry
- Antigens, Viral/chemistry
- Binding Sites
- Chlorocebus aethiops
- Chromatography, Gel
- Circular Dichroism
- Cloning, Molecular
- Coronavirus 229E, Human/metabolism
- Coronavirus Nucleocapsid Proteins
- Cross-Linking Reagents/pharmacology
- DNA/chemistry
- DNA, Complementary/metabolism
- Dimerization
- Electrophoresis, Polyacrylamide Gel
- Enzyme-Linked Immunosorbent Assay
- Epitopes/chemistry
- Humans
- Microscopy, Fluorescence
- Molecular Sequence Data
- Nucleocapsid/chemistry
- Nucleocapsid Proteins/chemistry
- Open Reading Frames
- Peptides/chemistry
- Protein Array Analysis/methods
- Protein Binding
- Protein Structure, Tertiary
- Proteomics/methods
- RNA/chemistry
- Rabbits
- Severe acute respiratory syndrome-related coronavirus/metabolism
- Sequence Homology, Amino Acid
- Severe Acute Respiratory Syndrome/diagnosis
- Vero Cells
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Affiliation(s)
| | | | | | - Ming‐Hon Hou
- Institute of Biological Chemistry, Academia Sinica
| | | | - Fu‐Ming Pan
- Institute of Biological Chemistry, Academia Sinica
| | - Hui‐Ming Yu
- Institute of Biological Chemistry, Academia Sinica
| | - Jenn‐Han Chen
- School of Dentistry, National Defense Medical Center
- Biochip R&D Center, Department of Pathology, Tri‐Service General Hospital, National Defense University, Taipei, Taiwan
| | - Chen‐Wen Yao
- Biochip R&D Center, Department of Pathology, Tri‐Service General Hospital, National Defense University, Taipei, Taiwan
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34
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Chou THW, Wang S, Sakhatskyy PV, Mboudjeka I, Mboudoudjeck I, Lawrence JM, Huang S, Coley S, Yang B, Li J, Zhu Q, Lu S. Epitope mapping and biological function analysis of antibodies produced by immunization of mice with an inactivated Chinese isolate of severe acute respiratory syndrome-associated coronavirus (SARS-CoV). Virology 2005; 334:134-43. [PMID: 15749129 PMCID: PMC7111783 DOI: 10.1016/j.virol.2005.01.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 01/10/2005] [Accepted: 01/25/2005] [Indexed: 11/26/2022]
Abstract
Inactivated severe acute respiratory syndrome-associated coronavirus (SARS-CoV) has been tested as a candidate vaccine against the re-emergence of SARS. In order to understand the efficacy and safety of this approach, it is important to know the antibody specificities generated with inactivated SARS-CoV. In the current study, a panel of twelve monoclonal antibodies (mAbs) was established by immunizing Balb/c mice with the inactivated BJ01 strain of SARS-CoV isolated from the lung tissue of a SARS-infected Chinese patient. These mAbs could recognize SARS-CoV-infected cells by immunofluorescence analysis (IFA). Seven of them were mapped to the specific segments of recombinant spike (S) protein: six on S1 subunit (aa 12-798) and one on S2 subunit (aa 797-1192). High neutralizing titers against SARS-CoV were detected with two mAbs (1A5 and 2C5) targeting at a subdomain of S protein (aa 310-535), consistent with the previous report that this segment of S protein contains the major neutralizing domain. Some of these S-specific mAbs were able to recognize cleaved products of S protein in SARS-CoV-infected Vero E6 cells. None of the remaining five mAbs could recognize either of the recombinant S, N, M, or E antigens by ELISA. This study demonstrated that the inactivated SARS-CoV was able to preserve the immunogenicity of S protein including its major neutralizing domain. The relative ease with which these mAbs were generated against SARS-CoV virions further supports that subunit vaccination with S constructs may also be able to protect animals and perhaps humans. It is somewhat unexpected that no N-specific mAbs were identified albeit anti-N IgG was easily identified in SARS-CoV-infected patients. The availability of this panel of mAbs also provided potentially useful agents with applications in therapy, diagnosis, and basic research of SARS-CoV.
