1
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Hardy K, Lutz M, Takimoto T. Human coronavirus NL63 nsp1 induces degradation of RNA polymerase II to inhibit host protein synthesis. PLoS Pathog 2024; 20:e1012329. [PMID: 38900816 DOI: 10.1371/journal.ppat.1012329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 06/09/2024] [Indexed: 06/22/2024] Open
Abstract
Coronavirus (CoV) nonstructural protein 1 (nsp1) is considered a pathogenic factor due to its ability to inhibit host antiviral responses by inducing general shutoff of host protein synthesis. Nsp1 is expressed by α- and β-CoVs, but its functions and strategies to induce host shutoff are not fully elucidated. We compared the nsp1s from two β-CoVs (SARS-CoV and SARS-CoV-2) and two α-CoVs (NL63 and 229E) and found that NL63 nsp1 has the strongest shutoff activity. Unlike SARS-CoV nsp1s, which bind to 40S ribosomes and block translation of cellular mRNA, NL63 nsp1 did not inhibit translation of mRNAs transfected into cells. Instead, NL63 nsp1 localized to the nucleus and specifically inhibited transcription of genes under an RNA polymerase II (RNAPII) promoter. Further analysis revealed that NL63 nsp1 induces degradation of the largest subunit of RNAPII, Rpb1. This degradation was detected regardless of the phosphorylation state of Rpb1 and was blocked by the proteasome inhibitor MG132. We also found that Rpb1 was ubiquitinated in NL63-infected cells, and inhibition of ubiquitination by a ubiquitin activating enzyme inhibitor (TAK243) prevented degradation of Rpb1 in virus-infected cells. These data reveal an unrecognized strategy of host shutoff by human α-CoV NL63: targeting host transcription by inducing Rpb1 degradation to prevent host protein expression. Our study indicates that viruses within the same family can use completely distinct mechanisms to regulate host antiviral responses.
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Affiliation(s)
- Kala Hardy
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Michael Lutz
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Toru Takimoto
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
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2
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Li M. Innate immune response against vector-borne bunyavirus infection and viral countermeasures. Front Cell Infect Microbiol 2024; 14:1365221. [PMID: 38711929 PMCID: PMC11070517 DOI: 10.3389/fcimb.2024.1365221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 03/29/2024] [Indexed: 05/08/2024] Open
Abstract
Bunyaviruses are a large group of important viral pathogens that cause significant diseases in humans and animals worldwide. Bunyaviruses are enveloped, single-stranded, negative-sense RNA viruses that infect a wide range of hosts. Upon entry into host cells, the components of viruses are recognized by host innate immune system, leading to the activation of downstream signaling cascades to induce interferons (IFNs) and other proinflammatory cytokines. IFNs bind to their receptors and upregulate the expression of hundreds of interferon-stimulated genes (ISGs). Many ISGs have antiviral activities and confer an antiviral state to host cells. For efficient replication and spread, viruses have evolved different strategies to antagonize IFN-mediated restriction. Here, we discuss recent advances in our understanding of the interactions between bunyaviruses and host innate immune response.
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Affiliation(s)
- Minghua Li
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
- Center for Tropical Diseases, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
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3
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Lee JS, Kim C. Role of CARD9 in Cell- and Organ-Specific Immune Responses in Various Infections. Int J Mol Sci 2024; 25:2598. [PMID: 38473845 DOI: 10.3390/ijms25052598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/20/2024] [Accepted: 02/21/2024] [Indexed: 03/14/2024] Open
Abstract
The caspase recruitment domain-containing protein 9 (CARD9) is an intracellular adaptor protein that is abundantly expressed in cells of the myeloid lineage, such as neutrophils, macrophages, and dendritic cells. CARD9 plays a critical role in host immunity against infections caused by fungi, bacteria, and viruses. A CARD9 deficiency impairs the production of inflammatory cytokines and chemokines as well as migration and infiltration, thereby increasing susceptibility to infections. However, CARD9 signaling varies depending on the pathogen causing the infection. Furthermore, different studies have reported altered CARD9-mediated signaling even with the same pathogen. Therefore, this review focuses on and elucidates the current literature on varied CARD9 signaling in response to various infectious stimuli in humans and experimental mice models.
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Affiliation(s)
- Ji Seok Lee
- Laboratory of Leukocyte Signaling Research, Department of Pharmacology, Inha University School of Medicine, Incheon 22212, Republic of Korea
- BK21, Program in Biomedical Science & Engineering, Inha University, Incheon 22212, Republic of Korea
| | - Chaekyun Kim
- Laboratory of Leukocyte Signaling Research, Department of Pharmacology, Inha University School of Medicine, Incheon 22212, Republic of Korea
- BK21, Program in Biomedical Science & Engineering, Inha University, Incheon 22212, Republic of Korea
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4
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Okajima M, Takenaka-Uema A, Fujii Y, Izumi F, Kojima I, Ozawa M, Naitou K, Suda Y, Nishiyama S, Murakami S, Horimoto T, Ito N, Shirafuji H, Yanase T, Masatani T. Differential role of NSs genes in the neurovirulence of two genogroups of Akabane virus causing postnatal encephalomyelitis. Arch Virol 2023; 169:7. [PMID: 38082138 DOI: 10.1007/s00705-023-05929-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 10/14/2023] [Indexed: 12/18/2023]
Abstract
Akabane virus (AKAV) is a member of the genus Orthobunyavirus, family Peribunyaviridae. In addition to AKAV strains that cause fetal Akabane disease, which is characterized by abortion in ruminants, some AKAV strains cause postnatal infection characterized by nonsuppurative encephalomyelitis in ruminants. Here, we focused on the NSs protein, a virulence factor for most viruses belonging to the genus Orthobunyavirus, and we hypothesized that this protein would act as a neurovirulence factor in AKAV strains causing postnatal encephalomyelitis. We generated AKAV strains that were unable to produce the NSs protein, derived from two different genogroups, genogroups I and II, and then examined the role of their NSs proteins by inoculating mice intracerebrally with these modified viruses. Our results revealed that the neurovirulence of genogroup II strains is dependent on the NSs protein, whereas that of genogroup I strains is independent of this protein. Notably, infection of primary cultured bovine cells with these viruses suggested that the NSs proteins of both genogroups suppress innate immune-related gene expression with equal efficiency. These results indicate differences in the determinants of virulence of orthobunyaviruses.
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Affiliation(s)
- Misuzu Okajima
- Joint Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Akiko Takenaka-Uema
- Laboratory of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuji Fujii
- Joint Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Fumiki Izumi
- Joint Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Isshu Kojima
- Joint Graduate School of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
| | - Makoto Ozawa
- Joint Graduate School of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
- Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
- Transboundary Animal Diseases Research Center, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
| | - Kiyotada Naitou
- Department of Basic Veterinary Science, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
| | - Yuto Suda
- Kagoshima Research Station, National Institute of Animal Health, NARO, Kagoshima, Japan
| | - Shoko Nishiyama
- Laboratory of Zoonotic Diseases, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Shin Murakami
- Laboratory of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Taisuke Horimoto
- Laboratory of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Naoto Ito
- Joint Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
- Laboratory of Zoonotic Diseases, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
- Center for One Medicine Innovative Translational Research (COMIT), Gifu University, Gifu, Japan
| | - Hiroaki Shirafuji
- Kagoshima Research Station, National Institute of Animal Health, NARO, Kagoshima, Japan
| | - Tohru Yanase
- Kagoshima Research Station, National Institute of Animal Health, NARO, Kagoshima, Japan
| | - Tatsunori Masatani
- Joint Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
- Laboratory of Zoonotic Diseases, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan.
- Center for One Medicine Innovative Translational Research (COMIT), Gifu University, Gifu, Japan.
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5
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Bergant V, Schnepf D, de Andrade Krätzig N, Hubel P, Urban C, Engleitner T, Dijkman R, Ryffel B, Steiger K, Knolle PA, Kochs G, Rad R, Staeheli P, Pichlmair A. mRNA 3'UTR lengthening by alternative polyadenylation attenuates inflammatory responses and correlates with virulence of Influenza A virus. Nat Commun 2023; 14:4906. [PMID: 37582777 PMCID: PMC10427651 DOI: 10.1038/s41467-023-40469-6] [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: 02/13/2023] [Accepted: 07/27/2023] [Indexed: 08/17/2023] Open
Abstract
Changes of mRNA 3'UTRs by alternative polyadenylation (APA) have been associated to numerous pathologies, but the mechanisms and consequences often remain enigmatic. By combining transcriptomics, proteomics and recombinant viruses we show that all tested strains of IAV, including A/PR/8/34(H1N1) (PR8) and A/Cal/07/2009 (H1N1) (Cal09), cause APA. We mapped the effect to the highly conserved glycine residue at position 184 (G184) of the viral non-structural protein 1 (NS1). Unbiased mass spectrometry-based analyses indicate that NS1 causes APA by perturbing the function of CPSF4 and that this function is unrelated to virus-induced transcriptional shutoff. Accordingly, IAV strain PR8, expressing an NS1 variant with weak CPSF binding, does not induce host shutoff but only APA. However, recombinant IAV (PR8) expressing NS1(G184R) lacks binding to CPSF4 and thereby also the ability to cause APA. Functionally, the impaired ability to induce APA leads to an increased inflammatory cytokine production and an attenuated phenotype in a mouse infection model. Investigating diverse viral infection models showed that APA induction is a frequent ability of many pathogens. Collectively, we propose that targeting of the CPSF complex, leading to widespread alternative polyadenylation of host transcripts, constitutes a general immunevasion mechanism employed by a variety of pathogenic viruses.
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Affiliation(s)
- Valter Bergant
- Institute of Virology, TUM School of Medicine, Technical University of Munich, Munich, Germany
- Max Planck Institute of Biochemistry, Munich, Germany
| | - Daniel Schnepf
- Institute of Virology, Medical Center University of Freiburg, Freiburg, Germany
- Immunoregulation Laboratory, The Francis Crick Institute, London, UK
| | - Niklas de Andrade Krätzig
- Institute of Molecular Oncology and Functional Genomics, TUM School of Medicine, Technical University of Munich, Munich, Germany
- Center for Translational Cancer Research (TranslaTUM), TUM School of Medicine, Technical University of Munich, Munich, Germany
| | - Philipp Hubel
- Max Planck Institute of Biochemistry, Munich, Germany
| | - Christian Urban
- Institute of Virology, TUM School of Medicine, Technical University of Munich, Munich, Germany
- Max Planck Institute of Biochemistry, Munich, Germany
| | - Thomas Engleitner
- Institute of Molecular Oncology and Functional Genomics, TUM School of Medicine, Technical University of Munich, Munich, Germany
- Center for Translational Cancer Research (TranslaTUM), TUM School of Medicine, Technical University of Munich, Munich, Germany
| | - Ronald Dijkman
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Institute of Virology and Immunology, Bern & Mittelhäusern, Switzerland
- Department of Infectious diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Bernhard Ryffel
- CNRS, UMR7355, Orleans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Katja Steiger
- Institut für allgemeine Pathologie und Pathologische Anatomie, TUM School of Medicine, Technical University of Munich, Munich, Germany
| | - Percy A Knolle
- Institute of Molecular Immunology and Experimental Oncology, TUM School of Medicine, Technical University of Munich, Munich, Germany
| | - Georg Kochs
- Institute of Virology, Medical Center University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Roland Rad
- Institute of Molecular Oncology and Functional Genomics, TUM School of Medicine, Technical University of Munich, Munich, Germany
- Center for Translational Cancer Research (TranslaTUM), TUM School of Medicine, Technical University of Munich, Munich, Germany
- Department of Medicine II, TUM School of Medicine, Technical University of Munich, Munich, Germany
| | - Peter Staeheli
- Institute of Virology, Medical Center University of Freiburg, Freiburg, Germany
| | - Andreas Pichlmair
- Institute of Virology, TUM School of Medicine, Technical University of Munich, Munich, Germany.
