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Hong T, Yang Y, Wang P, Zhu G, Zhu C. Pestiviruses infection: Interferon-virus mutual regulation. Front Cell Infect Microbiol 2023; 13:1146394. [PMID: 36936761 PMCID: PMC10018205 DOI: 10.3389/fcimb.2023.1146394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 02/17/2023] [Indexed: 03/06/2023] Open
Abstract
Pestiviruses are a class of viruses that in some cases can cause persistent infection of the host, thus posing a threat to the livestock industry. Interferons (IFNs) are a group of secreted proteins that play a crucial role in antiviral defense. In this review, on the one hand, we elaborate on how pestiviruses are recognized by the host retinoic acid-inducible gene-I (RIG-I), melanoma-differentiation-associated protein 5 (MDA5), and Toll-like receptor 3 (TLR3) proteins to induce the synthesis of IFNs. On the other hand, we focus on reviewing how pestiviruses antagonize the production of IFNs utilizing various strategies mediated by self-encoded proteins, such as the structural envelope protein (Erns) and non-structural protein (Npro). Hence, the IFN signal transduction pathway induced by pestiviruses infection and the process of pestiviruses blockade on the production of IFNs intertwines into an intricate regulatory network. By reviewing the interaction between IFN and pestiviruses (based on studies on BVDV and CSFV), we expect to provide a theoretical basis and reference for a better understanding of the mechanisms of induction and evasion of the innate immune response during infection with these viruses.
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Affiliation(s)
- Tianqi Hong
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
- Joint Laboratory of International Cooperation on Prevention and Control Technology of Important Animal Diseases and Zoonoses of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, China
| | - Yi Yang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
- Joint Laboratory of International Cooperation on Prevention and Control Technology of Important Animal Diseases and Zoonoses of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, China
| | - Pengzhi Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
- Joint Laboratory of International Cooperation on Prevention and Control Technology of Important Animal Diseases and Zoonoses of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, China
| | - Guoqiang Zhu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
- Joint Laboratory of International Cooperation on Prevention and Control Technology of Important Animal Diseases and Zoonoses of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, China
- *Correspondence: Guoqiang Zhu, ; Congrui Zhu,
| | - Congrui Zhu
- College of Animal Science, South China Agricultural University, Guangzhou, China
- *Correspondence: Guoqiang Zhu, ; Congrui Zhu,
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Frazier MN, Wilson IM, Krahn JM, Butay KJ, Dillard LB, Borgnia MJ, Stanley RE. Flipped over U: structural basis for dsRNA cleavage by the SARS-CoV-2 endoribonuclease. Nucleic Acids Res 2022; 50:8290-8301. [PMID: 35801916 DOI: 10.1093/nar/gkac589] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 01/13/2023] Open
Abstract
Coronaviruses generate double-stranded (ds) RNA intermediates during viral replication that can activate host immune sensors. To evade activation of the host pattern recognition receptor MDA5, coronaviruses employ Nsp15, which is a uridine-specific endoribonuclease. Nsp15 is proposed to associate with the coronavirus replication-transcription complex within double-membrane vesicles to cleave these dsRNA intermediates. How Nsp15 recognizes and processes dsRNA is poorly understood because previous structural studies of Nsp15 have been limited to small single-stranded (ss) RNA substrates. Here we present cryo-EM structures of SARS-CoV-2 Nsp15 bound to a 52nt dsRNA. We observed that the Nsp15 hexamer forms a platform for engaging dsRNA across multiple protomers. The structures, along with site-directed mutagenesis and RNA cleavage assays revealed critical insight into dsRNA recognition and processing. To process dsRNA Nsp15 utilizes a base-flipping mechanism to properly orient the uridine within the active site for cleavage. Our findings show that Nsp15 is a distinctive endoribonuclease that can cleave both ss- and dsRNA effectively.
