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Chen S, Jiang Z, Li Q, Pan W, Chen Y, Liu J. Viral RNA capping: Mechanisms and antiviral therapy. J Med Virol 2024; 96:e29622. [PMID: 38682614 DOI: 10.1002/jmv.29622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 03/25/2024] [Accepted: 04/11/2024] [Indexed: 05/01/2024]
Abstract
RNA capping is an essential trigger for protein translation in eukaryotic cells. Many viruses have evolved various strategies for initiating the translation of viral genes and generating progeny virions in infected cells via synthesizing cap structure or stealing the RNA cap from nascent host messenger ribonucleotide acid (mRNA). In addition to protein translation, a new understanding of the role of the RNA cap in antiviral innate immunity has advanced the field of mRNA synthesis in vitro and therapeutic applications. Recent studies on these viral RNA capping systems have revealed startlingly diverse ways and molecular machinery. A comprehensive understanding of how viruses accomplish the RNA capping in infected cells is pivotal for designing effective broad-spectrum antiviral therapies. Here we systematically review the contemporary insights into the RNA-capping mechanisms employed by viruses causing human and animal infectious diseases, while also highlighting its impact on host antiviral innate immune response. The therapeutic applications of targeting RNA capping against viral infections and the development of RNA-capping inhibitors are also summarized.
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Affiliation(s)
- Saini Chen
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Zhimin Jiang
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Qiuchen Li
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Wenliang Pan
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yu Chen
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jinhua Liu
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory for Prevention and Control of Avian Influenza and Other Major Poultry Diseases, Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
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2
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Liu K, Li L, Liu Y, Wang X, Liu J, Li J, Deng F, Zhang R, Zhou Y, Hu Z, Zhong W, Wang M, Guo C. Discovery of baloxavir sodium as a novel anti-CCHFV inhibitor: Biological evaluation of in vitro and in vivo. Antiviral Res 2024; 227:105890. [PMID: 38657838 DOI: 10.1016/j.antiviral.2024.105890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/05/2024] [Accepted: 04/18/2024] [Indexed: 04/26/2024]
Abstract
Crimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic bunyavirus with a fatality rate of up to 40%. Currently, there are no licensed antiviral drugs for the treatment of CCHF; thus, the World Health Organization (WHO) listed the disease as a priority. A unique viral transcription initiation mechanism called "cap-snatching" is shared by influenza viruses and bunyaviruses. Thus, we tested whether baloxavir (an FDA-approved anti-influenza drug that targets the "cap-snatching" mechanism) could inhibit CCHFV infection. In cell culture, baloxavir acid effectively inhibited CCHFV infection and targeted CCHFV RNA transcription/replication. However, it has weak oral bioavailability. Baloxavir marboxil (the oral prodrug of baloxavir) failed to protect mice against a lethal dose challenge of CCHFV. To solve this problem, baloxavir sodium was synthesized owing to its enhanced aqueous solubility and pharmacokinetic properties. It consistently and significantly improved survival rates and decreased tissue viral loads. This study identified baloxavir sodium as a novel scaffold structure and mechanism of anti-CCHF compound, providing a promising new strategy for clinical treatment of CCHF after further optimization.
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Affiliation(s)
- Kai Liu
- School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China; National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Liushuai Li
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Yajie Liu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
| | - Xi Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
| | - Jia Liu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
| | - Jiang Li
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
| | - Fei Deng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
| | - Runze Zhang
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Yiwu Zhou
- Department of Forensic Medicine, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430010, China
| | - Zhihong Hu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Wu Zhong
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Manli Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China; Hubei Jiangxia Laboratory, Wuhan, 430200, China.
| | - Chun Guo
- School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China.
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3
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Kuhn JH, Alkhovsky [Альховский Сергей Владимирови] SV, Avšič-Županc T, Bergeron É, Burt F, Ergünay K, Garrison AR, Marklewitz M, Mirazimi A, Papa [Άννα Παπά] A, Pawęska JT, Spengler JR, Palacios G. ICTV Virus Taxonomy Profile: Nairoviridae 2024. J Gen Virol 2024; 105:001974. [PMID: 38687001 PMCID: PMC11094370 DOI: 10.1099/jgv.0.001974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 03/16/2024] [Indexed: 05/02/2024] Open
Abstract
Nairoviridae is a family for negative-sense RNA viruses with genomes of about 17.2-21.1 kb. These viruses are maintained in and/or transmitted by arthropods among birds, reptiles and mammals. Norwaviruses and orthonairoviruses can cause febrile illness in humans. Several orthonairoviruses can infect mammals, causing mild, severe and sometimes, fatal diseases. Nairovirids produce enveloped virions containing two or three single-stranded RNA segments with open reading frames that encode a nucleoprotein (N), sometimes a glycoprotein precursor (GPC), and a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) report on the family Nairoviridae, which is available at www.ictv.global/report/nairoviridae.
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Affiliation(s)
- Jens H. Kuhn
- Integrated Research Facility at Fort Detrick, Frederick MD, USA
| | | | | | - Éric Bergeron
- Centers for Disease Control and Prevention, Atlanta GA, USA
| | - Felicity Burt
- University of the Free State, Bloemfontein, South Africa
| | - Koray Ergünay
- Hacettepe University Faculty of Medicine, Ankara, Turkey
- Smithsonian Institution, Museum Support Center, Suitland MD, USA
- Walter Reed Army Institute of Research, Silver Spring MD, USA
- Smithsonian Institution–National Museum of Natural History, Washington, DC, USA
| | - Aura R. Garrison
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick MD, USA
| | | | | | | | - Janusz T. Pawęska
- National Institute for Communicable Diseases of the National Health Laboratory Service, Sandringham-Johannesburg, Gauteng, South Africa
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Abstract
Crimean-Congo haemorrhagic fever (CCHF) is a severe tick-borne illness with a wide geographical distribution and case fatality rates of 30% or higher. Caused by infection with the CCHF virus (CCHFV), cases are reported throughout Africa, the Middle East, Asia and southern and eastern Europe. The expanding range of the Hyalomma tick vector is placing new populations at risk for CCHF, and no licensed vaccines or specific antivirals exist to treat CCHF. Furthermore, despite cases of CCHF being reported annually, the host and viral determinants of CCHFV pathogenesis are poorly understood. CCHFV can productively infect a multitude of animal species, yet only humans develop a severe illness. Within human populations, subclinical infections are underappreciated and may represent a substantial proportion of clinical outcomes. Compared with other members of the Bunyavirales order, CCHFV has a more complex genomic organization, with many viral proteins having unclear functions in viral pathogenesis. In recent years, improved animal models have led to increased insights into CCHFV pathogenesis, and several antivirals and vaccines for CCHFV have shown robust efficacy in preclinical models. Translation of these insights and candidate therapeutics to the clinic will hopefully reduce the morbidity and mortality caused by CCHFV.
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Williams HM, Thorkelsson SR, Vogel D, Milewski M, Busch C, Cusack S, Grünewald K, Quemin EJ, Rosenthal M. Structural insights into viral genome replication by the severe fever with thrombocytopenia syndrome virus L protein. Nucleic Acids Res 2023; 51:1424-1442. [PMID: 36651274 PMCID: PMC9943659 DOI: 10.1093/nar/gkac1249] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/29/2022] [Accepted: 12/14/2022] [Indexed: 01/19/2023] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a phenuivirus that has rapidly become endemic in several East Asian countries. The large (L) protein of SFTSV, which includes the RNA-dependent RNA polymerase (RdRp), is responsible for catalysing viral genome replication and transcription. Here, we present 5 cryo-electron microscopy (cryo-EM) structures of the L protein in several states of the genome replication process, from pre-initiation to late-stage elongation, at a resolution of up to 2.6 Å. We identify how the L protein binds the 5' viral RNA in a hook-like conformation and show how the distal 5' and 3' RNA ends form a duplex positioning the 3' RNA terminus in the RdRp active site ready for initiation. We also observe the L protein stalled in the early and late stages of elongation with the RdRp core accommodating a 10-bp product-template duplex. This duplex ultimately splits with the template binding to a designated 3' secondary binding site. The structural data and observations are complemented by in vitro biochemical and cell-based mini-replicon assays. Altogether, our data provide novel key insights into the mechanism of viral genome replication by the SFTSV L protein and will aid drug development against segmented negative-strand RNA viruses.