- Max Planck Institute of Biochemistry, Munich, Germany.
- German Center for Infection Research (DZIF), Munich Partner Site, Munich, Germany.
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6
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Pan L, Xue Y, Wang K, Zheng X, Islam A, Tapryal N, Chakraborty A, Bacsi A, Ba X, Hazra TK, Boldogh I. Nei-like DNA glycosylase 2 selectively antagonizes interferon-β expression upon respiratory syncytial virus infection. J Biol Chem 2023; 299:105028. [PMID: 37423306 PMCID: PMC10403741 DOI: 10.1016/j.jbc.2023.105028] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 06/20/2023] [Accepted: 06/22/2023] [Indexed: 07/11/2023] Open
Abstract
As part of the antiviral response, cells activate the expressions of type I interferons (IFNs) and proinflammatory mediators to control viral spreading. Viral infections can impact DNA integrity; however, how DNA damage repair coordinates antiviral response remains elusive. Here we report Nei-like DNA glycosylase 2 (NEIL2), a transcription-coupled DNA repair protein, actively recognizes the oxidative DNA substrates induced by respiratory syncytial virus (RSV) infection to set the threshold of IFN-β expression. Our results show that NEIL2 antagonizes nuclear factor κB (NF-κB) acting on the IFN-β promoter early after infection, thus limiting gene expression amplified by type I IFNs. Mice lacking Neil2 are far more susceptible to RSV-induced illness with an exuberant expression of proinflammatory genes and tissue damage, and the administration of NEIL2 protein into the airway corrected these defects. These results suggest a safeguarding function of NEIL2 in controlling IFN-β levels against RSV infection. Due to the short- and long-term side effects of type I IFNs applied in antiviral therapy, NEIL2 may provide an alternative not only for ensuring genome fidelity but also for controlling immune responses.
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Affiliation(s)
- Lang Pan
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, USA
| | - Yaoyao Xue
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, USA
| | - Ke Wang
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, USA
| | - Xu Zheng
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, USA
| | - Azharul Islam
- Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, USA
| | - Nisha Tapryal
- Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, USA
| | - Anirban Chakraborty
- Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, USA
| | - Attila Bacsi
- Faculty of Medicine, Department of Immunology, University of Debrecen, Debrecen, Hungary
| | - Xueqing Ba
- Key Laboratory of Molecular Epigenetics of Ministry of Education, School of Life Science, Northeast Normal University, Changchun, Jilin, China
| | - Tapas K Hazra
- Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, USA
| | - Istvan Boldogh
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, USA.
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7
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Boutzoukas AE, Freedman DA, Koterba C, Hunt GW, Mack K, Cass J, Yildiz VO, de Los Reyes E, Twanow J, Chung MG, Ouellette CP. La Crosse Virus Neuroinvasive Disease in Children: A Contemporary Analysis of Clinical/Neurobehavioral Outcomes and Predictors of Disease Severity. Clin Infect Dis 2023; 76:e1114-e1122. [PMID: 35607778 PMCID: PMC10169387 DOI: 10.1093/cid/ciac403] [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: 12/10/2021] [Revised: 04/19/2022] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND La Crosse virus (LACV) is the most common neuroinvasive arboviral infection in children in the United States. However, data regarding predictors of disease severity and neurologic outcome are limited. Additionally, long-term neurologic and neurobehavioral outcomes remain relatively sparse. METHODS This was a single-center, retrospective cohort study, followed by recruitment for a cross-sectional analysis of long-term neurobehavioral outcomes, among children aged 0-18 years with proven or probable LACV neuroinvasive disease (LACV-ND) between January 2009 and December 2018. Case ascertainment was assured by International Classification of Diseases, Ninth and Tenth Revision, Clinical Modification codes cross-referenced with laboratory results detecting LACV. Demographics, diagnostics, radiographs, and outcomes were evaluated. Recruitment of patients with prior diagnosis of LACV-ND occurred from January 2020 to March 2020, with assessment performed by validated pediatric questionnaires. RESULTS One-hundred fifty-two children (83 males; median age, 8 years [interquartile range, 5-11.5 years]) were diagnosed with proven (n = 61 [47%]) and probable (n = 91 [60%]) LACV-ND. Sixty-five patients (43%) had severe disease. Altered mental status (AMS) (odds ratio [OR], 6.36 [95% confidence interval {CI}, 2.03-19.95]; P = .0002) and seizures at presentation (OR, 10.31 [95% CI, 3.45-30.86]; P = .0001) were independent predictors of severe disease. Epileptiform discharges on electroencephalogram (EEG) were independently associated with epilepsy diagnosis at follow-up (OR, 13.45 [95% CI, 1.4-128.77]; P = .024). Fifty-four patients were recruited for long-term neurobehavioral follow-up, with frequent abnormal assessments identified (19%-54%) irrespective of disease severity. CONCLUSIONS Severe disease was observed frequently among children with LACV-ND. Seizures and AMS at presentation were independent predictors of severe disease. EEG may help determine long-term epilepsy risk. Long-term neurobehavioral issues are frequent and likely underrecognized among children with LACV-ND.
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Affiliation(s)
- Angelique E Boutzoukas
- Department of Pediatrics, Duke University, Durham, North Carolina, USA.,Duke Clinical Research Institute, Durham, North Carolina, USA
| | | | - Christine Koterba
- Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University, Columbus, Ohio, USA.,Division of Psychology and Neuropsychology, Nationwide Children's Hospital, Columbus, OH, USA
| | - Garrett W Hunt
- Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University, Columbus, Ohio, USA.,Division of Infectious Diseases, Nationwide Children's Hospital, Columbus, OH, USA
| | - Kathy Mack
- Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University, Columbus, Ohio, USA.,Division of Laboratory Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Jennifer Cass
- Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University, Columbus, Ohio, USA.,Division of Psychology and Neuropsychology, Nationwide Children's Hospital, Columbus, OH, USA
| | - Vedat O Yildiz
- Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Emily de Los Reyes
- Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University, Columbus, Ohio, USA.,Division of Neurology, Nationwide Children's Hospital, Columbus, OH, USA
| | - Jaime Twanow
- Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University, Columbus, Ohio, USA.,Division of Neurology, Nationwide Children's Hospital, Columbus, OH, USA
| | - Melissa G Chung
- Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University, Columbus, Ohio, USA.,Division of Neurology, Nationwide Children's Hospital, Columbus, OH, USA.,Division of Critical Care Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Christopher P Ouellette
- Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University, Columbus, Ohio, USA.,Division of Infectious Diseases, Nationwide Children's Hospital, Columbus, OH, USA.,Host Defense Program, Nationwide Children's Hospital, Columbus, OH, USA
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8
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Gulyas L, Glaunsinger BA. RNA polymerase II subunit modulation during viral infection and cellular stress. Curr Opin Virol 2022; 56:101259. [PMID: 36162260 PMCID: PMC10150648 DOI: 10.1016/j.coviro.2022.101259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/10/2022] [Accepted: 08/15/2022] [Indexed: 11/03/2022]
Abstract
Control of gene expression, including transcription, is central in dictating the outcome of viral infection. One of the profound alterations induced by viruses is modification to the integrity and function of eukaryotic RNA polymerase II (Pol II). Here, we discuss how infection perturbs the Pol II complex by altering subunit phosphorylation and turnover, as well as how cellular genotoxic stress (e.g. DNA damage) elicits similar outcomes. By highlighting emerging parallels and differences in Pol II control during viral infection and abiotic stress, we hope to bolster identification of pathways that target Pol II and regulate the transcriptome.
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Affiliation(s)
- Leah Gulyas
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - Britt A Glaunsinger
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA 94709, USA.
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9
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Boshra H. An Overview of the Infectious Cycle of Bunyaviruses. Viruses 2022; 14:v14102139. [PMID: 36298693 PMCID: PMC9610998 DOI: 10.3390/v14102139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 09/19/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
Bunyaviruses represent the largest group of RNA viruses and are the causative agent of a variety of febrile and hemorrhagic illnesses. Originally characterized as a single serotype in Africa, the number of described bunyaviruses now exceeds over 500, with its presence detected around the world. These predominantly tri-segmented, single-stranded RNA viruses are transmitted primarily through arthropod and rodent vectors and can infect a wide variety of animals and plants. Although encoding for a small number of proteins, these viruses can inflict potentially fatal disease outcomes and have even developed strategies to suppress the innate antiviral immune mechanisms of the infected host. This short review will attempt to provide an overall description of the order Bunyavirales, describing the mechanisms behind their infection, replication, and their evasion of the host immune response. Furthermore, the historical context of these viruses will be presented, starting from their original discovery almost 80 years ago to the most recent research pertaining to viral replication and host immune response.
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Affiliation(s)
- Hani Boshra
- Global Urgent and Advanced Research and Development (GUARD), 911 Rue Principale, Batiscan, QC G0X 1A0, Canada
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10
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Hollidge BS, Salzano MV, Ibrahim JM, Fraser JW, Wagner V, Leitner NE, Weiss SR, Weber F, González-Scarano F, Soldan SS. Targeted Mutations in the Fusion Peptide Region of La Crosse Virus Attenuate Neuroinvasion and Confer Protection against Encephalitis. Viruses 2022; 14:1464. [PMID: 35891445 PMCID: PMC9317099 DOI: 10.3390/v14071464] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/25/2022] [Accepted: 06/29/2022] [Indexed: 02/06/2023] Open
Abstract
La Crosse virus (LACV) is a major cause of pediatric encephalitis and aseptic meningitis in the Midwestern, Mid-Atlantic, and Southern United States, where it is an emerging pathogen. The LACV Gc glycoprotein plays a critical role in the neuropathogenesis of LACV encephalitis as the putative virus attachment protein. Previously, we identified and experimentally confirmed the location of the LACV fusion peptide within Gc and generated a panel of recombinant LACVs (rLACVs) containing mutations in the fusion peptide as well as the wild-type sequence. These rLACVs retained their ability to cause neuronal death in a primary embryonic rat neuronal culture system, despite decreased replication and fusion phenotypes. To test the role of the fusion peptide in vivo, we tested rLACVs in an age-dependent murine model of LACV encephalitis. When inoculated directly into the CNS of young adult mice (P28), the rLACV fusion peptide mutants were as neurovirulent as the rLACV engineered with a wild-type sequence, confirming the results obtained in tissue culture. In contrast, the fusion peptide mutant rLACVs were less neuroinvasive when suckling (P3) or weanling (P21) mice were inoculated peripherally, demonstrating that the LACV fusion peptide is a determinant of neuroinvasion, but not of neurovirulence. In a challenge experiment, we found that peripheral challenge of weanling (P21) mice with fusion peptide mutant rLACVs protected from a subsequent WT-LACV challenge, suggesting that mutations in the fusion peptide are an attractive target for generating live-attenuated virus vaccines. Importantly, the high degree of conservation of the fusion peptide amongst the Bunyavirales and, structurally, other arboviruses suggests that these findings are broadly applicable to viruses that use a class II fusion mechanism and cause neurologic disease.
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Affiliation(s)
- Bradley S. Hollidge
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA; (B.S.H.); (M.-V.S.); (J.M.I.); (J.W.F.); (N.E.L.); (S.R.W.); (F.G.-S.)