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Affiliation(s)
- Meredith N Frazier
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Isha M Wilson
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Juno M Krahn
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Kevin John Butay
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Lucas B Dillard
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Mario J Borgnia
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Robin E Stanley
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
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3
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Frazier MN, Wilson IM, Krahn JM, Butay KJ, Dillard LB, Borgnia MJ, Stanley RE. Flipped Over U: Structural Basis for dsRNA Cleavage by the SARS-CoV-2 Endoribonuclease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.03.02.480688. [PMID: 35262076 PMCID: PMC8902873 DOI: 10.1101/2022.03.02.480688] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Coronaviruses generate double-stranded (ds) RNA intermediates during viral replication that can activate host immune sensors. To evade activation of the host pattern recognition receptor MDA5, coronaviruses employ Nsp15, which is uridine-specific endoribonuclease. Nsp15 is proposed to associate with the coronavirus replication-transcription complex within double-membrane vesicles to cleave these dsRNA intermediates. How Nsp15 recognizes and processes dsRNA is poorly understood because previous structural studies of Nsp15 have been limited to small single-stranded (ss) RNA substrates. Here we present cryo-EM structures of SARS-CoV-2 Nsp15 bound to a 52nt dsRNA. We observed that the Nsp15 hexamer forms a platform for engaging dsRNA across multiple protomers. The structures, along with site-directed mutagenesis and RNA cleavage assays revealed critical insight into dsRNA recognition and processing. To process dsRNA Nsp15 utilizes a base-flipping mechanism to properly orient the uridine within the active site for cleavage. Our findings show that Nsp15 is a distinctive endoribonuclease that can cleave both ss- and dsRNA effectively.
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Affiliation(s)
- Meredith N. Frazier
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Isha M. Wilson
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Juno M. Krahn
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Kevin John Butay
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Lucas B. Dillard
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Mario J. Borgnia
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Robin E. Stanley
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
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4
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de Martin E, Schweizer M. Fifty Shades of Erns: Innate Immune Evasion by the Viral Endonucleases of All Pestivirus Species. Viruses 2022; 14:v14020265. [PMID: 35215858 PMCID: PMC8880635 DOI: 10.3390/v14020265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/25/2022] [Accepted: 01/25/2022] [Indexed: 12/10/2022] Open
Abstract
The genus Pestivirus, family Flaviviridae, includes four historically accepted species, i.e., bovine viral diarrhea virus (BVDV)-1 and -2, classical swine fever virus (CSFV), and border disease virus (BDV). A large number of new pestivirus species were identified in recent years. A common feature of most members is the presence of two unique proteins, Npro and Erns, that pestiviruses evolved to regulate the host’s innate immune response. In addition to its function as a structural envelope glycoprotein, Erns is also released in the extracellular space, where it is endocytosed by neighboring cells. As an endoribonuclease, Erns is able to cleave viral ss- and dsRNAs, thus preventing the stimulation of the host’s interferon (IFN) response. Here, we characterize the basic features of soluble Erns of a large variety of classified and unassigned pestiviruses that have not yet been described. Its ability to form homodimers, its RNase activity, and the ability to inhibit dsRNA-induced IFN synthesis were investigated. Overall, we found large differences between the various Erns proteins that cannot be predicted solely based on their primary amino acid sequences, and that might be the consequence of different virus-host co-evolution histories. This provides valuable information to delineate the structure-function relationship of pestiviral endoribonucleases.
