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DePaula-Silva AB. The Contribution of Microglia and Brain-Infiltrating Macrophages to the Pathogenesis of Neuroinflammatory and Neurodegenerative Diseases during TMEV Infection of the Central Nervous System. Viruses 2024; 16:119. [PMID: 38257819 PMCID: PMC10819099 DOI: 10.3390/v16010119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/06/2024] [Accepted: 01/09/2024] [Indexed: 01/24/2024] Open
Abstract
The infection of the central nervous system (CNS) with neurotropic viruses induces neuroinflammation and is associated with the development of neuroinflammatory and neurodegenerative diseases, including multiple sclerosis and epilepsy. The activation of the innate and adaptive immune response, including microglial, macrophages, and T and B cells, while required for efficient viral control within the CNS, is also associated with neuropathology. Under healthy conditions, resident microglia play a pivotal role in maintaining CNS homeostasis. However, during pathological events, such as CNS viral infection, microglia become reactive, and immune cells from the periphery infiltrate into the brain, disrupting CNS homeostasis and contributing to disease development. Theiler's murine encephalomyelitis virus (TMEV), a neurotropic picornavirus, is used in two distinct mouse models: TMEV-induced demyelination disease (TMEV-IDD) and TMEV-induced seizures, representing mouse models of multiple sclerosis and epilepsy, respectively. These murine models have contributed substantially to our understanding of the pathophysiology of MS and seizures/epilepsy following viral infection, serving as critical tools for identifying pharmacological targetable pathways to modulate disease development. This review aims to discuss the host-pathogen interaction during a neurotropic picornavirus infection and to shed light on our current understanding of the multifaceted roles played by microglia and macrophages in the context of these two complexes viral-induced disease.
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Affiliation(s)
- Ana Beatriz DePaula-Silva
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA
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2
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Li H, Zheng X, Li Y, Zhu Y, Xu Y, Yu Z, Feng WH. African swine fever virus S273R protein antagonizes type I interferon production by interfering with TBK1 and IRF3 interaction. Virol Sin 2023; 38:911-921. [PMID: 37659477 PMCID: PMC10786655 DOI: 10.1016/j.virs.2023.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 08/28/2023] [Indexed: 09/04/2023] Open
Abstract
African swine fever (ASF) is originally reported in East Africa as an acute hemorrhagic fever. African swine fever virus (ASFV) is a giant and complex DNA virus with icosahedral structure and encodes a variety of virulence factors to resist host innate immune response. S273R protein (pS273R), as a SUMO-1 specific cysteine protease, can affect viral packaging by cutting polymeric proteins. In this study, we found that pS273R was an important antagonistic viral factor that suppressed cGAS-STING-mediated type I interferon (IFN-I) production. A detailed analysis showed that pS273R inhibited IFN-I production by interacting with interferon regulatory factor 3 (IRF3). Subsequently, we showed that pS273R disrupted the association between TBK1 and IRF3, leading to the repressed IRF3 phosphorylation and dimerization. Deletion and point mutation analysis verified that pS273R impaired IFN-I production independent of its cysteine protease activity. These findings will help us further understand ASFV pathogenesis.
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Affiliation(s)
- Hui Li
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xiaojie Zheng
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - You Li
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yingqi Zhu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yangyang Xu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Zilong Yu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Wen-Hai Feng
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
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3
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Guo J, Zhu Y, Ma X, Shang G, Liu B, Zhang K. Virus Infection and mRNA Nuclear Export. Int J Mol Sci 2023; 24:12593. [PMID: 37628773 PMCID: PMC10454920 DOI: 10.3390/ijms241612593] [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: 04/21/2023] [Revised: 07/29/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Gene expression in eukaryotes begins with transcription in the nucleus, followed by the synthesis of messenger RNA (mRNA), which is then exported to the cytoplasm for its translation into proteins. Along with transcription and translation, mRNA export through the nuclear pore complex (NPC) is an essential regulatory step in eukaryotic gene expression. Multiple factors regulate mRNA export and hence gene expression. Interestingly, proteins from certain types of viruses interact with these factors in infected cells, and such an interaction interferes with the mRNA export of the host cell in favor of viral RNA export. Thus, these viruses hijack the host mRNA nuclear export mechanism, leading to a reduction in host gene expression and the downregulation of immune/antiviral responses. On the other hand, the viral mRNAs successfully evade the host surveillance system and are efficiently exported from the nucleus to the cytoplasm for translation, which enables the continuation of the virus life cycle. Here, we present this review to summarize the mechanisms by which viruses suppress host mRNA nuclear export during infection, as well as the key strategies that viruses use to facilitate their mRNA nuclear export. These studies have revealed new potential antivirals that may be used to inhibit viral mRNA transport and enhance host mRNA nuclear export, thereby promoting host gene expression and immune responses.
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Affiliation(s)
- Jiayin Guo
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Yaru Zhu
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Xiaoya Ma
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Guijun Shang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China;
| | - Bo Liu
- Key Laboratory of Molecular Virology and Immunology, Chinese Academy of Sciences, Shanghai 200031, China
- Shanghai Huashen Institute of Microbes and Infections, Shanghai 200052, China
| | - Ke Zhang
- Key Laboratory of Molecular Virology and Immunology, Chinese Academy of Sciences, Shanghai 200031, China
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4
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Bühler M, Li D, Li L, Runft S, Waltl I, Pavlou A, Kalinke U, Ciurkiewicz M, Huehn J, Floess S, Beineke A, Baumgärtner W, Gerhauser I. IFNAR signaling of neuroectodermal cells is essential for the survival of C57BL/6 mice infected with Theiler's murine encephalomyelitis virus. J Neuroinflammation 2023; 20:58. [PMID: 36872323 PMCID: PMC9985866 DOI: 10.1186/s12974-023-02737-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 02/16/2023] [Indexed: 03/07/2023] Open
Abstract
BACKGROUND Theiler's murine encephalomyelitis virus (TMEV) is a single-stranded RNA virus that causes encephalitis followed by chronic demyelination in SJL mice and spontaneous seizures in C57BL/6 mice. Since earlier studies indicated a critical role of type I interferon (IFN-I) signaling in the control of viral replication in the central nervous system (CNS), mouse strain-specific differences in pathways induced by the IFN-I receptor (IFNAR) might determine the outcome of TMEV infection. METHODS Data of RNA-seq analysis and immunohistochemistry were used to compare the gene and protein expression of IFN-I signaling pathway members between mock- and TMEV-infected SJL and C57BL/6 mice at 4, 7 and 14 days post-infection (dpi). To address the impact of IFNAR signaling in selected brain-resident cell types, conditional knockout mice with an IFNAR deficiency in cells of the neuroectodermal lineage (NesCre±IFNARfl/fl), neurons (Syn1Cre±IFNARfl/fl), astrocytes (GFAPCre±IFNARfl/fl), and microglia (Sall1CreER±IFNARfl/fl) on a C57BL/6 background were tested. PCR and an immunoassay were used to quantify TMEV RNA and cytokine and chemokine expression in their brain at 4 dpi. RESULTS RNA-seq analysis revealed upregulation of most ISGs in SJL and C57BL/6 mice, but Ifi202b mRNA transcripts were only increased in SJL and Trim12a only in C57BL/6 mice. Immunohistochemistry showed minor differences in ISG expression (ISG15, OAS, PKR) between both mouse strains. While all immunocompetent Cre-negative control mice and the majority of mice with IFNAR deficiency in neurons or microglia survived until 14 dpi, lack of IFNAR expression in all cells (IFNAR-/-), neuroectodermal cells, or astrocytes induced lethal disease in most of the analyzed mice, which was associated with unrestricted viral replication. NesCre±IFNARfl/fl mice showed more Ifnb1, Tnfa, Il6, Il10, Il12b and Ifng mRNA transcripts than Cre-/-IFNARfl/fl mice. IFNAR-/- mice also demonstrated increased IFN-α, IFN-β, IL1-β, IL-6, and CXCL-1 protein levels, which highly correlated with viral load. CONCLUSIONS Ifi202b and Trim12a expression levels likely contribute to mouse strain-specific susceptibility to TMEV-induced CNS lesions. Restriction of viral replication is strongly dependent on IFNAR signaling of neuroectodermal cells, which also controls the expression of key pro- and anti-inflammatory cytokines during viral brain infection.
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Affiliation(s)
- Melanie Bühler
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany
| | - Dandan Li
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.,Centre for Systems Neuroscience (ZSN), Hannover, Germany
| | - Lin Li
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.,Centre for Systems Neuroscience (ZSN), Hannover, Germany.,c/o School of Basic Medical Sciences, Shanxi Medical University, Shanxi, China
| | - Sandra Runft
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.,Centre for Systems Neuroscience (ZSN), Hannover, Germany
| | - Inken Waltl
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany
| | - Andreas Pavlou
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany
| | - Ulrich Kalinke
- Centre for Systems Neuroscience (ZSN), Hannover, Germany.,Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany
| | - Malgorzata Ciurkiewicz
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany
| | - Jochen Huehn
- Experimental Immunology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124, Brunswick, Germany
| | - Stefan Floess
- Experimental Immunology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124, Brunswick, Germany
| | - Andreas Beineke
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.,Centre for Systems Neuroscience (ZSN), Hannover, Germany
| | - Wolfgang Baumgärtner
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.,Centre for Systems Neuroscience (ZSN), Hannover, Germany
| | - Ingo Gerhauser
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.
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Esmael A, Petro TM. IL-33 promotes increased replication of Theiler's Murine Encephalomyelitis Virus in RAW264.7 macrophage cells with an IRF3-dependent response. Virus Res 2023; 323:199007. [PMID: 36414191 PMCID: PMC10194383 DOI: 10.1016/j.virusres.2022.199007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 11/03/2022] [Accepted: 11/18/2022] [Indexed: 11/21/2022]
Abstract
Interleukin-33 (IL-33), which promotes M2 macrophage development, may influence the control of viruses, such as Theiler's Murine Encephalomyelitis Virus (TMEV) that infect macrophages. Because Interferon Regulatory Factor-3 (IRF3) is also critical to control of TMEV infection in macrophages, information on the relationship between IL-33 and IRF3 is important. Thus, RAW264.7 Lucia murine macrophage lineage cells with an endogenous IRF3-ISRE promoter driving secreted luciferase and IRF3KO RAW Lucia, a subline deficient in IRF3, were challenged with TMEV. After the challenge, considerable TMEV RNA detected at 18 and 24 h in RAW cells was significantly elevated in IRF3KO RAW cells. TMEV induction of ISRE-IRF3 promoter activity, IFN-β and IL-33 gene expression, and IL-6 and IL-10 protein production, which was strong in RAW cells, was less in IRF3KO RAW cells. In contrast, expression of CD206 and ARG1, classical M2 macrophage markers, was significantly elevated in IRF3KO RAW cells. Moreover, RAW and IRF3KO RAW cells produced extracellular IL-33 prior to and after infection with TMEV and antibody blockade of the IL-33 receptor, ST2, reduced CD206 and ARG1 expression, but increased IL-6 gene expression. Pre-treating both RAW and IRF3KO RAW cells with IL-33 prior to challenge significantly increased TMEV infection, but also increased IL-33, IL-10, IL-6 mRNA expression, and NO production without increasing IFN-β. Notably, IL-33 induction of IL-33, IRF3-ISRE promoter activity, and IL-10 by TMEV or poly I:C/IFN-γ was significantly dependent upon IRF3. The results show that the expression of IL-33 and the repression of M2 macrophage phenotypic markers are dependent on IRF3 and that IL-33 decreases the ability of macrophages to control infection with macrophage-tropic viruses.
