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Gurukkalot K, Rajendran V. Repurposing Polyether Ionophores as a New-Class of Anti-SARS-Cov-2 Agents as Adjunct Therapy. Curr Microbiol 2023; 80:273. [PMID: 37414909 DOI: 10.1007/s00284-023-03366-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 06/05/2023] [Indexed: 07/08/2023]
Abstract
The emergence of SARS-CoV-2 and its variants have posed a significant threat to humankind in tackling the viral spread. Furthermore, currently repurposed drugs and frontline antiviral agents have failed to cure severe ongoing infections effectively. This insufficiency has fuelled research for potent and safe therapeutic agents to treat COVID-19. Nonetheless, various vaccine candidates have displayed a differential efficacy and need for repetitive dosing. The FDA-approved polyether ionophore veterinary antibiotic for treating coccidiosis has been repurposed for treating SARS-CoV-2 infection (as shown by both in vitro and in vivo studies) and other deadly human viruses. Based on selectivity index values, ionophores display therapeutic effects at sub-nanomolar concentrations and exhibit selective killing ability. They act on different viral targets (structural and non-structural proteins), host-cell components leading to SARS-CoV-2 inhibition, and their activity is further enhanced by Zn2+ supplementation. This review summarizes the anti-SARS-CoV-2 potential and molecular viral targets of selective ionophores like monensin, salinomycin, maduramicin, CP-80,219, nanchangmycin, narasin, X-206 and valinomycin. Ionophore combinations with Zn2+ are a new therapeutic strategy that warrants further investigation for possible human benefits.
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Affiliation(s)
- Keerthana Gurukkalot
- Department of Microbiology, School of Life Sciences, Pondicherry University, Puducherry, 605014, India
| | - Vinoth Rajendran
- Department of Microbiology, School of Life Sciences, Pondicherry University, Puducherry, 605014, India.
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2
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Khalifa SAM, Yosri N, El-Mallah MF, Ghonaim R, Guo Z, Musharraf SG, Du M, Khatib A, Xiao J, Saeed A, El-Seedi HHR, Zhao C, Efferth T, El-Seedi HR. Screening for natural and derived bio-active compounds in preclinical and clinical studies: One of the frontlines of fighting the coronaviruses pandemic. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2021; 85:153311. [PMID: 33067112 PMCID: PMC7455571 DOI: 10.1016/j.phymed.2020.153311] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 07/15/2020] [Accepted: 08/21/2020] [Indexed: 02/05/2023]
Abstract
BACKGROUND Starting December 2019, mankind faced an unprecedented enemy, the COVID-19 virus. The world convened in international efforts, experiences and technologies in order to fight the emerging pandemic. Isolation, hygiene measure, diagnosis, and treatment are the most efficient ways of prevention and intervention nowadays. The health organizations and global care systems screened the available resources and offered recommendations of approved and proposed medications. However, the search for a specific selective therapy or vaccine against COVID-19 remains a challenge. METHODS A literature search was performed for the screening of natural and derived bio-active compounds which showed potent antiviral activity against coronaviruses using published articles, patents, clinical trials website (https://clinicaltrials.gov/) and web databases (PubMed, SCI Finder, Science Direct, and Google Scholar). RESULTS Through the screening for natural products with antiviral activities against different types of the human coronavirus, extracts of Lycoris radiata (L'Hér.), Gentiana scabra Bunge, Dioscorea batatas Decne., Cassia tora L., Taxillus chinensis (DC.), Cibotium barometz L. and Echinacea purpurea L. showed a promising effect against SARS-CoV. Out of the listed compound Lycorine, emetine dihydrochloride hydrate, pristimerin, harmine, conessine, berbamine, 4`-hydroxychalcone, papaverine, mycophenolic acid, mycophenolate mofetil, monensin sodium, cycloheximide, oligomycin and valinomycin show potent activity against human coronaviruses. Additionally, it is worth noting that some compounds have already moved into clinical trials for their activity against COVID-19 including fingolimod, methylprednisolone, chloroquine, tetrandrine and tocilizumab. CONCLUSION Natural compounds and their derivatives could be used for developing potent therapeutics with significant activity against SARS-COV-2, providing a promising frontline in the fighting against COVID-19.
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Affiliation(s)
- Shaden A M Khalifa
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-106 91, Stockholm, Sweden
| | - Nermeen Yosri
- Department of Chemistry, Faculty of Science, Menoufia University, 32512 Shebin El-Kom, Egypt; School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Mohamed F El-Mallah
- Department of Chemistry, Faculty of Science, Menoufia University, 32512 Shebin El-Kom, Egypt
| | - Reem Ghonaim
- Department of Chemistry, Faculty of Science, Menoufia University, 32512 Shebin El-Kom, Egypt
| | - Zhiming Guo
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Syed Ghulam Musharraf
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan
| | - Ming Du
- School of Food Science and Technology, National Engineering Research Center of Seafood, Dalian Polytechnic University, Dalian 116024, China
| | - Alfi Khatib
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, International Islamic University Malaysia, Kuantan, 25200, Pahang, Malaysia; Faculty of Pharmacy, Airlangga University, Surabaya 60155, Indonesia
| | - Jianbo Xiao
- Institute of Chinese Medical Sciences, State Key Laboratory of Quality Control in Chinese Medicine, University of Macau, Macau
| | - Aamer Saeed
- Department of Chemistry, Quaid-i-Azam University, Islamabad, Pakistan
| | | | - Chao Zhao
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Thomas Efferth
- Department of Pharmaceutical Biology, Institute of Pharmceutical and Biomedical Sciences, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany
| | - Hesham R El-Seedi
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-106 91, Stockholm, Sweden; Department of Chemistry, Faculty of Science, Menoufia University, 32512 Shebin El-Kom, Egypt; H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan; International Research Center for Food Nutrition and Safety, Jiangsu University, Zhenjiang 212013, China.
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3
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Ju X, Zhu Y, Wang Y, Li J, Zhang J, Gong M, Ren W, Li S, Zhong J, Zhang L, Zhang QC, Zhang R, Ding Q. A novel cell culture system modeling the SARS-CoV-2 life cycle. PLoS Pathog 2021; 17:e1009439. [PMID: 33711082 PMCID: PMC7990224 DOI: 10.1371/journal.ppat.1009439] [Citation(s) in RCA: 98] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/24/2021] [Accepted: 03/01/2021] [Indexed: 12/11/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the global pandemic of COVID-19. SARS-CoV-2 is classified as a biosafety level-3 (BSL-3) agent, impeding the basic research into its biology and the development of effective antivirals. Here, we developed a biosafety level-2 (BSL-2) cell culture system for production of transcription and replication-competent SARS-CoV-2 virus-like-particles (trVLP). This trVLP expresses a reporter gene (GFP) replacing viral nucleocapsid gene (N), which is required for viral genome packaging and virion assembly (SARS-CoV-2 GFP/ΔN trVLP). The complete viral life cycle can be achieved and exclusively confined in the cells ectopically expressing SARS-CoV or SARS-CoV-2 N proteins, but not MERS-CoV N. Genetic recombination of N supplied in trans into viral genome was not detected, as evidenced by sequence analysis after one-month serial passages in the N-expressing cells. Moreover, intein-mediated protein trans-splicing approach was utilized to split the viral N gene into two independent vectors, and the ligated viral N protein could function in trans to recapitulate entire viral life cycle, further securing the biosafety of this cell culture model. Based on this BSL-2 SARS-CoV-2 cell culture model, we developed a 96-well format high throughput screening for antivirals discovery. We identified salinomycin, tubeimoside I, monensin sodium, lycorine chloride and nigericin sodium as potent antivirals against SARS-CoV-2 infection. Collectively, we developed a convenient and efficient SARS-CoV-2 reverse genetics tool to dissect the virus life cycle under a BSL-2 condition. This powerful tool should accelerate our understanding of SARS-CoV-2 biology and its antiviral development.