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Affiliation(s)
- Elena de Martin
- Institute of Virology and Immunology, Länggass-Str. 122, POB, CH-3001 Bern, Switzerland;
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, CH-3012 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Matthias Schweizer
- Institute of Virology and Immunology, Länggass-Str. 122, POB, CH-3001 Bern, Switzerland;
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, CH-3012 Bern, Switzerland
- Correspondence:
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5
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Lussi C, de Martin E, Schweizer M. Positively Charged Amino Acids in the Pestiviral E rns Control Cell Entry, Endoribonuclease Activity and Innate Immune Evasion. Viruses 2021; 13:v13081581. [PMID: 34452446 PMCID: PMC8402660 DOI: 10.3390/v13081581] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 11/16/2022] Open
Abstract
The genus Pestivirus, family Flaviviridae, includes four economically important viruses of livestock, i.e., bovine viral diarrhea virus-1 (BVDV-1) and -2 (BVDV-2), border disease virus (BDV) and classical swine fever virus (CSFV). Erns and Npro, both expressed uniquely by pestiviruses, counteract the host's innate immune defense by interfering with the induction of interferon (IFN) synthesis. The structural envelope protein Erns also exists in a soluble form and, by its endoribonuclease activity, degrades immunostimulatory RNA prior to their activation of pattern recognition receptors. Here, we show that at least three out of four positively-charged residues in the C-terminal glycosaminoglycan (GAG)-binding site of BVDV-Erns are required for efficient cell entry, and that a positively charged region more upstream is not involved in cell entry but rather in RNA-binding. Moreover, the C-terminal domain on its own determines intracellular targeting, as GFP fused to the C-terminal amino acids of Erns was found at the same compartments as wt Erns. In summary, RNase activity and uptake into cells are both required for Erns to act as an IFN antagonist, and the C-terminal amphipathic helix containing the GAG-binding site determines the efficiency of cell entry and its intracellular localization.
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Affiliation(s)
- Carmela Lussi
- Institute of Virology and Immunology (IVI), CH-3001 Bern, Switzerland; (C.L.); (E.d.M.)
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, CH-3001 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, CH-3012 Bern, Switzerland
| | - Elena de Martin
- Institute of Virology and Immunology (IVI), CH-3001 Bern, Switzerland; (C.L.); (E.d.M.)
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, CH-3001 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, CH-3012 Bern, Switzerland
| | - Matthias Schweizer
- Institute of Virology and Immunology (IVI), CH-3001 Bern, Switzerland; (C.L.); (E.d.M.)
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, CH-3001 Bern, Switzerland
- Correspondence:
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Wang M, Bohórquez JA, Hinojosa Y, Muñoz-González S, Gerber M, Coronado L, Perera CL, Liniger M, Ruggli N, Ganges L. Abrogation of the RNase activity of E rns in a low virulence classical swine fever virus enhances the humoral immune response and reduces virulence, transmissibility, and persistence in pigs. Virulence 2021; 12:2037-2049. [PMID: 34339338 PMCID: PMC8331007 DOI: 10.1080/21505594.2021.1959715] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The prevalence of low virulence classical swine fever virus (CSFV) strains makes viral eradication difficult in endemic countries. However, the determinants for natural CSFV attenuation and persistence in the field remain unidentified. The aim of the present study was to assess the role of the RNase activity of CSFV Erns in pathogenesis, immune response, persistent infection, and viral transmission in pigs. To this end, a functional cDNA clone pPdR-H30K-36U with an Erns lacking RNase activity was constructed based on the low virulence CSFV field isolate Pinar de Rio (PdR). Eighteen 5-day-old piglets were infected with vPdR-H30K-36U. Nine piglets were introduced as contacts. The vPdR-H30K-36U virus was attenuated in piglets compared to the parental vPdR-36U. Only RNA traces were detected in sera and body secretions and no virus was isolated from tonsils, showing that RNase inactivation may reduce CSFV persistence and transmissibility. The vPdR-H30K-36U mutant strongly activated the interferon-α (IFN-α) production in plasmacytoid dendritic cells, while in vivo, the IFN-α response was variable, from moderate to undetectable depending on the animal. This suggests a role of the CSFV Erns RNase activity in the regulation of innate immune responses. Infection with vPdR-H30K-36U resulted in higher antibody levels against the E2 and Erns glycoproteins and in enhanced neutralizing antibody responses when compared with vPdR-36U. These results pave the way toward a better understanding of viral attenuation mechanisms of CSFV in pigs. In addition, they provide novel insights relevant for the development of DIVA vaccines in combination with diagnostic assays for efficient CSF control.