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Affiliation(s)
- Ahmed Esmael
- Nebraska Center for Virology, University of Nebraska Lincoln, Lincoln, NE 68583, USA; Botany and Microbiology Department, Faculty of Science, Benha University, Benha 13518, Egypt
| | - Thomas M Petro
- Nebraska Center for Virology, University of Nebraska Lincoln, Lincoln, NE 68583, USA; Dept. of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, 68583, USA.
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6
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Lizcano-Perret B, Lardinois C, Wavreil F, Hauchamps P, Herinckx G, Sorgeloos F, Vertommen D, Gatto L, Michiels T. Cardiovirus leader proteins retarget RSK kinases toward alternative substrates to perturb nucleocytoplasmic traffic. PLoS Pathog 2022; 18:e1011042. [PMID: 36508477 PMCID: PMC9779665 DOI: 10.1371/journal.ppat.1011042] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 12/22/2022] [Accepted: 12/01/2022] [Indexed: 12/14/2022] Open
Abstract
Proteins from some unrelated pathogens, including small RNA viruses of the family Picornaviridae, large DNA viruses such as Kaposi sarcoma-associated herpesvirus and even bacteria of the genus Yersinia can recruit cellular p90-ribosomal protein S6 kinases (RSKs) through a common linear motif and maintain the kinases in an active state. On the one hand, pathogens' proteins might hijack RSKs to promote their own phosphorylation (direct target model). On the other hand, some data suggested that pathogens' proteins might dock the hijacked RSKs toward a third interacting partner, thus redirecting the kinase toward a specific substrate. We explored the second hypothesis using the Cardiovirus leader protein (L) as a paradigm. The L protein is known to trigger nucleocytoplasmic trafficking perturbation, which correlates with hyperphosphorylation of phenylalanine-glycine (FG)-nucleoporins (FG-NUPs) such as NUP98. Using a biotin ligase fused to either RSK or L, we identified FG-NUPs as primary partners of the L-RSK complex in infected cells. An L protein mutated in the central RSK-interaction motif was readily targeted to the nuclear envelope whereas an L protein mutated in the C-terminal domain still interacted with RSK but failed to interact with the nuclear envelope. Thus, L uses distinct motifs to recruit RSK and to dock the L-RSK complex toward the FG-NUPs. Using an analog-sensitive RSK2 mutant kinase, we show that, in infected cells, L can trigger RSK to use NUP98 and NUP214 as direct substrates. Our data therefore illustrate a novel virulence mechanism where pathogens' proteins hijack and retarget cellular protein kinases toward specific substrates, to promote their replication or to escape immunity.
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Affiliation(s)
- Belén Lizcano-Perret
- Molecular Virology unit, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Cécile Lardinois
- Molecular Virology unit, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Fanny Wavreil
- Molecular Virology unit, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Philippe Hauchamps
- Computational Biology and Bioinformatics unit, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Gaëtan Herinckx
- MASSPROT platform, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Frédéric Sorgeloos
- Molecular Virology unit, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Didier Vertommen
- MASSPROT platform, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Laurent Gatto
- Computational Biology and Bioinformatics unit, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Thomas Michiels
- Molecular Virology unit, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
- * E-mail:
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Shi W, Shi M, Que TC, Cui XM, Ye RZ, Xia LY, Hou X, Zheng JJ, Jia N, Xie X, Wu WC, He MH, Wang HF, Wei YJ, Wu AQ, Zhang SF, Pan YS, Chen PY, Wang Q, Li SS, Zhong YL, Li YJ, Tan LH, Zhao L, Jiang JF, Hu YL, Cao WC. Trafficked Malayan pangolins contain viral pathogens of humans. Nat Microbiol 2022; 7:1259-1269. [PMID: 35918420 PMCID: PMC9352580 DOI: 10.1038/s41564-022-01181-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 06/21/2022] [Indexed: 12/03/2022]
Abstract
Pangolins are the most trafficked wild animal in the world according to the World Wildlife Fund. The discovery of SARS-CoV-2-related coronaviruses in Malayan pangolins has piqued interest in the viromes of these wild, scaly-skinned mammals. We sequenced the viromes of 161 pangolins that were smuggled into China and assembled 28 vertebrate-associated viruses, 21 of which have not been previously reported in vertebrates. We named 16 members of Hunnivirus, Pestivirus and Copiparvovirus pangolin-associated viruses. We report that the l-protein has been lost from all hunniviruses identified in pangolins. Sequences of four human-associated viruses were detected in pangolin viromes, including respiratory syncytial virus, Orthopneumovirus, RotavirusA and Mammalian orthoreovirus. The genomic sequences of five mammal-associated and three tick-associated viruses were also present. Notably, a coronavirus related to HKU4-CoV, which was originally found in bats, was identified. The presence of these viruses in smuggled pangolins identifies these mammals as a potential source of emergent pathogenic viruses. Multiple pathogenic viruses are identified in a large set of pangolins, which shows that trading pangolins for scales or flesh may increase the risk of emergence of viral infections.
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Affiliation(s)
- Wenqiang Shi
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China
| | - Mang Shi
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, Guangdong, P. R. China
| | - Teng-Cheng Que
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, P. R. China
| | - Xiao-Ming Cui
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China.,Research Unit of Discovery and Tracing of Natural Focus Diseases, Chinese Academy of Medical Sciences, Beijing, P. R. China
| | - Run-Ze Ye
- Institute of EcoHealth, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, P. R. China
| | - Luo-Yuan Xia
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China.,Institute of EcoHealth, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, P. R. China
| | - Xin Hou
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, Guangdong, P. R. China
| | - Jia-Jing Zheng
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China.,College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, P. R. China
| | - Na Jia
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China.,Research Unit of Discovery and Tracing of Natural Focus Diseases, Chinese Academy of Medical Sciences, Beijing, P. R. China
| | - Xing Xie
- Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, P. R. China
| | - Wei-Chen Wu
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, Guangdong, P. R. China
| | - Mei-Hong He
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, P. R. China
| | - Hui-Feng Wang
- Center for Genomic and Personalized Medicine, Guangxi Key Laboratory for Genomic and Personalized Medicine, Guangxi Collaborative Innovation Center for Genomic and Personalized Medicine, Guangxi Medical University, Nanning, Guangxi, P. R. China
| | - Yong-Jie Wei
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, P. R. China
| | - Ai-Qiong Wu
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, P. R. China
| | - Sheng-Feng Zhang
- Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, P. R. China
| | - Yu-Sheng Pan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China
| | - Pan-Yu Chen
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, P. R. China
| | - Qian Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China.,Institute of EcoHealth, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, P. R. China
| | - Shou-Sheng Li
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, P. R. China
| | - Yan-Li Zhong
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, P. R. China
| | - Ying-Jiao Li
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, P. R. China
| | - Luo-Hao Tan
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, P. R. China
| | - Lin Zhao
- Institute of EcoHealth, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, P. R. China
| | - Jia-Fu Jiang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China. .,Research Unit of Discovery and Tracing of Natural Focus Diseases, Chinese Academy of Medical Sciences, Beijing, P. R. China.
| | - Yan-Ling Hu
- Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, P. R. China. .,Center for Genomic and Personalized Medicine, Guangxi Key Laboratory for Genomic and Personalized Medicine, Guangxi Collaborative Innovation Center for Genomic and Personalized Medicine, Guangxi Medical University, Nanning, Guangxi, P. R. China.
| | - Wu-Chun Cao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P. R. China. .,Research Unit of Discovery and Tracing of Natural Focus Diseases, Chinese Academy of Medical Sciences, Beijing, P. R. China. .,Institute of EcoHealth, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, P. R. China.
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8
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Bühler M, Runft S, Li D, Götting J, Detje CN, Nippold V, Stoff M, Beineke A, Schulz T, Kalinke U, Baumgärtner W, Gerhauser I. IFN-β Deficiency Results in Fatal or Demyelinating Disease in C57BL/6 Mice Infected With Theiler's Murine Encephalomyelitis Viruses. Front Immunol 2022; 13:786940. [PMID: 35222374 PMCID: PMC8864290 DOI: 10.3389/fimmu.2022.786940] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 01/20/2022] [Indexed: 11/13/2022] Open
Abstract
Type I Interferons (IFN-I) are important inducers of the antiviral immune response and immune modulators. IFN-β is the most highly expressed IFN-I in the central nervous system (CNS). The infection of SJL mice with the BeAn or the DA strain of Theiler's murine encephalomyelitis virus (TMEV) results in a progressive demyelinating disease. C57BL/6 mice are usually resistant to TMEV-induced demyelination and eliminate these strains from the CNS within several weeks. Using C57BL/6 IFN-β knockout (IFN-β-/-) mice infected with TMEV, we evaluated the role of IFN-β in neuroinfection. Despite the resistance of C57BL/6 wild type (WT) mice to TMEV infection, DA-infected IFN-β-/- mice had to be killed at 7 to 8 days post infection (dpi) due to severe clinical disease. In contrast, BeAn-infected IFN-β-/- mice survived until 98 dpi. Nevertheless at 14 dpi, BeAn-infected IFN-β-/- mice showed a stronger encephalitis and astrogliosis, higher viral load as well as higher mRNA levels of Isg15, Eif2ak2 (PKR), Tnfa, Il1b, Il10, Il12 and Ifng in the cerebrum than BeAn-infected WT mice. Moreover, the majority of IFN-β-/- mice did not clear the virus from the CNS and developed mild demyelination in the spinal cord at 98 dpi, whereas virus and lesions were absent in the spinal cord of WT mice. Persistently infected IFN-β-/- mice also had higher Isg15, Eif2ak1, Tnfa, Il1a, Il1b and Ifng mRNA levels in the spinal cord at 98 dpi than their virus-negative counterparts indicating an activation of IFN-I signaling and ongoing inflammation. Most importantly, BeAn-infected NesCre+/- IFN-βfl/fl mice, which do not express IFN-β in neurons, astrocytes and oligodendrocytes, only developed mild brain lesions similar to WT mice. Consequently, IFN-β produced by neuroectodermal cells does not seem to play a critical role in the resistance of C57BL/6 mice against fatal and demyelinating disease induced by TMEV strains.
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Affiliation(s)
- Melanie Bühler
- University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Sandra Runft
- University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Dandan Li
- University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Jasper Götting
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Claudia N Detje
- Institute for Experimental Infection Research, Twincore, Centre for Experimental and Clinical Infection Research, a Joint Venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Vanessa Nippold
- University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Melanie Stoff
- University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Andreas Beineke
- University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Thomas Schulz
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Ulrich Kalinke
- Institute for Experimental Infection Research, Twincore, Centre for Experimental and Clinical Infection Research, a Joint Venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover, Germany
| | | | - Ingo Gerhauser
- University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
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9
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Shen Q, Wang YE, Palazzo AF. Crosstalk between nucleocytoplasmic trafficking and the innate immune response to viral infection. J Biol Chem 2021; 297:100856. [PMID: 34097873 PMCID: PMC8254040 DOI: 10.1016/j.jbc.2021.100856] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 05/24/2021] [Accepted: 06/03/2021] [Indexed: 12/16/2022] Open
Abstract
The nuclear pore complex is the sole gateway connecting the nucleoplasm and cytoplasm. In humans, the nuclear pore complex is one of the largest multiprotein assemblies in the cell, with a molecular mass of ∼110 MDa and consisting of 8 to 64 copies of about 34 different nuclear pore proteins, termed nucleoporins, for a total of 1000 subunits per pore. Trafficking events across the nuclear pore are mediated by nuclear transport receptors and are highly regulated. The nuclear pore complex is also used by several RNA viruses and almost all DNA viruses to access the host cell nucleoplasm for replication. Viruses hijack the nuclear pore complex, and nuclear transport receptors, to access the nucleoplasm where they replicate. In addition, the nuclear pore complex is used by the cell innate immune system, a network of signal transduction pathways that coordinates the first response to foreign invaders, including viruses and other pathogens. Several branches of this response depend on dynamic signaling events that involve the nuclear translocation of downstream signal transducers. Mounting evidence has shown that these signaling cascades, especially those steps that involve nucleocytoplasmic trafficking events, are targeted by viruses so that they can evade the innate immune system. This review summarizes how nuclear pore proteins and nuclear transport receptors contribute to the innate immune response and highlights how viruses manipulate this cellular machinery to favor infection. A comprehensive understanding of nuclear pore proteins in antiviral innate immunity will likely contribute to the development of new antiviral therapeutic strategies.