- Neuroscience Graduate Group, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Mary-Virginia Salzano
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA; (B.S.H.); (M.-V.S.); (J.M.I.); (J.W.F.); (N.E.L.); (S.R.W.); (F.G.-S.)
| | - John M. Ibrahim
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA; (B.S.H.); (M.-V.S.); (J.M.I.); (J.W.F.); (N.E.L.); (S.R.W.); (F.G.-S.)
| | - Jonathan W. Fraser
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA; (B.S.H.); (M.-V.S.); (J.M.I.); (J.W.F.); (N.E.L.); (S.R.W.); (F.G.-S.)
| | - Valentina Wagner
- Abteilung Virologie, Institut für Medizinische Mikrobiologie und Hygiene, Universität Freiburg, 79008 Freiburg, Germany; (V.W.); (F.W.)
| | - Nicole E. Leitner
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA; (B.S.H.); (M.-V.S.); (J.M.I.); (J.W.F.); (N.E.L.); (S.R.W.); (F.G.-S.)
| | - Susan R. Weiss
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA; (B.S.H.); (M.-V.S.); (J.M.I.); (J.W.F.); (N.E.L.); (S.R.W.); (F.G.-S.)
| | - Friedemann Weber
- Abteilung Virologie, Institut für Medizinische Mikrobiologie und Hygiene, Universität Freiburg, 79008 Freiburg, Germany; (V.W.); (F.W.)
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, 35392 Giessen, Germany
| | - Francisco González-Scarano
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA; (B.S.H.); (M.-V.S.); (J.M.I.); (J.W.F.); (N.E.L.); (S.R.W.); (F.G.-S.)
| | - Samantha S. Soldan
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA; (B.S.H.); (M.-V.S.); (J.M.I.); (J.W.F.); (N.E.L.); (S.R.W.); (F.G.-S.)
- The Wistar Institute, Philadelphia, PA 19104, USA
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11
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Evans AB, Winkler CW, Peterson KE. Differences in neuroinvasion and protective innate immune pathways between encephalitic California Serogroup orthobunyaviruses. PLoS Pathog 2022; 18:e1010384. [PMID: 35245345 PMCID: PMC8926202 DOI: 10.1371/journal.ppat.1010384] [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: 08/19/2021] [Revised: 03/16/2022] [Accepted: 02/18/2022] [Indexed: 11/22/2022] Open
Abstract
The California serogroup (CSG) of Orthobunyaviruses comprises several members capable of causing neuroinvasive disease in humans, including La Crosse orthobunyavirus (LACV), Jamestown Canyon orthobunyavirus (JCV), and Inkoo orthobunyavirus (INKV). Despite being genetically and serologically closely related, their disease incidences and pathogenesis in humans and mice differ. We have previously shown that following intraperitoneal inoculation of weanling mice, LACV was highly pathogenic while JCV and INKV were not. To determine why there were differences, we examined the ability of these viruses to invade the CNS and compared the host innate immune responses that regulated viral pathogenesis. We found that LACV was always neuroinvasive, which correlated with its high level of neuroinvasive disease. Interestingly, JCV was not neuroinvasive in any mice, while INKV was neuroinvasive in most mice. The type I interferon (IFN) response was critical for protecting mice from both JCV and INKV disease, although in the periphery JCV induced little IFN expression, while INKV induced high IFN expression. Despite their differing neuroinvasive abilities, JCV and INKV shared innate signaling components required for protection. The presence of either cytoplasmic Rig-I-Like Receptor signaling or endosomal Toll-Like Receptor signaling was sufficient to protect mice from JCV or INKV, however, inhibition of both pathways rendered mice highly susceptible to neurological disease. Comparison of IFN and IFN-stimulated gene (ISG) responses to INKV in the brains of resistant wild type (WT) mice and susceptible immune knockout mice showed similar IFN responses in the brain, but WT mice had higher ISG responses, suggesting induction of key ISGs in the brain is critical for protection of mice from INKV. Overall, these results show that the CSG viruses differ in neuroinvasiveness, which can be independent from their neuropathogenicity. The type I IFN response was crucial for protecting mice from CSG virus-induced neurological disease, however, the exact correlates of protection appear to vary between CSG viruses.
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Affiliation(s)
- Alyssa B. Evans
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Clayton W. Winkler
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Karin E. Peterson
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
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12
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Yu J, Zhang W, Huo W, Meng X, Zhong T, Su Y, Liu Y, Liu J, Wang Z, Song F, Zhang S, Li Z, Yu X, Yu X, Hua S. Regulation of host factor γ-H2AX level and location by enterovirus A71 for viral replication. Virulence 2022; 13:241-257. [PMID: 35067196 PMCID: PMC8786350 DOI: 10.1080/21505594.2022.2028482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Numerous viruses manipulate host factors for viral production. We demonstrated that human enterovirus A71 (EVA71), a primary causative agent for hand, foot, and mouth disease (HFMD), increased the level of the DNA damage response (DDR) marker γ-H2AX. DDR is primarily mediated by the ataxia telangiectasia mutated (ATM), ATM and Rad3-related (ATR), or DNA-dependent protein kinase (DNA-PK) pathways. Upregulation of γ-H2AX by EVA71 was dependent on the ATR but not the ATM or DNA-PK pathway. As a nuclear factor, there is no previous evidence of cytoplasmic distribution of γ-H2AX. However, the present findings demonstrated that EVA71 encouraged the localization of γ-H2AX to the cytoplasm. Of note, γ-H2AX formed a complex with structural protein VP3, non-structural protein 3D, and the viral genome. Treatment with an inhibitor or CRISPR/Cas9 technology to decrease or silence the expression of γ-H2AX decreased viral genome replication in host cells; this effect was accompanied by decreased viral protein expression and virions. In animal experiments, caffeine was used to inhibit DDR; the results revealed that caffeine protected neonatal mice from death after infection with EVA71, laying the foundation for new therapeutic applications of caffeine. More importantly, in children with HFMD, γ-H2AX was upregulated in peripheral blood lymphocytes. The consistent in vitro and in vivo data on γ-H2AX from this study suggested that caffeine or other inhibitors of DDR might be novel therapeutic agents for HFMD.
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Affiliation(s)
- Jinghua Yu
- Institute of Virology and AIDS Research, the First Hospital of Jilin University, Jilin University, Changchun, China
| | - Wenyan Zhang
- Institute of Virology and AIDS Research, the First Hospital of Jilin University, Jilin University, Changchun, China
| | - Wenbo Huo
- Department of Experimental Pharmacology and Toxicology, School of Pharmacy, Jilin University, Changchun, China
| | - Xiangling Meng
- Department of Experimental Pharmacology and Toxicology, School of Pharmacy, Jilin University, Changchun, China
| | - Ting Zhong
- Medicinal Chemistry, College of Pharmacy, Changchun University of Chinese Medicine, Changchun, China
| | - Ying Su
- Department of Experimental Pharmacology and Toxicology, School of Pharmacy, Jilin University, Changchun, China
| | - Yumeng Liu
- Department of Experimental Pharmacology and Toxicology, School of Pharmacy, Jilin University, Changchun, China
| | - Jinming Liu
- Department of Experimental Pharmacology and Toxicology, School of Pharmacy, Jilin University, Changchun, China
| | - Zengyan Wang
- Department of Internal Medicine, The First Hospital of Jilin University, Jilin University, Changchun, China
| | - Fengmei Song
- Department of Experimental Pharmacology and Toxicology, School of Pharmacy, Jilin University, Changchun, China
| | - Shuxia Zhang
- Department of Experimental Pharmacology and Toxicology, School of Pharmacy, Jilin University, Changchun, China
| | - Zhaolong Li
- Institute of Virology and AIDS Research, the First Hospital of Jilin University, Jilin University, Changchun, China
| | - Xiaoyan Yu
- Department of Experimental Pharmacology and Toxicology, School of Pharmacy, Jilin University, Changchun, China
| | - Xiaofang Yu
- Institute of Virology and AIDS Research, the First Hospital of Jilin University, Jilin University, Changchun, China
| | - Shucheng Hua
- Department of Internal Medicine, The First Hospital of Jilin University, Jilin University, Changchun, China
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13
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Pei J, Beri NR, Zou AJ, Hubel P, Dorando HK, Bergant V, Andrews RD, Pan J, Andrews JM, Sheehan KCF, Pichlmair A, Amarasinghe GK, Brody SL, Payton JE, Leung DW. Nuclear-localized human respiratory syncytial virus NS1 protein modulates host gene transcription. Cell Rep 2021; 37:109803. [PMID: 34644581 PMCID: PMC8609347 DOI: 10.1016/j.celrep.2021.109803] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 04/28/2021] [Accepted: 09/16/2021] [Indexed: 12/13/2022] Open
Abstract
Human respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections in the pediatric, elderly, and immunocompromised individuals. RSV non-structural protein NS1 is a known cytosolic immune antagonist, but how NS1 modulates host responses remains poorly defined. Here, we observe NS1 partitioning into the nucleus of RSV-infected cells, including the human airway epithelium. Nuclear NS1 coimmunoprecipitates with Mediator complex and is chromatin associated. Chromatin-immunoprecipitation demonstrates enrichment of NS1 that overlaps Mediator and transcription factor binding within the promoters and enhancers of differentially expressed genes during RSV infection. Mutation of the NS1 C-terminal helix reduces NS1 impact on host gene expression. These data suggest that nuclear NS1 alters host responses to RSV infection by binding at regulatory elements of immune response genes and modulating host gene transcription. Our study identifies another layer of regulation by virally encoded proteins that shapes host response and impacts immunity to RSV.
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Affiliation(s)
- Jingjing Pei
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Nina R Beri
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Angela J Zou
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Philipp Hubel
- Innate Immunity Laboratory, Max-Planck Institute of Biochemistry, Martinsried/Munich 82152, Germany
| | - Hannah K Dorando
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Valter Bergant
- Institute for Virology, Technical University of Munich, School of Medicine, 81675 Munich, Germany
| | - Rebecca D Andrews
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jiehong Pan
- Department of Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jared M Andrews
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Kathleen C F Sheehan
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Andreas Pichlmair
- Innate Immunity Laboratory, Max-Planck Institute of Biochemistry, Martinsried/Munich 82152, Germany; Institute for Virology, Technical University of Munich, School of Medicine, 81675 Munich, Germany
| | - Gaya K Amarasinghe
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Steven L Brody
- Department of Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jacqueline E Payton
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Daisy W Leung
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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14
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Host Cell Restriction Factors of Bunyaviruses and Viral Countermeasures. Viruses 2021; 13:v13050784. [PMID: 33925004 PMCID: PMC8146327 DOI: 10.3390/v13050784] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/14/2021] [Accepted: 04/20/2021] [Indexed: 01/01/2023] Open
Abstract
The Bunyavirales order comprises more than 500 viruses (generally defined as bunyaviruses) classified into 12 families. Some of these are highly pathogenic viruses infecting different hosts, including humans, mammals, reptiles, arthropods, birds, and/or plants. Host cell sensing of infection activates the innate immune system that aims at inhibiting viral replication and propagation. Upon recognition of pathogen-associated molecular patterns (PAMPs) by cellular pattern recognition receptors (PRRs), numerous signaling cascades are activated, leading to the production of interferons (IFNs). IFNs act in an autocrine and paracrine manner to establish an antiviral state by inducing the expression of hundreds of IFN-stimulated genes (ISGs). Some of these ISGs are known to restrict bunyavirus infection. Along with other constitutively expressed host cellular factors with antiviral activity, these proteins (hereafter referred to as “restriction factors”) target different steps of the viral cycle, including viral entry, genome transcription and replication, and virion egress. In reaction to this, bunyaviruses have developed strategies to circumvent this antiviral response, by avoiding cellular recognition of PAMPs, inhibiting IFN production or interfering with the IFN-mediated response. Herein, we review the current knowledge on host cellular factors that were shown to restrict infections by bunyaviruses. Moreover, we focus on the strategies developed by bunyaviruses in order to escape the antiviral state developed by the infected cells.