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Affiliation(s)
- Te-hui W Chou
- Laboratory of Nucleic Acid Vaccines, Department of Medicine, University of Massachusetts Medical School, 364 Plantation Street, Lazare Research Building, Worcester, MA 01605-2397, USA
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35
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Thackray LB, Turner BC, Holmes KV. Substitutions of conserved amino acids in the receptor-binding domain of the spike glycoprotein affect utilization of murine CEACAM1a by the murine coronavirus MHV-A59. Virology 2005; 334:98-110. [PMID: 15749126 PMCID: PMC7111733 DOI: 10.1016/j.virol.2005.01.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Revised: 11/15/2004] [Accepted: 01/12/2005] [Indexed: 01/17/2023]
Abstract
The host range of the murine coronavirus (MHV) is limited to susceptible mice and murine cell lines by interactions of the spike glycoprotein (S) with its receptor, mCEACAM1a. We identified five residues in S (S33, L79, T82, Y162 and K183) that are conserved in the receptor-binding domain of MHV strains, but not in related coronaviruses. We used targeted RNA recombination to generate isogenic viruses that differ from MHV-A59 by amino acid substitutions in S. Viruses with S33R and K183R substitutions had wild type growth, while L79A/T82A viruses formed small plaques. Viruses with S33G, L79M/T82M or K183G substitutions could only be recovered from cells that over-expressed a mutant mCEACAM1a. Viruses with Y162H or Y162Q substitutions were never recovered, while Y162A viruses formed minute plaques. However, viruses with Y162F substitutions had wild type growth, suggesting that Y162 may comprise part of a hydrophobic domain that contacts the MHV-binding site of mCEACAM1a.
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MESH Headings
- Amino Acid Substitution
- Animals
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, Differentiation/genetics
- Antigens, Differentiation/metabolism
- Base Sequence
- Binding Sites/genetics
- Carcinoembryonic Antigen
- Cell Adhesion Molecules
- Cell Line
- Conserved Sequence
- Coronavirus/genetics
- Coronavirus/growth & development
- Coronavirus/metabolism
- Coronavirus/pathogenicity
- Cricetinae
- DNA, Complementary/genetics
- DNA, Viral/genetics
- Green Fluorescent Proteins/genetics
- Humans
- Membrane Glycoproteins/chemistry
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Mice
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Protein Structure, Tertiary
- Rats
- Receptors, Virus/genetics
- Receptors, Virus/metabolism
- Recombination, Genetic
- Species Specificity
- Spike Glycoprotein, Coronavirus
- Viral Envelope Proteins/chemistry
- Viral Envelope Proteins/genetics
- Viral Envelope Proteins/metabolism
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36
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Zheng BJ, Guan Y, He ML, Sun H, Du L, Zheng Y, Wong KL, Chen H, Chen Y, Lu L, Tanner JA, Watt RM, Niccolai N, Bernini A, Spiga O, Woo PCY, Kung HF, Yuen KY, Huang JD. Synthetic Peptides outside the Spike Protein Heptad Repeat Regions as Potent Inhibitors of Sars-Associated Coronavirus. Antivir Ther 2005. [DOI: 10.1177/135965350501000301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A novel severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) has been identified as the aetiological agent of SARS. We previously isolated and characterized SARS-CoV and SARS-CoV-like viruses from human and animals, respectively, suggesting that SARS could be transmitted from wild/farmed animals to humans. Comparison of the viral genomes indicated that sequence variation between animal and human isolates existed mainly in the spike (S) gene. We hypothesized that these variations may underlie a change of binding specificity of the S protein to the host cells, permitting viral transmission from animals to humans. Here we report that four 20-mer synthetic peptides (S protein fragments), designed to span these sequence variation otspots, exhibited significant antiviral activities in a cell line. SARS-CoV infectivity was reduced over 10 000-fold through pre-incubation with two of these peptides, while it was completely inhibited in the presence of three peptides. Molecular modelling of the SARS-CoV peplomer suggests that three of these antiviral peptides map to the interfaces between the three monomers of the trimeric peplomer rather than the heptad repeat region from which short peptides are known to inhibit viral entry. Our results revealed novel regions in the spike protein that can be targeted to inhibit viral infection. The peptides identified in this study could be further developed into antiviral drugs.