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Affiliation(s)
- Miaomiao Wang
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, Barcelona, Spain
| | | | - Yoandry Hinojosa
- Division of Virology, Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.,Department of Infectious Diseases and Pathobiology (DIP), Vetsuisse Faculty, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Bern, Switzerland.,Centro Nacional De Sanidad Agropecuaria (CENSA), Mayabeque, Cuba
| | - Sara Muñoz-González
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, Barcelona, Spain
| | - Markus Gerber
- Division of Virology, Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.,Department of Infectious Diseases and Pathobiology (DIP), Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Liani Coronado
- Centro Nacional De Sanidad Agropecuaria (CENSA), Mayabeque, Cuba
| | | | - Matthias Liniger
- Division of Virology, Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.,Department of Infectious Diseases and Pathobiology (DIP), Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Nicolas Ruggli
- Division of Virology, Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.,Department of Infectious Diseases and Pathobiology (DIP), Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Llilianne Ganges
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, Barcelona, Spain
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The E rns Carboxyterminus: Much More Than a Membrane Anchor. Viruses 2021; 13:v13071203. [PMID: 34201636 PMCID: PMC8310223 DOI: 10.3390/v13071203] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/15/2021] [Accepted: 06/17/2021] [Indexed: 12/12/2022] Open
Abstract
Pestiviruses express the unique essential envelope protein Erns, which exhibits RNase activity, is attached to membranes by a long amphipathic helix, and is partially secreted from infected cells. The RNase activity of Erns is directly connected with pestivirus virulence. Formation of homodimers and secretion of the protein are hypothesized to be important for its role as a virulence factor, which impairs the host's innate immune response to pestivirus infection. The unusual membrane anchor of Erns raises questions with regard to proteolytic processing of the viral polyprotein at the Erns carboxy-terminus. Moreover, the membrane anchor is crucial for establishing the critical equilibrium between retention and secretion and ensures intracellular accumulation of the protein at the site of virus budding so that it is available to serve both as structural component of the virion and factor controlling host immune reactions. In the present manuscript, we summarize published as well as new data on the molecular features of Erns including aspects of its interplay with the other two envelope proteins with a special focus on the biochemistry of the Erns membrane anchor.
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Al-Kubati AAG, Hussen J, Kandeel M, Al-Mubarak AIA, Hemida MG. Recent Advances on the Bovine Viral Diarrhea Virus Molecular Pathogenesis, Immune Response, and Vaccines Development. Front Vet Sci 2021; 8:665128. [PMID: 34055953 PMCID: PMC8160231 DOI: 10.3389/fvets.2021.665128] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 04/16/2021] [Indexed: 12/20/2022] Open
Abstract
The bovine viral diarrhea virus (BVDV) consists of two species and various subspecies of closely related viruses of varying antigenicity, cytopathology, and virulence-induced pathogenesis. Despite the great ongoing efforts to control and prevent BVDV outbreaks and the emergence of new variants, outbreaks still reported throughout the world. In this review, we are focusing on the molecular biology of BVDV, its molecular pathogenesis, and the immune response of the host against the viral infection. Special attention was paid to discuss some immune evasion strategies adopted by the BVDV to hijack the host immune system to ensure the success of virus replication. Vaccination is one of the main strategies for prophylaxis and contributes to the control and eradication of many viral diseases including BVDV. We discussed the recent advances of various types of currently available classical and modern BVDV vaccines. However, with the emergence of new strains and variants of the virus, it is urgent to find some other novel targets for BVDV vaccines that may overcome the drawbacks of some of the currently used vaccines. Effective vaccination strategy mainly based on the preparation of vaccines from the homologous circulating strains. The BVDV-E2 protein plays important role in viral infection and pathogenesis. We mapped some important potential neutralizing epitopes among some BVDV genomes especially the E2 protein. These novel epitopes could be promising targets against the currently circulating strains of BVDV. More research is needed to further explore the actual roles of these epitopes as novel targets for the development of novel vaccines against BVDV. These potential vaccines may contribute to the global eradication campaign of the BVDV.