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15
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A Look into Bunyavirales Genomes: Functions of Non-Structural (NS) Proteins. Viruses 2021; 13:v13020314. [PMID: 33670641 PMCID: PMC7922539 DOI: 10.3390/v13020314] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/12/2021] [Accepted: 02/16/2021] [Indexed: 12/13/2022] Open
Abstract
In 2016, the Bunyavirales order was established by the International Committee on Taxonomy of Viruses (ICTV) to incorporate the increasing number of related viruses across 13 viral families. While diverse, four of the families (Peribunyaviridae, Nairoviridae, Hantaviridae, and Phenuiviridae) contain known human pathogens and share a similar tri-segmented, negative-sense RNA genomic organization. In addition to the nucleoprotein and envelope glycoproteins encoded by the small and medium segments, respectively, many of the viruses in these families also encode for non-structural (NS) NSs and NSm proteins. The NSs of Phenuiviridae is the most extensively studied as a host interferon antagonist, functioning through a variety of mechanisms seen throughout the other three families. In addition, functions impacting cellular apoptosis, chromatin organization, and transcriptional activities, to name a few, are possessed by NSs across the families. Peribunyaviridae, Nairoviridae, and Phenuiviridae also encode an NSm, although less extensively studied than NSs, that has roles in antagonizing immune responses, promoting viral assembly and infectivity, and even maintenance of infection in host mosquito vectors. Overall, the similar and divergent roles of NS proteins of these human pathogenic Bunyavirales are of particular interest in understanding disease progression, viral pathogenesis, and developing strategies for interventions and treatments.
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16
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Tufegdžić Vidaković A, Mitter R, Kelly GP, Neumann M, Harreman M, Rodríguez-Martínez M, Herlihy A, Weems JC, Boeing S, Encheva V, Gaul L, Milligan L, Tollervey D, Conaway RC, Conaway JW, Snijders AP, Stewart A, Svejstrup JQ. Regulation of the RNAPII Pool Is Integral to the DNA Damage Response. Cell 2020; 180:1245-1261.e21. [PMID: 32142654 PMCID: PMC7103762 DOI: 10.1016/j.cell.2020.02.009] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 12/23/2019] [Accepted: 02/04/2020] [Indexed: 12/27/2022]
Abstract
In response to transcription-blocking DNA damage, cells orchestrate a multi-pronged reaction, involving transcription-coupled DNA repair, degradation of RNA polymerase II (RNAPII), and genome-wide transcription shutdown. Here, we provide insight into how these responses are connected by the finding that ubiquitylation of RNAPII itself, at a single lysine (RPB1 K1268), is the focal point for DNA-damage-response coordination. K1268 ubiquitylation affects DNA repair and signals RNAPII degradation, essential for surviving genotoxic insult. RNAPII degradation results in a shutdown of transcriptional initiation, in the absence of which cells display dramatic transcriptome alterations. Additionally, regulation of RNAPII stability is central to transcription recovery-persistent RNAPII depletion underlies the failure of this process in Cockayne syndrome B cells. These data expose regulation of global RNAPII levels as integral to the cellular DNA-damage response and open the intriguing possibility that RNAPII pool size generally affects cell-specific transcription programs in genome instability disorders and even normal cells.
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Affiliation(s)
- Ana Tufegdžić Vidaković
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Richard Mitter
- Bioinformatics and Biostatistics, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Gavin P Kelly
- Bioinformatics and Biostatistics, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michelle Neumann
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michelle Harreman
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Marta Rodríguez-Martínez
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Anna Herlihy
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Juston C Weems
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Stefan Boeing
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Vesela Encheva
- Protein Analysis and Proteomics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Liam Gaul
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Laura Milligan
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, Scotland
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, Scotland
| | - Ronald C Conaway
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Joan W Conaway
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Ambrosius P Snijders
- Protein Analysis and Proteomics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Aengus Stewart
- Bioinformatics and Biostatistics, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Jesper Q Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
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17
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Elongin C Contributes to RNA Polymerase II Degradation by the Interferon Antagonist NSs of La Crosse Orthobunyavirus. J Virol 2020; 94:JVI.02134-19. [PMID: 31941775 PMCID: PMC7081911 DOI: 10.1128/jvi.02134-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 12/26/2019] [Indexed: 12/21/2022] Open
Abstract
The mosquito-borne La Crosse virus (LACV; genus Orthobunyavirus, family Peribunyaviridae, order Bunyavirales) is prevalent in the United States and can cause severe childhood meningoencephalitis. Its main virulence factor, the nonstructural protein NSs, is a strong inhibitor of the antiviral type I interferon (IFN) system. NSs acts by imposing a global host mRNA synthesis shutoff, mediated by NSs-driven proteasomal degradation of the RPB1 subunit of RNA polymerase II. Here, we show that RPB1 degradation commences as early as 1 h postinfection, and identify the E3 ubiquitin ligase subunit Elongin C (and its binding partners Elongins A and B) as an NSs cofactor involved in RPB1 degradation and in suppression of global as well as IFN-related mRNA synthesis. Mosquito-borne La Crosse virus (LACV; genus Orthobunyavirus, family Peribunyaviridae, order Bunyavirales) causes up to 100 annual cases of severe meningoencephalitis in children and young adults in the United States. A major virulence factor of LACV is the nonstructural protein NSs, which inhibits host cell mRNA synthesis to prevent the induction of antiviral type I interferons (IFN-α/β). To achieve this host transcriptional shutoff, LACV NSs drives the proteasomal degradation of RPB1, the large subunit of mammalian RNA polymerase II. Here, we show that NSs acts in a surprisingly rapid manner, as RPB1 degradation was commencing already at 1 h postinfection. The RPB1 degradation was partially dependent on the cellular E3 ubiquitin ligase subunit Elongin C. Consequently, removal of Elongin C, but also of the subunits Elongin A or B by siRNA transfection partially rescued general RNAP II transcription and IFN-beta mRNA synthesis from the blockade by NSs. In line with these results, LACV NSs was found to trigger the redistribution of Elongin C out of nucleolar speckles, which, however, is an epiphenomenon rather than part of the NSs mechanism. Our study also shows that the molecular phenotype of LACV NSs is different from RNA polymerase II inhibitors like α-amanitin or Rift Valley fever virus NSs, indicating that LACV is unique in involving the Elongin complex to shut off host transcription and IFN response. IMPORTANCE The mosquito-borne La Crosse virus (LACV; genus Orthobunyavirus, family Peribunyaviridae, order Bunyavirales) is prevalent in the United States and can cause severe childhood meningoencephalitis. Its main virulence factor, the nonstructural protein NSs, is a strong inhibitor of the antiviral type I interferon (IFN) system. NSs acts by imposing a global host mRNA synthesis shutoff, mediated by NSs-driven proteasomal degradation of the RPB1 subunit of RNA polymerase II. Here, we show that RPB1 degradation commences as early as 1 h postinfection, and identify the E3 ubiquitin ligase subunit Elongin C (and its binding partners Elongins A and B) as an NSs cofactor involved in RPB1 degradation and in suppression of global as well as IFN-related mRNA synthesis.
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18
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La Crosse Virus Infection of Human Keratinocytes Leads to Interferon-Dependent Apoptosis of Bystander Non-Infected Cells In Vitro. Viruses 2020; 12:v12030253. [PMID: 32106552 PMCID: PMC7150866 DOI: 10.3390/v12030253] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 02/20/2020] [Accepted: 02/20/2020] [Indexed: 12/11/2022] Open
Abstract
Resident cells in the skin serve as the first innate line of defense against insect-borne pathogens, but the role of these cell types in promoting or limiting arbovirus replication is not completely understood. Here, we have examined the outcome of infection of cultured human keratinocyte cells with La Crosse virus (LACV), using a spontaneously transformed cell line, HaCaT. In single cycle infections, keratinocyte HaCaT cells supported rapid and high level LACV replication, resulting in high virus yields and extensive caspase-dependent cell death. By contrast, multi-cycle LACV replication in HaCaT cells was restricted by an antiviral response elicited by the production of both IFN-β and IFN-λ. During low multiplicity LACV infections, HaCaT cell death was seen in non-infected bystander cells. Media from LACV-infected cells induced caspase-dependent killing of naïve non-infected HaCaT cells, and this bystander cell death was relieved by IFN-β neutralizing antibodies or by an inhibitor of JAK-STAT signaling. Naïve HaCaT cells showed dose-dependent killing by treatment with exogenous IFN-β but not IFN-λ. Our data suggest a model whereby keratinocytes produce IFNs which limit virus spread through both antiviral signaling and by induction of bystander cell death of potential new target cells for infection.
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19
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Hartenian E, Gilbertson S, Federspiel JD, Cristea IM, Glaunsinger BA. RNA decay during gammaherpesvirus infection reduces RNA polymerase II occupancy of host promoters but spares viral promoters. PLoS Pathog 2020; 16:e1008269. [PMID: 32032393 PMCID: PMC7032723 DOI: 10.1371/journal.ppat.1008269] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 02/20/2020] [Accepted: 12/09/2019] [Indexed: 12/11/2022] Open
Abstract
In mammalian cells, widespread acceleration of cytoplasmic mRNA degradation is linked to impaired RNA polymerase II (Pol II) transcription. This mRNA decay-induced transcriptional repression occurs during infection with gammaherpesviruses including Kaposi’s sarcoma-associated herpesvirus (KSHV) and murine gammaherpesvirus 68 (MHV68), which encode an mRNA endonuclease that initiates widespread RNA decay. Here, we show that MHV68-induced mRNA decay leads to a genome-wide reduction of Pol II occupancy at mammalian promoters. This reduced Pol II occupancy is accompanied by down-regulation of multiple Pol II subunits and TFIIB in the nucleus of infected cells, as revealed by mass spectrometry-based global measurements of protein abundance. Viral genes, despite the fact that they require Pol II for transcription, escape transcriptional repression. Protection is not governed by viral promoter sequences; instead, location on the viral genome is both necessary and sufficient to escape the transcriptional repression effects of mRNA decay. We propose a model in which the ability to escape from transcriptional repression is linked to the localization of viral DNA within replication compartments, providing a means for these viruses to counteract decay-induced transcript loss. While transcription and messenger RNA (mRNA) decay are often considered to be the unlinked beginning and end of gene expression, recent data indicate that alterations to either stage can impact the other. Here we study this connection in the context of lytic gammaherpesvirus infection, which accelerates mRNA degradation through the expression of the viral endonuclease muSOX. We show that RNA polymerase II promoter occupancy is broadly reduced across mammalian promoters in response to infection-induced mRNA decay, and that this phenotype correlates with a reduction in the abundance of several proteins involved in transcription. Notably, gammaherpesviral promoters are resistant to the ensuing transcriptional repression. We show that viral transcriptional escape is conferred by localization of the viral DNA within the protective environment of replication compartments, which are sites of viral genome replication and transcription during infection. Collectively, these findings clarify how mRNA degradation by gammaherpesviruses reshapes the cellular environment and selectively dampens host gene transcription.
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Affiliation(s)
- Ella Hartenian
- Department of Molecular and Cell Biology, University of California Berkeley, CA, United States of America
| | - Sarah Gilbertson
- Department of Molecular and Cell Biology, University of California Berkeley, CA, United States of America
| | - Joel D. Federspiel
- Department of Molecular Biology, Princeton University, Princeton, United States of America
| | - Ileana M. Cristea
- Department of Molecular Biology, Princeton University, Princeton, United States of America
| | - Britt A. Glaunsinger
- Department of Molecular and Cell Biology, University of California Berkeley, CA, United States of America
- Department of Plant and Microbial Biology, University of California Berkeley, CA, United States of America
- Howard Hughes Medical Institute, University of California Berkeley, CA, United States of America
- * E-mail:
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20
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Throw out the Map: Neuropathogenesis of the Globally Expanding California Serogroup of Orthobunyaviruses. Viruses 2019; 11:v11090794. [PMID: 31470541 PMCID: PMC6784171 DOI: 10.3390/v11090794] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 12/19/2022] Open
Abstract
The California serogroup (CSG) comprises 18 serologically and genetically related mosquito-borne orthobunyaviruses. Of these viruses, at least seven have been shown to cause neurological disease in humans, including the leading cause of pediatric arboviral encephalitis in the USA, La Crosse virus. Despite the disease burden from these viruses, much is still unknown about the CSG viruses. This review summarizes our current knowledge of the CSG viruses, including human disease and the mechanisms of neuropathogenesis.