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Affiliation(s)
- Xiaohui Ju
- School of Medicine, Tsinghua University, Beijing, China
| | - Yunkai Zhu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Biosafety Level 3 Laboratory, Fudan University, Shanghai, China
| | - Yuyan Wang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Biosafety Level 3 Laboratory, Fudan University, Shanghai, China
| | - Jingrui Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jiaxing Zhang
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Mingli Gong
- School of Medicine, Tsinghua University, Beijing, China
| | - Wenlin Ren
- School of Medicine, Tsinghua University, Beijing, China
| | - Sai Li
- School of Life Sciences, Tsinghua University, Beijing, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China
| | - Jin Zhong
- Unit of Viral Hepatitis, CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Linqi Zhang
- School of Medicine, Tsinghua University, Beijing, China
| | - Qiangfeng Cliff Zhang
- School of Life Sciences, Tsinghua University, Beijing, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China
| | - Rong Zhang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Biosafety Level 3 Laboratory, Fudan University, Shanghai, China
| | - Qiang Ding
- School of Medicine, Tsinghua University, Beijing, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China
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Huang M, Liu Y, Zou C, Tan Y, Han Z, Xue C, Cao Y. A highly pathogenic recombinant infectious bronchitis virus with adaptability in cultured cells. Virus Res 2020; 292:198229. [PMID: 33207263 DOI: 10.1016/j.virusres.2020.198229] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/10/2020] [Accepted: 11/10/2020] [Indexed: 10/25/2022]
Abstract
Infectious bronchitis virus (IBV) of GI-19 (QX), GI-7 (TW), GI-13 (4/91) and GI-1 (Mass) lineages have been frequently detected in China in recent years. Here, An IBV strain, referred as GD17/04, was isolated from the dead yellow feather chicken vaccinated with H52 and 4/91 vaccines, whose genome sequence was obtained through high-throughput sequencing. Then it has been confirmed by the RDP and SimPlot analysis that GD17/04 is a recombinant strain deriving from YX10, 4/91, TW 2575/98 and H52 strains. Therein S1 gene of GD17/04 consists of sequences of TW2575/98 and 4/91, the former for the region of 20,371 to 21,072 nt and 21,847 to 21,975 nt, the latter for the sandwiched region of 21,073 to 21,846 nt. Moreover, as a nephropathogenic variant which caused high morbidity of 100 % and mortality of 60 %, unlike most other IBV strains, GD17/04 can cause obvious cell lesion in primary CEK cell, and even in DF-1 cells, without the process of continuous passage. As the few IBV strain can infect avian passage cell line, GD17/04 provides a material basis for further study of the interaction mechanism between IBV and avian host. Collectively, the findings highlight the significance that biological characteristics of novel strain should be studied, in addition to constant epidemiologic and molecular surveillance for IBV.
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Affiliation(s)
- Mengjiao Huang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yuan Liu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Chuangchao Zou
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yazhuo Tan
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Zhenling Han
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Chunyi Xue
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
| | - Yongchang Cao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
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The S2 Subunit of QX-type Infectious Bronchitis Coronavirus Spike Protein Is an Essential Determinant of Neurotropism. Viruses 2019; 11:v11100972. [PMID: 31652591 PMCID: PMC6832359 DOI: 10.3390/v11100972] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 10/17/2019] [Accepted: 10/21/2019] [Indexed: 01/23/2023] Open
Abstract
Some coronaviruses (CoVs) have an extra furin cleavage site (RRKR/S, furin-S2′ site) upstream of the fusion peptide in the spike protein, which plays roles in virion adsorption and fusion. Mutation of the S2′ site of QX genotype (QX-type) infectious bronchitis virus (IBV) spike protein (S) in a recombinant virus background results in higher pathogenicity, pronounced neural symptoms and neurotropism when compared with conditions in wild-type IBV (WT-IBV) infected chickens. In this study, we present evidence suggesting that recombinant IBV with a mutant S2′ site (furin-S2′ site) leads to higher mortality. Infection with mutant IBV induces severe encephalitis and breaks the blood–brain barrier. The results of a neutralization test and immunoprotection experiment show that an original serum and vaccine can still provide effective protection in vivo and in vitro. This is the first demonstration of IBV-induced neural symptoms in chickens with encephalitis and the furin-S2′ site as a determinant of neurotropism.
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Dinan AM, Keep S, Bickerton E, Britton P, Firth AE, Brierley I. Comparative Analysis of Gene Expression in Virulent and Attenuated Strains of Infectious Bronchitis Virus at Subcodon Resolution. J Virol 2019; 93:e00714-19. [PMID: 31243124 PMCID: PMC6714804 DOI: 10.1128/jvi.00714-19] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 06/17/2019] [Indexed: 12/27/2022] Open
Abstract
Like all coronaviruses, avian infectious bronchitis virus (IBV) possesses a long, single-stranded, positive-sense RNA genome (∼27 kb) and has a complex replication strategy that includes the production of a nested set of subgenomic mRNAs (sgmRNAs). Here, we used whole-transcriptome sequencing (RNASeq) and ribosome profiling (RiboSeq) to delineate gene expression in the IBV M41-CK and Beau-R strains at subcodon resolution. RNASeq facilitated a comparative analysis of viral RNA synthesis and revealed two novel transcription junction sites in the attenuated Beau-R strain, one of which would generate a sgmRNA encoding a ribosomally occupied open reading frame (dORF) located downstream of the nucleocapsid coding region. RiboSeq permitted quantification of the translational efficiency of virus gene expression and identified, for the first time, sites of ribosomal pausing on the genome. Quantification of reads flanking the programmed ribosomal frameshifting (PRF) signal at the genomic RNA ORF1a/ORF1b junction revealed that PRF in IBV is highly efficient (33 to 40%). Triplet phasing of RiboSeq data allowed precise determination of reading frames and revealed the translation of two ORFs (ORF4b and ORF4c on sgmRNA IR), which are widely conserved across IBV isolates. Analysis of differential gene expression in infected primary chick kidney cells indicated that the host cell response to IBV occurs primarily at the level of transcription, with global upregulation of immune-related mRNA transcripts following infection and comparatively modest changes in the translation efficiencies of host genes. Cellular genes and gene networks differentially expressed during virus infection were also identified, giving insights into the host cell response to IBV infection.IMPORTANCE IBV is a major avian pathogen and presents a substantial economic burden to the poultry industry. Improved vaccination strategies are urgently needed to curb the global spread of this virus, and the development of suitable vaccine candidates will be aided by an improved understanding of IBV molecular biology. Our high-resolution data have enabled a precise study of transcription and translation in cells infected with both pathogenic and attenuated forms of IBV and expand our understanding of gammacoronaviral gene expression. We demonstrate that gene expression shows considerable intraspecies variation, with single nucleotide polymorphisms being associated with altered production of sgmRNA transcripts, and our RiboSeq data sets enabled us to uncover novel ribosomally occupied ORFs in both strains. The numerous cellular genes and gene networks found to be differentially expressed during virus infection provide insights into the host cell response to IBV infection.