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Affiliation(s)
- Bo-Jian Zheng
- Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Yi Guan
- Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Ming-Liang He
- Institute of Molecular Biology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
- Centre for Emerging Infectious Diseases, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong SAR, China
| | - Hongzhe Sun
- Department of Chemistry and Open Laboratory of Chemical Biology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Lanying Du
- Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Ying Zheng
- Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Kin-Ling Wong
- Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Honglin Chen
- Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Ying Chen
- Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Linyu Lu
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Julian A Tanner
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Rory M Watt
- Department of Chemistry and Open Laboratory of Chemical Biology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Neri Niccolai
- Biomolecular Structure Research Centre, University of Siena, Siena, Italy
| | - Andrea Bernini
- Biomolecular Structure Research Centre, University of Siena, Siena, Italy
| | - Ottavia Spiga
- Biomolecular Structure Research Centre, University of Siena, Siena, Italy
| | - Patrick CY Woo
- Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Hsiang-fu Kung
- Institute of Molecular Biology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
- Centre for Emerging Infectious Diseases, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong SAR, China
| | - Kwok-Yung Yuen
- Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Jian-Dong Huang
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong SAR, China
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37
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Bernini A, Spiga O, Ciutti A, Chiellini S, Bracci L, Yan X, Zheng B, Huang J, He ML, Song HD, Hao P, Zhao G, Niccolai N. Prediction of quaternary assembly of SARS coronavirus peplomer. Biochem Biophys Res Commun 2005; 325:1210-4. [PMID: 15555555 PMCID: PMC7092937 DOI: 10.1016/j.bbrc.2004.10.156] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2004] [Indexed: 11/29/2022]
Abstract
The tertiary structures of the S1 and S2 domains of the spike protein of the coronavirus which is responsible of the severe acute respiratory syndrome (SARS) have been recently predicted. Here a molecular assembly of SARS coronavirus peplomer which accounts for the available functional data is suggested. The interaction between S1 and S2 appears to be stabilised by a large hydrophobic network of aromatic side chains present in both domains. This feature results to be common to all coronaviruses, suggesting potential targeting for drugs preventing coronavirus-related infections.
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Affiliation(s)
- Andrea Bernini
- Department of Molecular Biology, Biomolecular Structure Research Center, University of Siena, I-53100 Siena, Italy
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38
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Coronavirus Receptors. EXPERIMENTAL MODELS OF MULTIPLE SCLEROSIS 2005. [PMCID: PMC7122215 DOI: 10.1007/0-387-25518-4_46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The major receptor for murine coronavirus, mouse hepatitis virus (MHV), is identified as a protein, cell-adhesion molecule 1 in the carcinoembryonic antigen family (CEACAM1), which is classified in the immunoglobulin superfamily. There are four CEACAM1 isoforms, with either four or two ectodomains, resulting from an alternative splicing mechanism. CEACAM1 is expressed on the epithelium and in endothelial cells of a variety of tissues and hemopoietic cells, and functions as a homophilic and heterophilic adhesion molecule. It is used as a receptor for some bacteria as well. The N terminal domain participates in mediating homophilic adhesion. This domain is also responsible for binding to the MHV spike (S) protein; the CC’ face protruding in this domain interacts with an N terminal region of the S protein composed of 330 amino acids (called S1N330). The binding of CEACAM1 with MHV S protein induces S protein conformational changes and converts fusion-negative S protein to a fusion-positive form. The allelic forms of CEACAM1 found among mouse strains are thought to be an important determinant for mouse susceptibility to MHV.
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39
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Xiao X, Feng Y, Chakraborti S, Dimitrov DS. Oligomerization of the SARS-CoV S glycoprotein: dimerization of the N-terminus and trimerization of the ectodomain. Biochem Biophys Res Commun 2004; 322:93-9. [PMID: 15313178 PMCID: PMC7092807 DOI: 10.1016/j.bbrc.2004.07.084] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2004] [Indexed: 11/30/2022]
Abstract
Viral envelope glycoproteins are oligomeric and the quaternary structure is critical for their membrane fusion activity. Typically the transmembrane glycoproteins of class I fusion proteins contain the oligomerization domains and the surface glycoproteins (SU) are monomeric. However, it has been previously demonstrated [J. Biol. Chem. 277 (2002) 19727] that the SU of a murine hepatitis coronavirus (MHV) forms dimers, the dimerization domain overlaps the receptor-binding domain (RBD) and that this dimeric state is important for binding to receptor molecules that initiates entry into cells. We have previously expressed various soluble fragments of the SARS-CoV SU and identified stably folded fragments (residues 272–537) that contain the RBD [Biochem. Biophys. Res. Commun. 312 (2003) 1159]. Here, we further characterize these and other fragments in an attempt to identify possible dimerization domains and their role for membrane fusion. We demonstrate that the SU and a shorter 260-amino acid N-terminal fragment (residues 17–276), which folds independently, form dimers. In contrast to the previously characterized MHV SU dimerization, this fragment is upstream and distinct from the RBD. Its deletion abolished S-mediated cell membrane fusion but retained the SU-receptor-binding function indicating the possibility for a role in post-receptor binding steps of the virus entry mechanism. Interestingly, the whole soluble S ectodomain (Se) that contains the dimerization domain but not the transmembrane domain and the cytoplasmic tail forms trimers suggesting the existence of a trimerization domain in the TM subunit in its prefusion state that may lead to a conformation unfavorable for formation of higher-order multimeric structures. These results demonstrate the existence of SU dimers and Se trimers, and indicate the possibility for an unknown mechanism of their role in entry. They also further characterize the S-mediated membrane fusion and could be important for understanding the mechanisms of virus entry, and in the development of therapeutics and vaccines.