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Affiliation(s)
| | | | - Dominik Vogel
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
| | - Morlin Milewski
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
| | - Carola Busch
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
| | | | - Kay Grünewald
- Centre for Structural Systems Biology, Leibniz Institute of Virology, Hamburg, Germany,University of Hamburg, Hamburg, Germany
| | - Emmanuelle R J Quemin
- Centre for Structural Systems Biology, Leibniz Institute of Virology, Hamburg, Germany
| | - Maria Rosenthal
- To whom correspondence should be addressed. Tel: +49 40 285380 930;
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Malet H, Williams HM, Cusack S, Rosenthal M. The mechanism of genome replication and transcription in bunyaviruses. PLoS Pathog 2023; 19:e1011060. [PMID: 36634042 PMCID: PMC9836281 DOI: 10.1371/journal.ppat.1011060] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Bunyaviruses are negative sense, single-strand RNA viruses that infect a wide range of vertebrate, invertebrate and plant hosts. WHO lists three bunyavirus diseases as priority diseases requiring urgent development of medical countermeasures highlighting their high epidemic potential. While the viral large (L) protein containing the RNA-dependent RNA polymerase is a key enzyme in the viral replication cycle and therefore a suitable drug target, our knowledge on the structure and activities of this multifunctional protein has, until recently, been very limited. However, in the last few years, facilitated by the technical advances in the field of cryogenic electron microscopy, many structures of bunyavirus L proteins have been solved. These structures significantly enhance our mechanistic understanding of bunyavirus genome replication and transcription processes and highlight differences and commonalities between the L proteins of different bunyavirus families. Here, we provide a review of our current understanding of genome replication and transcription in bunyaviruses with a focus on the viral L protein. Further, we compare within bunyaviruses and with the related influenza virus polymerase complex and highlight open questions.
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Affiliation(s)
- Hélène Malet
- University Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
- Institut Universitaire de France (IUF), Paris, France
| | - Harry M. Williams
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
| | | | - Maria Rosenthal
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Discovery Research ScreeningPort, Hamburg, Germany
- * E-mail:
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7
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Shamsi W, Kondo H, Ulrich S, Rigling D, Prospero S. Novel RNA viruses from the native range of Hymenoscyphus fraxineus, the causal fungal agent of ash dieback. Virus Res 2022; 320:198901. [PMID: 36058013 DOI: 10.1016/j.virusres.2022.198901] [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: 07/15/2022] [Revised: 08/22/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022]
Abstract
The native Japanese population of the fungus Hymenoscyphus fraxineus, the causal agent of ash dieback in Europe, was screened for viruses using a high-throughput sequencing method. Five RNA viruses were detected in 116 fungal isolates sequenced via Illumina RNA-seq platform, with an overall virus prevalence of 11.2%. The viruses were completely sequenced by RNA ligase mediated rapid amplification of cDNA ends (RLM-RACE) followed by Sanger sequencing. The sequences appear to represent new species from three established families (Mito-, Endorna- and Partitiviridae), one recognized genus (Botybirnavirus) and a negative-sense single-stranded RNA virus in the order Bunyavirales from the proposed family "Mybuviridae". The highest prevalence was found for the mitovirus (7.8%), that had two genomic forms (linear and circular), while the other viruses were detected each in one isolate. Co-infection of a mitovirus and an endornavirus was also observed in one of the infected isolates. Here we describe the molecular characterization of the identified viruses. This study expands the diversity of viruses in H. fraxineus and provides the basis for investigating the virus-mediated control of ash dieback in Europe.
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Affiliation(s)
- Wajeeha Shamsi
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse 111, Birmensdorf 8903, Switzerland.
| | - Hideki Kondo
- Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan
| | - Sven Ulrich
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse 111, Birmensdorf 8903, Switzerland
| | - Daniel Rigling
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse 111, Birmensdorf 8903, Switzerland
| | - Simone Prospero
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse 111, Birmensdorf 8903, Switzerland
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8
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Geerling E, Murphy V, Mai MC, Stone ET, Casals AG, Hassert M, O’Dea AT, Cao F, Donlin MJ, Elagawany M, Elgendy B, Pardali V, Giannakopoulou E, Zoidis G, Schiavone DV, Berkowitz AJ, Agyemang NB, Murelli RP, Tavis JE, Pinto AK, Brien JD. Metal coordinating inhibitors of Rift Valley fever virus replication. PLoS One 2022; 17:e0274266. [PMID: 36112605 PMCID: PMC9481026 DOI: 10.1371/journal.pone.0274266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 08/24/2022] [Indexed: 11/18/2022] Open
Abstract
Rift Valley fever virus (RVFV) is a veterinary and human pathogen and is an agent of bioterrorism concern. Currently, RVFV treatment is limited to supportive care, so new drugs to control RVFV infection are urgently needed. RVFV is a member of the order Bunyavirales, whose replication depends on the enzymatic activity of the viral L protein. Screening for RVFV inhibitors among compounds with divalent cation-coordinating motifs similar to known viral nuclease inhibitors identified 47 novel RVFV inhibitors with selective indexes from 1.1–103 and 50% effective concentrations of 1.2–56 μM in Vero cells, primarily α-Hydroxytropolones and N-Hydroxypyridinediones. Inhibitor activity and selective index was validated in the human cell line A549. To evaluate specificity, select compounds were tested against a second Bunyavirus, La Crosse Virus (LACV), and the flavivirus Zika (ZIKV). These data indicate that the α-Hydroxytropolone and N-Hydroxypyridinedione chemotypes should be investigated in the future to determine their mechanism(s) of action allowing further development as therapeutics for RVFV and LACV, and these chemotypes should be evaluated for activity against related pathogens, including Hantaan virus, severe fever with thrombocytopenia syndrome virus, Crimean-Congo hemorrhagic fever virus.