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Affiliation(s)
- Qingtang Shen
- School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China.
| | - Yifan E Wang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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10
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Nucleocytoplasmic Trafficking Perturbation Induced by Picornaviruses. Viruses 2021; 13:v13071210. [PMID: 34201715 PMCID: PMC8310216 DOI: 10.3390/v13071210] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/17/2021] [Accepted: 06/19/2021] [Indexed: 12/15/2022] Open
Abstract
Picornaviruses are positive-stranded RNA viruses. Even though replication and translation of their genome take place in the cytoplasm, these viruses evolved different strategies to disturb nucleocytoplasmic trafficking of host proteins and RNA. The major targets of picornavirus are the phenylalanine-glycine (FG)-nucleoporins, which form a mesh in the central channel of the nuclear pore complex through which protein cargos and karyopherins are actively transported in both directions. Interestingly, while enteroviruses use the proteolytic activity of their 2A protein to degrade FG-nucleoporins, cardioviruses act by triggering phosphorylation of these proteins by cellular kinases. By targeting the nuclear pore complex, picornaviruses recruit nuclear proteins to the cytoplasm, where they increase viral genome translation and replication; they affect nuclear translocation of cytoplasmic proteins such as transcription factors that induce innate immune responses and retain host mRNA in the nucleus thereby preventing cell emergency responses and likely making the ribosomal machinery available for translation of viral RNAs.
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11
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De Jesús-González LA, Palacios-Rápalo S, Reyes-Ruiz JM, Osuna-Ramos JF, Cordero-Rivera CD, Farfan-Morales CN, Gutiérrez-Escolano AL, del Ángel RM. The Nuclear Pore Complex Is a Key Target of Viral Proteases to Promote Viral Replication. Viruses 2021; 13:v13040706. [PMID: 33921849 PMCID: PMC8073804 DOI: 10.3390/v13040706] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/13/2021] [Accepted: 04/16/2021] [Indexed: 12/17/2022] Open
Abstract
Various viruses alter nuclear pore complex (NPC) integrity to access the nuclear content favoring their replication. Alteration of the nuclear pore complex has been observed not only in viruses that replicate in the nucleus but also in viruses with a cytoplasmic replicative cycle. In this last case, the alteration of the NPC can reduce the transport of transcription factors involved in the immune response or mRNA maturation, or inhibit the transport of mRNA from the nucleus to the cytoplasm, favoring the translation of viral mRNAs or allowing access to nuclear factors necessary for viral replication. In most cases, the alteration of the NPC is mediated by viral proteins, being the viral proteases, one of the most critical groups of viral proteins that regulate these nucleus–cytoplasmic transport changes. This review focuses on the description and discussion of the role of viral proteases in the modification of nucleus–cytoplasmic transport in viruses with cytoplasmic replicative cycles and its repercussions in viral replication.
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12
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Petro TM. IFN Regulatory Factor 3 in Health and Disease. THE JOURNAL OF IMMUNOLOGY 2021; 205:1981-1989. [PMID: 33020188 DOI: 10.4049/jimmunol.2000462] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/07/2020] [Indexed: 12/14/2022]
Abstract
Immunity to viruses requires an array of critical cellular proteins that include IFN regulatory factor 3 (IRF3). Consequently, most viruses that infect vertebrates encode proteins that interfere with IRF3 activation. This review describes the cellular pathways linked to IRF3 activation and where those pathways are targeted by human viral pathogens. Moreover, key regulatory pathways that control IRF3 are discussed. Besides viral infections, IRF3 is also involved in resistance to some bacterial infections, in anticancer immunity, and in anticancer therapies involving DNA damage agents. A recent finding shows that IRF3 is needed for T cell effector functions that are involved in anticancer immunity and also in T cell autoimmune diseases. In contrast, unregulated IRF3 activity is clearly not beneficial, considering it is implicated in certain interferonopathies, in which heightened IRF3 activity leads to IFN-β-induced disease. Therefore, IRF3 is involved largely in maintaining health but sometimes contributing to disease.
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Affiliation(s)
- Thomas M Petro
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE 68583; and Nebraska Center for Virology, University of Nebraska Medical Center, Lincoln, NE 68583
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13
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Guha S, Bhaumik SR. Viral regulation of mRNA export with potentials for targeted therapy. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1864:194655. [PMID: 33246183 DOI: 10.1016/j.bbagrm.2020.194655] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 10/15/2020] [Accepted: 11/05/2020] [Indexed: 12/12/2022]
Abstract
Eukaryotic gene expression begins with transcription in the nucleus to synthesize mRNA (messenger RNA), which is subsequently exported to the cytoplasm for translation to protein. Like transcription and translation, mRNA export is an important regulatory step of eukaryotic gene expression. Various factors are involved in regulating mRNA export, and thus gene expression. Intriguingly, some of these factors interact with viral proteins, and such interactions interfere with mRNA export of the host cell, favoring viral RNA export. Hence, viruses hijack host mRNA export machinery for export of their own RNAs from nucleus to cytoplasm for translation to proteins for viral life cycle, suppressing host mRNA export (and thus host gene expression and immune/antiviral response). Therefore, the molecules that can impair the interactions of these mRNA export factors with viral proteins could emerge as antiviral therapeutic agents to suppress viral RNA transport and enhance host mRNA export, thereby promoting host gene expression and immune response. Thus, there has been a number of studies to understand how virus hijacks mRNA export machinery in suppressing host gene expression and promoting its own RNA export to the cytoplasm for translation to proteins required for viral replication/assembly/life cycle towards developing targeted antiviral therapies, as concisely described here.
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Affiliation(s)
- Shalini Guha
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.
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14
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Schwanke H, Stempel M, Brinkmann MM. Of Keeping and Tipping the Balance: Host Regulation and Viral Modulation of IRF3-Dependent IFNB1 Expression. Viruses 2020; 12:v12070733. [PMID: 32645843 PMCID: PMC7411613 DOI: 10.3390/v12070733] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/03/2020] [Accepted: 07/03/2020] [Indexed: 02/06/2023] Open
Abstract
The type I interferon (IFN) response is a principal component of our immune system that allows to counter a viral attack immediately upon viral entry into host cells. Upon engagement of aberrantly localised nucleic acids, germline-encoded pattern recognition receptors convey their find via a signalling cascade to prompt kinase-mediated activation of a specific set of five transcription factors. Within the nucleus, the coordinated interaction of these dimeric transcription factors with coactivators and the basal RNA transcription machinery is required to access the gene encoding the type I IFN IFNβ (IFNB1). Virus-induced release of IFNβ then induces the antiviral state of the system and mediates further mechanisms for defence. Due to its key role during the induction of the initial IFN response, the activity of the transcription factor interferon regulatory factor 3 (IRF3) is tightly regulated by the host and fiercely targeted by viral proteins at all conceivable levels. In this review, we will revisit the steps enabling the trans-activating potential of IRF3 after its activation and the subsequent assembly of the multi-protein complex at the IFNβ enhancer that controls gene expression. Further, we will inspect the regulatory mechanisms of these steps imposed by the host cell and present the manifold strategies viruses have evolved to intervene with IFNβ transcription downstream of IRF3 activation in order to secure establishment of a productive infection.
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Affiliation(s)
- Hella Schwanke
- Institute of Genetics, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (H.S.); (M.S.)
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Markus Stempel
- Institute of Genetics, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (H.S.); (M.S.)
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Melanie M. Brinkmann
- Institute of Genetics, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (H.S.); (M.S.)
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
- Correspondence: ; Tel.: +49-531-6181-3069
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15
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Holmes AC, Semler BL. Picornaviruses and RNA Metabolism: Local and Global Effects of Infection. J Virol 2019; 93:e02088-17. [PMID: 31413128 PMCID: PMC6803262 DOI: 10.1128/jvi.02088-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 08/06/2019] [Indexed: 11/20/2022] Open
Abstract
Due to the limiting coding capacity for members of the Picornaviridae family of positive-strand RNA viruses, their successful replication cycles require complex interactions with host cell functions. These interactions span from the down-modulation of many aspects of cellular metabolism to the hijacking of specific host functions used during viral translation, RNA replication, and other steps of infection by picornaviruses, such as human rhinovirus, coxsackievirus, poliovirus, foot-and-mouth disease virus, enterovirus D-68, and a wide range of other human and nonhuman viruses. Although picornaviruses replicate exclusively in the cytoplasm of infected cells, they have extensive interactions with host cell nuclei and the proteins and RNAs that normally reside in this compartment of the cell. This review will highlight some of the more recent studies that have revealed how picornavirus infections impact the RNA metabolism of the host cell posttranscriptionally and how they usurp and modify host RNA binding proteins as well as microRNAs to potentiate viral replication.
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Affiliation(s)
- Autumn C Holmes
- Department of Microbiology & Molecular Genetics, University of California, Irvine, California, USA
- Center for Virus Research, University of California, Irvine, California, USA
| | - Bert L Semler
- Department of Microbiology & Molecular Genetics, University of California, Irvine, California, USA
- Center for Virus Research, University of California, Irvine, California, USA
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16
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The Leader Protein of Theiler's Virus Prevents the Activation of PKR. J Virol 2019; 93:JVI.01010-19. [PMID: 31292248 DOI: 10.1128/jvi.01010-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 07/02/2019] [Indexed: 11/20/2022] Open
Abstract
Leader (L) proteins encoded by cardioviruses are multifunctional proteins that contribute to innate immunity evasion. L proteins of Theiler's murine encephalomyelitis virus (TMEV), Saffold virus (SAFV), and encephalomyocarditis virus (EMCV) were reported to inhibit stress granule assembly in infected cells. Here, we show that TMEV L can act at two levels in the stress granule formation pathway: on the one hand, it can inhibit sodium arsenite-induced stress granule assembly without preventing eIF2α phosphorylation and, thus, acts downstream of eIF2α; on the other hand, it can inhibit eucaryotic translation initiation factor 2 alpha kinase 2 (PKR) activation and the consequent PKR-mediated eIF2α phosphorylation. Interestingly, coimmunostaining experiments revealed that PKR colocalizes with viral double-stranded RNA (dsRNA) in cells infected with L-mutant viruses but not in cells infected with the wild-type virus. Furthermore, PKR coprecipitated with dsRNA from cells infected with L-mutant viruses significantly more than from cells infected with the wild-type virus. These data strongly suggest that L blocks PKR activation by preventing the interaction between PKR and viral dsRNA. In infected cells, L also rendered PKR refractory to subsequent activation by poly(I·C). However, no interaction was observed between L and either dsRNA or PKR. Taken together, our results suggest that, unlike other viral proteins, L indirectly acts on PKR to negatively regulate its responsiveness to dsRNA.IMPORTANCE The leader (L) protein encoded by cardioviruses is a very short multifunctional protein that contributes to evasion of the host innate immune response. This protein notably prevents the formation of stress granules in infected cells. Using Theiler's virus as a model, we show that L proteins can act at two levels in the stress response pathway leading to stress granule formation, the most striking one being the inhibition of eucaryotic translation initiation factor 2 alpha kinase 2 (PKR) activation. Interestingly, the leader protein appears to inhibit PKR via a novel mechanism by rendering this kinase unable to detect double-stranded RNA, its typical activator. Unlike other viral proteins, such as influenza virus NS1, the leader protein appears to interact with neither PKR nor double-stranded RNA, suggesting that it acts indirectly to trigger the inhibition of the kinase.