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Affiliation(s)
- Adam M Dinan
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Sarah Keep
- The Pirbright Institute, Woking, Surrey, United Kingdom
| | | | - Paul Britton
- The Pirbright Institute, Woking, Surrey, United Kingdom
| | - Andrew E Firth
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Ian Brierley
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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Lin J, Wang Z, Wang J, Yang Q. Microarray analysis of infectious bronchitis virus infection of chicken primary dendritic cells. BMC Genomics 2019; 20:557. [PMID: 31286855 PMCID: PMC6615177 DOI: 10.1186/s12864-019-5940-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 06/26/2019] [Indexed: 02/07/2023] Open
Abstract
Background Avian infectious bronchitis virus (IBV) is a major respiratory disease-causing agent in birds that leads to significant losses. Dendritic cells (DCs) are specialised cells responsible for sampling antigens and presenting them to T cells, which also play an essential role in recognising and neutralising viruses. Recent studies have suggested that non-coding RNAs may regulate the functional program of DCs. Expression of host non-coding RNAs changes markedly during infectious bronchitis virus infection, but their role in regulating host immune function has not been explored. Here, microarrays of mRNAs, miRNAs, and lncRNAs were globally performed to analyse how avian DCs respond to IBV. Results First, we found that IBV stimulation did not enhance the maturation ability of avian DCs. Interestingly, inactivated IBV was better able than IBV to induce DC maturation and activate lymphocytes. We identified 1093 up-regulated and 845 down-regulated mRNAs in IBV-infected avian DCs. Gene Ontology analysis suggested that cellular macromolecule and protein location (GO-BP) and transcription factor binding (GO-MF) were abundant in IBV-stimulated avian DCs. Meanwhile, pathway analysis indicated that the oxidative phosphorylation and leukocyte transendothelial migration signalling pathways might be activated in the IBV group. Moreover, alteration of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) was detected in IBV-stimulated avian DCs. In total, 19 significantly altered (7 up and 12 down) miRNAs and 101 (75 up and 26 down) lncRNAs were identified in the IBV-treated group. Further analysis showed that the actin cytoskeleton and MAPK signal pathway were related to the target genes of IBV-stimulated miRNAs. Finally, our study identified 2 TF-microRNA and 53 TF–microRNA–mRNA interactions involving 1 TF, 2 miRNAs, and 53 mRNAs in IBV-stimulated avian DCs. Conclusions Our research suggests a new mechanism to explain why IBV actively blocks innate responses needed for inducing immune gene expression and also provides insight into the pathogenic mechanisms of avian IBV. Electronic supplementary material The online version of this article (10.1186/s12864-019-5940-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jian Lin
- College of Life Sciences, Nanjing Agricultural University, Wei gang 1, Nanjing, Jiangsu, 210095, People's Republic of China.,College of Veterinary medicine, Nanjing Agricultural University, Wei gang 1, Nanjing, Jiangsu, 210095, People's Republic of China
| | - Zhisheng Wang
- National Veterinary Product Engineering Research Center, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Jialu Wang
- College of Veterinary medicine, Nanjing Agricultural University, Wei gang 1, Nanjing, Jiangsu, 210095, People's Republic of China
| | - Qian Yang
- College of Life Sciences, Nanjing Agricultural University, Wei gang 1, Nanjing, Jiangsu, 210095, People's Republic of China. .,College of Veterinary medicine, Nanjing Agricultural University, Wei gang 1, Nanjing, Jiangsu, 210095, People's Republic of China.
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High-Throughput Screening and Identification of Potent Broad-Spectrum Inhibitors of Coronaviruses. J Virol 2019; 93:JVI.00023-19. [PMID: 30918074 PMCID: PMC6613765 DOI: 10.1128/jvi.00023-19] [Citation(s) in RCA: 205] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/17/2019] [Indexed: 12/28/2022] Open
Abstract
Currently, there is no approved therapy to treat coronavirus infection; therefore, broad-spectrum inhibitors of emerging and endemic CoVs are needed. Based on our high-throughput screening assay using a compound library, we identified seven compounds with broad-spectrum efficacy against the replication of four CoVs in vitro. Additionally, one compound (lycorine) was found to protect BALB/c mice against HCoV-OC43-induced lethality by decreasing viral load in the central nervous system. This inhibitor might offer promising therapeutic possibilities for combatting novel CoV infections in the future. Coronaviruses (CoVs) act as cross-species viruses and have the potential to spread rapidly into new host species and cause epidemic diseases. Despite the severe public health threat of severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome CoV (MERS-CoV), there are currently no drugs available for their treatment; therefore, broad-spectrum inhibitors of emerging and endemic CoVs are urgently needed. To search for effective inhibitory agents, we performed high-throughput screening (HTS) of a 2,000-compound library of approved drugs and pharmacologically active compounds using the established genetically engineered human CoV OC43 (HCoV-OC43) strain expressing Renilla luciferase (rOC43-ns2Del-Rluc) and validated the inhibitors using multiple genetically distinct CoVs in vitro. We screened 56 hits from the HTS data and validated 36 compounds in vitro using wild-type HCoV-OC43. Furthermore, we identified seven compounds (lycorine, emetine, monensin sodium, mycophenolate mofetil, mycophenolic acid, phenazopyridine, and pyrvinium pamoate) as broad-spectrum inhibitors according to their strong inhibition of replication by four CoVs in vitro at low-micromolar concentrations. Additionally, we found that emetine blocked MERS-CoV entry according to pseudovirus entry assays and that lycorine protected BALB/c mice against HCoV-OC43-induced lethality by decreasing viral load in the central nervous system. This represents the first demonstration of in vivo real-time bioluminescence imaging to monitor the effect of lycorine on the spread and distribution of HCoV-OC43 in a mouse model. These results offer critical information supporting the development of an effective therapeutic strategy against CoV infection. IMPORTANCE Currently, there is no approved therapy to treat coronavirus infection; therefore, broad-spectrum inhibitors of emerging and endemic CoVs are needed. Based on our high-throughput screening assay using a compound library, we identified seven compounds with broad-spectrum efficacy against the replication of four CoVs in vitro. Additionally, one compound (lycorine) was found to protect BALB/c mice against HCoV-OC43-induced lethality by decreasing viral load in the central nervous system. This inhibitor might offer promising therapeutic possibilities for combatting novel CoV infections in the future.
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Zhou X, Cong Y, Veenendaal T, Klumperman J, Shi D, Mari M, Reggiori F. Ultrastructural Characterization of Membrane Rearrangements Induced by Porcine Epidemic Diarrhea Virus Infection. Viruses 2017; 9:v9090251. [PMID: 28872588 PMCID: PMC5618017 DOI: 10.3390/v9090251] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 08/28/2017] [Accepted: 08/31/2017] [Indexed: 02/06/2023] Open
Abstract
The porcine epidemic diarrhea virus (PEDV) is a coronavirus (CoV) belonging to the α-CoV genus and it causes high mortality in infected sucking piglets, resulting in substantial losses in the farming industry. CoV trigger a drastic reorganization of host cell membranes to promote their replication and egression, but a detailed description of the intracellular remodeling induced by PEDV is still missing. In this study, we examined qualitatively and quantitatively, using electron microscopy, the intracellular membrane reorganization induced by PEDV over the course of an infection. With our ultrastructural approach, we reveal that, as most of CoV, PEDV initially forms double-membrane vesicles (DMVs) and convoluted membranes (CMs), which probably serve as replication/transcription platforms. Interestingly, we also found that viral particles start to form almost simultaneously in both the endoplasmic reticulum and the large virion-containing vacuoles (LVCVs), which are compartments originating from the Golgi, confirming that α-CoV assemble indistinguishably in two different organelles of the secretory pathway. Moreover, PEDV virons appear to have an immature and a mature form, similar to another α-CoV the transmissible gastroenteritis coronavirus (TGEV). Altogether, our study underlies the similarities and differences between the lifecycle of α-CoV and that of viruses belonging to other CoV subfamilies.