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40
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Schickli JH, Thackray LB, Sawicki SG, Holmes KV. The N-terminal region of the murine coronavirus spike glycoprotein is associated with the extended host range of viruses from persistently infected murine cells. J Virol 2004; 78:9073-83. [PMID: 15308703 PMCID: PMC506962 DOI: 10.1128/jvi.78.17.9073-9083.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although murine coronaviruses naturally infect only mice, several virus variants derived from persistently infected murine cell cultures have an extended host range. The mouse hepatitis virus (MHV) variant MHV/BHK can infect hamster, rat, cat, dog, monkey, and human cell lines but not the swine testis (ST) porcine cell line (J. H. Schickli, B. D. Zelus, D. E. Wentworth, S. G. Sawicki, and K. V. Holmes, J. Virol. 71:9499-9507, 1997). The spike (S) gene of MHV/BHK had 63 point mutations and a 21-bp insert that encoded 56 amino acid substitutions and a 7-amino-acid insert compared to the parental MHV strain A59. Recombinant viruses between MHV-A59 and MHV/BHK were selected in hamster cells. All of the recombinants retained 21 amino acid substitutions and a 7-amino-acid insert found in the N-terminal region of S of MHV/BHK, suggesting that these residues were responsible for the extended host range of MHV/BHK. Flow cytometry showed that MHV-A59 bound only to cells that expressed the murine glycoprotein receptor CEACAM1a. In contrast, MHV/BHK and a recombinant virus, k6c, with the 21 amino acid substitutions and 7-amino-acid insert in S bound to hamster (BHK) and ST cells as well as murine cells. Thus, 21 amino acid substitutions and a 7-amino-acid insert in the N-terminal region of the S glycoprotein of MHV/BHK confer the ability to bind and in some cases infect cells of nonmurine species.
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Affiliation(s)
- Jeanne H Schickli
- Department of Microbiology, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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41
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Bosch BJ, de Haan CAM, Rottier PJM. Coronavirus spike glycoprotein, extended at the carboxy terminus with green fluorescent protein, is assembly competent. J Virol 2004; 78:7369-78. [PMID: 15220410 PMCID: PMC434101 DOI: 10.1128/jvi.78.14.7369-7378.2004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Due to the limited ultrastructural information about the coronavirion, little is known about the interactions acting at the interface between nucleocapsid and viral envelope. Knowing that subtle mutations in the carboxy-terminal endodomain of the M protein are already lethal, we have now probed the equivalent domain of the spike (S) protein by extending it terminally with a foreign sequence of 27 kDa: the green fluorescent protein (GFP). When expressed individually in murine cells, the S-GFP chimeric protein induced the formation of fluorescent syncytia, indicating that it was synthesized and folded properly, trimerized, and transported to the plasma membrane, where it exhibited the two key S protein functions, i.e., interaction with virus receptor molecules and membrane fusion. Incorporation into virus-like particles demonstrated the assembly competence of the chimeric spike protein. The wild-type S gene of mouse hepatitis coronavirus (MHV) was subsequently replaced by the chimeric construct through targeted recombination. A viable MHV-SGFP was obtained, infection by which could be visualized by the fluorescence induced. The efficiency of incorporation of the chimeric protein into particles was, however, reduced relative to that in wild-type particles which may explain, at least in part, the reduced infectivity produced by MHV-SGFP infection. We conclude that the incorporation of spikes carrying the large GFP moiety is apparently impaired by geometrical constraints and selected against during the assembly of virions. Probably due to this disadvantage, deletion mutants, having lost the foreign sequences, rapidly evolved and outcompeted the chimeric viruses during virus propagation. The fluorescent MHV-SGFP will now be a convenient tool to study coronaviral cell entry.