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Affiliation(s)
- Elizabeth Geerling
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Valerie Murphy
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Maria C. Mai
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - E. Taylor Stone
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Andreu Gazquez Casals
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Mariah Hassert
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Austin T. O’Dea
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Feng Cao
- John Cochran Division, Department of Veterans Affairs Medical Center, Saint Louis, Missouri, United States of America
| | - Maureen J. Donlin
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Mohamed Elagawany
- Center for Clinical Pharmacology, Washington University School of Medicine and University of Health Sciences and Pharmacy, Saint Louis, Missouri, United States of America
| | - Bahaa Elgendy
- Center for Clinical Pharmacology, Washington University School of Medicine and University of Health Sciences and Pharmacy, Saint Louis, Missouri, United States of America
- Department of Pharmaceutical and Administrative Sciences, University of Health Sciences and Pharmacy, Saint Louis, Missouri, United States of America
| | - Vasiliki Pardali
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, Athens, Greece
| | - Erofili Giannakopoulou
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, Athens, Greece
| | - Grigoris Zoidis
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, Athens, Greece
| | - Daniel V. Schiavone
- Department of Chemistry and The Graduate Center of The City University of New York, Brooklyn College, The City University of New York, Brooklyn, New York, United States of America
| | - Alex J. Berkowitz
- Department of Chemistry and The Graduate Center of The City University of New York, Brooklyn College, The City University of New York, Brooklyn, New York, United States of America
| | - Nana B. Agyemang
- Department of Chemistry and The Graduate Center of The City University of New York, Brooklyn College, The City University of New York, Brooklyn, New York, United States of America
| | - Ryan P. Murelli
- Department of Chemistry and The Graduate Center of The City University of New York, Brooklyn College, The City University of New York, Brooklyn, New York, United States of America
| | - John E. Tavis
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Amelia K. Pinto
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - James D. Brien
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail:
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9
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Toba S, Sato A, Kawai M, Taoda Y, Unoh Y, Kusakabe S, Nobori H, Uehara S, Uemura K, Taniguchi K, Kobayashi M, Noshi T, Yoshida R, Naito A, Shishido T, Maruyama J, Paessler S, Carr MJ, Hall WW, Yoshimatsu K, Arikawa J, Matsuno K, Sakoda Y, Sasaki M, Orba Y, Sawa H, Kida H. Identification of cap-dependent endonuclease inhibitors with broad-spectrum activity against bunyaviruses. Proc Natl Acad Sci U S A 2022; 119:e2206104119. [PMID: 36037386 PMCID: PMC9457168 DOI: 10.1073/pnas.2206104119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/07/2022] [Indexed: 11/18/2022] Open
Abstract
Viral hemorrhagic fevers caused by members of the order Bunyavirales comprise endemic and emerging human infections that are significant public health concerns. Despite the disease severity, there are few therapeutic options available, and therefore effective antiviral drugs are urgently needed to reduce disease burdens. Bunyaviruses, like influenza viruses (IFVs), possess a cap-dependent endonuclease (CEN) that mediates the critical cap-snatching step of viral RNA transcription. We screened compounds from our CEN inhibitor (CENi) library and identified specific structural compounds that are 100 to 1,000 times more active in vitro than ribavirin against bunyaviruses, including Lassa virus, lymphocytic choriomeningitis virus (LCMV), and Junin virus. To investigate their inhibitory mechanism of action, drug-resistant viruses were selected in culture. Whole-genome sequencing revealed that amino acid substitutions in the CEN region of drug-resistant viruses were located in similar positions as those of the CEN α3-helix loop of IFVs derived under drug selection. Thus, our studies suggest that CENi compounds inhibit both bunyavirus and IFV replication in a mechanistically similar manner. Structural analysis revealed that the side chain of the carboxyl group at the seventh position of the main structure of the compound was essential for the high antiviral activity against bunyaviruses. In LCMV-infected mice, the compounds significantly decreased blood viral load, suppressed symptoms such as thrombocytopenia and hepatic dysfunction, and improved survival rates. These data suggest a potential broad-spectrum clinical utility of CENis for the treatment of both severe influenza and hemorrhagic diseases caused by bunyaviruses.
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Affiliation(s)
- Shinsuke Toba
- Shionogi & Co., Ltd., Osaka 561-0825, Japan
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Akihiko Sato
- Shionogi & Co., Ltd., Osaka 561-0825, Japan
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | | | | | - Yuto Unoh
- Shionogi & Co., Ltd., Osaka 561-0825, Japan
| | - Shinji Kusakabe
- Shionogi & Co., Ltd., Osaka 561-0825, Japan
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | | | | | - Kentaro Uemura
- Shionogi & Co., Ltd., Osaka 561-0825, Japan
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Keiichi Taniguchi
- Shionogi & Co., Ltd., Osaka 561-0825, Japan
- Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
| | | | | | | | | | | | - Junki Maruyama
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555
| | - Slobodan Paessler
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555
| | - Michael J. Carr
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
- National Virus Reference Laboratory, School of Medicine, University College Dublin, Dublin, Ireland
| | - William W. Hall
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
- National Virus Reference Laboratory, School of Medicine, University College Dublin, Dublin, Ireland
- Global Virus Network, Baltimore, MD 21201
| | - Kumiko Yoshimatsu
- Laboratory of Animal Experimentation, Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido 060-0815, Japan
| | - Jiro Arikawa
- Office for Biosafety Auditor, Nagasaki University, Nagasaki 852-8521, Japan
| | - Keita Matsuno
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
- Division of Risk Analysis and Management, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
- One Health Research Center, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Yoshihiro Sakoda
- Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Michihito Sasaki
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Yasuko Orba
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Hirofumi Sawa
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
- Global Virus Network, Baltimore, MD 21201
- One Health Research Center, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Hiroshi Kida
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
- Division of Biologics Development, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
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Vivek-Ananth RP, Sahoo AK, Srivastava A, Samal A. Virtual screening of phytochemicals from Indian medicinal plants against the endonuclease domain of SFTS virus L polymerase. RSC Adv 2022; 12:6234-6247. [PMID: 35424542 PMCID: PMC8982020 DOI: 10.1039/d1ra06702h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 02/16/2022] [Indexed: 12/25/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) causes a highly infectious disease with reported mortality in the range 2.8% to 47%. The replication and transcription of the SFTSV genome is performed by L polymerase, which has both an RNA dependent RNA polymerase domain and an N-terminal endonuclease (endoN) domain. Due to its crucial role in the cap-snatching mechanism required for initiation of viral RNA transcription, the endoN domain is an ideal antiviral drug target. In this virtual screening study for the identification of potential inhibitors of the endoN domain of SFTSV L polymerase, we have used molecular docking and molecular dynamics (MD) simulation to explore the natural product space of 14 011 phytochemicals from Indian medicinal plants. After generating a heterogeneous ensemble of endoN domain structures reflecting conformational diversity of the corresponding active site using MD simulations, ensemble docking of the phytochemicals was performed against the endoN domain structures. Apart from the ligand binding energy from docking, our virtual screening workflow imposes additional filters such as drug-likeness, non-covalent interactions with key active site residues, toxicity and chemical similarity with other hits, to identify top 5 potential phytochemical inhibitors of endoN domain of SFTSV L polymerase. Further, the stability of the protein–ligand docked complexes for the top 5 potential inhibitors was analyzed using MD simulations. The potential phytochemical inhibitors, predicted in this study using contemporary computational methods, are expected to serve as lead molecules in future experimental studies towards development of antiviral drugs against SFTSV. Virtual screening of a large phytochemical library from Indian medicinal plants to identify potential endonuclease inhibitors against emerging virus SFTSV.![]()
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Affiliation(s)
- R P Vivek-Ananth
- The Institute of Mathematical Sciences (IMSc) Chennai 600113 India .,Homi Bhabha National Institute (HBNI) Mumbai 400094 India
| | - Ajaya Kumar Sahoo
- The Institute of Mathematical Sciences (IMSc) Chennai 600113 India .,Homi Bhabha National Institute (HBNI) Mumbai 400094 India
| | - Ashutosh Srivastava
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar Gandhinagar 382355 India
| | - Areejit Samal
- The Institute of Mathematical Sciences (IMSc) Chennai 600113 India .,Homi Bhabha National Institute (HBNI) Mumbai 400094 India
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11
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Lin Y, Gross ML. Mass Spectrometry-Based Structural Proteomics for Metal Ion/Protein Binding Studies. Biomolecules 2022; 12:135. [PMID: 35053283 PMCID: PMC8773722 DOI: 10.3390/biom12010135] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/13/2022] [Accepted: 01/13/2022] [Indexed: 01/01/2023] Open
Abstract
Metal ions are critical for the biological and physiological functions of many proteins. Mass spectrometry (MS)-based structural proteomics is an ever-growing field that has been adopted to study protein and metal ion interactions. Native MS offers information on metal binding and its stoichiometry. Footprinting approaches coupled with MS, including hydrogen/deuterium exchange (HDX), "fast photochemical oxidation of proteins" (FPOP) and targeted amino-acid labeling, identify binding sites and regions undergoing conformational changes. MS-based titration methods, including "protein-ligand interactions by mass spectrometry, titration and HD exchange" (PLIMSTEX) and "ligand titration, fast photochemical oxidation of proteins and mass spectrometry" (LITPOMS), afford binding stoichiometry, binding affinity, and binding order. These MS-based structural proteomics approaches, their applications to answer questions regarding metal ion protein interactions, their limitations, and recent and potential improvements are discussed here. This review serves as a demonstration of the capabilities of these tools and as an introduction to wider applications to solve other questions.