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Affiliation(s)
- Xingdong Zhou
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China.
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Yingying Cong
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Tineke Veenendaal
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
| | - Judith Klumperman
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
| | - Dongfang Shi
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China.
| | - Muriel Mari
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Fulvio Reggiori
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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Guo H, Huang M, Yuan Q, Wei Y, Gao Y, Mao L, Gu L, Tan YW, Zhong Y, Liu D, Sun S. The Important Role of Lipid Raft-Mediated Attachment in the Infection of Cultured Cells by Coronavirus Infectious Bronchitis Virus Beaudette Strain. PLoS One 2017; 12:e0170123. [PMID: 28081264 PMCID: PMC5231368 DOI: 10.1371/journal.pone.0170123] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 12/29/2016] [Indexed: 11/19/2022] Open
Abstract
Lipid raft is an important element for the cellular entry of some viruses, including coronavirus infectious bronchitis virus (IBV). However, the exact role of lipid rafts in the cellular membrane during the entry of IBV into host cells is still unknown. In this study, we biochemically fractionated IBV-infected cells via sucrose density gradient centrifugation after depleting plasma membrane cholesterol with methyl-β-cyclodextrin or Mevastatin. Our results demonstrated that unlike IBV non-structural proteins, IBV structural proteins co-localized with lipid raft marker caveolin-1. Infectivity assay results of Vero cells illustrated that the drug-induced disruption of lipid rafts significantly suppressed IBV infection. Further studies revealed that lipid rafts were not required for IBV genome replication or virion release at later stages. However, the drug-mediated depletion of lipid rafts in Vero cells before IBV attachment significantly reduced the expression of viral structural proteins, suggesting that drug treatment impaired the attachment of IBV to the cell surface. Our results indicated that lipid rafts serve as attachment factors during the early stages of IBV infection, especially during the attachment stage.
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Affiliation(s)
- Huichen Guo
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping, Lanzhou, Gansu, The P.R. China
| | - Mei Huang
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping, Lanzhou, Gansu, The P.R. China
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Quan Yuan
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Yanquan Wei
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping, Lanzhou, Gansu, The P.R. China
| | - Yuan Gao
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping, Lanzhou, Gansu, The P.R. China
| | - Lejiao Mao
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping, Lanzhou, Gansu, The P.R. China
| | - Lingjun Gu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping, Lanzhou, Gansu, The P.R. China
- College of Animal Science, Yangtze University, Jingzhou, P.R. China
| | - Yong Wah Tan
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Yanxin Zhong
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Dingxiang Liu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping, Lanzhou, Gansu, The P.R. China
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * E-mail: (SS); (DL)
| | - Shiqi Sun
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping, Lanzhou, Gansu, The P.R. China
- * E-mail: (SS); (DL)
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11
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Abstract
To replicate their genomes in cells and generate new progeny, viruses typically require factors provided by the cells that they have infected. Subversion of the cellular machinery that controls replication of the infected host cell is a common activity of many viruses. Viruses employ different strategies to deregulate cell cycle checkpoint controls and modulate cell proliferation pathways. A number of DNA and RNA viruses encode proteins that target critical cell cycle regulators to achieve cellular conditions that are beneficial for viral replication. Many DNA viruses induce quiescent cells to enter the cell cycle; this is thought to increase pools of deoxynucleotides and thus, facilitate viral replication. In contrast, some viruses can arrest cells in a particular phase of the cell cycle that is favorable for replication of the specific virus. Cell cycle arrest may inhibit early cell death of infected cells, allow the cells to evade immune defenses, or help promote virus assembly. Although beneficial for the viral life cycle, virus-mediated alterations in normal cell cycle control mechanisms could have detrimental effects on cellular physiology and may ultimately contribute to pathologies associated with the viral infection, including cell transformation and cancer progression and maintenance. In this chapter, we summarize various strategies employed by DNA and RNA viruses to modulate the replication cycle of the virus-infected cell. When known, we describe how these virus-associated effects influence replication of the virus and contribute to diseases associated with infection by that specific virus.
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Affiliation(s)
- Eishi Noguchi
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania USA
| | - Mariana C. Gadaleta
- Dept of Biochemistry & Molecular Biology, Drexel University College of Medicine, Philadelphia, USA
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12
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Ulasli M, Verheije MH, de Haan CAM, Reggiori F. Qualitative and quantitative ultrastructural analysis of the membrane rearrangements induced by coronavirus. Cell Microbiol 2010; 12:844-61. [PMID: 20088951 PMCID: PMC7159092 DOI: 10.1111/j.1462-5822.2010.01437.x] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Coronaviruses (CoV) are enveloped positive‐strand RNA viruses that induce different membrane rearrangements in infected cells in order to efficiently replicate and assemble. The origin, the protein composition and the function of these structures are not well established. To shed further light on these structures, we have performed a time‐course experiment in which the mouse hepatitis virus (MHV)‐induced membrane rearrangements were examined qualitatively and quantitatively by (immuno)‐electron microscopy. With our approach we were able to confirm the appearance of 6, previously reported, membranous structures during the course of a complete infection cycle. These structures include the well‐characterized double‐membrane vesicles (DMVs), convoluted membranes (CMs) and virions but also the more enigmatic large virion‐containing vacuoles (LVCVs), tubular bodies (TBs) and cubic membrane structures (CMSs). We have characterized the LVCVs, TBs and CMSs, and found that the CoV‐induced structures appear in a strict order. By combining these data with quantitative analyses on viral RNA, protein synthesis and virion release, this study generates an integrated molecular and ultrastructural overview of CoV infection. In particular, it provides insights in the role of each CoV‐induced structure and reveals that LVCVs are ERGIC/Golgi compartments that expand to accommodate an increasing production of viral particles.