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Affiliation(s)
- Berend Jan Bosch
- Department of Infectious Diseases and Immunology, Yalelaan 1, 3584CL Utrecht, The Netherlands
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42
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Cavanagh D. Severe acute respiratory syndrome vaccine development: experiences of vaccination against avian infectious bronchitis coronavirus. Avian Pathol 2004; 32:567-82. [PMID: 14676007 PMCID: PMC7154303 DOI: 10.1080/03079450310001621198] [Citation(s) in RCA: 225] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Vaccines against infectious bronchitis of chickens (Gallus gallus domesticus) have arguably been the most successful, and certainly the most widely used, of vaccines for diseases caused by coronaviruses, the others being against bovine, canine, feline and porcine coronaviruses. Infectious bronchitis virus (IBV), together with the genetically related coronaviruses of turkey (Meleagris gallopovo) and ring-necked pheasant (Phasianus colchicus), is a group 3 coronavirus, severe acute respiratory syndrome (SARS) coronavirus being tentatively in group 4, the other known mammalian coronaviruses being in groups 1 and 2. IBV replicates not only in respiratory tissues (including the nose, trachea, lungs and airsacs, causing respiratory disease), but also in the kidney (associated with minor or major nephritis), oviduct, and in many parts of the alimentary tract--the oesophagus, proventriculus, duodenum, jejunum, bursa of Fabricius, caecal tonsils (near the distal end of the tract), rectum and cloaca (the common opening for release of eggs and faeces), usually without clinical effects. The virus can persist, being re-excreted at the onset of egg laying (4 to 5 months of age), believed to be a consequence of the stress of coming into lay. Genetic lines of chickens differ in the extent to which IBV causes mortality in chicks, and in respect of clearance of the virus after the acute phase. Live attenuated (by passage in chicken embryonated eggs) IBV strains were introduced as vaccines in the 1950s, followed a couple of decades later by inactivated vaccines for boosting protection in egg-laying birds. Live vaccines are usually applied to meat-type chickens at 1 day of age. In experimental situations this can result in sterile immunity when challenged by virulent homologous virus. Although 100% of chickens may be protected (against clinical signs and loss of ciliary activity in trachea), sometimes 10% of vaccinated chicks do not respond with a protective immune response. Protection is short lived, the start of the decline being apparent 9 weeks after vaccination with vaccines based on highly attenuated strains. IBV exists as scores of serotypes (defined by the neutralization test), cross-protection often being poor. Consequently, chickens may be re-vaccinated, with the same or another serotype, two or three weeks later. Single applications of inactivated virus has generally led to protection of <50% of chickens. Two applications have led to 90 to 100% protection in some reports, but remaining below 50% in others. In practice in the field, inactivated vaccines are used in laying birds that have previously been primed with two or three live attenuated virus vaccinations. This increases protection of the laying birds against egg production losses and induces a sustained level of serum antibody, which is passed to progeny. The large spike glycoprotein (S) comprises a carboxy-terminal S2 subunit (approximately 625 amino acid residues), which anchors S in the virus envelope, and an amino-terminal S1 subunit (approximately 520 residues), believed to largely form the distal bulbous part of S. The S1 subunit (purified from IBV virus, expressed using baculovirus or expressed in birds from a fowlpoxvirus vector) induced virus neutralizing antibody. Although protective immune responses were induced, multiple inoculations were required and the percentage of protected chickens was too low (<50%) for commercial application. Remarkably, expression of S1 in birds using a non-pathogenic fowl adenovirus vector induced protection in 90% and 100% of chickens in two experiments. Differences of as little as 5% between the S1 sequences can result in poor cross-protection. Differences in S1 of 2 to 3% (10 to 15 amino acids) can change serotype, suggesting that a small number of epitopes are immunodominant with respect to neutralizing antibody. Initial studies of the role of the IBV nucleocapsid protein (N) in immunity suggested that immunization with bacterially expressed N, while not inducing protection directly, improved the induction of protection by a subsequent inoculation with inactivated IBV. In another study, two intramuscular immunizations of a plasmid expressing N induced protective immunity. The basis of immunity to IBV is not well understood. Serum antibody levels do not correlate with protection, although local antibody is believed to play a role. Adoptive transfer of IBV-infection-induced alphabeta T cells bearing CD8 antigen protected chicks from challenge infection. In conclusion, live attenuated IBV vaccines induce good, although short-lived, protection against homologous challenge, although a minority of individuals may respond poorly. Inactivated IBV vaccines are insufficiently efficacious when applied only once and in the absence of priming by live vaccine. Two applications of inactivated IBV are much more efficacious, although this is not a commercially viable proposition in the poultry industry. However, the cost and logistics of multiple application of a SARS inactivated vaccine would be more acceptable for the protection of human populations, especially if limited to targeted groups (e.g. health care workers and high-risk contacts). Application of a SARS vaccine is perhaps best limited to a minimal number of targeted individuals who can be monitored, as some vaccinated persons might, if infected by SARS coronavirus, become asymptomatic excretors of virus, thereby posing a risk to non-vaccinated people. Looking further into the future, the high efficacy of the fowl adenovirus vector expressing the IBV S1 subunit provides optimism for a live SARS vaccine, if that were deemed to be necessary, with the possibility of including the N protein gene.