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Affiliation(s)
- Yanchun Lin
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
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12
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Pyle JD, Whelan SPJ, Bloyet LM. Structure and function of negative-strand RNA virus polymerase complexes. Enzymes 2021; 50:21-78. [PMID: 34861938 DOI: 10.1016/bs.enz.2021.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Viruses with negative-strand RNA genomes (NSVs) include many highly pathogenic and economically devastating disease-causing agents of humans, livestock, and plants-highlighted by recent Ebola and measles virus epidemics, and continuously circulating influenza virus. Because of their protein-coding orientation, NSVs face unique challenges for efficient gene expression and genome replication. To overcome these barriers, NSVs deliver a large and multifunctional RNA-dependent RNA polymerase into infected host cells. NSV-encoded polymerases contain all the enzymatic activities required for transcription and replication of their genome-including RNA synthesis and mRNA capping. Here, we review the structures and functions of NSV polymerases with a focus on key domains responsible for viral replication and gene expression. We highlight shared and unique features among polymerases of NSVs from the Mononegavirales, Bunyavirales, and Articulavirales orders.
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Affiliation(s)
- Jesse D Pyle
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, United States; Ph.D. Program in Virology, Harvard Medical School, Boston, MA, United States
| | - Sean P J Whelan
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, United States.
| | - Louis-Marie Bloyet
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, United States.
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Abstract
Rift Valley fever virus (RVFV) belongs to the order Bunyavirales and is the type species of genus Phlebovirus, which accounts for over 50% of family Phenuiviridae species. RVFV is mosquito-borne and causes severe diseases in both humans and livestock, and consists of three segments (S, M, L) in the genome. The L segment encodes an RNA-dependent RNA polymerase (RdRp, L protein) that is responsible for facilitating the replication and transcription of the virus. It is essential for the virus and has multiple drug targets. Here, we established an expression system and purification procedures for full-length L protein, which is composed of an endonuclease domain, RdRp domain, and cap-binding domain. A cryo-EM L protein structure was reported at 3.6 Å resolution. In this first L protein structure of genus Phlebovirus, the priming loop of RVFV L protein is distinctly different from those of other L proteins and undergoes large movements related to its replication role. Structural and biochemical analyses indicate that a single template can induce initiation of RNA synthesis, which is notably enhanced by 5' viral RNA. These findings help advance our understanding of the mechanism of RNA synthesis and provide an important basis for developing antiviral inhibitors. Importance The zoonosis RVF virus (RVFV) is one of the most serious arbovirus threats to both human and animal health. RNA-dependent RNA polymerase (RdRp) is a multifunctional enzyme catalyzing genome replication as well as viral transcription, so the RdRp is essential for studying the virus and has multiple drug targets. In our study, we report the structure of RVFV L protein at 3.6 Å resolution by cryo-EM. This is the first L protein structure of genus Phlebovirus. Strikingly, a single template can initiate RNA replication. The structure and assays provide a comprehensive and in-depth understanding of the catalytic and substrate recognition mechanism of RdRp.
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Abstract
Arenaviruses initiate infection by delivering a transcriptionally competent ribonucleoprotein (RNP) complex into the cytosol of host cells. The arenavirus RNP consists of the large (L) RNA-dependent RNA polymerase (RdRP) bound to a nucleoprotein (NP)-encapsidated genomic RNA (viral RNA [vRNA]) template. During transcription and replication, L must transiently displace RNA-bound NP to allow for template access into the RdRP active site. Concomitant with RNA replication, new subunits of NP must be added to the nascent complementary RNAs (cRNA) as they emerge from the product exit channel of L. Interactions between L and NP thus play a central role in arenavirus gene expression. We developed an approach to purify recombinant functional RNPs from mammalian cells in culture using a synthetic vRNA and affinity-tagged L and NP. Negative-stain electron microscopy of purified RNPs revealed they adopt diverse and flexible structures, like RNPs of other Bunyavirales members. Monodispersed L-NP and trimeric ring-like NP complexes were also obtained in excess of flexible RNPs, suggesting that these heterodimeric structures self-assemble in the absence of suitable RNA templates. This work allows for further biochemical analysis of the interaction between arenavirus L and NP proteins and provides a framework for future high-resolution structural analyses of this replication-associated complex. IMPORTANCE Arenaviruses are rodent-borne pathogens that can cause severe disease in humans. All arenaviruses begin the infection cycle with delivery of the virus replication machinery into the cytoplasm of the host cell. This machinery consists of an RNA-dependent RNA polymerase-which copies the viral genome segments and synthesizes all four viral mRNAs-bound to the two nucleoprotein-encapsidated genomic RNAs. How this complex assembles remains a mystery. Our findings provide direct evidence for the formation of diverse intracellular arenavirus replication complexes using purification strategies for the polymerase, nucleoprotein, and genomic RNA of Machupo virus, which causes Bolivian hemorrhagic fever in humans. We demonstrate that the polymerase and nucleoprotein assemble into higher-order structures within cells, providing a model for the molecular events of arenavirus RNA synthesis. These findings provide a framework for probing the architectures and functions of the arenavirus replication machinery and thus advancing antiviral strategies targeting this essential complex.
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15
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Ter Horst S, Fernandez-Garcia Y, Bassetto M, Günther S, Brancale A, Neyts J, Rocha-Pereira J. Enhanced efficacy of endonuclease inhibitor baloxavir acid against orthobunyaviruses when used in combination with ribavirin. J Antimicrob Chemother 2021; 75:3189-3193. [PMID: 32766680 DOI: 10.1093/jac/dkaa337] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 07/30/2020] [Indexed: 01/13/2023] Open
Abstract
OBJECTIVES Baloxavir acid is an endonuclease inhibitor approved for use against influenza. We evaluated whether this compound also targets the endonuclease domain of orthobunyaviruses and therefore could potentially be used against orthobunyavirus infections. METHODS We performed a thermal shift assay and a fluorescence resonance energy transfer (FRET)-based nuclease monitoring assay using the La Crosse virus (LACV) endonuclease and baloxavir acid to prove their interaction and identify an inhibitory effect. Their interaction was further studied in a docking simulation using Glide SP. We show that baloxavir acid inhibits the viral replication of Bunyamwera virus (BUNV)-mCherry in vitro using high-content imaging and virus yield assay. Lastly, we investigated the use of baloxavir acid in combination with ribavirin in vitro by implementing the Zero Interaction Potency response surface model. RESULTS We show that baloxavir acid augments LACV enzyme's melting temperature with ΔTm 9.5 ± 0.4°C and inhibited substrate cleavage with IC50 0.39 ± 0.03 μM. Moreover, our docking simulation suggests that baloxavir acid is able to establish an efficient binding with the LACV endonuclease. In the cell-based assay, we observed that baloxavir acid and ribavirin inhibited BUNV-mCherry with an EC50 of 0.7 ± 0.2 μM and 26.6 ± 8.9 μM, respectively. When used in combination, we found a maximum synergistic effect of 8.64. CONCLUSIONS The influenza endonuclease inhibitor baloxavir acid is able to bind to and interfere with the endonuclease domain of orthobunyaviruses and yields a more potent antiviral effect than ribavirin against BUNV-mCherry. The combination of both compounds results in a more potent antiviral effect, suggesting that these molecules could potentially be combined to treat orthobunyavirus-infected patients.