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17
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Bijalwan M, Young CR, Tingling J, Zhou XJ, Rimmelin AR, Leibowitz JL, Welsh CJ. Characterization of Plaque-Sized Variants of Daniel's (DA) Strain in Theiler's Virus-Induced Epilepsy. Sci Rep 2019; 9:3444. [PMID: 30837498 PMCID: PMC6401140 DOI: 10.1038/s41598-019-38967-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 01/09/2019] [Indexed: 12/20/2022] Open
Abstract
Epilepsy is a complex neurological disease characterized by recurrent seizures. Patients with viral encephalitis have a 16-fold increased risk of developing epilepsy, and this risk can persist for about 15 years after the occurrence of initial viral infection. Theiler's murine encephalomyelitis virus (TMEV) infection induces a well-characterized experimental model of epilepsy in C57BL/6 mice. In response to intracerebral (I.C.) injection of Daniel's (DA) strain of TMEV, there is vigorous immune response, which is detrimental to neurons and contributes to acute seizures, rendering mice susceptible to epilepsy. A comparative in vivo challenge study with either one of the two variants of the DA strain, small (DA-DS) or large (DA-CL) plaque forming variants, revealed differences in the diseases they induced in C57BL/6 mice. Compared to DA-CL-, DA-DS-infected mice exhibited significantly more seizures, higher clinical scores, neuroinflammation, and neuronal damage (mainly in the CA1-CA2 regions of hippocampus). Moreover, the brains of DA-DS infected mice contained approximately five-fold higher virus than those of DA-CL infected mice. A sequence comparison of the DA-CL and DA-DS genome sequences showed mutations in the leader (L) and L* proteins of DA-CL variant, which may be the cause of attenuating phenotype of DA-CL variant in the C57BL/6 mouse model of epilepsy.
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Affiliation(s)
- M Bijalwan
- Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, College Station, Texas, USA
| | - C R Young
- Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, College Station, Texas, USA
| | - J Tingling
- Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College Station, Texas, USA
| | - X J Zhou
- Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College Station, Texas, USA
- College Station High School, Texas A&M Health Science Center, College Station, Texas, USA
| | - A R Rimmelin
- Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, College Station, Texas, USA
| | - J L Leibowitz
- Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College Station, Texas, USA
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, Texas, USA
| | - C J Welsh
- Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, College Station, Texas, USA.
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, Texas, USA.
- Women's Health in Neuroscience Program, Texas A&M Health Science Center, College Station, Texas, USA.
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18
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Wang Y, Ma L, Stipkovits L, Szathmary S, Li X, Liu Y. The Strategy of Picornavirus Evading Host Antiviral Responses: Non-structural Proteins Suppress the Production of IFNs. Front Microbiol 2018; 9:2943. [PMID: 30619109 PMCID: PMC6297142 DOI: 10.3389/fmicb.2018.02943] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 11/15/2018] [Indexed: 12/22/2022] Open
Abstract
Viral infections trigger the innate immune system to produce interferons (IFNs), which play important role in host antiviral responses. Co-evolution of viruses with their hosts has favored development of various strategies to evade the effects of IFNs, enabling viruses to survive inside host cells. One such strategy involves inhibition of IFN signaling pathways by non-structural proteins. In this review, we provide a brief overview of host signaling pathways inducing IFN production and their suppression by picornavirus non-structural proteins. Using this strategy, picornaviruses can evade the host immune response and replicate inside host cells.
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Affiliation(s)
- Yining Wang
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Lina Ma
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | | | | | - Xuerui Li
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Yongsheng Liu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
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19
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Freundt EC, Drappier M, Michiels T. Innate Immune Detection of Cardioviruses and Viral Disruption of Interferon Signaling. Front Microbiol 2018; 9:2448. [PMID: 30369921 PMCID: PMC6194174 DOI: 10.3389/fmicb.2018.02448] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/25/2018] [Indexed: 12/24/2022] Open
Abstract
Cardioviruses are members of the Picornaviridae family and infect a variety of mammals, from mice to humans. Replication of cardioviruses produces double stranded RNA that is detected by helicases in the RIG-I-like receptor family and leads to a signaling cascade to produce type I interferon. Like other viruses within Picornaviridae, however, cardioviruses have evolved several mechanisms to inhibit interferon production. In this review, we summarize recent findings that have uncovered several proteins enabling efficient detection of cardiovirus dsRNA and discuss which cell types may be most important for interferon production in vivo. Additionally, we describe how cardiovirus proteins L, 3C and L∗ disrupt interferon production and antagonize the antiviral activity of interferon effector molecules.
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Affiliation(s)
- Eric C Freundt
- Department of Biology, The University of Tampa, Tampa, FL, United States
| | - Melissa Drappier
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Thomas Michiels
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
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20
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Rubicon Modulates Antiviral Type I Interferon (IFN) Signaling by Targeting IFN Regulatory Factor 3 Dimerization. J Virol 2017; 91:JVI.00248-17. [PMID: 28468885 DOI: 10.1128/jvi.00248-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 04/28/2017] [Indexed: 11/20/2022] Open
Abstract
Rubicon is part of a Beclin-1-Vps34-containing autophagy complex. Rubicon induces antimicrobial responses upon Toll-like receptor (TLR) stimulation and functions as a feedback inhibitor to prevent unbalanced proinflammatory responses depending on dectin-1 signaling. However, the role played by Rubicon during antiviral immune responses, particularly the type I interferon (IFN) responses, remains largely unknown. Here, we report that Rubicon acts as a negative regulator for virus-triggered IFN signaling. Knockdown of Rubicon promoted type I interferon signaling and inhibited virus replication, while overexpression of Rubicon had the opposite effect. Rubicon specifically interacts with the interferon regulatory factor (IRF) association domain (IAD) of IRF3, and this interaction leads to inhibition of the dimerization of IRF3, which negatively regulates IFN-mediated antiviral response. Thus, our findings suggest the novel additional role of Rubicon as a negative regulator that inhibits the IFN signaling and cellular antiviral responses, providing a novel cellular mechanism of IRF3 inhibition.IMPORTANCE The type I IFN system is a critical innate immune response that protects organisms against virus infection. However, type I IFN signaling must be tightly regulated to avoid excessive production of IFNs. Hence, negative regulatory mechanisms for type I IFN signaling are important, and to date, several related molecules have been identified. Here, we show that Rubicon is a major negative regulator of type I IFN signaling, and unlike previous reports of cellular molecules that inhibit IRF3 activation via proteasomal degradation or dephosphorylation of IRF3, we show that Rubicon interacts with IRF3 and that ultimately this interaction leads to inhibition of the dimerization of IRF3. Thus, we identified a novel negative regulator of type I IFN signaling pathways and a novel cellular mechanism of IRF3 inhibition. The results of this study will increase our understanding of the role of negative-feedback mechanisms that regulate type I IFN signaling and maintain immune homeostasis.
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21
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Sun D, Chen S, Cheng A, Wang M. Roles of the Picornaviral 3C Proteinase in the Viral Life Cycle and Host Cells. Viruses 2016; 8:82. [PMID: 26999188 PMCID: PMC4810272 DOI: 10.3390/v8030082] [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: 12/12/2015] [Revised: 02/27/2016] [Accepted: 03/07/2016] [Indexed: 12/12/2022] Open
Abstract
The Picornaviridae family comprises a large group of non-enveloped viruses that have a major impact on human and veterinary health. The viral genome contains one open reading frame encoding a single polyprotein that can be processed by viral proteinases. The crucial 3C proteinases (3C(pro)s) of picornaviruses share similar spatial structures and it is becoming apparent that 3C(pro) plays a significant role in the viral life cycle and virus host interaction. Importantly, the proteinase and RNA-binding activity of 3C(pro) are involved in viral polyprotein processing and the initiation of viral RNA synthesis. In addition, 3C(pro) can induce the cleavage of certain cellular factors required for transcription, translation and nucleocytoplasmic trafficking to modulate cell physiology for viral replication. Due to interactions between 3C(pro) and these essential factors, 3C(pro) is also involved in viral pathogenesis to support efficient infection. Furthermore, based on the structural conservation, the development of irreversible inhibitors and discovery of non-covalent inhibitors for 3C(pro) are ongoing and a better understanding of the roles played by 3C(pro) may provide insights into the development of potential antiviral treatments. In this review, the current knowledge regarding the structural features, multiple functions in the viral life cycle, pathogen host interaction, and development of antiviral compounds for 3C(pro) is summarized.
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Affiliation(s)
- Di Sun
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
| | - Shun Chen
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Wenjiang, Chengdu 611130, China.
| | - Anchun Cheng
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Wenjiang, Chengdu 611130, China.
| | - Mingshu Wang
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Wenjiang, Chengdu 611130, China.
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Li L, Ulrich R, Baumgärtner W, Gerhauser I. Interferon-stimulated genes-essential antiviral effectors implicated in resistance to Theiler's virus-induced demyelinating disease. J Neuroinflammation 2015; 12:242. [PMID: 26703877 PMCID: PMC4690264 DOI: 10.1186/s12974-015-0462-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 12/17/2015] [Indexed: 01/08/2023] Open
Abstract
Background Experimental infection of mice with Theiler’s murine encephalomyelitis virus (TMEV) is used as an animal model of human multiple sclerosis. TMEV persists in susceptible mouse strains and causes a biphasic disease consisting of acute polioencephalomyelitis and chronic demyelinating leukomyelitis. In contrast, resistant mice eliminate the virus within 2 to 4 weeks, which seems to be based on a strong antiviral innate immune response including the activation of the type I interferon (IFN) pathway. Several interferon-stimulated genes (ISGs) such as IFN-stimulated protein of 15 kDa (ISG15), protein kinase R (PKR), and 2′5′-oligoadenylate synthetase (OAS) function as antiviral effectors and might contribute to virus elimination. Nevertheless, detailed investigations of the type I IFN pathway during TMEV-induced demyelinating disease (TMEV-IDD) are lacking. Methods The present study evaluated microarray data of the spinal cord obtained from susceptible SJL/J mice after TMEV infection focusing on IFN-related genes. Moreover, ISG gene and protein expression was determined in mock- and TMEV-infected SJL/J mice and compared to its expression in resistant C57BL/6 mice using real- time PCR, immunohistochemistry, and immunofluorescence. Results Interestingly, despite of increased ISG gene expression during TMEV-IDD, ISG protein expression was impaired in SJL/J mice and mainly restricted to demyelinated lesions. In contrast, high ISG protein levels were found in spinal cord gray and white matter of C57BL/6 compared to SJL/J mice in the acute and chronic phase of TMEV-IDD. In both mouse strains, ISG15 was mainly found in astrocytes and endothelial cells, whereas PKR was predominantly expressed by microglia/macrophages, oligodendrocytes, and neurons. Only few cells were immunopositive for OAS proteins. Conclusions High levels of antiviral ISG15 and PKR proteins in the spinal cord of C57BL/6 mice might block virus replication and play an important role in the resistance to TMEV-IDD. Electronic supplementary material The online version of this article (doi:10.1186/s12974-015-0462-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lin Li
- Department of Pathology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hannover, Germany. .,Center of Systems Neuroscience Hannover, Hannover, Germany.
| | - Reiner Ulrich
- Department of Pathology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hannover, Germany. .,Center of Systems Neuroscience Hannover, Hannover, Germany.
| | - Wolfgang Baumgärtner
- Department of Pathology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hannover, Germany. .,Center of Systems Neuroscience Hannover, Hannover, Germany.
| | - Ingo Gerhauser
- Department of Pathology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hannover, Germany.