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Affiliation(s)
- Mustafa Ulasli
- Department of Cell Biology and Institute of Biomembranes, University Medical Centre Utrecht, The Netherlands
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13
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Yamada Y, Liu XB, Fang SG, Tay FPL, Liu DX. Acquisition of cell-cell fusion activity by amino acid substitutions in spike protein determines the infectivity of a coronavirus in cultured cells. PLoS One 2009; 4:e6130. [PMID: 19572016 PMCID: PMC2700284 DOI: 10.1371/journal.pone.0006130] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 06/03/2009] [Indexed: 12/30/2022] Open
Abstract
Coronavirus host and cell specificities are determined by specific interactions between the viral spike (S) protein and host cell receptor(s). Avian coronavirus infectious bronchitis (IBV) has been adapted to embryonated chicken eggs, primary chicken kidney (CK) cells, monkey kidney cell line Vero, and other human and animal cells. Here we report that acquisition of the cell–cell fusion activity by amino acid mutations in the S protein determines the infectivity of IBV in cultured cells. Expression of S protein derived from Vero- and CK-adapted strains showed efficient induction of membrane fusion. However, expression of S protein cloned from the third passage of IBV in chicken embryo (EP3) did not show apparent syncytia formation. By construction of chimeric S constructs and site-directed mutagenesis, a point mutation (L857-F) at amino acid position 857 in the heptad repeat 1 region of S protein was shown to be responsible for its acquisition of the cell–cell fusion activity. Furthermore, a G405-D point mutation in the S1 domain, which was acquired during further propagation of Vero-adapted IBV in Vero cells, could enhance the cell–cell fusion activity of the protein. Re-introduction of L857 back to the S gene of Vero-adapted IBV allowed recovery of variants that contain the introduced L857. However, compensatory mutations in S1 and some distant regions of S2 were required for restoration of the cell–cell fusion activity of S protein carrying L857 and for the infectivity of the recovered variants in cultured cells. This study demonstrates that acquisition of the cell–cell fusion activity in S protein determines the selection and/or adaptation of a coronavirus from chicken embryo to cultured cells of human and animal origins.
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Affiliation(s)
- Yoshiyuki Yamada
- Institute of Molecular and Cell Biology, Proteos, Singapore, Singapore
| | - Xiao Bo Liu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Shou Guo Fang
- Institute of Molecular and Cell Biology, Proteos, Singapore, Singapore
| | - Felicia P. L. Tay
- Institute of Molecular and Cell Biology, Proteos, Singapore, Singapore
| | - Ding Xiang Liu
- Institute of Molecular and Cell Biology, Proteos, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * E-mail:
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14
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Proteolytic activation of the spike protein at a novel RRRR/S motif is implicated in furin-dependent entry, syncytium formation, and infectivity of coronavirus infectious bronchitis virus in cultured cells. J Virol 2009; 83:8744-58. [PMID: 19553314 DOI: 10.1128/jvi.00613-09] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The spike (S) protein of the coronavirus (CoV) infectious bronchitis virus (IBV) is cleaved into S1 and S2 subunits at the furin consensus motif RRFRR(537)/S in virus-infected cells. In this study, we observe that the S2 subunit of the IBV Beaudette strain is additionally cleaved at the second furin site (RRRR(690)/S) in cells expressing S constructs and in virus-infected cells. Detailed time course experiments showed that a peptide furin inhibitor, decanoyl-Arg-Val-Lys-Arg-chloromethylketone, blocked both viral entry and syncytium formation. Site-directed mutagenesis studies revealed that the S1/S2 cleavage by furin was not necessary for, but could promote, syncytium formation by and infectivity of IBV in Vero cells. In contrast, the second site is involved in the furin dependence of viral entry and syncytium formation. Mutations of the second site from furin-cleavable RRRR/S to non-furin-cleavable PRRRS and AAARS, respectively, abrogated the furin dependence of IBV entry. Instead, a yet-to-be-identified serine protease(s) was involved, as revealed by protease inhibitor studies. Furthermore, sequence analysis of CoV S proteins by multiple alignments showed conservation of an XXXR/S motif, cleavable by either furin or other trypsin-like proteases, at a position equivalent to the second IBV furin site. Taken together, these results suggest that proteolysis at a novel XXXR/S motif in the S2 subunit might be a common mechanism for the entry of CoV into cells.
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15
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Harrison SM, Tarpey I, Rothwell L, Kaiser P, Hiscox JA. Lithium chloride inhibits the coronavirus infectious bronchitis virus in cell culture. Avian Pathol 2007; 36:109-14. [PMID: 17479370 PMCID: PMC7154305 DOI: 10.1080/03079450601156083] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The avian coronavirus infectious bronchitis virus (IBV) is a major economic pathogen of domestic poultry that, despite vaccination, causes mortality and significant losses in production. During replication of the RNA genome there is a high frequency of mutation and recombination, which has given rise to many strains of IBV and results in the potential for new and emerging strains. Currently the live-attenuated vaccine gives poor cross-strain immunity. Effective antiviral agents may therefore be advantageous in the treatment of IBV. Lithium chloride (LiCl) is a potent inhibitor of the DNA virus herpes simplex virus but not RNA viruses. The effect of LiCl on the replication of IBV was examined in cell culture using two model cell types; Vero cells, an African Green monkey kidney-derived epithelial cell line; and DF-1 cells, an immortalized chicken embryo fibroblast cell line. When treated with a range of LiCl concentrations, IBV RNA and protein levels and viral progeny production were reduced in a dose-dependent manner in both cell types, and the data indicated that inhibition was a cellular rather than a virucidal effect. Host cell protein synthesis still took place in LiCl-treated cells and the level of a standard cellular housekeeping protein remained unchanged, indicating that the effect of LiCl was specifically against IBV.
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Affiliation(s)
- Sally M. Harrison
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
- To whom correspondence should be addressed. Tel: +44 113 343 5582. Fax: +44 113 343 3167. E-mail
| | | | | | | | - Julian A. Hiscox
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
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16
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van der Meer FJUM, de Haan CAM, Schuurman NMP, Haijema BJ, Peumans WJ, Van Damme EJM, Delputte PL, Balzarini J, Egberink HF. Antiviral activity of carbohydrate-binding agents against Nidovirales in cell culture. Antiviral Res 2007; 76:21-9. [PMID: 17560666 PMCID: PMC7132385 DOI: 10.1016/j.antiviral.2007.04.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 04/15/2007] [Accepted: 04/24/2007] [Indexed: 01/25/2023]
Abstract
Coronaviruses are important human and animal pathogens, the relevance of which increased due to the emergence of new human coronaviruses like SARS-CoV, HKU1 and NL63. Together with toroviruses, arteriviruses, and roniviruses the coronaviruses belong to the order Nidovirales. So far antivirals are hardly available to combat infections with viruses of this order. Therefore, various antiviral strategies to counter nidoviral infections are under evaluation. Lectins, which bind to N-linked oligosaccharide elements of enveloped viruses, can be considered as a conceptionally new class of virus inhibitors. These agents were recently evaluated for their antiviral activity towards a variety of enveloped viruses and were shown in most cases to inhibit virus infection at low concentrations. However, limited knowledge is available for their efficacy towards nidoviruses. In this article the application of the plant lectins Hippeastrum hybrid agglutinin (HHA), Galanthus nivalis agglutinin (GNA), Cymbidium sp. agglutinin (CA) and Urtica dioica agglutinin (UDA) as well as non-plant derived pradimicin-A (PRM-A) and cyanovirin-N (CV-N) as potential antiviral agents was evaluated. Three antiviral tests were compared based on different evaluation principles: cell viability (MTT-based colorimetric assay), number of infected cells (immunoperoxidase assay) and amount of viral protein expression (luciferase-based assay). The presence of carbohydrate-binding agents strongly inhibited coronaviruses (transmissible gastroenteritis virus, infectious bronchitis virus, feline coronaviruses serotypes I and II, mouse hepatitis virus), arteriviruses (equine arteritis virus and porcine respiratory and reproductive syndrome virus) and torovirus (equine Berne virus). Remarkably, serotype II feline coronaviruses and arteriviruses were not inhibited by PRM-A, in contrast to the other viruses tested.