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Tufegdzic Vidakovic A, Harreman M, Dirac-Svejstrup AB, Boeing S, Roy A, Encheva V, Neumann M, Wilson M, Snijders AP, Svejstrup JQ. Analysis of RNA polymerase II ubiquitylation and proteasomal degradation. Methods 2019; 159-160:146-156. [PMID: 30769100 PMCID: PMC6617506 DOI: 10.1016/j.ymeth.2019.02.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 12/19/2022] Open
Abstract
Transcribing RNA polymerase II (RNAPII) is decorated by a plethora of post-translational modifications that mark different stages of transcription. One important modification is RNAPII ubiquitylation, which occurs in response to numerous different stimuli that cause RNAPII stalling, such as DNA damaging agents, RNAPII inhibitors, or depletion of the nucleotide pool. Stalled RNAPII triggers a so-called "last resort pathway", which involves RNAPII poly-ubiquitylation and proteasome-mediated degradation. Different approaches have been described to study RNAPII poly-ubiquitylation and degradation, each method with its own advantages and caveats. Here, we describe optimised strategies for detecting ubiquitylated RNAPII and studying its degradation, but these protocols are suitable for studying other ubiquitylated proteins as well.
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Affiliation(s)
- Ana Tufegdzic Vidakovic
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michelle Harreman
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - A Barbara Dirac-Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Stefan Boeing
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Anindya Roy
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Vesela Encheva
- Protein Analysis and Proteomics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michelle Neumann
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Marcus Wilson
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Ambrosius P Snijders
- Protein Analysis and Proteomics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Jesper Q Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
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22
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Monteiro JT, Schön K, Ebbecke T, Goethe R, Ruland J, Baumgärtner W, Becker SC, Lepenies B. The CARD9-Associated C-Type Lectin, Mincle, Recognizes La Crosse Virus (LACV) but Plays a Limited Role in Early Antiviral Responses against LACV. Viruses 2019; 11:v11030303. [PMID: 30917612 PMCID: PMC6466035 DOI: 10.3390/v11030303] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/22/2019] [Accepted: 03/25/2019] [Indexed: 12/12/2022] Open
Abstract
La Crosse virus (LACV) is a mosquito-transmitted arbovirus and the main cause of virus-mediated neurological diseases in children. To date, little is known about the role of C-type lectin receptors (CLRs)—an important class of pattern recognition receptors—in LACV recognition. DC-SIGN remains the only well-described CLR that recognizes LACV. In this study, we investigated the role of additional CLR/LACV interactions. To this end, we applied a flow-through chromatography method for the purification of LACV to perform an unbiased high-throughput screening of LACV with a CLR-hFc fusion protein library. Interestingly, the CARD9-associated CLRs Mincle, Dectin-1, and Dectin-2 were identified to strongly interact with LACV. Since CARD9 is a common adaptor protein for signaling via Mincle, Dectin-1, and Dectin-2, we performed LACV infection of Mincle−/− and CARD9−/− DCs. Mincle−/− and CARD9−/− DCs produced less amounts of proinflammatory cytokines, namely IL-6 and TNF-α, albeit no reduction of the LACV titer was observed. Together, novel CLR/LACV interactions were identified; however, the Mincle/CARD9 axis plays a limited role in early antiviral responses against LACV.
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Affiliation(s)
- João T Monteiro
- Immunology Unit & Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.
| | - Kathleen Schön
- Immunology Unit & Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.
- Institute for Parasitology and & Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.
| | - Tim Ebbecke
- Immunology Unit & Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.
| | - Ralph Goethe
- Institute for Microbiology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany.
| | - Jürgen Ruland
- Institute of Clinical Chemistry and Pathobiochemistry, School of Medicine, Technical University of Munich, 81675 Munich, Germany.
| | - Wolfgang Baumgärtner
- Department of Pathology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.
| | - Stefanie C Becker
- Institute for Parasitology and & Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.
| | - Bernd Lepenies
- Immunology Unit & Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.
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23
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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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24
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Abstract
Urbanisation and climate change are altering the pattern of California serogroup viruses in North America. As La Crosse virus (LACV) is the most pathogenic of the California serogroup, it is important to identify changes in distribution, transmission and pathogenesis. A scoping review (ScR) was prioritised to summarise the global evidence on LACV. A comprehensive search strategy was used, identified references were screened for relevance and relevant articles were characterised. Each step was conducted by two independent reviewers using pre-tested forms. Analysis identified areas of research saturation and gaps. The ScR included 481 research articles that were mostly journal articles (78.2%) conducted in North America (90.9%) from 1969 to 2016. Most evidence focused on epidemiology (44.9%), virus characteristics (25.8%), transmission conditions (18.7%) and pathogenesis of LACV in hosts (18.3%). Fewer studies evaluated the accuracy of diagnostic tests (8.7%), the efficacy of treatments (3.5%), prevention and control strategies (3.1%), the economic burden of infection (0.6%) and social impact (0.2%) of LACV. None of the literature predicted the impact of climate change on LACV, nor were any cases reported in Canada. These findings are intended to guide research to close knowledge gaps and inform evidence-based decisions surrounding activities for the prevention and control of LACV.
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25
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Comparison of Schmallenberg virus sequences isolated from mammal host and arthropod vector. Virus Genes 2018; 54:792-803. [PMID: 30341640 PMCID: PMC6244546 DOI: 10.1007/s11262-018-1607-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 10/09/2018] [Indexed: 12/20/2022]
Abstract
Schmallenberg virus (SBV) is the member of Peribunyaviridae family, which comprises pathogens of importance for human and veterinary medicine. The virus is transmitted only between animals and mainly by biting midges of the genus Culicoides. This study was performed in order to determine SBV genetic diversity and elucidate the host–vector adaptation. All three viral segments were analysed for sequence variability and phylogenetic relations. The Polish SBV strains obtained from acute infections of cattle, congenital cases in sheep, and from Culicoides midges were sequenced using Sanger and next-generation sequencing (NGS) methods. The obtained sequences were genetically similar (99.2–100% identity) to the first-detected strain BH80/11—4 from German cattle. The sampling year and origin of Polish sequences had no effect on molecular diversity of SBV. Considering all analysed Polish as well as European sequences, ovine-derived sequences were the most variable, while the midge ones were more conserved and encompassed unique substitutions located mainly in nonstructural protein S. SBV sequences isolated from Culicoides are the first submitted to GenBank and reported.
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Abstract
Interferon alpha/beta (IFN-α/β) is a critical mediator of protection against most viruses, with host survival frequently impossible in its absence. Many studies have investigated the pathways involved in the induction of IFN-α/β after virus infection and the resultant upregulation of antiviral IFN-stimulated genes (ISGs) through IFN-α/β receptor complex signaling. However, other than examining the effects of genetic deletion of induction or effector pathway components, little is known regarding the functionality of these responses in intact hosts and whether host genetic or environmental factors might influence their potency. Here, we demonstrate that the IFN-α/β response against multiple arthropod-vectored viruses, which replicate over a wide temperature range, is extremely sensitive to fluctuations in temperature, exhibiting reduced antiviral efficacy at subnormal cellular temperatures and increased efficacy at supranormal temperatures. The effect involves both IFN-α/β and ISG upregulation pathways with a major aspect of altered potency reflecting highly temperature-dependent transcription of IFN response genes that leads to altered IFN-α/β and ISG protein levels. Discordantly, signaling steps prior to transcription that were examined showed the opposite effect from gene transcription, with potentiation at low temperature and inhibition at high temperature. Finally, we demonstrate that by lowering the temperature of mice, chikungunya arbovirus replication and disease are exacerbated in an IFN-α/β-dependent manner. This finding raises the potential for use of hyperthermia as a therapeutic modality for viral infections and in other contexts such as antitumor therapy. The increased IFN-α/β efficacy at high temperatures may also reflect an innate immune-relevant aspect of the febrile response. The interferon alpha/beta (IFN-α/β) response is a first-line innate defense against arthropod-borne viruses (arboviruses). Arboviruses, such as chikungunya virus (CHIKV), can infect cells and replicate across a wide temperature range due to their replication in both mammalian/avian and arthropod hosts. Accordingly, these viruses can cause human disease in tissues regularly exposed to temperatures below the normal mammalian core temperature, 37°C. We questioned whether temperature variation could affect the efficacy of IFN-α/β responses against these viruses and help to explain some aspects of human disease manifestations. We observed that IFN-α/β efficacy was dramatically lower at subnormal temperatures and modestly enhanced at febrile temperatures, with the effects involving altered IFN-α/β response gene transcription but not IFN-α/β pathway signaling. These results provide insight into the functioning of the IFN-α/β response in vivo and suggest that temperature elevation may represent an immune-enhancing therapeutic modality for a wide variety of IFN-α/β-sensitive infections and pathologies.
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27
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Hepatitis C Virus NS5A Targets Nucleosome Assembly Protein NAP1L1 To Control the Innate Cellular Response. J Virol 2017; 91:JVI.00880-17. [PMID: 28659470 DOI: 10.1128/jvi.00880-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 06/19/2017] [Indexed: 12/14/2022] Open
Abstract
Hepatitis C virus (HCV) is a single-stranded positive-sense RNA hepatotropic virus. Despite cellular defenses, HCV is able to replicate in hepatocytes and to establish a chronic infection that could lead to severe complications and hepatocellular carcinoma. An important player in subverting the host response to HCV infection is the viral nonstructural protein NS5A, which, in addition to its role in replication and assembly, targets several pathways involved in the cellular response to viral infection. Several unbiased screens identified nucleosome assembly protein 1-like 1 (NAP1L1) as an interaction partner of HCV NS5A. Here we confirmed this interaction and mapped it to the C terminus of NS5A of both genotype 1 and 2. NS5A sequesters NAP1L1 in the cytoplasm, blocking its nuclear translocation. However, only NS5A from genotype 2 HCV, and not that from genotype 1, targets NAP1L1 for proteosome-mediated degradation. NAP1L1 is a nuclear chaperone involved in chromatin remodeling, and we demonstrated the NAP1L1-dependent regulation of specific pathways involved in cellular responses to viral infection and cell survival. Among those, we showed that lack of NAP1L1 leads to a decrease of RELA protein levels and a strong defect of IRF3 TBK1/IKKε-mediated phosphorylation, leading to inefficient RIG-I and Toll-like receptor 3 (TLR3) responses. Hence, HCV is able to modulate the host cell environment by targeting NAP1L1 through NS5A.IMPORTANCE Viruses have evolved to replicate and to overcome antiviral countermeasures of the infected cell. Hepatitis C virus is capable of establishing a lifelong chronic infection in the liver, which could develop into cirrhosis and cancer. Chronic viruses are particularly able to interfere with the cellular antiviral pathways by several different mechanisms. In this study, we identified a novel cellular target of the viral nonstructural protein NS5A and demonstrated its role in antiviral signaling. This factor, called nucleosome assembly protein 1-like 1 (NAP1L1), is a nuclear chaperone involved in the remodeling of chromatin during transcription. When it is depleted, specific signaling pathways leading to antiviral effectors are affected. Therefore, we provide evidence for both a novel strategy of virus evasion from cellular immunity and a novel role for a cellular protein, which has not been described to date.