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Affiliation(s)
- Dave Cavanagh
- Institute for Animal Health, Division of Molecular Biology, Compton Laboratory, Newbury, Berkshire, UK.
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Bosch BJ, Martina BEE, Van Der Zee R, Lepault J, Haijema BJ, Versluis C, Heck AJR, De Groot R, Osterhaus ADME, Rottier PJM. Severe acute respiratory syndrome coronavirus (SARS-CoV) infection inhibition using spike protein heptad repeat-derived peptides. Proc Natl Acad Sci U S A 2004; 101:8455-60. [PMID: 15150417 PMCID: PMC420415 DOI: 10.1073/pnas.0400576101] [Citation(s) in RCA: 292] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The coronavirus SARS-CoV is the primary cause of the life-threatening severe acute respiratory syndrome (SARS). With the aim of developing therapeutic agents, we have tested peptides derived from the membrane-proximal (HR2) and membrane-distal (HR1) heptad repeat region of the spike protein as inhibitors of SARS-CoV infection of Vero cells. It appeared that HR2 peptides, but not HR1 peptides, were inhibitory. Their efficacy was, however, significantly lower than that of corresponding HR2 peptides of the murine coronavirus mouse hepatitis virus (MHV) in inhibiting MHV infection. Biochemical and electron microscopical analyses showed that, when mixed, SARS-CoV HR1 and HR2 peptides assemble into a six-helix bundle consisting of HR1 as a central triple-stranded coiled coil in association with three HR2 alpha-helices oriented in an antiparallel manner. The stability of this complex, as measured by its resistance to heat dissociation, appeared to be much lower than that of the corresponding MHV complex, which may explain the different inhibitory potencies of the HR2 peptides. Analogous to other class I viral fusion proteins, the six-helix complex supposedly represents a postfusion conformation that is formed after insertion of the fusion peptide, proposed here for coronaviruses to be located immediately upstream of HR1, into the target membrane. The resulting close apposition of fusion peptide and spike transmembrane domain facilitates membrane fusion. The inhibitory potency of the SARS-CoV HR2-peptides provides an attractive basis for the development of a therapeutic drug for SARS.
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Affiliation(s)
- Berend Jan Bosch
- Division of Virology, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, and Institute of Biomembranes, Utrecht University, 3584 CL Utrecht, The Netherlands
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Fu L, Gonzales DM, Das Sarma J, Lavi E. A combination of mutations in the S1 part of the spike glycoprotein gene of coronavirus MHV-A59 abolishes demyelination. J Neurovirol 2004; 10:41-51. [PMID: 14982727 PMCID: PMC7095319 DOI: 10.1080/13550280490262229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The A59 strain of coronavirus, mouse hepatitis virus (MHV), produces acute hepatitis, meningoencephalitis, and chronic demyelination. The authors have previously shown that the spike (S) glycoprotein gene of MHV contains determinants of virulence, hepatitis, and demyelination. They then identified viruses containing mutations in the S gene that exhibit alterations in viral pathogenesis. In the present study, the authors produced new recombinant viruses with each one of these S gene mutations by site-directed mutagenesis and targeted recombination and studied the effect of each individual mutation on the pathogenesis of the virus. They identified a combination of mutations in the S1 gene (I375M and L652I) that abolishes demyelination. Individual mutation and other combinations of mutations in the S gene only interfere with virulence and hepatitis and only reduce demyelination (I375M), but do not abolish demyelination completely. Thus, demyelination determinants exist within genomic regions on both sides of the hypervariable region, downstream from the receptor-binding domain in the S1 part of the MHV spike glycoprotein gene. The structure and precise function of these regions awaits further investigation.