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Affiliation(s)
- F J U M van der Meer
- Department of Immunology and Infectious Diseases, Division of Virology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
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17
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Madu IG, Chu VC, Lee H, Regan AD, Bauman BE, Whittaker GR. Heparan sulfate is a selective attachment factor for the avian coronavirus infectious bronchitis virus Beaudette. Avian Dis 2007; 51:45-51. [PMID: 17461266 DOI: 10.1637/0005-2086(2007)051[0045:hsiasa]2.0.co;2] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The avian coronavirus infectious bronchitis virus (IBV) strain Beaudette is an embryo-adapted virus that has extended species tropism in cell culture. In order to understand the acquired tropism of the Beaudette strain, we compared the S protein sequences of several IBV strains. The Beaudette strain was found to contain a putative heparan sulfate (HS)-binding site, indicating that the Beaudette virus may use HS as a selective receptor. To ascertain the requirements of cell-surface HS for Beaudette infectivity, we assayed for infectivity in the presence of soluble heparin as a competitor and determined infectivity in mutant cell lines with no HS or glycosaminoglycan expression. Our results indicate that HS plays a role as an attachment factor for IBV, working in concert with other factors like sialic acid to mediate virus binding to cells, and may explain in part the extended tropism of IBV Beaudette.
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Affiliation(s)
- Ikenna G Madu
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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18
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Reed ML, Howell G, Harrison SM, Spencer KA, Hiscox JA. Characterization of the nuclear export signal in the coronavirus infectious bronchitis virus nucleocapsid protein. J Virol 2007; 81:4298-304. [PMID: 17202223 PMCID: PMC1866115 DOI: 10.1128/jvi.02239-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 12/27/2006] [Indexed: 01/13/2023] Open
Abstract
The nucleocapsid (N) protein of infectious bronchitis virus (IBV) localizes to the cytoplasm and nucleolus and contains an eight-amino-acid nucleolar retention motif. In this study, a leucine-rich nuclear export signal (NES) (291-LQLDGLHL-298) present in the C-terminal region of the IBV N protein was analyzed by using alanine substitution and deletion mutagenesis to investigate the relative contributions that leucine residues make to nuclear export and where these residues are located on the structure of the IBV N protein. The analysis indicated that Leu296 and Leu298 are required for efficient nuclear export of the protein. Structural information indicated that both of these amino acids are available for interaction with protein complexes involved in this process. However, export of N protein from the nucleus/nucleolus was not inhibited by leptomycin B treatment, indicating that N protein nuclear export is independent of the CRM1-mediated export pathway.
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Affiliation(s)
- Mark L Reed
- Institute of Molecular and Cellular Biology, Faculty of Biology Sciences, Garstang Building, University of Leeds, Leeds LS2 6JT, United Kingdom
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19
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Harrison SM, Dove BK, Rothwell L, Kaiser P, Tarpey I, Brooks G, Hiscox JA. Characterisation of cyclin D1 down-regulation in coronavirus infected cells. FEBS Lett 2007; 581:1275-86. [PMID: 17359980 PMCID: PMC7094712 DOI: 10.1016/j.febslet.2007.02.039] [Citation(s) in RCA: 21] [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: 11/03/2006] [Revised: 01/30/2007] [Accepted: 02/13/2007] [Indexed: 01/02/2023]
Abstract
The positive strand RNA coronavirus, infectious bronchitis virus (IBV), induces a G2/M phase arrest and reduction in the G1 and G1/S phase transition regulator cyclin D1. Quantitative real-time RT-PCR and Western blot analysis demonstrated that cyclin D1 was reduced post-transcriptionally within infected cells independently of the cell-cycle stage at the time of infection. Confocal microscopy revealed that cyclin D1 decreased in IBV-infected cells as infection progressed and inhibition studies indicated that a population of cyclin D1 could be targeted for degradation by a virus mediated pathway. In contrast to the SARS-coronavirus, IBV nucleocapsid protein did not interact with cyclin D1.
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Affiliation(s)
- Sally M. Harrison
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Brian K. Dove
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Lisa Rothwell
- Institute for Animal Health (Compton Laboratory), UK
| | - Pete Kaiser
- Institute for Animal Health (Compton Laboratory), UK
| | | | - Gavin Brooks
- School of Pharmacy, University of Reading, Reading, UK
| | - Julian A. Hiscox
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
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20
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Dove BK, You JH, Reed ML, Emmett SR, Brooks G, Hiscox JA. Changes in nucleolar morphology and proteins during infection with the coronavirus infectious bronchitis virus. Cell Microbiol 2006; 8:1147-57. [PMID: 16819967 PMCID: PMC7162191 DOI: 10.1111/j.1462-5822.2006.00698.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The nucleolus is a dynamic subnuclear structure involved in ribosome subunit biogenesis, cell cycle control and mediating responses to cell stress, among other functions. While many different viruses target proteins to the nucleolus and recruit nucleolar proteins to facilitate virus replication, the effect of infection on the nucleolus in terms of morphology and protein content is unknown. Previously we have shown that the coronavirus nucleocapsid protein will localize to the nucleolus. In this study, using the avian infectious bronchitis coronavirus, we have shown that virus infection results in a number of changes to the nucleolus both in terms of gross morphology and protein content. Using confocal microscopy coupled with fluorescent labelled nucleolar marker proteins we observed changes in the morphology of the nucleolus including an enlarged fibrillar centre. We found that the tumour suppressor protein, p53, which localizes normally to the nucleus and nucleolus, was redistributed predominately to the cytoplasm.
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Affiliation(s)
- Brian K Dove
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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21
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Dove B, Brooks G, Bicknell K, Wurm T, Hiscox JA. Cell cycle perturbations induced by infection with the coronavirus infectious bronchitis virus and their effect on virus replication. J Virol 2006; 80:4147-56. [PMID: 16571830 PMCID: PMC1440480 DOI: 10.1128/jvi.80.8.4147-4156.2006] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In eukaryotic cells, cell growth and division occur in a stepwise, orderly fashion described by a process known as the cell cycle. The relationship between positive-strand RNA viruses and the cell cycle and the concomitant effects on virus replication are not clearly understood. We have shown that infection of asynchronously replicating and synchronized replicating cells with the avian coronavirus infectious bronchitis virus (IBV), a positive-strand RNA virus, resulted in the accumulation of infected cells in the G2/M phase of the cell cycle. Analysis of various cell cycle-regulatory proteins and cellular morphology indicated that there was a down-regulation of cyclins D1 and D2 (G1 regulatory cyclins) and that a proportion of virus-infected cells underwent aberrant cytokinesis, in which the cells underwent nuclear, but not cytoplasmic, division. We assessed the impact of the perturbations on the cell cycle for virus-infected cells and found that IBV-infected G2/M-phase-synchronized cells exhibited increased viral protein production when released from the block when compared to cells synchronized in the G0 phase or asynchronously replicating cells. Our data suggested that IBV induces a G2/M phase arrest in infected cells to promote favorable conditions for viral replication.