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Ciomperlik JJ, Basta HA, Palmenberg AC. Three cardiovirus Leader proteins equivalently inhibit four different nucleocytoplasmic trafficking pathways. Virology 2015; 484:194-202. [PMID: 26115166 PMCID: PMC4567469 DOI: 10.1016/j.virol.2015.06.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 05/07/2015] [Accepted: 06/04/2015] [Indexed: 11/17/2022]
Abstract
Cardiovirus infections inhibit nucleocytoplasmic trafficking by Leader protein-induced phosphorylation of Phe/Gly-containing nucleoporins (Nups). Recombinant Leader from encephalomyocarditis virus, Theiler׳s murine encephalomyelitis virus and Saffold virus target the same subset of Nups, including Nup62 and Nup98, but not Nup50. Reporter cell lines with fluorescence mCherry markers for M9, RS and classical SV40 import pathways, as well as the Crm1-mediated export pathway, all responded to transfection with the full panel of Leader proteins, showing consequent cessation of path-specific active import/export. For this to happen, the Nups had to be presented in the context of intact nuclear pores and exposed to cytoplasmic extracts. The Leader phosphorylation cascade was not effective against recombinant Nup proteins. The findings support a model of Leader-dependent Nup phosphorylation with the purpose of disrupting Nup-transportin interactions.
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Affiliation(s)
- Jessica J Ciomperlik
- Institute for Molecular Virology, and Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, United States
| | - Holly A Basta
- Department of Biology, Rocky Mountain College, Billings, MT, United States
| | - Ann C Palmenberg
- Institute for Molecular Virology, and Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, United States.
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Copeland AM, Van Deusen NM, Schmaljohn CS. Rift Valley fever virus NSS gene expression correlates with a defect in nuclear mRNA export. Virology 2015; 486:88-93. [PMID: 26410240 DOI: 10.1016/j.virol.2015.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 08/04/2015] [Accepted: 09/03/2015] [Indexed: 11/25/2022]
Abstract
We investigated the localization of host mRNA during Rift Valley fever virus (RVFV) infection. Fluorescence in situ hybridization revealed that infection with RVFV altered the localization of host mRNA. mRNA accumulated in the nuclei of RVFV-infected but not mock-infected cells. Further, overexpression of the NSS gene, but not the N, GN or NSM genes correlated with mRNA nuclear accumulation. Nuclear accumulation of host mRNA was not observed in cells infected with a strain of RVFV lacking the gene encoding NSS, confirming that expression of NSS is likely responsible for this phenomenon.
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Affiliation(s)
- Anna Maria Copeland
- United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Nicole M Van Deusen
- United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Connie S Schmaljohn
- United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA.
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Selective Removal of FG Repeat Domains from the Nuclear Pore Complex by Enterovirus 2A(pro). J Virol 2015; 89:11069-79. [PMID: 26311873 DOI: 10.1128/jvi.00956-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 08/20/2015] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Enteroviruses proteolyze nuclear pore complex (NPC) proteins (Nups) during infection, leading to disruption of host nuclear transport pathways and alterations in nuclear permeability. To better understand how enteroviruses exert these effects on nuclear transport, the mechanisms and consequences of Nup98 proteolysis were examined. The results indicate that Nup98 is rapidly targeted for degradation following enterovirus infection and that this is mediated by the enterovirus 2A protease (2A(pro)). Incubation of bacterially expressed or in vitro-translated Nup98 with 2A(pro) results in proteolytic cleavage at multiple sites in vitro, indicating that 2A(pro) cleaves Nup98 directly. Site-directed mutagenesis of putative cleavage sites identified Gly374 and Gly552 as the sites of 2A(pro) proteolysis in Nup98 in vitro and in infected cells. Indirect immunofluorescence assays using an antibody that recognizes the N terminus of Nup98 revealed that proteolysis releases the N-terminal FG-rich region from the NPC. In contrast, similar analyses using an antibody to the C terminus indicated that this region is retained at the nuclear rim. Nup88, a core NPC component that serves as a docking site for Nup98, also remains at the NPC in infected cells. These findings support a model whereby the selective removal of Nup FG repeat domains leads to increased NPC permeability and inhibition of certain transport pathways, while retention of structural domains maintains the overall NPC structure and leaves other transport pathways unaffected. IMPORTANCE Enteroviruses are dependent upon host nuclear RNA binding proteins for efficient replication. This study examines the mechanisms responsible for alterations in nuclear transport in enterovirus-infected cells that lead to the cytoplasmic accumulation of these proteins. The results demonstrate that the enterovirus 2A protease directly cleaves the nuclear pore complex (NPC) protein, Nup98, at amino acid positions G374 and G552 both in vitro and in infected cells. Cleavage at these positions results in the selective removal of the FG-containing N terminus of Nup98 from the NPC, while the C terminus remains associated. Nup88, a core component of the NPC that serves as a docking site for the C terminus of Nup98, remains associated with the NPC in infected cells. These findings help to explain the alterations in permeability and nuclear transport in enterovirus-infected cells and how NPCs remain functional for certain trafficking pathways despite significant alterations to their compositions.
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Flather D, Semler BL. Picornaviruses and nuclear functions: targeting a cellular compartment distinct from the replication site of a positive-strand RNA virus. Front Microbiol 2015; 6:594. [PMID: 26150805 PMCID: PMC4471892 DOI: 10.3389/fmicb.2015.00594] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 05/29/2015] [Indexed: 11/13/2022] Open
Abstract
The compartmentalization of DNA replication and gene transcription in the nucleus and protein production in the cytoplasm is a defining feature of eukaryotic cells. The nucleus functions to maintain the integrity of the nuclear genome of the cell and to control gene expression based on intracellular and environmental signals received through the cytoplasm. The spatial separation of the major processes that lead to the expression of protein-coding genes establishes the necessity of a transport network to allow biomolecules to translocate between these two regions of the cell. The nucleocytoplasmic transport network is therefore essential for regulating normal cellular functioning. The Picornaviridae virus family is one of many viral families that disrupt the nucleocytoplasmic trafficking of cells to promote viral replication. Picornaviruses contain positive-sense, single-stranded RNA genomes and replicate in the cytoplasm of infected cells. As a result of the limited coding capacity of these viruses, cellular proteins are required by these intracellular parasites for both translation and genomic RNA replication. Being of messenger RNA polarity, a picornavirus genome can immediately be translated upon entering the cell cytoplasm. However, the replication of viral RNA requires the activity of RNA-binding proteins, many of which function in host gene expression, and are consequently localized to the nucleus. As a result, picornaviruses disrupt nucleocytoplasmic trafficking to exploit protein functions normally localized to a different cellular compartment from which they translate their genome to facilitate efficient replication. Furthermore, picornavirus proteins are also known to enter the nucleus of infected cells to limit host-cell transcription and down-regulate innate antiviral responses. The interactions of picornavirus proteins and host-cell nuclei are extensive, required for a productive infection, and are the focus of this review.
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Affiliation(s)
- Dylan Flather
- Department of Microbiology and Molecular Genetics, Center for Virus Research, School of Medicine, University of California, Irvine Irvine, CA, USA
| | - Bert L Semler
- Department of Microbiology and Molecular Genetics, Center for Virus Research, School of Medicine, University of California, Irvine Irvine, CA, USA
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Lloyd RE. Nuclear proteins hijacked by mammalian cytoplasmic plus strand RNA viruses. Virology 2015; 479-480:457-74. [PMID: 25818028 PMCID: PMC4426963 DOI: 10.1016/j.virol.2015.03.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 01/12/2015] [Accepted: 03/03/2015] [Indexed: 01/18/2023]
Abstract
Plus strand RNA viruses that replicate in the cytoplasm face challenges in supporting the numerous biosynthetic functions required for replication and propagation. Most of these viruses are genetically simple and rely heavily on co-opting cellular proteins, particularly cellular RNA-binding proteins, into new roles for support of virus infection at the level of virus-specific translation, and building RNA replication complexes. In the course of infectious cycles many nuclear-cytoplasmic shuttling proteins of mostly nuclear distribution are detained in the cytoplasm by viruses and re-purposed for their own gain. Many mammalian viruses hijack a common group of the same factors. This review summarizes recent gains in our knowledge of how cytoplasmic RNA viruses use these co-opted host nuclear factors in new functional roles supporting virus translation and virus RNA replication and common themes employed between different virus groups. Nuclear shuttling host proteins are commonly hijacked by RNA viruses to support replication. A limited group of ubiquitous RNA binding proteins are commonly hijacked by a broad range of viruses. Key virus proteins alter roles of RNA binding proteins in different stages of virus replication.
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Affiliation(s)
- Richard E Lloyd
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, United States.
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Solution structures of Mengovirus Leader protein, its phosphorylated derivatives, and in complex with nuclear transport regulatory protein, RanGTPase. Proc Natl Acad Sci U S A 2014; 111:15792-7. [PMID: 25331866 DOI: 10.1073/pnas.1411098111] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cardiovirus Leader (L) proteins induce potent antihost inhibition of active cellular nucleocytoplasmic trafficking by triggering aberrant hyperphosphorylation of nuclear pore proteins (Nup). To achieve this, L binds protein RanGTPase (Ran), a key trafficking regulator, and diverts it into tertiary or quaternary complexes with required kinases. The activity of L is regulated by two phosphorylation events not required for Ran binding. Matched NMR studies on the unphosphorylated, singly, and doubly phosphorylated variants of Mengovirus L (L(M)) show both modifications act together to partially stabilize a short internal α-helix comprising L(M) residues 43-46. This motif implies that ionic and Van der Waals forces contributed by phosphorylation help organize downstream residues 48-67 into a new interface. The full structure of L(M) as bound to Ran (unlabeled) and Ran (216 aa) as bound by L(M) (unlabeled) places L(M) into the BP1 binding site of Ran, wrapped by the conformational flexible COOH tail. The arrangement explains the tight KD for this complex and places the LM zinc finger and phosphorylation interface as surface exposed and available for subsequent reactions. The core structure of Ran, outside the COOH tail, is not altered by L(M) binding and remains accessible for canonical RanGTP partner interactions. Pull-down assays identify at least one putative Ran:L(M) partner as an exportin, Crm1, or CAS. A model of Ran:L(M):Crm1, based on the new structures suggests LM phosphorylation status may mediate Ran's selection of exportin(s) and cargo(s), perverting these native trafficking elements into the lethal antihost Nup phosphorylation pathways.