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Affiliation(s)
- Li Fu
- Division of Neuropathology, Department of Pathology and Laboratory Medicine, 613 Stellar-Chance Laboratories, University of Pennsylvania, School of Medicine, 422 Curie Boulevard, 19104-6100 Philadelphia, PA USA
| | - Donna M. Gonzales
- Division of Neuropathology, Department of Pathology and Laboratory Medicine, 613 Stellar-Chance Laboratories, University of Pennsylvania, School of Medicine, 422 Curie Boulevard, 19104-6100 Philadelphia, PA USA
| | - Jayasri Das Sarma
- Division of Neuropathology, Department of Pathology and Laboratory Medicine, 613 Stellar-Chance Laboratories, University of Pennsylvania, School of Medicine, 422 Curie Boulevard, 19104-6100 Philadelphia, PA USA
- Present Address: Department of Physiology, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania USA
| | - Ehud Lavi
- Division of Neuropathology, Department of Pathology and Laboratory Medicine, 613 Stellar-Chance Laboratories, University of Pennsylvania, School of Medicine, 422 Curie Boulevard, 19104-6100 Philadelphia, PA USA
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Thorp EB, Gallagher TM. Requirements for CEACAMs and cholesterol during murine coronavirus cell entry. J Virol 2004; 78:2682-92. [PMID: 14990688 PMCID: PMC353758 DOI: 10.1128/jvi.78.6.2682-2692.2004] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous reports have documented that cholesterol supplementations increase cytopathic effects in tissue culture and also intensify in vivo pathogenicities during infection by the enveloped coronavirus murine hepatitis virus (MHV). To move toward a mechanistic understanding of these phenomena, we used growth media enriched with methyl-beta-cyclodextrin or cholesterol to reduce or elevate cellular membrane sterols, respectively. Cholesterol depletions reduced plaque development 2- to 20-fold, depending on the infecting MHV strain, while supplementations increased susceptibility 2- to 10-fold. These various cholesterol levels had no effect on the binding of viral spike (S) proteins to cellular carcinoembryonic antigen-related cell adhesion molecule (CEACAM) receptors, rather they correlated directly with S-protein-mediated membrane fusion activities. We considered whether cholesterol was indirectly involved in membrane fusion by condensing CEACAMs into "lipid raft" membrane microdomains, thereby creating opportunities for simultaneous binding of multiple S proteins that subsequently cooperate in the receptor-triggered membrane fusion process. However, the vast majority of CEACAMs were solubilized by cold Triton X-100 (TX-100), indicating their absence from lipid rafts. Furthermore, engineered CEACAMs appended to glycosylphosphatidylinositol anchors partitioned with TX-100-resistant lipid rafts, but cells bearing these raft-associated CEACAMs were not hypersensitive to MHV infection. These findings argued against the importance of cholesterol-dependent CEACAM localizations into membrane microdomains for MHV entry, instead suggesting that cholesterol had a more direct role. Indeed, we found that cholesterol was required even for those rare S-mediated fusions taking place in the absence of CEACAMs. We conclude that cholesterol is an essential membrane fusion cofactor that can act with or without CEACAMs to promote MHV entry.
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Affiliation(s)
- Edward B Thorp
- Department of Microbiology and Immunology, Loyola University Medical Center, Maywood, Illinois 60153, USA
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Miura HS, Nakagaki K, Taguchi F. N-terminal domain of the murine coronavirus receptor CEACAM1 is responsible for fusogenic activation and conformational changes of the spike protein. J Virol 2004; 78:216-23. [PMID: 14671103 PMCID: PMC303413 DOI: 10.1128/jvi.78.1.216-223.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mouse hepatitis virus (MHV) receptor (MHVR), CEACAM1, has two different functions for MHV entry into cells: binding to MHV spike protein (S protein) and activation of the S protein to execute virus-cell membrane fusion, the latter of which is accompanied by conformational changes of the S protein. The MHVR comprising the N-terminal and fourth domains [R1(1,4)] displays these two activities, and the N domain is thought to be critical for binding to MHV. In this study, we have addressed whether or not the N domain alone is sufficient for these activities. We examined three types of soluble form MHVR (soMHVR), one consisting of the N domain alone [soR1(1)], one with the N and second domains [soR1(1,2)], and one [soR1(1,4)] expressed by recombinant baculoviruses. We assessed the abilities of these three types of soMHVR to bind to MHV, activate fusogenicity, and induce conformational changes of the S protein. All three types of soMHVR similarly bound to MHV, as examined by a solid-phase binding assay and neutralized MHV infectivity. They also activated S protein fusogenicity and induced its conformational changes with similar levels of efficiency. However, R1(1) expressed on the BHK cell surface failed to serve as a receptor in spite of a sufficient level of expression. The inability of expressed R1(1) to work as a receptor was due to the inaccessibility of virions to R1(1); however, these were accessible using the MHVR-specific monoclonal antibody CC1. These results collectively indicated that the N domain retains all biological activities necessary for receptor function.