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Affiliation(s)
- Brian Dove
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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22
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Casais R, Thiel V, Siddell SG, Cavanagh D, Britton P. Reverse genetics system for the avian coronavirus infectious bronchitis virus. J Virol 2001; 75:12359-69. [PMID: 11711626 PMCID: PMC116132 DOI: 10.1128/jvi.75.24.12359-12369.2001] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2001] [Accepted: 09/06/2001] [Indexed: 11/20/2022] Open
Abstract
Major advances in the study of the molecular biology of RNA viruses have resulted from the ability to generate and manipulate full-length genomic cDNAs of the viral genomes with the subsequent synthesis of infectious RNA for the generation of recombinant viruses. Coronaviruses have the largest RNA virus genomes and, together with genetic instability of some cDNA sequences in Escherichia coli, this has hampered the generation of a reverse-genetics system for this group of viruses. In this report, we describe the assembly of a full-length cDNA from the positive-sense genomic RNA of the avian coronavirus, infectious bronchitis virus (IBV), an important poultry pathogen. The IBV genomic cDNA was assembled immediately downstream of a T7 RNA polymerase promoter by in vitro ligation and cloned directly into the vaccinia virus genome. Infectious IBV RNA was generated in situ after the transfection of restricted recombinant vaccinia virus DNA into primary chick kidney cells previously infected with a recombinant fowlpox virus expressing T7 RNA polymerase. Recombinant IBV, containing two marker mutations, was recovered from the transfected cells. These results describe a reverse-genetics system for studying the molecular biology of IBV and establish a paradigm for generating genetically defined vaccines for IBV.
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Affiliation(s)
- R Casais
- Division of Molecular Biology, Institute for Animal Health, Compton Laboratory, Compton, Newbury, Berkshire RG20 7NN, United Kingdom
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23
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Xu HY, Lim KP, Shen S, Liu DX. Further identification and characterization of novel intermediate and mature cleavage products released from the ORF 1b region of the avian coronavirus infectious bronchitis virus 1a/1b polyprotein. Virology 2001; 288:212-22. [PMID: 11601893 PMCID: PMC7134593 DOI: 10.1006/viro.2001.1098] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The coronavirus 3C-like proteinase is one of the viral proteinases responsible for processing of the 1a and 1a/1b polyproteins to multiple mature products. In cells infected with avian coronavirus infectious bronchitis virus (IBV), three proteins of 100, 39, and 35 kDa, respectively, were previously identified as mature cleavage products released from the 1b region of the 1a/1b polyprotein by the 3C-like proteinase. In this report, we show the identification of two more cleavage products of 68 and 58 kDa released from the same region of the polyprotein. In addition, two stable intermediate cleavage products with molecular masses of 160 and 132 kDa, respectively, were identified in IBV-infected cells. The 160-kDa protein was shown to be an intermediate cleavage product covering the 100- and 68-kDa proteins, and the 132-kDa protein to be an intermediate cleavage product covering the 58-, 39-, and 35-kDa proteins. Immunofluorescent staining of IBV-infected cells and cells expressing individual cleavage products showed that the 100-, 68-, and 58-kDa proteins were associated with the membranes of the endoplasmic reticulum, and the 39- and 35-kDa proteins displayed diffuse distribution patterns.
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Affiliation(s)
- H Y Xu
- Institute of Molecular Agrobiology, 1 Research Link, The National University of Singapore, Singapore 117604
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24
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Lim KP, Liu DX. The missing link in coronavirus assembly. Retention of the avian coronavirus infectious bronchitis virus envelope protein in the pre-Golgi compartments and physical interaction between the envelope and membrane proteins. J Biol Chem 2001; 276:17515-23. [PMID: 11278557 PMCID: PMC7982318 DOI: 10.1074/jbc.m009731200] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2000] [Revised: 01/29/2001] [Indexed: 11/18/2022] Open
Abstract
One missing link in the coronavirus assembly is the physical interaction between two crucial structural proteins, the membrane (M) and envelope (E) proteins. In this study, we demonstrate that the coronavirus infectious bronchitis virus E can physically interact, via a putative peripheral domain, with M. Deletion of this domain resulted in a drastic reduction in the incorporation of M into virus-like particles. Immunofluorescent staining of cells coexpressing M and E supports that E interacts with M and relocates M to the same subcellular compartments that E resides in. E was retained in the pre-Golgi membranes, prior to being translocated to the Golgi apparatus and the secretory vesicles; M was observed to exhibit similar localization and translocation profiles as E when coexpressed with E. Deletion studies identified the C-terminal 6-residue RDKLYS as the endoplasmic reticulum retention signal of E, and site-directed mutagenesis of the -4 lysine residue to glutamine resulted in the accumulation of E in the Golgi apparatus. The third domain of E that plays a crucial role in virus budding is a putative transmembrane domain present at the N-terminal region, because deletion of the domain resulted in a free distribution of the mutant protein and in dysfunctional viral assembly.
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Affiliation(s)
- K P Lim
- Institute of Molecular Agrobiology, The National University of Singapore, 1 Research Link, Singapore 117604
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25
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Liu DX, Shen S, Xu HY, Wang SF. Proteolytic mapping of the coronavirus infectious bronchitis virus 1b polyprotein: evidence for the presence of four cleavage sites of the 3C-like proteinase and identification of two novel cleavage products. Virology 1998; 246:288-97. [PMID: 9657947 PMCID: PMC7131314 DOI: 10.1006/viro.1998.9199] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously reported that the 3C-like proteinase of the coronavirus infectious bronchitis virus (IBV) is responsible for processing of the 1a and 1a/1b polyproteins to three mature products of 24, 10, and 100 kDa (Liu et al., 1994, 1997; Ng and Liu, 1998). The C-terminal cleavage site of the 100-kDa protein was defined to be the Q891(1b)-S892(1b) dipeptide bond encoded by nucleotides 15,129 to 15,134 (Liu and Brown, 1995). In this report, other cleavage sites of the 3C-like proteinase in the polyprotein encoded by the ORF 1b region were mapped by coexpression, deletion, and site-directed mutagenesis studies. Using two ORF 1b-specific antisera, V58 and V17, three more Q-S(G) dipeptide bonds, encoded by nucleotides 16,929 to 16,934, 18,492 to 18,497, and 19,506 to 19,511, respectively, were demonstrated to be the cleavage sites of the 3C-like proteinase. Cleavage at these four positions would result in the release of four mature products with molecular masses of approximately 68, 58, 39, and 35 kDa. Among them, the 39- and 35-kDa proteins were specifically identified in IBV-infected cells. Taken together with the 100-kDa protein previously identified, these results suggest that the ORF 1b region of IBV mRNA1 may be able to encode five mature products.
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Affiliation(s)
- D X Liu
- Institute of Molecular Agrobiology, National University of Singapore, Singapore.
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Ng LF, Liu DX. Identification of a 24-kDa polypeptide processed from the coronavirus infectious bronchitis virus 1a polyprotein by the 3C-like proteinase and determination of its cleavage sites. Virology 1998; 243:388-95. [PMID: 9568037 PMCID: PMC7131520 DOI: 10.1006/viro.1998.9058] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report here the identification of a 24-kDa polypeptide in IBV-infected Vero cells by immunoprecipitation with a region-specific antiserum raised in rabbits against the IBV sequence encoded between nucleotides 10,928 and 11,493. Coexpression, deletion, and mutagenesis studies have demonstrated that this protein is encoded by ORF 1a from nucleotide 10,915 to 11,544 and is released from the 1a polyprotein by the 3C-like proteinase-mediated proteolysis. A previously predicted Q-S (Q3462S3463) dipeptide bond encoded by the IBV sequence from nucleotide 10,912 to 10,917 is identified as the N-terminal cleavage site, and a Q-N (Q3672N3673) dipeptide bond encoded by the IBV sequence between nucleotides 11,542 and 11,547 is identified as the C-terminal cleavage site of the 24-kDa polypeptide.