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Affiliation(s)
- Sebastiaan Ter Horst
- KU Leuven, Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Yaiza Fernandez-Garcia
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Germany
| | - Marcella Bassetto
- Department of Chemistry, College of Science, Swansea University, Swansea, UK
| | - Stephan Günther
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Germany
| | - Andrea Brancale
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, UK
| | - Johan Neyts
- KU Leuven, Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Joana Rocha-Pereira
- KU Leuven, Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
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16
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Simanjuntak Y, Schamoni-Kast K, Grün A, Uetrecht C, Scaturro P. Top-Down and Bottom-Up Proteomics Methods to Study RNA Virus Biology. Viruses 2021; 13:668. [PMID: 33924391 PMCID: PMC8070632 DOI: 10.3390/v13040668] [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: 03/13/2021] [Revised: 04/01/2021] [Accepted: 04/10/2021] [Indexed: 02/06/2023] Open
Abstract
RNA viruses cause a wide range of human diseases that are associated with high mortality and morbidity. In the past decades, the rise of genetic-based screening methods and high-throughput sequencing approaches allowed the uncovering of unique and elusive aspects of RNA virus replication and pathogenesis at an unprecedented scale. However, viruses often hijack critical host functions or trigger pathological dysfunctions, perturbing cellular proteostasis, macromolecular complex organization or stoichiometry, and post-translational modifications. Such effects require the monitoring of proteins and proteoforms both on a global scale and at the structural level. Mass spectrometry (MS) has recently emerged as an important component of the RNA virus biology toolbox, with its potential to shed light on critical aspects of virus-host perturbations and streamline the identification of antiviral targets. Moreover, multiple novel MS tools are available to study the structure of large protein complexes, providing detailed information on the exact stoichiometry of cellular and viral protein complexes and critical mechanistic insights into their functions. Here, we review top-down and bottom-up mass spectrometry-based approaches in RNA virus biology with a special focus on the most recent developments in characterizing host responses, and their translational implications to identify novel tractable antiviral targets.
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Affiliation(s)
- Yogy Simanjuntak
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (Y.S.); (K.S.-K.); (A.G.)
| | - Kira Schamoni-Kast
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (Y.S.); (K.S.-K.); (A.G.)
| | - Alice Grün
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (Y.S.); (K.S.-K.); (A.G.)
- Centre for Structural Systems Biology, 22607 Hamburg, Germany
| | - Charlotte Uetrecht
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (Y.S.); (K.S.-K.); (A.G.)
- Centre for Structural Systems Biology, 22607 Hamburg, Germany
- European XFEL GmbH, 22869 Schenefeld, Germany
| | - Pietro Scaturro
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (Y.S.); (K.S.-K.); (A.G.)
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17
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The Polarity of an Amino Acid at Position 1891 of Severe Fever with Thrombocytopenia Syndrome Virus L Protein Is Critical for the Polymerase Activity. Viruses 2020; 13:v13010033. [PMID: 33375489 PMCID: PMC7823514 DOI: 10.3390/v13010033] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/20/2020] [Accepted: 12/23/2020] [Indexed: 11/30/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome virus subclone B7 shows strong plaque formation and cytopathic effect induction compared with other subclones and the parental strain YG1. Compared to YG1 and the other subclones, only B7 possesses a single substitution in the L protein at the amino acid position 1891, in which N is changed to K (N1891K). In this study, we evaluate the effects of this mutation on L protein activity via a cell-based minigenome assay. Substitutions of N with basic amino acids (K or R) enhanced polymerase activity, while substitutions with an acidic amino acid (E) decreased this activity. Mutation to other neutral amino acids showed no significant effect on activity. These results suggest that the characteristic of the amino acid at position 1891 of the L protein are critical for its function, especially with respect to the charge status. Our data indicate that this C-terminal domain of the L protein may be crucial to its functions in genome transcription and viral replication.
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18
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Fernández-García Y, Horst ST, Bassetto M, Brancale A, Neyts J, Rogolino D, Sechi M, Carcelli M, Günther S, Rocha-Pereira J. Diketo acids inhibit the cap-snatching endonuclease of several Bunyavirales. Antiviral Res 2020; 183:104947. [PMID: 32980445 DOI: 10.1016/j.antiviral.2020.104947] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 08/26/2020] [Accepted: 08/29/2020] [Indexed: 12/12/2022]
Abstract
Several fatal bunyavirus infections lack specific treatment. Here, we show that diketo acids engage a panel of bunyavirus cap-snatching endonucleases, inhibit their catalytic activity and reduce viral replication of a taxonomic representative in vitro. Specifically, the non-salt form of L-742,001 and its derivatives exhibited EC50 values between 5.6 and 6.9 μM against a recombinant BUNV-mCherry virus. Structural analysis and molecular docking simulations identified traits of both the class of chemical entities and the viral target that could help the design of novel, more potent molecules for the development of pan-bunyavirus antivirals.
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Affiliation(s)
- Yaiza Fernández-García
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Germany.
| | | | - Marcella Bassetto
- Department of Chemistry, College of Science, Swansea University, United Kingdom
| | - Andrea Brancale
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff University, United Kingdom
| | - Johan Neyts
- KU Leuven, Rega Institute for Medical Research, Belgium
| | - Dominga Rogolino
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area Delle Scienze, Parma, Italy
| | - Mario Sechi
- Department of Chemistry and Pharmacy, Laboratory of Drug Design and Nanomedicine, University of Sassari, Italy
| | - Mauro Carcelli
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area Delle Scienze, Parma, Italy
| | - Stephan Günther
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Germany
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19
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Garrison AR, Alkhovsky [Альховский Сергей Владимирович] SV, Avšič-Županc T, Bente DA, Bergeron É, Burt F, Di Paola N, Ergünay K, Hewson R, Kuhn JH, Mirazimi A, Papa [Άννα Παπά] A, Sall AA, Spengler JR, Palacios G, Consortium ICTVR. ICTV Virus Taxonomy Profile: Nairoviridae. J Gen Virol 2020; 101:798-799. [PMID: 32840475 PMCID: PMC7641396 DOI: 10.1099/jgv.0.001485] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 08/02/2020] [Indexed: 11/24/2022] Open
Abstract
Members of the family Nairoviridae produce enveloped virions with three single-stranded RNA segments comprising 17.1 to 22.8 kb in total. These viruses are maintained in arthropods and transmitted by ticks to mammals or birds. Crimean-Congo hemorrhagic fever virus is tick-borne and is endemic in most of Asia, Africa, Southern and Eastern Europe whereas Nairobi sheep disease virus, which is also tick-borne, causes lethal haemorrhagic gastroenteritis in small ruminants in Africa and India. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Nairoviridae, which is available at ictv.global/report/nairoviridae.