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Affiliation(s)
- Hideka S Miura
- National Institute of Neuroscience, NCNP, Kodaira, Tokyo 187-8502, Japan
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Tsai JC, Groot LD, Pinon JD, Iacono KT, Phillips JJ, Seo SH, Lavi E, Weiss SR. Amino acid substitutions within the heptad repeat domain 1 of murine coronavirus spike protein restrict viral antigen spread in the central nervous system. Virology 2003; 312:369-80. [PMID: 12919742 PMCID: PMC7125853 DOI: 10.1016/s0042-6822(03)00248-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Targeted recombination was carried out to select mouse hepatitis viruses (MHVs) in a defined genetic background, containing an MHV-JHM spike gene encoding either three heptad repeat 1 (HR1) substitutions (Q1067H, Q1094H, and L1114R) or L1114R alone. The recombinant virus, which expresses spike with the three substitutions, was nonfusogenic at neutral pH. Its replication was significantly inhibited by lysosomotropic agents, and it was highly neuroattenuated in vivo. In contrast, the recombinant expressing spike with L1114R alone mediated cell-to-cell fusion at neutral pH and replicated efficiently despite the presence of lysosomotropic agents; however, it still caused only subclinical morbidity and no mortality in animals. Thus, both recombinant viruses were highly attenuated and expressed viral antigen which was restricted to the olfactory bulbs and was markedly absent from other regions of the brains at 5 days postinfection. These data demonstrate that amino acid substitutions, in particular L1114R, within HR1 of the JHM spike reduced the ability of MHV to spread in the central nervous system. Furthermore, the requirements for low pH for fusion and viral entry are not prerequisites for the highly attenuated phenotype.
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Affiliation(s)
- Jean C Tsai
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6076, USA
| | - Linda de Groot
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6076, USA
| | - Josefina D Pinon
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6076, USA
| | - Kathryn T Iacono
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6076, USA
| | - Joanna J Phillips
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6076, USA
| | - Su-hun Seo
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6076, USA
| | - Ehud Lavi
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6076, USA
| | - Susan R Weiss
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6076, USA
- Corresponding author. Department of Microbiology, 203A Johnson Pavilion, University of Pennsylvania, Philadelphia, PA 19104-6076, USA. Fax: +1-215-573-4858.
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Bosch BJ, van der Zee R, de Haan CAM, Rottier PJM. The coronavirus spike protein is a class I virus fusion protein: structural and functional characterization of the fusion core complex. J Virol 2003; 77:8801-11. [PMID: 12885899 PMCID: PMC167208 DOI: 10.1128/jvi.77.16.8801-8811.2003] [Citation(s) in RCA: 1034] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Coronavirus entry is mediated by the viral spike (S) glycoprotein. The 180-kDa oligomeric S protein of the murine coronavirus mouse hepatitis virus strain A59 is posttranslationally cleaved into an S1 receptor binding unit and an S2 membrane fusion unit. The latter is thought to contain an internal fusion peptide and has two 4,3 hydrophobic (heptad) repeat regions designated HR1 and HR2. HR2 is located close to the membrane anchor, and HR1 is some 170 amino acids (aa) upstream of it. Heptad repeat (HR) regions are found in fusion proteins of many different viruses and form an important characteristic of class I viral fusion proteins. We investigated the role of these regions in coronavirus membrane fusion. Peptides HR1 (96 aa) and HR2 (39 aa), corresponding to the HR1 and HR2 regions, were produced in Escherichia coli. When mixed together, the two peptides were found to assemble into an extremely stable oligomeric complex. Both on their own and within the complex, the peptides were highly alpha helical. Electron microscopic analysis of the complex revealed a rod-like structure approximately 14.5 nm in length. Limited proteolysis in combination with mass spectrometry indicated that HR1 and HR2 occur in the complex in an antiparallel fashion. In the native protein, such a conformation would bring the proposed fusion peptide, located in the N-terminal domain of HR1, and the transmembrane anchor into close proximity. Using biological assays, the HR2 peptide was shown to be a potent inhibitor of virus entry into the cell, as well as of cell-cell fusion. Both biochemical and functional data show that the coronavirus spike protein is a class I viral fusion protein.
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Affiliation(s)
- Berend Jan Bosch
- Virology Division, Department of Infectious Diseases and Immunity, Faculty of Veterinary Medicine, and Institute of Biomembranes, Utrecht University, 3584 CL Utrecht, The Netherlands
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49
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Affiliation(s)
- Kathryn V Holmes
- University of Colorado Health Sciences Center, Department of Microbiology, Denver, Colorado 80262, USA.
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50
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Affiliation(s)
- Kathryn V Holmes
- University of Colorado Health Sciences Center, Department of Microbiology, Denver, Colorado 80262, USA.
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