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28
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Nonstructural Protein NSs of Schmallenberg Virus Is Targeted to the Nucleolus and Induces Nucleolar Disorganization. J Virol 2016; 91:JVI.01263-16. [PMID: 27795408 PMCID: PMC5165206 DOI: 10.1128/jvi.01263-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/04/2016] [Indexed: 01/04/2023] Open
Abstract
Schmallenberg virus (SBV) was discovered in Germany in late 2011 and then spread rapidly to many European countries. SBV is an orthobunyavirus that causes abortion and congenital abnormalities in ruminants. A virus-encoded nonstructural protein, termed NSs, is a major virulence factor of SBV, and it is known to promote the degradation of Rpb1, a subunit of the RNA polymerase II (Pol II) complex, and therefore hampers global cellular transcription. In this study, we found that NSs is mainly localized in the nucleus of infected cells and specifically appears to target the nucleolus through a nucleolar localization signal (NoLS) localized between residues 33 and 51 of the protein. NSs colocalizes with nucleolar markers such as B23 (nucleophosmin) and fibrillarin. We observed that in SBV-infected cells, B23 undergoes a nucleolus-to-nucleoplasm redistribution, evocative of virus-induced nucleolar disruption. In contrast, the nucleolar pattern of B23 was unchanged upon infection with an SBV recombinant mutant with NSs lacking the NoLS motif (SBVΔNoLS). Interestingly, unlike wild-type SBV, the inhibitory activity of SBVΔNoLS toward RNA Pol II transcription is impaired. Overall, our results suggest that a putative link exists between NSs-induced nucleolar disruption and its inhibitory function on cellular transcription, which consequently precludes the cellular antiviral response and/or induces cell death. IMPORTANCE Schmallenberg virus (SBV) is an emerging arbovirus of ruminants that spread in Europe between 2011 and 2013. SBV induces fetal abnormalities during gestation, with the central nervous system being one of the most affected organs. The virus-encoded NSs protein acts as a virulence factor by impairing host cell transcription. Here, we show that NSs contains a nucleolar localization signal (NoLS) and induces disorganization of the nucleolus. The NoLS motif in the SBV NSs is absolutely necessary for virus-induced inhibition of cellular transcription. To our knowledge, this is the first report of nucleolar functions for NSs within the Bunyaviridae family.
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29
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Bhalla N, Sun C, Metthew Lam LK, Gardner CL, Ryman KD, Klimstra WB. Host translation shutoff mediated by non-structural protein 2 is a critical factor in the antiviral state resistance of Venezuelan equine encephalitis virus. Virology 2016; 496:147-165. [PMID: 27318152 PMCID: PMC5821108 DOI: 10.1016/j.virol.2016.06.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/06/2016] [Accepted: 06/08/2016] [Indexed: 10/21/2022]
Abstract
Most previous studies of interferon-alpha/beta (IFN-α/β) response antagonism by alphaviruses have focused upon interruption of IFN-α/β induction and/or receptor signaling cascades. Infection of mice with Venezuelan equine encephalitis alphavirus (VEEV) or Sindbis virus (SINV) induces serum IFN-α/β, that elicits a systemic antiviral state in uninfected cells successfully controlling SINV but not VEEV replication. Furthermore, VEEV replication is more resistant than that of SINV to a pre-existing antiviral state in vitro. While host macromolecular shutoff is proposed as a major antagonist of IFN-α/β induction, the underlying mechanisms of alphavirus resistance to a pre-existing antiviral state are not fully defined, nor is the mechanism for the greater resistance of VEEV. Here, we have separated viral transcription and translation shutoff with multiple alphaviruses, identified the viral proteins that induce each activity, and demonstrated that VEEV nonstructural protein 2-induced translation shutoff is likely a critical factor in enhanced antiviral state resistance of this alphavirus.
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Affiliation(s)
- Nishank Bhalla
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Chengqun Sun
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - L K Metthew Lam
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Christina L Gardner
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Kate D Ryman
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - William B Klimstra
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States.
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30
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Ly HJ, Ikegami T. Rift Valley fever virus NSs protein functions and the similarity to other bunyavirus NSs proteins. Virol J 2016; 13:118. [PMID: 27368371 PMCID: PMC4930582 DOI: 10.1186/s12985-016-0573-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 06/23/2016] [Indexed: 12/31/2022] Open
Abstract
Rift Valley fever is a mosquito-borne zoonotic disease that affects both ruminants and humans. The nonstructural (NS) protein, which is a major virulence factor for Rift Valley fever virus (RVFV), is encoded on the S-segment. Through the cullin 1-Skp1-Fbox E3 ligase complex, the NSs protein promotes the degradation of at least two host proteins, the TFIIH p62 and the PKR proteins. NSs protein bridges the Fbox protein with subsequent substrates, and facilitates the transfer of ubiquitin. The SAP30-YY1 complex also bridges the NSs protein with chromatin DNA, affecting cohesion and segregation of chromatin DNA as well as the activation of interferon-β promoter. The presence of NSs filaments in the nucleus induces DNA damage responses and causes cell-cycle arrest, p53 activation, and apoptosis. Despite the fact that NSs proteins have poor amino acid similarity among bunyaviruses, the strategy utilized to hijack host cells are similar. This review will provide and summarize an update of recent findings pertaining to the biological functions of the NSs protein of RVFV as well as the differences from those of other bunyaviruses.
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Affiliation(s)
- Hoai J Ly
- Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Tetsuro Ikegami
- Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX, USA. .,The Sealy Center for Vaccine Development, The University of Texas Medical Branch at Galveston, Galveston, TX, USA. .,The Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch at Galveston, Galveston, TX, USA.
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31
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Salimi H, Cain MD, Klein RS. Encephalitic Arboviruses: Emergence, Clinical Presentation, and Neuropathogenesis. Neurotherapeutics 2016; 13:514-34. [PMID: 27220616 PMCID: PMC4965410 DOI: 10.1007/s13311-016-0443-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Arboviruses are arthropod-borne viruses that exhibit worldwide distribution, contributing to systemic and neurologic infections in a variety of geographical locations. Arboviruses are transmitted to vertebral hosts during blood feedings by mosquitoes, ticks, biting flies, mites, and nits. While the majority of arboviral infections do not lead to neuroinvasive forms of disease, they are among the most severe infectious risks to the health of the human central nervous system. The neurologic diseases caused by arboviruses include meningitis, encephalitis, myelitis, encephalomyelitis, neuritis, and myositis in which virus- and immune-mediated injury may lead to severe, persisting neurologic deficits or death. Here we will review the major families of emerging arboviruses that cause neurologic infections, their neuropathogenesis and host neuroimmunologic responses, and current strategies for treatment and prevention of neurologic infections they cause.
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Affiliation(s)
- Hamid Salimi
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Matthew D Cain
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Robyn S Klein
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, USA.
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32
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Fros JJ, Pijlman GP. Alphavirus Infection: Host Cell Shut-Off and Inhibition of Antiviral Responses. Viruses 2016; 8:v8060166. [PMID: 27294951 PMCID: PMC4926186 DOI: 10.3390/v8060166] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Revised: 06/01/2016] [Accepted: 06/07/2016] [Indexed: 12/18/2022] Open
Abstract
Alphaviruses cause debilitating disease in humans and animals and are transmitted by blood-feeding arthropods, typically mosquitoes. With a traditional focus on two models, Sindbis virus and Semliki Forest virus, alphavirus research has significantly intensified in the last decade partly due to the re-emergence and dramatic expansion of chikungunya virus in Asia, Europe, and the Americas. As a consequence, alphavirus–host interactions are now understood in much more molecular detail, and important novel mechanisms have been elucidated. It has become clear that alphaviruses not only cause a general host shut-off in infected vertebrate cells, but also specifically suppress different host antiviral pathways using their viral nonstructural proteins, nsP2 and nsP3. Here we review the current state of the art of alphavirus host cell shut-off of viral transcription and translation, and describe recent insights in viral subversion of interferon induction and signaling, the unfolded protein response, and stress granule assembly.
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Affiliation(s)
- Jelke J Fros
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford OX1 3SY, England, UK.
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen 6700 AB, The Netherlands.
| | - Gorben P Pijlman
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen 6700 AB, The Netherlands.
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33
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RNA-Free and Ribonucleoprotein-Associated Influenza Virus Polymerases Directly Bind the Serine-5-Phosphorylated Carboxyl-Terminal Domain of Host RNA Polymerase II. J Virol 2016; 90:6014-6021. [PMID: 27099314 PMCID: PMC4907247 DOI: 10.1128/jvi.00494-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 04/13/2016] [Indexed: 11/20/2022] Open
Abstract
Influenza viruses subvert the transcriptional machinery of their hosts to synthesize their own viral mRNA. Ongoing transcription by cellular RNA polymerase II (Pol II) is required for viral mRNA synthesis. By a process known as cap snatching, the virus steals short 5′ capped RNA fragments from host capped RNAs and uses them to prime viral transcription. An interaction between the influenza A virus RNA polymerase and the C-terminal domain (CTD) of the large subunit of Pol II has been established, but the molecular details of this interaction remain unknown. We show here that the influenza virus ribonucleoprotein (vRNP) complex binds to the CTD of transcriptionally engaged Pol II. Furthermore, we provide evidence that the viral polymerase binds directly to the serine-5-phosphorylated form of the Pol II CTD, both in the presence and in the absence of viral RNA, and show that this interaction is conserved in evolutionarily distant influenza viruses. We propose a model in which direct binding of the viral RNA polymerase in the context of vRNPs to Pol II early in infection facilitates cap snatching, while we suggest that binding of free viral polymerase to Pol II late in infection may trigger Pol II degradation. IMPORTANCE Influenza viruses cause yearly epidemics and occasional pandemics that pose a threat to human health, as well as represent a large economic burden to health care systems globally. Existing vaccines are not always effective, as they may not exactly match the circulating viruses. Furthermore, there are a limited number of antivirals available, and development of resistance to these is a concern. New measures to combat influenza are needed, but before they can be developed, it is necessary to better understand the molecular interactions between influenza viruses and their host cells. By providing further insights into the molecular details of how influenza viruses hijack the host transcriptional machinery, we aim to uncover novel targets for the development of antivirals.
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34
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NSs Virulence Factor of Rift Valley Fever Virus Engages the F-Box Proteins FBXW11 and β-TRCP1 To Degrade the Antiviral Protein Kinase PKR. J Virol 2016; 90:6140-7. [PMID: 27122577 PMCID: PMC4907219 DOI: 10.1128/jvi.00016-16] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/18/2016] [Indexed: 01/01/2023] Open
Abstract
Rift Valley fever virus (RVFV, family Bunyaviridae, genus Phlebovirus) is a relevant pathogen of both humans and livestock in Africa. The nonstructural protein NSs is a major virulence factor known to suppress the type I interferon (IFN) response by inhibiting host cell transcription and by proteasomal degradation of a major antiviral IFN effector, the translation-inhibiting protein kinase PKR. Here, we identified components of the modular SCF (Skp1, Cul1, F-box protein)-type E3 ubiquitin ligases as mediators of PKR destruction by NSs. Small interfering RNAs (siRNAs) against the conserved SCF subunit Skp1 protected PKR from NSs-mediated degradation. Consequently, RVFV replication was severely reduced in Skp1-depleted cells when PKR was present. SCF complexes have a variable F-box protein subunit that determines substrate specificity for ubiquitination. We performed an siRNA screen for all (about 70) human F-box proteins and found FBXW11 to be involved in PKR degradation. The partial stabilization of PKR by FBXW11 depletion upregulated PKR autophosphorylation and phosphorylation of the PKR substrate eIF2α and caused a shutoff of host cell protein synthesis in RVFV-infected cells. To maximally protect PKR from the action of NSs, knockdown of structurally and functionally related FBXW1 (also known as β-TRCP1), in addition to FBXW11 deletion, was necessary. Consequently, NSs was found to interact with both FBXW11 and β-TRCP1. Thus, NSs eliminates the antiviral kinase PKR by recruitment of SCF-type E3 ubiquitin ligases containing FBXW11 and β-TRCP1 as substrate recognition subunits. This antagonism of PKR by NSs is essential for efficient RVFV replication in mammalian cells. IMPORTANCE Rift Valley fever virus is a pathogen of humans and animals that has the potential to spread from Africa and the Arabian Peninsula to other regions. A major virulence mechanism is the proteasomal degradation of the antiviral kinase PKR by the viral protein NSs. Here, we demonstrate that NSs requires E3 ubiquitin ligase complexes of the SCF (Skp1, Cul1, F-box protein) type to destroy PKR. SCF-type complexes can engage variant ubiquitination substrate recognition subunits, and we found the F-box proteins FBXW11 and β-TRCP1 to be relevant for the action of NSs against PKR. Thus, we identified the host cell factors that are critically needed by Rift Valley fever virus to uphold its replication against the potent antiviral kinase PKR.