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Binding interactions between the encephalomyocarditis virus leader and protein 2A. J Virol 2014; 88:13503-9. [PMID: 25210192 DOI: 10.1128/jvi.02148-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
UNLABELLED The leader (L) and 2A proteins of cardioviruses are the primary antihost agents produced during infection. For encephalomyocarditis virus (EMCV), the prototype of the genus Cardiovirus, these proteins interact independently with key cellular partners to bring about inhibition of active nucleocytoplasmic trafficking and cap-dependent translation, respectively. L and 2A also bind each other and require this cooperation to achieve their effects during infection. Recombinant L and 2A interact with 1:1 stoichiometry at a KD (equilibrium dissociation constant) of 1.5 μM. The mapped contact domains include the amino-proximal third of 2A (first 50 amino acids) and the central hinge region of L. This contact partially overlaps the L segment that makes subsequent contact with Ran GTPase in the nucleus, and Ran can displace 2A from L. The equivalent proteins from Theiler's murine encephalomyelitis virus (TMEV; BeAn) and Saffold virus interact similarly in any subtype combination, with various affinities. The data suggest a mechanism whereby L takes advantage of the nuclear localization signal in the COOH region of 2A to enhance its trafficking to the nucleus. Once there, it exchanges partners in favor of Ran. This required cooperation during infection explains many observed codependent phenotypes of L and 2A mutations. IMPORTANCE Cardiovirus pathogenesis phenotypes vary dramatically, from asymptomatic, to mild gastrointestinal (GI) distress, to persistent demyelination and even encephalitic death. Leader and 2A are the primary viral determinants of pathogenesis, so understanding how these proteins cooperate to induce such a wide variety of outcomes for the host is of great important and interest to the field of virology, especially to those who use TMEV as a murine model for multiple sclerosis.
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Bonnet A, Palancade B. Regulation of mRNA trafficking by nuclear pore complexes. Genes (Basel) 2014; 5:767-91. [PMID: 25184662 PMCID: PMC4198930 DOI: 10.3390/genes5030767] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 11/17/2022] Open
Abstract
Over the last two decades, multiple studies have explored the mechanisms governing mRNA export out of the nucleus, a crucial step in eukaryotic gene expression. During transcription and processing, mRNAs are assembled into messenger ribonucleoparticles (mRNPs). mRNPs are then exported through nuclear pore complexes (NPCs), which are large multiprotein assemblies made of several copies of a limited number of nucleoporins. A considerable effort has been put into the dissection of mRNA export through NPCs at both cellular and molecular levels, revealing the conserved contributions of a subset of nucleoporins in this process, from yeast to vertebrates. Several reports have also demonstrated the ability of NPCs to sort out properly-processed mRNPs for entry into the nuclear export pathway. Importantly, changes in mRNA export have been associated with post-translational modifications of nucleoporins or changes in NPC composition, depending on cell cycle progression, development or exposure to stress. How NPC modifications also impact on cellular mRNA export in disease situations, notably upon viral infection, is discussed.
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Affiliation(s)
- Amandine Bonnet
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France.
| | - Benoit Palancade
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France.
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Noppe G, Dufeys C, Buchlin P, Marquet N, Castanares-Zapatero D, Balteau M, Hermida N, Bouzin C, Esfahani H, Viollet B, Bertrand L, Balligand JL, Vanoverschelde JL, Beauloye C, Horman S. Reduced scar maturation and contractility lead to exaggerated left ventricular dilation after myocardial infarction in mice lacking AMPKα1. J Mol Cell Cardiol 2014; 74:32-43. [DOI: 10.1016/j.yjmcc.2014.04.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 04/27/2014] [Accepted: 04/28/2014] [Indexed: 12/17/2022]
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Feng Q, Langereis MA, van Kuppeveld FJM. Induction and suppression of innate antiviral responses by picornaviruses. Cytokine Growth Factor Rev 2014; 25:577-85. [PMID: 25086453 PMCID: PMC7172595 DOI: 10.1016/j.cytogfr.2014.07.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 07/03/2014] [Indexed: 12/24/2022]
Abstract
The family Picornaviridae comprises of small, non-enveloped, positive-strand RNA viruses and contains many human and animal pathogens including enteroviruses (e.g. poliovirus, coxsackievirus, enterovirus 71 and rhinovirus), cardioviruses (e.g. encephalomyocarditis virus), hepatitis A virus and foot-and-mouth disease virus. Picornavirus infections activate a cytosolic RNA sensor, MDA5, which in turn, induces a type I interferon response, a crucial component of antiviral immunity. Moreover, picornaviruses activate the formation of stress granules (SGs), large aggregates of preassembled mRNPs (messenger ribonucleoprotein particles) to temporarily store these molecules upon cellular stress. Meanwhile, picornaviruses actively suppress these antiviral responses to ensure efficient replication. In this review we provide an overview of the induction and suppression of the MDA5-mediated IFN-α/β response and the cellular stress pathway by picornaviruses.
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Affiliation(s)
- Qian Feng
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, University of Utrecht, 3584CL Utrecht, The Netherlands
| | - Martijn A Langereis
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, University of Utrecht, 3584CL Utrecht, The Netherlands
| | - Frank J M van Kuppeveld
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, University of Utrecht, 3584CL Utrecht, The Netherlands.
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Cusick MF, Libbey JE, Fujinami RS. Picornavirus infection leading to immunosuppression. Future Virol 2014; 9:475-482. [PMID: 25214881 DOI: 10.2217/fvl.14.26] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Viruses, such as HIV, hepatitis A, poliovirus, coxsackievirus B3 and foot-and-mouth disease virus, use a variety of mechanisms to suppress the human immune system in order to evade clearance by the host. Therefore, investigating how a few changes in the viral genome of a nonlethal virus can lead to an alteration in disease, from survivable to immunosuppression and death, would provide valuable information into viral pathogenesis. In addition, we propose that gaining a better insight into how these viruses suppress an antiviral immune response could lead to viral-based therapeutics to combat specifc autoimmune diseases such as multiple sclerosis and Type 1 diabetes.
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Affiliation(s)
- Matthew F Cusick
- Department of Pathology, University of Utah, 15 North Medical Drive East, 2600 EEJMRB, Salt Lake City, UT 84112, USA
| | - Jane E Libbey
- Department of Pathology, University of Utah, 15 North Medical Drive East, 2600 EEJMRB, Salt Lake City, UT 84112, USA
| | - Robert S Fujinami
- Department of Pathology, University of Utah, 15 North Medical Drive East, 2600 EEJMRB, Salt Lake City, UT 84112, USA
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Connection between cardiac vascular permeability, myocardial edema, and inflammation during sepsis: role of the α1AMP-activated protein kinase isoform. Crit Care Med 2014; 41:e411-22. [PMID: 23963133 DOI: 10.1097/ccm.0b013e31829866dc] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECTIVE As adenosine monophosphate (AMP)-activated protein kinase both controls cytoskeleton organization in endothelial cells and exerts anti-inflammatory effects, we here postulated that it could influence vascular permeability and inflammation, thereby counteracting cardiac wall edema during sepsis. DESIGN Controlled animal study. SETTINGS University research laboratory. SUBJECTS C57BL/6J, α1AMPK, and α1AMPK mice. INTERVENTION Sepsis was triggered in vivo using a sublethal injection of lipopolysaccharide (O55B5, 10 mg/kg), inducing systolic left ventricular dysfunction. Left ventricular function, edema, vascular permeability, and inflammation were assessed in vivo in both wild-type mice (α1AMPK) and α1AMP-activated protein kinase-deficient mice (α1AMPK). The 5-aminoimidazole-4-carboxamide riboside served to study the impact of AMP-activated protein kinase activation on vascular permeability in vivo. The integrity of endothelial cell monolayers was also examined in vitro after lipopolysaccharide challenge in the presence of aminoimidazole-4-carboxamide riboside and/or after α1AMP-activated protein kinase silencing. MEASUREMENTS AND MAIN RESULTS α1AMP-activated protein kinase deficiency dramatically impaired tolerance to lipopolysaccharide challenge. Indeed, α1AMPK exhibited heightened cardiac vascular permeability after lipopolysaccharide challenge compared with α1AMPK. Consequently, an increase in left ventricular mass corresponding to exaggerated wall edema occurred in α1AMPK, without any further decrease in systolic function. Mechanistically, the lipopolysaccharide-induced α1AMPK cardiac phenotype could not be attributed to major changes in the systemic inflammatory response but was due to an increased disruption of interendothelial tight junctions. Accordingly, AMP-activated protein kinase activation by aminoimidazole-4-carboxamide riboside counteracted lipopolysaccharide-induced hyperpermeability in wild-type mice in vivo as well as in endothelial cells in vitro. This effect was associated with a potent protection of zonula occludens-1 linear border pattern in endothelial cells. CONCLUSIONS Our results demonstrate for the first time the involvement of a signaling pathway in the control of left ventricular wall edema during sepsis. AMP-activated protein kinase exerts a protective action through the preservation of interendothelial tight junctions. Interestingly, exaggerated left ventricular wall edema was not coupled with aggravated systolic dysfunction. However, it could contribute to diastolic dysfunction in patients with sepsis.
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Yasunaga A, Hanna SL, Li J, Cho H, Rose PP, Spiridigliozzi A, Gold B, Diamond MS, Cherry S. Genome-wide RNAi screen identifies broadly-acting host factors that inhibit arbovirus infection. PLoS Pathog 2014; 10:e1003914. [PMID: 24550726 PMCID: PMC3923753 DOI: 10.1371/journal.ppat.1003914] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 12/18/2013] [Indexed: 01/12/2023] Open
Abstract
Vector-borne viruses are an important class of emerging and re-emerging pathogens; thus, an improved understanding of the cellular factors that modulate infection in their respective vertebrate and insect hosts may aid control efforts. In particular, cell-intrinsic antiviral pathways restrict vector-borne viruses including the type I interferon response in vertebrates and the RNA interference (RNAi) pathway in insects. However, it is likely that additional cell-intrinsic mechanisms exist to limit these viruses. Since insects rely on innate immune mechanisms to inhibit virus infections, we used Drosophila as a model insect to identify cellular factors that restrict West Nile virus (WNV), a flavivirus with a broad and expanding geographical host range. Our genome-wide RNAi screen identified 50 genes that inhibited WNV infection. Further screening revealed that 17 of these genes were antiviral against additional flaviviruses, and seven of these were antiviral against other vector-borne viruses, expanding our knowledge of invertebrate cell-intrinsic immunity. Investigation of two newly identified factors that restrict diverse viruses, dXPO1 and dRUVBL1, in the Tip60 complex, demonstrated they contributed to antiviral defense at the organismal level in adult flies, in mosquito cells, and in mammalian cells. These data suggest the existence of broadly acting and functionally conserved antiviral genes and pathways that restrict virus infections in evolutionarily divergent hosts.
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Affiliation(s)
- Ari Yasunaga
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Penn Genome Frontiers Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sheri L. Hanna
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Penn Genome Frontiers Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jianqing Li
- Departments of Medicine, Molecular Microbiology, Pathology & Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Hyelim Cho
- Departments of Medicine, Molecular Microbiology, Pathology & Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Patrick P. Rose
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Penn Genome Frontiers Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Anna Spiridigliozzi
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Penn Genome Frontiers Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Beth Gold
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Penn Genome Frontiers Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Michael S. Diamond
- Departments of Medicine, Molecular Microbiology, Pathology & Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Sara Cherry
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Penn Genome Frontiers Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Moore TC, Kumm PM, Brown DM, Petro TM. Interferon response factor 3 is crucial to poly-I:C induced NK cell activity and control of B16 melanoma growth. Cancer Lett 2013; 346:122-8. [PMID: 24368188 DOI: 10.1016/j.canlet.2013.12.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 11/11/2013] [Accepted: 12/14/2013] [Indexed: 01/06/2023]
Abstract
Interferon Response Factor 3 (IRF3) induces several NK-cell activating factors, is activated by poly-I:C, an experimental cancer therapeutic, but is suppressed during many viral infections. IRF3 Knockout (KO) mice exhibited enhanced B16 melanoma growth, impaired intratumoral NK cell infiltration, but not an impaired poly-I:C therapeutic effect due to direct suppression of B16 growth. IRF3 was responsible for poly-I:C decrease in TIM-3 expression by intratumoral dendritic cells, induction of NK-cell Granzyme B and IFN-γ, and induction of macrophage IL-12, IL-15, IL-6, and IRF3-dependent NK-activating molecule (INAM). Thus, IRF3 is a key factor controlling melanoma growth through NK-cell activities, especially during poly-I:C therapy.