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Affiliation(s)
- Anwar A G Al-Kubati
- Department of Microbiology, College of Veterinary Medicine, King Faisal University, Al-Ahsa, Saudi Arabia.,Department of Biomedical Sciences, College of Veterinary Medicine, King Faisal University, Al-Hofuf, Saudi Arabia
| | - Jamal Hussen
- Department of Microbiology, College of Veterinary Medicine, King Faisal University, Al-Ahsa, Saudi Arabia
| | - Mahmoud Kandeel
- Department of Biomedical Sciences, College of Veterinary Medicine, King Faisal University, Al-Hofuf, Saudi Arabia.,Department of Pharmacology, Faculty of Veterinary Medicine, Kafrelsheikh University, Kafrelsheikh, Egypt
| | - Abdullah I A Al-Mubarak
- Department of Microbiology, College of Veterinary Medicine, King Faisal University, Al-Ahsa, Saudi Arabia
| | - Maged Gomaa Hemida
- Department of Microbiology, College of Veterinary Medicine, King Faisal University, Al-Ahsa, Saudi Arabia.,Department of Virology, Faculty of Veterinary Medicine, Kafrelsheikh University, Kafrelsheikh, Egypt
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9
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Downstream Sequences Control the Processing of the Pestivirus E rns-E1 Precursor. J Virol 2020; 95:JVI.01905-20. [PMID: 33028718 DOI: 10.1128/jvi.01905-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 02/06/2023] Open
Abstract
Like other enveloped viruses, pestiviruses employ cellular proteases for processing of their structural proteins. While typical signal peptidase cleavage motifs are present at the carboxy terminus of the signal sequence preceding Erns and the E1/E2 and E2/P7 sites, the Erns-E1 precursor is cleaved by signal peptidase at a highly unusual structure, in which the transmembrane sequence upstream of the cleavage site is replaced by an amphipathic helix. As shown before, the integrity of the amphipathic helix is crucial for efficient processing. The data presented here demonstrate that the E1 sequence downstream of this cleavage site is also important for the cleavage. Carboxy-terminal truncation of the E1 moiety as well as internal deletions in E1 reduced the cleavage efficiency to less than 30% of the wild-type (wt) level. Moreover, the C-terminal truncation by more than 30 amino acids resulted in strong secretion of the uncleaved fusion proteins. The reduced processing and increased secretion were even observed when 10 to 5 amino-terminal residues of E1 were left, whereas extensions by 1 or 3 E1 residues resulted in reduced processing but no significantly increased secretion. In contrast to the E1 sequences, a 10-amino-acid c-myc tag fused to the Erns C terminus had only marginal effect on secretion but was also not processed efficiently. Mutation of the von Heijne sequence upstream of E2 not only blocked the cleavage between E1 and E2 but also prevented the processing between Erns and E2. Thus, processing at the Erns-E1 site is a highly regulated process.IMPORTANCE Cellular signal peptidase (SPase) cleavage represents an important step in maturation of viral envelope proteins. Fine tuning of this system allows for establishment of concerted folding and processing processes in different enveloped viruses. We report here on SPase processing of the Erns-E1-E2 glycoprotein precursor of pestiviruses. Erns-E1 cleavage is delayed and only executed efficiently when the complete E1 sequence is present. C-terminal truncation of the Erns-E1 precursor impairs processing and leads to significant secretion of the protein. The latter is not detected when internal deletions preserving the E1 carboxy terminus are introduced, but also these constructs show impaired processing. Moreover, Erns-E1 is only processed after cleavage at the E1/E2 site. Thus, processing of the pestiviral glycoprotein precursor by SPase is done in an ordered way and depends on the integrity of the proteins for efficient cleavage. The functional importance of this processing scheme is discussed in the paper.