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de Souza WM, Acrani GO, Romeiro MF, Reis O, Tolardo AL, da Silva SP, de Almeida Medeiros DB, Varela M, Nunes MRT, Figueiredo LTM. Molecular characterization of Capim and Enseada orthobunyaviruses. INFECTION GENETICS AND EVOLUTION 2016; 40:47-53. [PMID: 26921797 DOI: 10.1016/j.meegid.2016.02.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/19/2016] [Accepted: 02/20/2016] [Indexed: 11/29/2022]
Abstract
Capim and Enseada viruses are members of the genus Orthobunyavirus isolated from mosquitoes and mammals in Brazil. Despite seroprevalence studies indicating human infections in Latin America, these viruses remain relatively unknown and unstudied. In order to better understand the genetic and evolutionary relationships among orthobunyaviruses, we sequenced the three genomic segments of Capim and Enseada orthobunyaviruses. Based on phylogenetic analysis, we demonstrated that these viruses depicted two new distinct clades, one represented by Enseada and another composed of Capim virus. In general, the genome organization and genetic traits of these viruses are similar to other orthobunyaviruses however, the open reading frame (ORF) of the putative nonstructural NSs protein of Enseada orthobunyavirus precedes the nucleocapsid ORF. Overall, our study provides details on the molecular characteristics of the prototype species of two groups within the Orthobunyavirus genus, revealing novel features into the genetic diversity and evolution of this genus.
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Affiliation(s)
- William Marciel de Souza
- Virology Research Center, School of Medicine of Ribeirao Preto of University of São Paulo, Ribeirao Preto, Brazil.
| | - Gustavo Olszanski Acrani
- Department of Cell and Molecular Biology, University of Sao Paulo School of Medicine, Ribeirão Preto, Brazil
| | - Marilia Farignoli Romeiro
- Virology Research Center, School of Medicine of Ribeirao Preto of University of São Paulo, Ribeirao Preto, Brazil
| | - Osvaldo Reis
- Laboratório Central de Tecnologias de Alto Desempenho em Ciências da Vida (LaCTAD), Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
| | - Aline Lavado Tolardo
- Virology Research Center, School of Medicine of Ribeirao Preto of University of São Paulo, Ribeirao Preto, Brazil
| | | | | | - Mariana Varela
- MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow G61 1QH, UK
| | | | - Luiz Tadeu Moraes Figueiredo
- Virology Research Center, School of Medicine of Ribeirao Preto of University of São Paulo, Ribeirao Preto, Brazil
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Activation of the DNA Damage Response by RNA Viruses. Biomolecules 2016; 6:2. [PMID: 26751489 PMCID: PMC4808796 DOI: 10.3390/biom6010002] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 11/17/2015] [Accepted: 11/24/2015] [Indexed: 12/11/2022] Open
Abstract
RNA viruses are a genetically diverse group of pathogens that are responsible for some of the most prevalent and lethal human diseases. Numerous viruses introduce DNA damage and genetic instability in host cells during their lifecycles and some species also manipulate components of the DNA damage response (DDR), a complex and sophisticated series of cellular pathways that have evolved to detect and repair DNA lesions. Activation and manipulation of the DDR by DNA viruses has been extensively studied. It is apparent, however, that many RNA viruses can also induce significant DNA damage, even in cases where viral replication takes place exclusively in the cytoplasm. DNA damage can contribute to the pathogenesis of RNA viruses through the triggering of apoptosis, stimulation of inflammatory immune responses and the introduction of deleterious mutations that can increase the risk of tumorigenesis. In addition, activation of DDR pathways can contribute positively to replication of viral RNA genomes. Elucidation of the interactions between RNA viruses and the DDR has provided important insights into modulation of host cell functions by these pathogens. This review summarises the current literature regarding activation and manipulation of the DDR by several medically important RNA viruses.
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Generation of Recombinant Oropouche Viruses Lacking the Nonstructural Protein NSm or NSs. J Virol 2015; 90:2616-27. [PMID: 26699638 DOI: 10.1128/jvi.02849-15] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/15/2015] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED Oropouche virus (OROV) is a midge-borne human pathogen with a geographic distribution in South America. OROV was first isolated in 1955, and since then, it has been known to cause recurring outbreaks of a dengue-like illness in the Amazonian regions of Brazil. OROV, however, remains one of the most poorly understood emerging viral zoonoses. Here we describe the successful recovery of infectious OROV entirely from cDNA copies of its genome and generation of OROV mutant viruses lacking either the NSm or the NSs coding region. Characterization of the recombinant viruses carried out in vitro demonstrated that the NSs protein of OROV is an interferon (IFN) antagonist as in other NSs-encoding bunyaviruses. Additionally, we demonstrate the importance of the nine C-terminal amino acids of OROV NSs in IFN antagonistic activity. OROV was also found to be sensitive to IFN-α when cells were pretreated; however, the virus was still capable of replicating at doses as high as 10,000 U/ml of IFN-α, in contrast to the family prototype BUNV. We found that OROV lacking the NSm protein displayed characteristics similar to those of the wild-type virus, suggesting that the NSm protein is dispensable for virus replication in the mammalian and mosquito cell lines that were tested. IMPORTANCE Oropouche virus (OROV) is a public health threat in Central and South America, where it causes periodic outbreaks of dengue-like illness. In Brazil, OROV is the second most frequent cause of arboviral febrile illness after dengue virus, and with the current rates of urban expansion, more cases of this emerging viral zoonosis could occur. To better understand the molecular biology of OROV, we have successfully rescued the virus along with mutants. We have established that the C terminus of the NSs protein is important in interferon antagonism and that the NSm protein is dispensable for virus replication in cell culture. The tools described in this paper are important in terms of understanding this important yet neglected human pathogen.
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Abortively Infected Astrocytes Appear To Represent the Main Source of Interferon Beta in the Virus-Infected Brain. J Virol 2015; 90:2031-8. [PMID: 26656686 DOI: 10.1128/jvi.02979-15] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 11/30/2015] [Indexed: 02/04/2023] Open
Abstract
UNLABELLED Interferon beta (IFN-β) is a key component of cellular innate immunity in mammals, and it constitutes the first line of defense during viral infection. Studies with cultured cells previously showed that almost all nucleated cells are able to produce IFN-β to various extents, but information about the in vivo sources of IFN-β remains incomplete. By applying immunohistochemistry and employing conditional-reporter mice that express firefly luciferase under the control of the IFN-β promoter in either all or only distinct cell types, we found that astrocytes are the main producers of IFN-β after infection of the brain with diverse neurotropic viruses, including rabies virus, Theiler's murine encephalomyelitis virus, and vesicular stomatitis virus. Analysis of a panel of knockout mouse strains revealed that sensing of viral components via both RIG-I-like helicases and Toll-like receptors contributes to IFN induction in the infected brain. A genetic approach to permanently mark rabies virus-infected cells in the brain showed that a substantial number of astrocytes became labeled and, therefore, must have been infected by the virus at least transiently. Thus, our results strongly indicate that abortive viral infection of astrocytes can trigger pattern recognition receptor signaling events which result in secretion of IFN-β that confers antiviral protection. IMPORTANCE Previous work indicated that astrocytes are the main producers of IFN after viral infection of the central nervous system (CNS), but it remained unclear how astrocytes might sense those viruses which preferentially replicate in neurons. We have now shown that virus sensing by both RIG-I-like helicases and Toll-like receptors is involved. Our results further demonstrate that astrocytes get infected in a nonproductive manner under these conditions, indicating that abortive infection of astrocytes plays a previously unappreciated role in the innate antiviral defenses of the CNS.
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Abstract
The taxonomic group of Orthobunyaviruses is gaining increased attention, as several emerging members are causing devastating illnesses among humans and livestock. These viruses are transmitted to mammals by arthropods (mostly mosquitoes) during the blood meal. The nature of their genomic RNA predisposes orthobunyaviruses for eliciting a strong innate immune response mediated by pathogen recognition receptors (PRRs), especially the cytoplasmic RIG-I. However, the PRR responses are in fact disabled by the viral non-structural protein NSs. NSs imposes a strong block of cellular gene expression by inhibiting elongating RNA polymerase II. In this review, we will give an overview on the current state of knowledge regarding the interactions between orthobunyaviruses, the PRR axis, and NSs.
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Affiliation(s)
- Andreas Schoen
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany.
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Deletion mutants of Schmallenberg virus are avirulent and protect from virus challenge. J Virol 2014; 89:1825-37. [PMID: 25410877 DOI: 10.1128/jvi.02729-14] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
UNLABELLED Since its emergence, Schmallenberg virus (SBV), a novel insect-transmitted orthobunyavirus which predominantly infects ruminants, has caused a large epidemic in European livestock. Newly developed inactivated vaccines are available, but highly efficacious and safe live vaccines are still not available. Here, the properties of novel recombinant SBV mutants lacking the nonstructural protein NSs (rSBVΔNSs) or NSm (rSBVΔNSm) or both of these proteins (rSBVΔNSs/ΔNSm) were tested in vitro and in vivo in type I interferon receptor knockout mice (IFNAR(-/-)) and in a vaccination/challenge trial in cattle. As for other bunyaviruses, both nonstructural proteins of SBV are not essential for viral growth in vitro. In interferon-defective BHK-21 cells, rSBVΔNSs and rSBVΔNSm replicated to levels comparable to that of the parental rSBV; the double mutant virus, however, showed a mild growth defect, resulting in lower final virus titers. Additionally, both mutants with an NSs deletion induced high levels of interferon and showed a marked growth defect in interferon-competent sheep SFT-R cells. Nevertheless, in IFNAR(-/-) mice, all mutants were virulent, with the highest mortality rate for rSBVΔNSs and a reduced virulence for the NSm-deleted virus. In cattle, SBV lacking NSm caused viremia and seroconversion comparable to those caused by the wild-type virus, while the NSs and the combined NSs/NSm deletion mutant induced no detectable virus replication or clinical disease after immunization. Furthermore, three out of four cattle immunized once with the NSs deletion mutant and all animals vaccinated with the virus lacking both nonstructural proteins were fully protected against a challenge infection. Therefore, the double deletion mutant will provide the basis for further developments of safe and efficacious modified live SBV vaccines which could be also a model for other viruses of the Simbu serogroup and related orthobunyaviruses. IMPORTANCE SBV induces only mild clinical signs in adult ruminants but causes severe fetal malformation and, thereby, can have an important impact on animal welfare and production. As SBV is an insect-transmitted pathogen, vaccination will be one of the most important aspects of disease control. Here, mutant viruses lacking one or two proteins that essentially contribute to viral pathogenicity were tested as modified live vaccines in cattle. It could be demonstrated that a novel recombinant double deletion mutant is a safe and efficacious vaccine candidate. This is the first description of a putative modified live vaccine for the complete genus Orthobunyavirus, and in addition, such a vaccine type has never been tested in cattle for any virus of the entire family Bunyaviridae. Therefore, the described vaccine also represents the first model for a broad range of related viruses and is of high importance to the field.