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Affiliation(s)
| | | | | | | | - Éric Bergeron
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, CDC, Atlanta, Georgia, USA
| | - Felicity Burt
- Division of Virology, National Health Laboratory Service and Division of Virology, University of the Free State, Bloemfontein, Republic of South Africa
| | | | - Koray Ergünay
- Virology Unit. Department of Medical Microbiology, Faulty of Medicine, Hacettepe University, Ankara, Turkey
| | - Roger Hewson
- Public Health England, Porton Down, UK, Wiltshire, Salisbury
| | - Jens H. Kuhn
- Integrated Research Facility at Fort Detrick. NIAID, NIH, Fort Detrick, Frederick, Maryland, USA
| | | | - Anna Papa [Άννα Παπά]
- National Reference Centre for Arboviruses and Haemorrhagic Fever viruses, Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Jessica R. Spengler
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, CDC, Atlanta, Georgia, USA
| | | | - ICTV Report Consortium
- USAMRIID, Fort Detrick, Frederick, Maryland, USA
- D. I. Ivanovsky Institute of Virology of N. F. Gamaleya National Center on Epidemiology and Microbiology of Ministry of Health of Russian Federation, Russia
- University of Ljubljana, Ljubljana Faculty of Medicine, Slovenia
- UTMB, Galveston, Texas, USA
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, CDC, Atlanta, Georgia, USA
- Division of Virology, National Health Laboratory Service and Division of Virology, University of the Free State, Bloemfontein, Republic of South Africa
- Virology Unit. Department of Medical Microbiology, Faulty of Medicine, Hacettepe University, Ankara, Turkey
- Public Health England, Porton Down, UK, Wiltshire, Salisbury
- Integrated Research Facility at Fort Detrick. NIAID, NIH, Fort Detrick, Frederick, Maryland, USA
- Folkhalsomyndigheten, Stockholm, Sweden
- National Reference Centre for Arboviruses and Haemorrhagic Fever viruses, Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
- Institut Pasteur de Dakar, Dakar, Senegal
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20
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Tchesnokov EP, Bailey-Elkin BA, Mark BL, Götte M. Independent inhibition of the polymerase and deubiquitinase activities of the Crimean-Congo Hemorrhagic Fever Virus full-length L-protein. PLoS Negl Trop Dis 2020; 14:e0008283. [PMID: 32497085 PMCID: PMC7271988 DOI: 10.1371/journal.pntd.0008283] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 04/09/2020] [Indexed: 11/17/2022] Open
Abstract
Background The Crimean-Congo hemorrhagic fever virus (CCHFV) is a segmented negative-sense RNA virus that can cause severe human disease. The World Health Organization (WHO) has listed CCHFVas a priority pathogen with an urgent need for enhanced research activities to develop effective countermeasures. Here we adopted a biochemical approach that targets the viral RNA-dependent RNA polymerase (RdRp). The CCHFV RdRp activity is part of a multifunctional L protein that is unusually large with a molecular weight of ~450 kDa. The CCHFV L-protein also contains an ovarian tumor (OTU) domain that exhibits deubiquitinating (DUB) activity, which was shown to interfere with innate immune responses and viral replication. We report on the expression, characterization and inhibition of the CCHFV full-length L-protein and studied both RNA synthesis and DUB activity. Methodology/Principle findings Recombinant full-length CCHFV L protein was expressed in insect cells and purified to near homogeneity using affinity chromatography. RdRp activity was monitored with model primer/templates during elongation in the presence of divalent metal ions. We observed a 14-mer full length RNA product as well as the expected shorter products when omitting certain nucleotides from the reaction mixture. The D2517N mutation of the putative active site rendered the enzyme inactive. Inhibition of RNA synthesis was studies with the broad-spectrum antivirals ribavirin and favipiravir that mimic nucleotide substrates. The triphosphate form of these compounds act like ATP or GTP; however, incorporation of ATP or GTP is markedly favored over the inhibitors. We also studied the effects of bona fide nucleotide analogues 2’-deoxy-2’-fluoro-CTP (FdC) and 2’-deoxy-2’-amino-CTP and demonstrate increased inhibitory effects due to higher rates of incorporation. We further show that the CCHFV L full-length protein and the isolated OTU domain cleave Lys48- and Lys63-linked polyubiqutin chains. Moreover, the ubiquitin analogue CC.4 inhibits the CCHFV-associated DUB activity of the full-length L protein and the isolated DUB domain to a similar extent. Inhibition of DUB activity does not affect elongation of RNA synthesis, and inhibition of RNA synthesis does not affect DUB activity. Both domains are functionally independent under these conditions. Conclusions/Significance The requirements for high biosafety measures hamper drug discovery and development efforts with infectious CCHFV. The availability of full-length CCHFV L-protein provides an important tool in this regard. High-throughput screening (HTS) campaigns are now feasible. The same enzyme preparations can be employed to identify novel polymerase and DUB inhibitors. The tick-born Crimean-Congo hemorrhagic fever virus (CCHFV) causes severe human disease with high fatality rates. Outbreaks have been documented in a large geographic area from Africa to Asia. Unfortunately, vaccines that would prevent infection with the virus or antiviral drugs that can be administered for disease treatment are not available. Biosafety requirements further impede research in this area. The development of biochemical tools could potentially address this problem. Here we have expressed recombinant viral L-protein in insect cells. The L-protein is unusually large and exhibits RNA synthesis and deubiquitinating activities that are required for efficient viral growth. We have demonstrated that two distinct activities can be monitored in biochemical assays. Inhibition of these activities was shown with prototypic compounds. Hence, the purified L-protein provides an attractive target and tool for future drug discovery and development efforts.
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Affiliation(s)
- Egor P Tchesnokov
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada.,Li Ka Shing Institute of Virology at University of Alberta, Edmonton, Alberta, Canada
| | | | - Brian L Mark
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Matthias Götte
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada.,Li Ka Shing Institute of Virology at University of Alberta, Edmonton, Alberta, Canada
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21
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Vogel D, Thorkelsson SR, Quemin ERJ, Meier K, Kouba T, Gogrefe N, Busch C, Reindl S, Günther S, Cusack S, Grünewald K, Rosenthal M. Structural and functional characterization of the severe fever with thrombocytopenia syndrome virus L protein. Nucleic Acids Res 2020; 48:5749-5765. [PMID: 32313945 PMCID: PMC7261188 DOI: 10.1093/nar/gkaa253] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/31/2020] [Accepted: 04/03/2020] [Indexed: 12/29/2022] Open
Abstract
The Bunyavirales order contains several emerging viruses with high epidemic potential, including Severe fever with thrombocytopenia syndrome virus (SFTSV). The lack of medical countermeasures, such as vaccines and antivirals, is a limiting factor for the containment of any virus outbreak. To develop such antivirals a profound understanding of the viral replication process is essential. The L protein of bunyaviruses is a multi-functional and multi-domain protein performing both virus transcription and genome replication and, therefore, is an ideal drug target. We established expression and purification procedures for the full-length L protein of SFTSV. By combining single-particle electron cryo-microscopy and X-ray crystallography, we obtained 3D models covering ∼70% of the SFTSV L protein in the apo-conformation including the polymerase core region, the endonuclease and the cap-binding domain. We compared this first L structure of the Phenuiviridae family to the structures of La Crosse peribunyavirus L protein and influenza orthomyxovirus polymerase. Together with a comprehensive biochemical characterization of the distinct functions of SFTSV L protein, this work provides a solid framework for future structural and functional studies of L protein-RNA interactions and the development of antiviral strategies against this group of emerging human pathogens.