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10
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Ganges L, Crooke HR, Bohórquez JA, Postel A, Sakoda Y, Becher P, Ruggli N. Classical swine fever virus: the past, present and future. Virus Res 2020; 289:198151. [PMID: 32898613 DOI: 10.1016/j.virusres.2020.198151] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/24/2020] [Accepted: 08/28/2020] [Indexed: 12/22/2022]
Abstract
Classical swine fever (CSF) is among the most relevant viral epizootic diseases of swine. Due to its severe economic impact, CSF is notifiable to the world organisation for animal health. Strict control policies, including systematic stamping out of infected herds with and without vaccination, have permitted regional virus eradication. Nevertheless, CSF virus (CSFV) persists in certain areas of the world and has re-emerged regularly. This review summarizes the basic established knowledge in the field and provides a comprehensive and updated overview of the recent advances in fundamental CSFV research, diagnostics and vaccine development. It covers the latest discoveries on the genetic diversity of pestiviruses, with implications for taxonomy, the progress in understanding disease pathogenesis, immunity against acute and persistent infections, and the recent findings in virus-host interactions and virulence determinants. We also review the progress and pitfalls in the improvement of diagnostic tools and the challenges in the development of modern and efficacious marker vaccines compatible with serological tests for disease surveillance. Finally, we highlight the gaps that require research efforts in the future.
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Affiliation(s)
- Llilianne Ganges
- OIE Reference Laboratory for Classical Swine Fever, Institute of Agrifood Research and Technology, Centre de Recerca en Sanitat Animal (CReSA), 08193 Barcelona, Spain.
| | - Helen R Crooke
- Virology Department, Animal and Plant Health Agency, APHA-Weybridge, Woodham Lane, New Haw, Addlestone, KT15 3NB, UK
| | - Jose Alejandro Bohórquez
- OIE Reference Laboratory for Classical Swine Fever, Institute of Agrifood Research and Technology, Centre de Recerca en Sanitat Animal (CReSA), 08193 Barcelona, Spain
| | - Alexander Postel
- EU & OIE Reference Laboratory for Classical Swine Fever, Institute of Virology, University of Veterinary Medicine, Hannover, Buenteweg 17, 30559 Hannover, Germany
| | - Yoshihiro Sakoda
- Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Kita 18 Nishi 9, Kita-ku, Sapporo, 060-0818, Japan
| | - Paul Becher
- EU & OIE Reference Laboratory for Classical Swine Fever, Institute of Virology, University of Veterinary Medicine, Hannover, Buenteweg 17, 30559 Hannover, Germany
| | - Nicolas Ruggli
- The Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland; Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland
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11
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Asín J, Hilbe M, de Miguel R, Rodríguez-Largo A, Lanau A, Akerman A, Stalder H, Schweizer M, Luján L. An outbreak of abortions, stillbirths and malformations in a Spanish sheep flock associated with a bovine viral diarrhoea virus 2-contaminated orf vaccine. Transbound Emerg Dis 2020; 68:233-239. [PMID: 32386079 DOI: 10.1111/tbed.13619] [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: 12/18/2019] [Revised: 03/10/2020] [Accepted: 04/17/2020] [Indexed: 12/24/2022]
Abstract
Bovine viral diarrhoea virus (BVDV) is a pestivirus that affects both cattle and sheep, causing an array of clinical signs, which include abortions and malformations in the offspring. Manufacturing of modified live virus (MLV) vaccines often includes the use of bovine-derived products, which implies a risk of contamination with viable BVDV. Recently, the circulation of a specific strain of BVDV 2b among Spanish sheep flocks, associated with outbreaks of abortions and malformations, and whose origin was not determined, has been observed. On February 2018, a MLV orf vaccine was applied to a 1,600 highly prolific sheep flock in the Northeast of Spain that included 550 pregnant ewes. In May 2018, during the lambing season, an unusual high rate (72.7%) of abortions, stillbirths, congenital malformations and neurological signs in the offspring was observed. It was estimated that about 1,000 lambs were lost. Three 1- to 3-day-old affected lambs and a sealed vial of the applied vaccine were studied. Lambs showed variable degrees of central nervous system malformations and presence of pestiviral antigen in the brain. Molecular studies demonstrated the presence of exactly the same BVDV 2b in the tissues of the three lambs and in the orf vaccine, thus pointing to a pestivirus contamination in the applied vaccine as the cause of the outbreak. Interestingly, sequencing at the 5'-untranslated region-(UTR) of the contaminating virus showed a complete match with the virus described in the previously reported outbreaks in Spain, thus indicating that the same contaminated vaccine could have also played a role in those cases. This communication provides a clear example of the effects of the application of this contaminated product in a sheep flock. The information presented here can be of interest in putative future cases of suspected circulation of this or other BVDV strains in ruminants.