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Differentiation of neurons restricts Arbovirus replication and increases expression of the alpha isoform of IRF-7. J Virol 2014; 89:48-60. [PMID: 25320290 DOI: 10.1128/jvi.02394-14] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED Susceptibility to alphavirus infection is age dependent, and host maturation is associated with decreased virus replication and less severe encephalitis. To identify factors associated with maturation-dependent restriction of virus replication, we studied AP-7 rat olfactory bulb neuronal cells, which can differentiate in vitro. Differentiation was associated with a 150- to 1,000-fold decrease in replication of the alphaviruses Sindbis virus and Venezuelan equine encephalitis virus, as well as La Crosse bunyavirus. Differentiation delayed synthesis of SINV RNA and protein but did not alter the susceptibility of neurons to infection or virion maturation. Additionally, differentiation slowed virus-induced translation arrest and death of infected cells. Differentiation of uninfected AP-7 neurons was associated with changes in expression of antiviral genes. Expression of key transcription factors was increased, including interferon regulatory factor 3 and 7 (IRF-3 and IRF-7) and STAT-1, suggesting that neuronal maturation may enhance the capacity for antiviral signaling upon infection. IRF-7 produced by undifferentiated AP-7 neurons was exclusively the short dominant negative γ-isoform, while that produced by differentiated neurons was the full-length α-isoform. A similar switch in IRF-7 isoforms also occurred in the brains of maturing C57BL/6J mice. Silencing of IRF expression did not improve virus multiplication in differentiated neurons. Therefore, neuronal differentiation is associated with upregulation of transcription factors that activate antiviral signaling, but this alone does not account for maturation-dependent restriction of virus replication. IMPORTANCE Viral encephalomyelitis is an important cause of age-dependent morbidity and mortality. Because mature neurons are not readily regenerated, recovery from encephalitis suggests that mature neurons utilize unique antiviral mechanisms to block infection and/or clear virus. To identify maturational changes in neurons that may improve outcome, we compared immature and mature cultured neurons for susceptibility to three encephalitic arboviruses and found that replication of Old World and New World alphaviruses and a bunyavirus was reduced in mature compared to immature neurons. Neuronal maturation was associated with increased baseline expression of interferon regulatory factor 3 and 7 mRNAs and production of distinct isoforms of interferon regulatory factor 7 protein. Overall, our studies identified maturational changes in neurons that likely contribute to assembly of immunoregulatory factors prior to infection, a more rapid antiviral response, increased resistance to virus infection, and improved survival.
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Weber M, Weber F. RIG-I-like receptors and negative-strand RNA viruses: RLRly bird catches some worms. Cytokine Growth Factor Rev 2014; 25:621-8. [PMID: 24894317 PMCID: PMC7108359 DOI: 10.1016/j.cytogfr.2014.05.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 05/12/2014] [Indexed: 12/16/2022]
Abstract
Negative strand RNA viruses with a nonsegmented genome (ns-NSVs) or a segmented genome (s-NSVs) are an important source of human and animal diseases. Survival of the host from those infections is critically dependent on rapidly reacting innate immune responses. Two cytoplasmic RNA helicases, RIG-I and MDA5 (collectively termed RIG-I-like receptors, RLRs), are essential for recognizing virus-specific RNA structures to initiate a signalling cascade, resulting in the production of the antiviral type I interferons. Here, we will review the current knowledge and views on RLR agonists, RLR signalling, and the wide variety of countermeasures ns-NSVs and s-NSVs have evolved. Specific aspects include the consequences of genome segmentation for RLR activation and a discussion on the physiological ligands of RLRs.
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Affiliation(s)
- Michaela Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany.
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Abstract
Orthobunyaviruses, which have small, tripartite, negative-sense RNA genomes and structurally simple virions composed of just four proteins, can have devastating effects on human health and well-being, either by causing disease in humans or by causing disease in livestock and crops. In this Review, I describe the recent genetic and structural advances that have revealed important insights into the composition of orthobunyavirus virions, viral transcription and replication and viral interactions with the host innate immune response. Lastly, I highlight outstanding questions and areas of future research.
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Affiliation(s)
- Richard M Elliott
- MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow G61 1QH, UK
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Age-dependent myeloid dendritic cell responses mediate resistance to la crosse virus-induced neurological disease. J Virol 2014; 88:11070-9. [PMID: 25008929 DOI: 10.1128/jvi.01866-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED La Crosse virus (LACV) is the major cause of pediatric viral encephalitis in the United States; however, the mechanisms responsible for age-related susceptibility in the pediatric population are not well understood. Our current studies in a mouse model of LACV infection indicated that differences in myeloid dendritic cell (mDC) responses between weanling and adult mice accounted for susceptibility to LACV-induced neurological disease. We found that type I interferon (IFN) responses were significantly stronger in adult than in weanling mice. Production of these IFNs required both endosomal Toll-like receptors (TLRs) and cytoplasmic RIG-I-like receptors (RLRs). Surprisingly, IFN expression was not dependent on plasmacytoid DCs (pDCs) but rather was dependent on mDCs, which were found in greater number and induced stronger IFN responses in adults than in weanlings. Inhibition of these IFN responses in adults resulted in susceptibility to LACV-induced neurological disease, whereas postinfection treatment with type I IFN provided protection in young mice. These studies provide a definitive mechanism for age-related susceptibility to LACV encephalitis, where mDCs in young mice are insufficiently activated to control peripheral virus replication, thereby allowing virus to persist and eventually cause central nervous system (CNS) disease. IMPORTANCE La Crosse virus (LACV) is the primary cause of pediatric viral encephalitis in the United States. Although the virus infects both adults and children, over 80% of the reported neurological disease cases are in children. To understand why LACV causes neurological disease primarily in young animals, we used a mouse model where weanling mice, but not adult mice, develop neurological disease following virus infection. We found that an early immune response cell type, myeloid dendritic cells, was critical for protection in adult animals and that these cells were reduced in young animals. Activation of these cells during virus infection or after treatment with type I interferon in young animals provided protection from LACV. Thus, this study demonstrates a reason for susceptibility to LACV infection in young animals and shows that early therapeutic treatment in young animals can prevent neurological disease.
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Weber M, Weber F. Segmented negative-strand RNA viruses and RIG-I: divide (your genome) and rule. Curr Opin Microbiol 2014; 20:96-102. [PMID: 24930021 DOI: 10.1016/j.mib.2014.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 05/02/2014] [Accepted: 05/11/2014] [Indexed: 11/18/2022]
Abstract
The group of negative-stranded RNA viruses (NSVs) with a segmented genome comprises pathogens like influenza virus (eight segments), Rift Valley fever virus and Hantavirus (three segments), or Lassa virus (two segments). Partitioning the genome allows rapid evolution of new strains by reassortment. Each segment carries a short double-stranded (ds) 'panhandle' structure which serves as promoter. Similar dsRNA structures, however, represent the optimal ligand for RIG-I, a cytoplasmic pathogen sensor of the antiviral interferon response. Thus, segmenting a virus genome can entail an increased RIG-I sensitivity. Here, we outline the astonishingly diverse and efficient strategies by which segmented NSVs are compensating for the elevated number of RIG-I ligands in their genome.
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Affiliation(s)
- Michaela Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany.
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Barry G, Varela M, Ratinier M, Blomström AL, Caporale M, Seehusen F, Hahn K, Schnettler E, Baumgärtner W, Kohl A, Palmarini M. NSs protein of Schmallenberg virus counteracts the antiviral response of the cell by inhibiting its transcriptional machinery. J Gen Virol 2014; 95:1640-1646. [PMID: 24828331 PMCID: PMC4103064 DOI: 10.1099/vir.0.065425-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Bunyaviruses have evolved a variety of strategies to counteract the antiviral defence systems of mammalian cells. Here we show that the NSs protein of Schmallenberg virus (SBV) induces the degradation of the RPB1 subunit of RNA polymerase II and consequently inhibits global cellular protein synthesis and the antiviral response. In addition, we show that the SBV NSs protein enhances apoptosis in vitro and possibly in vivo, suggesting that this protein could be involved in SBV pathogenesis in different ways.
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Affiliation(s)
- Gerald Barry
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
| | - Mariana Varela
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
| | - Maxime Ratinier
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
| | - Anne-Lie Blomström
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, Uppsala SE-750 07, Sweden.,MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
| | - Marco Caporale
- Istituto Zooprofilattico Sperimentale dell'Abruzzo e Molise 'G. Caporale', Teramo, Italy.,MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
| | - Frauke Seehusen
- Department of Pathology and Center of Systems Neuroscience, University of Veterinary Medicine, Hannover, Germany
| | - Kerstin Hahn
- Department of Pathology and Center of Systems Neuroscience, University of Veterinary Medicine, Hannover, Germany
| | | | - Wolfgang Baumgärtner
- Department of Pathology and Center of Systems Neuroscience, University of Veterinary Medicine, Hannover, Germany
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
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Non-structural proteins of arthropod-borne bunyaviruses: roles and functions. Viruses 2013; 5:2447-68. [PMID: 24100888 PMCID: PMC3814597 DOI: 10.3390/v5102447] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 09/20/2013] [Accepted: 09/25/2013] [Indexed: 12/24/2022] Open
Abstract
Viruses within the Bunyaviridae family are tri-segmented, negative-stranded RNA viruses. The family includes several emerging and re-emerging viruses of humans, animals and plants, such as Rift Valley fever virus, Crimean-Congo hemorrhagic fever virus, La Crosse virus, Schmallenberg virus and tomato spotted wilt virus. Many bunyaviruses are arthropod-borne, so-called arboviruses. Depending on the genus, bunyaviruses encode, in addition to the RNA-dependent RNA polymerase and the different structural proteins, one or several non-structural proteins. These non-structural proteins are not always essential for virus growth and replication but can play an important role in viral pathogenesis through their interaction with the host innate immune system. In this review, we will summarize current knowledge and understanding of insect-borne bunyavirus non-structural protein function(s) in vertebrate, plant and arthropod.
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Rice SA, Davido DJ. HSV-1 ICP22: hijacking host nuclear functions to enhance viral infection. Future Microbiol 2013; 8:311-21. [PMID: 23464370 DOI: 10.2217/fmb.13.4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During its productive infection, HSV-1 dramatically remodels the architecture and physiology of the host cell nucleus. The immediate-early proteins, the first viral proteins to be expressed during infection, are key players in this process. Here, we review the known properties and functions of immediate-early protein ICP22. Although this polypeptide has received less attention than other immediate-early proteins, the published evidence indicates that it mediates several striking changes to important host nuclear systems, including those involved in RNA polymerase II transcription, cell cycle regulation and protein quality control. Recent genetic analyses suggest that these alterations can promote HSV-1 productive infection. Thus, future work on ICP22 is likely to reveal novel mechanisms by which herpesviruses, and possibly other DNA viruses, manipulate the host cell nucleus to enhance their replication.
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Affiliation(s)
- Stephen A Rice
- Department of Microbiology, University of Minnesota, MMC 196, 420 Delaware Avenue S, Minneapolis, MN 55455, USA.
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Taylor KG, Peterson KE. Innate immune response to La Crosse virus infection. J Neurovirol 2013; 20:150-6. [DOI: 10.1007/s13365-013-0186-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/28/2013] [Accepted: 06/25/2013] [Indexed: 10/26/2022]
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