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Affiliation(s)
- Tyler C Moore
- School of Biological Sciences, University of Nebraska-Lincoln, United States
| | - Phyllis M Kumm
- Department of Oral Biology, University of Nebraska Medical Center, United States
| | - Deborah M Brown
- School of Biological Sciences, University of Nebraska-Lincoln, United States; Nebraska Center for Virology, University of Nebraska-Lincoln, United States
| | - Thomas M Petro
- Nebraska Center for Virology, University of Nebraska-Lincoln, United States; Department of Oral Biology, University of Nebraska Medical Center, United States.
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Encephalomyocarditis virus leader is phosphorylated by CK2 and syk as a requirement for subsequent phosphorylation of cellular nucleoporins. J Virol 2013; 88:2219-26. [PMID: 24335301 DOI: 10.1128/jvi.03150-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Encephalomyocarditis virus and Theilovirus are species in the Cardiovirus genus of the Picornaviridae family. For all cardioviruses, the viral polyprotein is initiated with a short Leader (L) protein unique to this genus. The nuclear magnetic resonance (NMR) structure of LE from encephalomyocarditis virus (EMCV) has been determined. The protein has an NH2-proximal CHCC zinc finger, a central linker, and a contiguous, highly acidic motif. The theiloviruses encode the same domains, with one or two additional, COOH-proximal domains, characteristic of the human Saffold viruses (SafV) and Theiler's murine encephalomyelitis viruses (TMEV), respectively. The expression of a cardiovirus L, in recombinant form, or during infection/transfection, triggers an extensive, cell-dependent, antihost phosphorylation cascade, targeting nucleoporins (Nups) that form the hydrophobic core of nuclear pore complexes (NPC). The consequent inhibition of active nucleocytoplasmic trafficking is potent and prevents the host from mounting an effective antiviral response. For this inhibition, the L proteins themselves must be phosphorylated. In cells (extracts or recombinant form), LE was shown to be phosphorylated at Thr47 and Tyr41. The first reaction (Thr47), catalyzed by casein kinase 2 (CK2), is an obligatory precedent to the second event (Tyr41), catalyzed by spleen tyrosine kinase (Syk). Site mutations in LE, or kinase-specific inhibitors, prevented LE phosphorylation and subsequent Nup phosphorylation. Parallel experiments with LS (SafV-2) and LT (TMEV BeAn) proteins confirmed the general cardiovirus requirement for L phosphorylation, but CK2 was not the culpable kinase. It is likely that LS and LT are both activated by alternative kinases in different cell types, probably reactive within the Theilo-specific domains. IMPORTANCE An understanding of the diverse methods used by viruses to interfere with cellular processes is important because they can teach us how to control virus infections. This report shows how viruses in the same genus use different cellular enzymes to phosphorylate their proteins. If these processes are interfered with, the viruses are severely disabled.
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Mutation of the Theiler's virus leader protein zinc-finger domain impairs apoptotic activity in murine macrophages. Virus Res 2013; 177:222-5. [PMID: 24036175 DOI: 10.1016/j.virusres.2013.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 08/27/2013] [Accepted: 09/02/2013] [Indexed: 01/01/2023]
Abstract
The Theiler's murine encephalomyelitis virus (TMEV) leader (L) protein zinc-finger domain was mutated to study its role in cell death in infection of the murine macrophage cell line M1-D, revealing that an intact zinc-finger domain is required for full apoptotic activity. A functional L zinc-finger domain was also required for activation of p38 MAPK that results in phosphorylation and activation of p53, and in turn, alteration of the conformation of the anti-apoptotic proteins Puma and Mcl-1, leading to the release of pro-apoptotic Bax and apoptosis through the intrinsic pathway. TMEV infection also inhibits host protein synthesis, a stress shown by others to induce apoptosis. Since inhibition of host protein synthesis follows rather than precedes activation of MKK3/6 and p38, it seems less likely that it triggers apoptosis in infected cells. Finally, we showed that the levels of reactive oxygen species following infection were consistent with apoptotic rather than necrotic cell death. Thus, these experiments support an important role for the TMEV L protein zinc-finger domain in apoptosis in an infected murine macrophage line.
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39
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Viral subversion of the nuclear pore complex. Viruses 2013; 5:2019-42. [PMID: 23959328 PMCID: PMC3761240 DOI: 10.3390/v5082019] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/29/2013] [Accepted: 08/08/2013] [Indexed: 12/17/2022] Open
Abstract
The nuclear pore complex (NPC) acts as a selective barrier between the nucleus and the cytoplasm and is responsible for mediating communication by regulating the transport of RNA and proteins. Numerous viral pathogens have evolved different mechanisms to hijack the NPC in order to regulate trafficking of viral proteins, genomes and even capsids into and out of the nucleus thus promoting virus replication. The present review examines the different strategies and the specific nucleoporins utilized during viral infections as a means of promoting their life cycle and inhibiting host viral defenses.
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Kuss SK, Mata MA, Zhang L, Fontoura BMA. Nuclear imprisonment: viral strategies to arrest host mRNA nuclear export. Viruses 2013; 5:1824-49. [PMID: 23872491 PMCID: PMC3738964 DOI: 10.3390/v5071824] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 06/27/2013] [Accepted: 07/11/2013] [Indexed: 12/15/2022] Open
Abstract
Viruses possess many strategies to impair host cellular responses to infection. Nuclear export of host messenger RNAs (mRNA) that encode antiviral factors is critical for antiviral protein production and control of viral infections. Several viruses have evolved sophisticated strategies to inhibit nuclear export of host mRNAs, including targeting mRNA export factors and nucleoporins to compromise their roles in nucleo-cytoplasmic trafficking of cellular mRNA. Here, we present a review of research focused on suppression of host mRNA nuclear export by viruses, including influenza A virus and vesicular stomatitis virus, and the impact of this viral suppression on host antiviral responses.
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Affiliation(s)
- Sharon K Kuss
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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41
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Encephalomyocarditis virus disrupts stress granules, the critical platform for triggering antiviral innate immune responses. J Virol 2013; 87:9511-22. [PMID: 23785203 DOI: 10.1128/jvi.03248-12] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In response to stress, cells induce ribonucleoprotein aggregates, termed stress granules (SGs). SGs are transient loci containing translation-stalled mRNA, which is eventually degraded or recycled for translation. Infection of some viruses, including influenza A virus with a deletion of nonstructural protein 1 (IAVΔNS1), induces SG-like protein aggregates. Previously, we showed that IAVΔNS1-induced SGs are required for efficient induction of type I interferon (IFN). Here, we investigated SG formation by different viruses using green fluorescent protein (GFP)-tagged Ras-Gap SH3 domain binding protein 1 (GFP-G3BP1) as an SG probe. HeLa cells stably expressing GFP-G3BP1 were infected with different viruses, and GFP fluorescence was monitored live with time-lapse microscopy. SG formations by different viruses was classified into 4 different patterns: no SG formation, stable SG formation, transient SG formation, and alternate SG formation. We focused on encephalomyocarditis virus (EMCV) infection, which exhibited transient SG formation. We found that EMCV disrupts SGs by cleavage of G3BP1 at late stages of infection (>8 h) through a mechanism similar to that used by poliovirus. Expression of a G3BP1 mutant that is resistant to the cleavage conferred persistent formation of SGs as well as an enhanced induction of IFN and other cytokines at late stages of infection. Additionally, knockdown of endogenous G3BP1 blocked SG formation with an attenuated induction of IFN and potentiated viral replication. Taken together, our findings suggest a critical role of SGs as an antiviral platform and shed light on one of the mechanisms by which a virus interferes with host stress and subsequent antiviral responses.
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42
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The epitope integration site for vaccine antigens determines virus control while maintaining efficacy in an engineered cancer vaccine. Mol Ther 2013; 21:1087-95. [PMID: 23568262 DOI: 10.1038/mt.2013.52] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Picornaviruses have been developed as potential therapies for gene delivery and vaccination. One drawback to their use is the potential for recombination and viral persistence. Therefore, the engineering strategies used must take into account the possibility for virus escape. We have developed Theiler's murine encephalomyelitis virus (TMEV) as a potential vaccine vector for use in immunotherapy. This study shows that insertion of a vaccine epitope at a unique site within the TMEV leader protein can dramatically increase the type I interferon (IFN) response to infection and promote rapid viral clearance. This live virus vaccine maintains its ability to drive antigen-specific CD8(+) T-cell responses to a model antigen as well as to the weakly immunogenic tumor antigen Her2/neu. Furthermore, the epitope integration site does not affect the efficacy of this vaccine as cancer immunotherapy for treating models of melanoma and breast cancer as demonstrated by delayed tumor outgrowth and increased survival in animals implanted with these tumors. These findings show that an attenuated virus retaining limited ability to replicate nonetheless can effectively mobilize CD8(+) cellular immunity and will be important for the design of picornavirus vectors used as immunotherapy in clinical settings.
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MDA5 localizes to stress granules, but this localization is not required for the induction of type I interferon. J Virol 2013; 87:6314-25. [PMID: 23536668 DOI: 10.1128/jvi.03213-12] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Virus infection can initiate a type I interferon (IFN-α/β) response via activation of the cytosolic RNA sensors retinoic acid-inducible gene-I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5). Furthermore, it can activate kinases that phosphorylate eukaryotic translation initiation factor 2α (eIF2α), which leads to inhibition of (viral) protein translation and formation of stress granules (SG). Most viruses have evolved mechanisms to suppress these cellular responses. Here, we show that a mutant mengovirus expressing an inactive leader (L) protein, which we have previously shown to be unable to suppress IFN-α/β, triggered SG formation in a protein kinase R (PKR)-dependent manner. Furthermore, we show that infection of cells that are defective in SG formation yielded higher viral RNA levels, suggesting that SG formation acts as an antiviral defense mechanism. Since the induction of both IFN-α/β and SG is suppressed by mengovirus L, we set out to investigate a potential link between these pathways. We observed that MDA5, the intracellular RNA sensor that recognizes picornaviruses, localized to SG. However, activation of the MDA5 signaling pathway did not trigger and was not required for SG formation. Moreover, cells that were unable to form SG-by protein kinase R (PKR) depletion, using cells expressing a nonphosphorylatable eIF2α protein, or by drug treatment that inhibits SG formation-displayed a normal IFN-α/β response. Thus, although MDA5 localizes to SG, this localization seems to be dispensable for induction of the IFN-α/β pathway.