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Affiliation(s)
- Dominik Vogel
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Hamburg 20359, Germany
| | - Sigurdur Rafn Thorkelsson
- Centre for Structural Systems Biology, Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, University of Hamburg, Hamburg, Germany
| | - Emmanuelle R J Quemin
- Centre for Structural Systems Biology, Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, University of Hamburg, Hamburg, Germany
| | - Kristina Meier
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Hamburg 20359, Germany
| | - Tomas Kouba
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Nadja Gogrefe
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Hamburg 20359, Germany
| | - Carola Busch
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Hamburg 20359, Germany
| | - Sophia Reindl
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Hamburg 20359, Germany
| | - Stephan Günther
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Hamburg 20359, Germany.,German Center for Infection Research (DZIF), Partner site Hamburg - Lübeck - Borstel - Riems, Hamburg 20359, Germany
| | - Stephen Cusack
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Kay Grünewald
- Centre for Structural Systems Biology, Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, University of Hamburg, Hamburg, Germany
| | - Maria Rosenthal
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Hamburg 20359, Germany
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22
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Jones R, Lessoued S, Meier K, Devignot S, Barata-García S, Mate M, Bragagnolo G, Weber F, Rosenthal M, Reguera J. Structure and function of the Toscana virus cap-snatching endonuclease. Nucleic Acids Res 2020; 47:10914-10930. [PMID: 31584100 PMCID: PMC6847833 DOI: 10.1093/nar/gkz838] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 09/14/2019] [Accepted: 10/01/2019] [Indexed: 12/03/2022] Open
Abstract
Toscana virus (TOSV) is an arthropod-borne human pathogen responsible for seasonal outbreaks of fever and meningoencephalitis in the Mediterranean basin. TOSV is a segmented negative-strand RNA virus (sNSV) that belongs to the genus phlebovirus (family Phenuiviridae, order Bunyavirales), encompassing other important human pathogens such as Rift Valley fever virus (RVFV). Here, we carried out a structural and functional characterization of the TOSV cap-snatching endonuclease, an N terminal domain of the viral polymerase (L protein) that provides capped 3′OH primers for transcription. We report TOSV endonuclease crystal structures in the apo form, in complex with a di-ketoacid inhibitor (DPBA) and in an intermediate state of inhibitor release, showing details on substrate binding and active site dynamics. The structure reveals substantial folding rearrangements absent in previously reported cap-snatching endonucleases. These include the relocation of the N terminus and the appearance of new structural motifs important for transcription and replication. The enzyme shows high activity rates comparable to other His+ cap-snatching endonucleases. Moreover, the activity is dependent on conserved residues involved in metal ion and substrate binding. Altogether, these results bring new light on the structure and function of cap-snatching endonucleases and pave the way for the development of specific and broad-spectrum antivirals.
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Affiliation(s)
- Rhian Jones
- Aix-Marseille Université, CNRS, AFMB UMR 7257, 13288 Marseille, France
| | - Sana Lessoued
- Aix-Marseille Université, CNRS, AFMB UMR 7257, 13288 Marseille, France
| | - Kristina Meier
- Bernhard Nocht Institute for Tropical Medicine, Department of Virology, D-20359 Hamburg, Germany
| | - Stéphanie Devignot
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, D-35392 Giessen, Germany
| | | | - Maria Mate
- Aix-Marseille Université, CNRS, AFMB UMR 7257, 13288 Marseille, France
| | | | - Friedemann Weber
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, D-35392 Giessen, Germany
| | - Maria Rosenthal
- Bernhard Nocht Institute for Tropical Medicine, Department of Virology, D-20359 Hamburg, Germany
| | - Juan Reguera
- Aix-Marseille Université, CNRS, AFMB UMR 7257, 13288 Marseille, France.,INSERM, AFMB UMR7257,13288 Marseille, France
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23
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Olschewski S, Cusack S, Rosenthal M. The Cap-Snatching Mechanism of Bunyaviruses. Trends Microbiol 2020; 28:293-303. [PMID: 31948728 DOI: 10.1016/j.tim.2019.12.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 12/09/2019] [Indexed: 11/25/2022]
Abstract
In common with all segmented negative-sense RNA viruses, bunyavirus transcripts contain heterologous sequences at their 5' termini originating from capped host cell RNAs. These heterologous sequences are acquired by a so-called cap-snatching mechanism. Whereas for nuclear replicating influenza virus the source of capped primers as well as the cap-binding and endonuclease activities of the viral polymerase needed for cap snatching have been functionally and structurally well characterized, our knowledge on the expected counterparts of cytoplasmic replicating bunyaviruses is still limited and controversial. This review focuses on the cap-snatching mechanism of bunyaviruses in the light of recent structural and functional data.
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Affiliation(s)
- Silke Olschewski
- Bernhard Nocht Institute for Tropical Medicine, Department of Virology, Hamburg, Germany
| | | | - Maria Rosenthal
- Bernhard Nocht Institute for Tropical Medicine, Department of Virology, Hamburg, Germany.
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24
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Dülfer J, Kadek A, Kopicki JD, Krichel B, Uetrecht C. Structural mass spectrometry goes viral. Adv Virus Res 2019; 105:189-238. [PMID: 31522705 DOI: 10.1016/bs.aivir.2019.07.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Over the last 20 years, mass spectrometry (MS), with its ability to analyze small sample amounts with high speed and sensitivity, has more and more entered the field of structural virology, aiming to investigate the structure and dynamics of viral proteins as close to their native environment as possible. The use of non-perturbing labels in hydrogen-deuterium exchange MS allows for the analysis of interactions between viral proteins and host cell factors as well as their dynamic responses to the environment. Cross-linking MS, on the other hand, can analyze interactions in viral protein complexes and identify virus-host interactions in cells. Native MS allows transferring viral proteins, complexes and capsids into the gas phase and has broken boundaries to overcome size limitations, so that now even the analysis of intact virions is possible. Different MS approaches not only inform about size, stability, interactions and dynamics of virus assemblies, but also bridge the gap to other biophysical techniques, providing valuable constraints for integrative structural modeling of viral complex assemblies that are often inaccessible by single technique approaches. In this review, recent advances are highlighted, clearly showing that structural MS approaches in virology are moving towards systems biology and ever more experiments are performed on cellular level.
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Affiliation(s)
- Jasmin Dülfer
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Alan Kadek
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany; European XFEL GmbH, Schenefeld, Germany
| | - Janine-Denise Kopicki
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Boris Krichel
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Charlotte Uetrecht
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany; European XFEL GmbH, Schenefeld, Germany.
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25
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Panicum Mosaic Virus and Its Satellites Acquire RNA Modifications Associated with Host-Mediated Antiviral Degradation. mBio 2019; 10:mBio.01900-19. [PMID: 31455653 PMCID: PMC6712398 DOI: 10.1128/mbio.01900-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Positive-sense RNA viruses in the Tombusviridae family have genomes lacking a 5' cap structure and prototypical 3' polyadenylation sequence. Instead, these viruses utilize an extensive network of intramolecular RNA-RNA interactions to direct viral replication and gene expression. Here we demonstrate that the genomic RNAs of Panicum mosaic virus (PMV) and its satellites undergo sequence modifications at their 3' ends upon infection of host cells. Changes to the viral and subviral genomes arise de novo within Brachypodium distachyon (herein called Brachypodium) and proso millet, two alternative hosts of PMV, and exist in the infections of a native host, St. Augustinegrass. These modifications are defined by polyadenylation [poly(A)] events and significant truncations of the helper virus 3' untranslated region-a region containing satellite RNA recombination motifs and conserved viral translational enhancer elements. The genomes of PMV and its satellite virus (SPMV) were reconstructed from multiple poly(A)-selected Brachypodium transcriptome data sets. Moreover, the polyadenylated forms of PMV and SPMV RNAs copurify with their respective mature icosahedral virions. The changes to viral and subviral genomes upon infection are discussed in the context of a previously understudied poly(A)-mediated antiviral RNA degradation pathway and the potential impact on virus evolution.IMPORTANCE The genomes of positive-sense RNA viruses have an intrinsic capacity to serve directly as mRNAs upon viral entry into a host cell. These RNAs often lack a 5' cap structure and 3' polyadenylation sequence, requiring unconventional strategies for cap-independent translation and subversion of the cellular RNA degradation machinery. For tombusviruses, critical translational regulatory elements are encoded within the 3' untranslated region of the viral genomes. Here we describe RNA modifications occurring within the genomes of Panicum mosaic virus (PMV), a prototypical tombusvirus, and its satellite agents (i.e., satellite virus and noncoding satellite RNAs), all of which depend on the PMV-encoded RNA polymerase for replication. The atypical RNAs are defined by terminal polyadenylation and truncation events within the 3' untranslated region of the PMV genome. These modifications are reminiscent of host-mediated RNA degradation strategies and likely represent a previously underappreciated defense mechanism against invasive nucleic acids.