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Affiliation(s)
- L F Ng
- Institute of Molecular Agrobiology, Singapore
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Li D, Cavanagh D. Role of pH in syncytium induction and genome uncoating of avian infectious bronchitis coronavirus (IBV). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1990; 276:33-6. [PMID: 1966419 DOI: 10.1007/978-1-4684-5823-7_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Syncytium formation induced in Vero cells by IBV-Beaudette was optimal at pH 6.7 and absent at pH 7.5. Reduction of IBV-Beaudette replication by ammonium chloride, which raises the pH in endosomes, further indicated that uncoating of the virus genome probably occurred within the acidic environment of endosomes. However, this would not appear to apply to all IBV strains, since one was unaffected by the drug. It would appear that some strains of IBV have the capacity to fuse with the plasma membrane at neutral pH, thereby leading to genome uncoating at that site. Other strains of IBV might also uncoat at the plasma membrane when the extracellular environment is slightly less than pH7.
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Affiliation(s)
- D Li
- AFRC Institute for Animal Health, Houghton Laboratory, Huntingdon, Cambridgeshire, UK
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Cavanagh D, Davis PJ, Pappin DJ, Binns MM, Boursnell ME, Brown TD. Coronavirus IBV: partial amino terminal sequencing of spike polypeptide S2 identifies the sequence Arg-Arg-Phe-Arg-Arg at the cleavage site of the spike precursor propolypeptide of IBV strains Beaudette and M41. Virus Res 1986; 4:133-43. [PMID: 3010595 PMCID: PMC7133853 DOI: 10.1016/0168-1702(86)90037-7] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The spike protein of avian infectious bronchitis coronavirus comprises two glycopolypeptides S1 and S2 derived by cleavage of a proglycopolypeptide So, the nucleotide sequence of which has recently been determined for the Beaudette strain (Binns, M.M. et al., 1985, J. Gen. Virol. 66, 719-726). The order of the two glycopolypeptides within So is aminoterminus(N)-S1-S2-carboxyterminus(C). To locate the N-terminus of S2 we have performed partial amino acid sequencing on S2 from IBV-Beaudette labelled with [3H]serine and from the related strain labelled with [3H]valine, leucine and isoleucine. The residues identified and their positions relative to the N-terminus of S2 were: serine, 13; valine, 6, 12; leucine, none in the first 20 residues; isoleucine, 2, 19. These results identified the N-terminus of S2 of IBV-Beaudette as serine, 520 residues from the N-terminus of S1, excluding the signal sequence. Immediately to the N-terminal side of residue 520 So has the sequence Arg-Arg-Phe-Arg-Arg; similar basic connecting peptides are a feature of several other virus spike glycoproteins. It was deduced that for IBV-Beaudette S1 comprises 519 residues (Mr 57.0K) or 514 residues (56.2K) if the connecting peptide was to be removed by carboxypeptidase-like activity in vivo while S2 has 625 residues (69.2K). Nucleotide sequencing of the cleavage region of the So gene of IBV-M41 revealed the same connecting peptide as IBV-Beaudette and that the first 20 N-terminal residues of S2 of IBV-M41 were identical to those of the Beaudette strain. IBV-Beaudette grown in Vero cells had some uncleaved So; this was cleavable by 10 micrograms/ml of trypsin and of chymotrypsin. Partial N-terminal analysis of S1 from IBV-M41 identified leucine and valine residues at positions 2 and 9 respectively from the N-terminus. This confirms the identification, made by Binns et al. (1985), of the N-terminus of S1 and the end of the signal sequence of the IBV-Beaudette spike propolypeptide. N-terminal sequencing of [3H]leucine-labelled IBV-Beaudette membrane (M) polypeptide showed leucine residues at positions 8, 16 and 22 from the N-terminus; these results confirm the open reading frame identified by M.E.G. Boursnell et al. (1984, Virus Res. 1, 303-313) in the nucleotide sequence of M. The N-terminus of the nucleocapsid (N) polypeptide appeared to be blocked.
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Yoshida T, Nakayama Y, Nagura H, Toyoda T, Nishikawa K, Hamaguchi M, Nagai Y. Inhibition of the assembly of Newcastle disease virus by monensin. Virus Res 1986; 4:179-95. [PMID: 3518275 PMCID: PMC7134188 DOI: 10.1016/0168-1702(86)90040-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Monensin inhibits the intracellular transport of the glycoproteins of Newcastle disease virus between cis and trans Golgi stacks of infected BHK cells, as evidenced by its effect upon their post-translational modifications such as fatty acid acylation, glycosylation and proteolytic cleavage. Thus the drug has markedly altered the subcellular distribution of the glycoproteins so that they accumulate in the internal smooth membranes but are virtually absent in the plasma membrane. These glycoproteins that accumulated in intracellular membranes have a cytoplasmic domain susceptible to protease digestion and thus are transmembranous. Under such conditions, the behavior of M protein, which plays a crucial role in virus assembly (Y. Nagai et al., 1976, Virology 69, 523-538), has been analyzed. It has been found that the M protein can neither associate with the internal membranes nor bind to the plasma membrane. Thus no virus budding has been observed, either at the plasma membranes or at internal membranes. These results substantiate the view that the interaction between M and glycoproteins is of great importance for virus assembly and suggest further that this interaction is possibly only when the glycoproteins have been incorporated into the plasma membrane.
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Kuismanen E, Saraste J, Pettersson RF. Effect of monensin on the assembly of Uukuniemi virus in the Golgi complex. J Virol 1985; 55:813-22. [PMID: 4020969 PMCID: PMC255066 DOI: 10.1128/jvi.55.3.813-822.1985] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The effect of the carboxylic ionophore monensin on the maturation of Uukuniemi virus, a bunyavirus, and the transport of its two membrane glycoproteins, G1 and G2, were studied in chicken embryo fibroblasts and baby hamster kidney cells. Virus maturation, which occurs in the Golgi complex (E. Kuismanen, K. Hedman, J. Saraste, and R. F. Pettersson, Mol. Cell. Biol. 2:1444-1458, 1982; E. Kuismanen, B. Bång, M. Hurme, and R. F. Pettersson, J. Virol. 51:137-146, 1984), was effectively inhibited by the drug (1 or 10 microM) as studied by electron microscopy and by assaying the release of infectious or radiolabeled virus. Immunoelectron microscopy showed that association of viral nucleocapsids with the cytoplasmic surface of glycoprotein-containing Golgi membranes, a prerequisite for virus budding, was unaffected by monensin. In the presence of the drug, the virus glycoproteins assembled into long, tubular structures extending into the lumen of Golgi-derived vacuoles, suggesting that monensin inhibited a terminal step in the assembly of the virus. Intracellular transport and expression of the virus membrane glycoproteins G1 and G2 at the cell surface were not inhibited by monensin as studied by immunocytochemical and radiolabeling techniques. Pulse-chase experiments in the presence of monensin showed that intracellular G1 acquired only partially endo-H-resistant glycans. The sialylation of G1 appearing on the cell surface in the presence of the drug was decreased, whereas sialylation of G2 apparently was inhibited to a lesser extent, as shown by external labeling of the cells with the periodate-boro[3H]hydride method. Thus, monensin exerted a differential effect on the terminal glycosylation of G1 and G2. Unlike several membrane and secretory glycoproteins, both G1 and G2 could enter a functional transport pathway in the presence of monensin and become expressed at the cell surface.
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