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Sorgeloos F, Kreit M, Hermant P, Lardinois C, Michiels T. Antiviral type I and type III interferon responses in the central nervous system. Viruses 2013; 5:834-57. [PMID: 23503326 PMCID: PMC3705299 DOI: 10.3390/v5030834] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 03/11/2013] [Accepted: 03/12/2013] [Indexed: 12/23/2022] Open
Abstract
The central nervous system (CNS) harbors highly differentiated cells, such as neurons that are essential to coordinate the functions of complex organisms. This organ is partly protected by the blood-brain barrier (BBB) from toxic substances and pathogens carried in the bloodstream. Yet, neurotropic viruses can reach the CNS either by crossing the BBB after viremia, or by exploiting motile infected cells as Trojan horses, or by using axonal transport. Type I and type III interferons (IFNs) are cytokines that are critical to control early steps of viral infections. Deficiencies in the IFN pathway have been associated with fatal viral encephalitis both in humans and mice. Therefore, the IFN system provides an essential protection of the CNS against viral infections. Yet, basal activity of the IFN system appears to be low within the CNS, likely owing to the toxicity of IFN to this organ. Moreover, after viral infection, neurons and oligodendrocytes were reported to be relatively poor IFN producers and appear to keep some susceptibility to neurotropic viruses, even in the presence of IFN. This review addresses some trends and recent developments concerning the role of type I and type III IFNs in: i) preventing neuroinvasion and infection of CNS cells; ii) the identity of IFN-producing cells in the CNS; iii) the antiviral activity of ISGs; and iv) the activity of viral proteins of neurotropic viruses that target the IFN pathway.
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Affiliation(s)
- Frédéric Sorgeloos
- Université catholique de Louvain, de Duve Institute, VIRO B1.74.07, 74 avenue Hippocrate, B-1200, Brussels, Belgium.
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Chafe SC, Pierce JB, Mangroo D. Nuclear-cytoplasmic trafficking of NTF2, the nuclear import receptor for the RanGTPase, is subjected to regulation. PLoS One 2012; 7:e42501. [PMID: 22880006 PMCID: PMC3411763 DOI: 10.1371/journal.pone.0042501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 07/06/2012] [Indexed: 11/18/2022] Open
Abstract
NTF2 is a cytosolic protein responsible for nuclear import of Ran, a small Ras-like GTPase involved in a number of critical cellular processes, including cell cycle regulation, chromatin organization during mitosis, reformation of the nuclear envelope following mitosis, and controlling the directionality of nucleocytoplasmic transport. Herein, we provide evidence for the first time that translocation of the mammalian NTF2 from the nucleus to the cytoplasm to collect Ran in the GDP form is subjected to regulation. Treatment of mammalian cells with polysorbitan monolaurate was found to inhibit nuclear export of tRNA and proteins, which are processes dependent on RanGTP in the nucleus, but not nuclear import of proteins. Inhibition of the export processes by polysorbitan monolaurate is specific and reversible, and is caused by accumulation of Ran in the cytoplasm because of a block in translocation of NTF2 to the cytoplasm. Nuclear import of Ran and the nuclear export processes are restored in polysorbitan monolaurate treated cells overproducing NTF2. Moreover, increased phosphorylation of a phospho-tyrosine protein and several phospho-threonine proteins was observed in polysorbitan monolaurate treated cells. Collectively, these findings suggest that nucleocytoplasmic translocation of NTF2 is regulated in mammalian cells, and may involve a tyrosine and/or threonine kinase-dependent signal transduction mechanism(s).
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Affiliation(s)
| | | | - Dev Mangroo
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- * E-mail:
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Cohen S, Etingov I, Panté N. Effect of viral infection on the nuclear envelope and nuclear pore complex. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 299:117-59. [PMID: 22959302 DOI: 10.1016/b978-0-12-394310-1.00003-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The nuclear envelope (NE) is a vital structure that separates the nucleus from the cytoplasm. Because the NE is such a critical cellular barrier, many viral pathogens have evolved to modulate its permeability. They do this either by breaching the NE or by disrupting the integrity and functionality of the nuclear pore complex (NPC). Viruses modulate NE permeability for different reasons. Some viruses disrupt NE to deliver the viral genome into the nucleus for replication, while others cause NE disruption during nuclear egress of newly assembled capsids. Yet, other viruses modulate NE permeability and affect the compartmentalization of host proteins or block the nuclear transport of host proteins involved in the host antiviral response. Recent scientific advances demonstrated that other viruses use proteins of the NPC for viral assembly or disassembly. Here we review the ways in which various viruses affect NE and NPC during infection.
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Affiliation(s)
- Sarah Cohen
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
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47
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Abstract
Stress granules (SG) are cytoplasmic aggregates of stalled translation preinitiation complexes that form in cells exposed to various environmental stresses. Here, we show that stress granules assemble in cells infected with Theiler's murine encephalomyelitis virus (TMEV) mutants carrying alterations in the leader (L) protein, but not in cells infected with wild-type TMEV. Stress granules also formed in STAT1-deficient cells, suggesting that SG formation was not a consequence of increased type I interferon (IFN) production when cells were infected with the mutant virus. Ectopic expression of the wild-type L protein was sufficient to inhibit stress granule formation induced by sodium arsenite or thapsigargin treatment. In conclusion, TMEV infection induces stress granule assembly, but this process is inhibited by the L protein. Unlike poliovirus-induced stress granules, TMEV-induced stress granules did not contain the nuclear protein Sam68 but contained polypyrimidine tract binding protein (PTB), an internal ribosome entry site (IRES)-interacting protein. Moreover, G3BP was not degraded and was found in SG after TMEV infection, suggesting that SG content could be virus specific. Despite the colocalization of PTB with SG and the known interaction of PTB with viral RNA, in situ hybridization and immunofluorescence assays failed to detect viral RNA trapped in infection-induced SG. Recombinant Theiler's viruses expressing the L protein of Saffold virus 2 (SAFV-2), a closely related human theilovirus, or the L protein of mengovirus, an encephalomyocarditis virus (EMCV) strain, also inhibited infection-induced stress granule assembly, suggesting that stress granule antagonism is a common feature of cardiovirus L proteins.
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48
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Rhoades RE, Tabor-Godwin JM, Tsueng G, Feuer R. Enterovirus infections of the central nervous system. Virology 2011; 411:288-305. [PMID: 21251690 PMCID: PMC3060663 DOI: 10.1016/j.virol.2010.12.014] [Citation(s) in RCA: 148] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 12/08/2010] [Indexed: 12/15/2022]
Abstract
Enteroviruses (EV) frequently infect the central nervous system (CNS) and induce neurological diseases. Although the CNS is composed of many different cell types, the spectrum of tropism for each EV is considerable. These viruses have the ability to completely shut down host translational machinery and are considered highly cytolytic, thereby causing cytopathic effects. Hence, CNS dysfunction following EV infection of neuronal or glial cells might be expected. Perhaps unexpectedly given their cytolytic nature, EVs may establish a persistent infection within the CNS, and the lasting effects on the host might be significant with unanticipated consequences. This review will describe the clinical aspects of EV-mediated disease, mechanisms of disease, determinants of tropism, immune activation within the CNS, and potential treatment regimes.
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Affiliation(s)
| | | | | | - Ralph Feuer
- Corresponding author. Cell & Molecular Biology Joint Doctoral Program, Department of Biology, San Diego State University, 5500 Campanile Drive; San Diego, CA 92182-4614, USA. Fax: +1 619 594 0777.
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Abstract
Viral reproduction involves not only replication but also interactions with host defences. Although various viral proteins can take part in counteracting innate and adaptive immunity, many viruses possess a subset of proteins that are specifically dedicated to counter-defensive activities. These proteins are sometimes referred to as 'virulence factors', but here we argue that the term 'security proteins' is preferable, for several reasons. The concept of security proteins of RNA-containing viruses can be considered using the leader (L and L*) and 2A proteins of picornaviruses as examples. The picornaviruses are a large group of human and animal viruses that include important pathogens such as poliovirus, hepatitis A virus and foot-and-mouth disease virus. The genomes of different picornaviruses have a similar organization, in which the genes for L and 2A occupy fixed positions upstream and downstream of the capsid genes, respectively. Both L and 2A are extremely heterogeneous with respect to size, sequence and biochemical properties. The similarly named proteins can be completely unrelated to each other in different viral genera, and the variation can be striking even among members of the same genus. A subset of picornaviruses lacks L altogether. The properties and functions of L and 2A of many picornaviruses are unknown, but in those viruses that have been investigated sufficiently it has been found that these proteins can switch off various aspects of host macromolecular synthesis and specifically suppress mechanisms involved in innate immunity. Thus, notwithstanding their unrelatedness, the security proteins carry out similar biological functions. It is proposed that other picornavirus L and 2A proteins that have not yet been investigated should also be primarily involved in security activities. The L, L* and 2A proteins are dispensable for viral reproduction, but their elimination or inactivation usually renders the viruses less pathogenic. The phenotypic changes associated with inactivation of security proteins are much less pronounced in cells or organisms that have innate immunity deficiencies. In several examples, the decreased fitness of a virus in which a security protein has been inactivated could be rescued by the experimental introduction of an unrelated security protein. It can be argued that L and 2A were acquired by different picornaviruses independently, and possibly by exploiting different mechanisms, late in the evolution of this viral family. It is proposed that the concept of security proteins is of general relevance and can be applied to viruses other than picornaviruses. The hallmarks of security proteins are: structural and biochemical unrelatedness in related viruses or even absence in some of them; dispensability of the entire protein or its functional domains for viral viability; and, for mutated versions of the proteins, fewer detrimental effects on viral reproduction in immune-compromised hosts than in immune-competent hosts.
Viral security proteins are structurally and biochemically unrelated proteins that function to counteract host defences. Here, Agol and Gmyl consider the impact of the picornavirus security proteins on viral reproduction, pathogenicity and evolution. Interactions with host defences are key aspects of viral infection. Various viral proteins perform counter-defensive functions, but a distinct class, called security proteins, is dedicated specifically to counteracting host defences. Here, the properties of the picornavirus security proteins L and 2A are discussed. These proteins have well-defined positions in the viral polyprotein, flanking the capsid precursor, but they are structurally and biochemically unrelated. Here, we consider the impact of these two proteins, as well as that of a third security protein, L*, on viral reproduction, pathogenicity and evolution. The concept of security proteins could serve as a paradigm for the dedicated counter-defensive proteins of other viruses.
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Affiliation(s)
- Vadim I Agol
- M. P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences, Moscow 142782, Russia.
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50
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Different strains of Theiler's murine encephalomyelitis virus antagonize different sites in the type I interferon pathway. J Virol 2010; 84:9181-9. [PMID: 20610716 DOI: 10.1128/jvi.00603-10] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The DA strain of Theiler's murine encephalomyelitis virus (TMEV), a member of the Cardiovirus genus of the family Picornaviridae, causes persistent infection in susceptible mice, associated with restricted expression of viral proteins, and induces a demyelinating disease of the central nervous system. DA-induced demyelinating disease serves as a model of human multiple sclerosis because of similarities in pathology and because host immune responses contribute to pathogenesis in both disorders. In contrast, the GDVII strain of TMEV causes acute lethal encephalitis with no virus persistence. Cardiovirus L is a multifunctional protein that blocks beta interferon (IFN-beta) gene transcription. We show that both DA L and GDVII L disrupt IFN-beta gene transcription induction by IFN regulatory factor 3 (IRF-3) but do so at different points in the signaling pathway. DA L blocks IFN-beta gene transcription downstream of mitochondrial antiviral signaling protein (MAVS) but upstream of IRF-3 activation, while GDVII L acts downstream of IRF-3 activation. Both DA L and GDVII L block IFN-beta gene transcription in infected mice; however, IFN-beta mRNA is expressed at low levels in the central nervous systems of mice persistently infected with DA. The particular level of IFN-beta mRNA expression set by DA L as well as other factors in the IRF-3 pathway may play a role in virus persistence, inflammation, and the restricted expression of viral proteins during the late stage of demyelinating disease.
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