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26
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Jérôme H, Rudolf M, Lelke M, Pahlmann M, Busch C, Bockholt S, Wurr S, Günther S, Rosenthal M, Kerber R. Rift Valley fever virus minigenome system for investigating the role of L protein residues in viral transcription and replication. J Gen Virol 2019; 100:1093-1098. [DOI: 10.1099/jgv.0.001281] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Affiliation(s)
- Hanna Jérôme
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Martin Rudolf
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Michaela Lelke
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Meike Pahlmann
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Carola Busch
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Sabrina Bockholt
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Stephanie Wurr
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Stephan Günther
- 2 German Center for Infection Research (DZIF), Partner site Hamburg – Lübeck – Borstel – Riems, Hamburg, Germany
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Maria Rosenthal
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Romy Kerber
- 1 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- 2 German Center for Infection Research (DZIF), Partner site Hamburg – Lübeck – Borstel – Riems, Hamburg, Germany
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27
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Gogrefe N, Reindl S, Günther S, Rosenthal M. Structure of a functional cap-binding domain in Rift Valley fever virus L protein. PLoS Pathog 2019; 15:e1007829. [PMID: 31136637 PMCID: PMC6555543 DOI: 10.1371/journal.ppat.1007829] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/07/2019] [Accepted: 05/08/2019] [Indexed: 11/25/2022] Open
Abstract
Rift Valley fever virus (RVFV) belongs to the family of Phenuiviridae within the order of Bunyavirales. The virus may cause fatal disease both in livestock and humans, and therefore, is of great economical and public health relevance. In analogy to the influenza virus polymerase complex, the bunyavirus L protein is assumed to bind to and cleave off cap structures of cellular mRNAs to prime viral transcription. However, even though the presence of an endonuclease in the N-terminal domain of the L protein has been demonstrated for several bunyaviruses, there is no evidence for a cap-binding site within the L protein. We solved the structure of a C-terminal 117 amino acid-long domain of the RVFV L protein by X-ray crystallography. The overall fold of the domain shows high similarity to influenza virus PB2 cap-binding domain and the putative non-functional cap-binding domain of reptarenaviruses. Upon co-crystallization with m7GTP, we detected the cap-analogue bound between two aromatic side chains as it has been described for other cap-binding proteins. We observed weak but specific interaction with m7GTP rather than GTP in vitro using isothermal titration calorimetry. The importance of m7GTP-binding residues for viral transcription was validated using a RVFV minigenome system. In summary, we provide structural and functional evidence for a cap-binding site located within the L protein of a virus from the Bunyavirales order. Rift Valley fever virus (RVFV) is endemic to sub-Saharan Africa and the Arabian Peninsula and leads to abortions in and death of ruminants. The virus can also be transmitted to humans causing febrile illness up to hemorrhagic fever with the possibility of fatal outcome. As there is currently no human vaccine or specific treatment available and because of the high epidemic potential, WHO has listed RVFV on its R&D Blueprint for urgent development of medical countermeasures. In order to amplify, the virus needs to transcribe and replicate the viral genome inside the cell cytoplasm. For transcription, the virus uses a process called cap-snatching, which is essentially depending on two functions presumed to reside within the large viral L protein: the ability to bind cap-structures and the activity of cleaving them off from cellular mRNA. Both functions could serve as specific targets for antiviral drug design. We identified and solved the structure of the cap-binding domain of RVFV and provide the first evidence for the presence of a functional cap-binding site in the L protein of bunyaviruses. Comparison with cap-binding proteins of related viruses revealed similarities and important differences critical for the development of potential broad-spectrum antivirals.
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Affiliation(s)
- Nadja Gogrefe
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Sophia Reindl
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Stephan Günther
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.,German Center for Infection Research (DZIF), Partner site Hamburg-Lübeck-Borstel-Riems, Germany
| | - Maria Rosenthal
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
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28
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Lin YH, Fujita M, Chiba S, Hyodo K, Andika IB, Suzuki N, Kondo H. Two novel fungal negative-strand RNA viruses related to mymonaviruses and phenuiviruses in the shiitake mushroom (Lentinula edodes). Virology 2019; 533:125-136. [PMID: 31153047 DOI: 10.1016/j.virol.2019.05.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/21/2019] [Accepted: 05/19/2019] [Indexed: 02/04/2023]
Abstract
There is still limited information on the diversity of (-)ssRNA viruses that infect fungi. Here, we have discovered two novel (-)ssRNA mycoviruses in the shiitake mushroom (Lentinula edodes). The first virus has a monopartite RNA genome and relates to that of mymonaviruses (Mononegavirales), especially to Hubei rhabdo-like virus 4 from arthropods and thus designated as Lentinula edodes negative-strand RNA virus 1. The second virus has a putative bipartite RNA genome and is related to the recently discovered bipartite or tripartite phenui-like viruses (Bunyavirales) associated with plants and ticks, and designated as Lentinula edodes negative-strand RNA virus 2 (LeNSRV2). LeNSRV2 is likely the first segmented (-)ssRNA virus known to infect fungi. Its smaller RNA segment encodes a putative nucleocapsid and a plant MP-like protein using a potential ambisense coding strategy. These findings enhance our understanding of the diversity, evolution and spread of (-)ssRNA viruses in fungi.
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Affiliation(s)
- Yu-Hsin Lin
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki 710-0046, Japan
| | - Miki Fujita
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki 710-0046, Japan
| | - Sotaro Chiba
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; Asian Satellite Campuses Institute, Nagoya University, Nagoya 464-8601, Japan
| | - Kiwamu Hyodo
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki 710-0046, Japan
| | - Ida Bagus Andika
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki 710-0046, Japan
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki 710-0046, Japan
| | - Hideki Kondo
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki 710-0046, Japan.
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29
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Ter Horst S, Conceição-Neto N, Neyts J, Rocha-Pereira J. Structural and functional similarities in bunyaviruses: Perspectives for pan-bunya antivirals. Rev Med Virol 2019; 29:e2039. [PMID: 30746831 PMCID: PMC7169261 DOI: 10.1002/rmv.2039] [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: 08/13/2018] [Revised: 11/29/2018] [Accepted: 01/17/2019] [Indexed: 01/03/2023]
Abstract
The order of Bunyavirales includes numerous (re)emerging viruses that collectively have a major impact on human and animal health worldwide. There are no vaccines for human use or antiviral drugs available to prevent or treat infections with any of these viruses. The development of efficacious and safe drugs and vaccines is a pressing matter. Ideally, such antivirals possess pan‐bunyavirus antiviral activity, allowing the containment of every bunya‐related threat. The fact that many bunyaviruses need to be handled in laboratories with biosafety level 3 or 4, the great variety of species and the frequent emergence of novel species complicate such efforts. We here examined the potential druggable targets of bunyaviruses, together with the level of conservation of their biological functions, structure, and genetic similarity by means of heatmap analysis. In the light of this, we revised the available models and tools currently available, pointing out directions for antiviral drug discovery.
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Affiliation(s)
- Sebastiaan Ter Horst
- Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, KU Leuven, Leuven, Belgium
| | - Nádia Conceição-Neto
- Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Clinical and Epidemiological Virology, KU Leuven, Leuven, Belgium
| | - Johan Neyts
- Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, KU Leuven, Leuven, Belgium
| | - Joana Rocha-Pereira
- Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, KU Leuven, Leuven, Belgium
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