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Affiliation(s)
- Javier Asín
- Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain
| | - Monika Hilbe
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Ricardo de Miguel
- Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain
| | | | - Antonio Lanau
- Sociedad Cooperativa Limitada Agropecuaria del Sobrarbe (SCLAS) Veterinary Service, Huesca, Spain
| | - Alberto Akerman
- Sociedad Cooperativa Limitada Agropecuaria del Sobrarbe (SCLAS) Veterinary Service, Huesca, Spain
| | - Hanspeter Stalder
- Institute of Virology and Immunology, Bern, Switzerland.,Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Switzerland
| | - Matthias Schweizer
- Institute of Virology and Immunology, Bern, Switzerland.,Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Switzerland
| | - Lluís Luján
- Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain.,Instituto Universitario de Investigación Mixto Agroalimentario de Aragón (IA2), Universidad de Zaragoza, Zaragoza, Spain
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Classical swine fever virus N pro antagonises IRF3 to prevent IFN-independent TLR3 and RIG-I-mediated apoptosis. J Virol 2020; 95:JVI.01136-20. [PMID: 33328306 PMCID: PMC8092839 DOI: 10.1128/jvi.01136-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Classical swine fever virus (CSFV) is the causative agent of classical swine fever, a notifiable disease of economic importance that causes severe leukopenia, fever and haemorrhagic disease in domesticated pigs and wild boar across the globe. CSFV has been shown to antagonise the induction of type I IFN, partly through a function of its N-terminal protease (Npro) which binds IRF3 and targets it for proteasomal degradation. Additionally, Npro has been shown to antagonise apoptosis triggered by the dsRNA-homolog poly(I:C), however the exact mechanism by which this is achieved has not been fully elucidated. In this study we confirm the ability of Npro to inhibit dsRNA-mediated apoptosis and show that Npro is also able to antagonise Sendai virus-mediated apoptosis in PK-15 cells. Gene edited PK-15 cell lines were used to show the dsRNA-sensing pathogen recognition receptors (PRRs) TLR3 and RIG-I specifically respond to poly(I:C) and SeV respectively, subsequently triggering apoptosis through pathways that converge on IRF3 and culminate in the cleavage of caspase-3. Importantly, this IRF3-mediated apoptosis was found to be dependent on transcription-independent functions of IRF3 and also on Bax, a pro-apoptotic Bcl-2 family protein, through a direct interaction between the two proteins. Deletion of IRF3, stable expression of Npro and infection with wild-type CSFV were found to antagonise the mitochondrial localisation of Bax, a key hallmark of the intrinsic, mitochondrial pathway of apoptosis. Together, these findings show that Npro's putative interaction with IRF3 is involved not only in its antagonism of type I IFN, but also dsRNA-mediated mitochondrial apoptosis.Importance Responsible for severe haemorrhagic disease in domestic pigs and wild boar, classical swine fever is recognised by the World Organisation for Animal Health (OIE) and European Union as a notifiable disease of economic importance. Persistent infection, immunotolerance and early dissemination of the virus at local sites of infection have been linked to the antagonism of type I IFN induction by Npro This protein may further contribute to these phenomena by antagonising the induction of dsRNA-mediated apoptosis. Ultimately, apoptosis is an important innate mechanism by which cells counter viruses at local sites of infection, thus preventing wider spread and dissemination within the host, potentially also contributing to the onset of persistence. Elucidation of the mechanism by which Npro antagonises the apoptotic response will help inform the development of rationally-designed live-attenuated vaccines and antivirals for control of outbreaks in typically CSFV-free countries.
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Itakura Y, Matsuno K, Ito A, Gerber M, Liniger M, Fujimoto Y, Tamura T, Kameyama KI, Okamatsu M, Ruggli N, Kida H, Sakoda Y. A cloned classical swine fever virus derived from the vaccine strain GPE - causes cytopathic effect in CPK-NS cells via type-I interferon-dependent necroptosis. Virus Res 2019; 276:197809. [PMID: 31715204 DOI: 10.1016/j.virusres.2019.197809] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 11/05/2019] [Accepted: 11/07/2019] [Indexed: 01/03/2023]
Abstract
Classical swine fever viruses (CSFVs) do typically not show cytopathic effect (CPE) in cell culture, while some strains such as vaccine strain the GPE- induce CPE in the swine kidney-derived CPK-NS cell line cultured in serum-free medium. These latter strains commonly lack Npro-mediated inhibition of type-I interferon (IFN) induction. In order to explore the molecular mechanisms of GPE--induced CPE, we analyzed the cellular pathways involved. In CPK-NS cells infected with the attenuated-vaccine-derived vGPE- strain, both, apoptosis and necroptosis were induced. Necroptosis was type-I IFN-dependent and critical for visible CPE. In contrast, the parental virulent vALD-A76 strain did not induce any of these pathways nor CPE. We used reverse genetics to investigate which viral factors regulate these cell-death pathways. Interestingly, a mutant vGPE- in which the Npro function was restored to inhibit type-I IFN induction did not induce necroptosis nor CPE but still induced apoptosis, while an Npro-mutant vALD-A76 incapable of inhibiting type-I IFN production induced necroptosis and CPE. Although Erns of CSFV is reportedly involved in controlling apoptosis, apoptosis induction by vGPE- or apoptosis inhibition by vALD-A76 were independent of the unique amino acid difference found in Erns of these two strains. Altogether, these results demonstrate that type-I IFN-dependent necroptosis related to non-functional Npro is the main mechanism for CPE induction by vGPE-, and that viral factor(s) other than Erns may induce or inhibit apoptosis in vGPE- or vALD-A76 infected CPK-NS cells, respectively.
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Affiliation(s)
- Yukari Itakura
- Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Keita Matsuno
- Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan; Global Station for Zoonotic Control, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido, Japan
| | - Asako Ito
- Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Markus Gerber
- Institute of Virology and Immunology (IVI), Mittelhäusern, Switzerland; Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland
| | - Matthias Liniger
- Institute of Virology and Immunology (IVI), Mittelhäusern, Switzerland; Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland
| | - Yuri Fujimoto
- Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Tomokazu Tamura
- Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Ken-Ichiro Kameyama
- Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Masatoshi Okamatsu
- Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Nicolas Ruggli
- Institute of Virology and Immunology (IVI), Mittelhäusern, Switzerland; Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland
| | - Hiroshi Kida
- Global Station for Zoonotic Control, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido, Japan; Laboratory of Biologics Development, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yoshihiro Sakoda
- Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan; Global Station for Zoonotic Control, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido, Japan.
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