151
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Fernández-Sanlés A, Ríos-Marco P, Romero-López C, Berzal-Herranz A. Functional Information Stored in the Conserved Structural RNA Domains of Flavivirus Genomes. Front Microbiol 2017; 8:546. [PMID: 28421048 PMCID: PMC5376627 DOI: 10.3389/fmicb.2017.00546] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/15/2017] [Indexed: 02/05/2023] Open
Abstract
The genus Flavivirus comprises a large number of small, positive-sense single-stranded, RNA viruses able to replicate in the cytoplasm of certain arthropod and/or vertebrate host cells. The genus, which has some 70 member species, includes a number of emerging and re-emerging pathogens responsible for outbreaks of human disease around the world, such as the West Nile, dengue, Zika, yellow fever, Japanese encephalitis, St. Louis encephalitis, and tick-borne encephalitis viruses. Like other RNA viruses, flaviviruses have a compact RNA genome that efficiently stores all the information required for the completion of the infectious cycle. The efficiency of this storage system is attributable to supracoding elements, i.e., discrete, structural units with essential functions. This information storage system overlaps and complements the protein coding sequence and is highly conserved across the genus. It therefore offers interesting potential targets for novel therapeutic strategies. This review summarizes our knowledge of the features of flavivirus genome functional RNA domains. It also provides a brief overview of the main achievements reported in the design of antiviral nucleic acid-based drugs targeting functional genomic RNA elements.
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Affiliation(s)
- Alba Fernández-Sanlés
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López-Neyra," Consejo Superior de Investigaciones Científicas (IPBLN-CSIC)Granada, Spain
| | - Pablo Ríos-Marco
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López-Neyra," Consejo Superior de Investigaciones Científicas (IPBLN-CSIC)Granada, Spain
| | - Cristina Romero-López
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López-Neyra," Consejo Superior de Investigaciones Científicas (IPBLN-CSIC)Granada, Spain
| | - Alfredo Berzal-Herranz
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López-Neyra," Consejo Superior de Investigaciones Científicas (IPBLN-CSIC)Granada, Spain
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152
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Japanese Encephalitis Virus NS5 Inhibits Type I Interferon (IFN) Production by Blocking the Nuclear Translocation of IFN Regulatory Factor 3 and NF-κB. J Virol 2017; 91:JVI.00039-17. [PMID: 28179530 DOI: 10.1128/jvi.00039-17] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 01/31/2017] [Indexed: 12/24/2022] Open
Abstract
The type I interferon (IFN) response is part of the first-line defense against viral infection. To initiate replication, viruses have developed powerful evasion strategies to counteract host IFN responses. In the present study, we found that the Japanese encephalitis virus (JEV) NS5 protein could inhibit double-stranded RNA (dsRNA)-induced IFN-β expression in a dose-dependent manner. Our data further demonstrated that JEV NS5 suppressed the activation of the IFN transcriptional factors IFN regulatory factor 3 (IRF3) and NF-κB. However, there was no defect in the phosphorylation of IRF3 and degradation of IκB, an upstream inhibitor of NF-κB, upon NS5 expression, indicating a direct inhibition of the nuclear localization of IRF3 and NF-κB by NS5. Mechanistically, NS5 was shown to interact with the nuclear transport proteins KPNA2, KPNA3, and KPNA4, which competitively blocked the interaction of KPNA3 and KPNA4 with their cargo molecules, IRF3 and p65, a subunit of NF-κB, and thus inhibited the nuclear translocation of IRF3 and NF-κB. Furthermore, overexpression of KPNA3 and KPNA4 restored the activity of IRF3 and NF-κB and increased the production of IFN-β in NS5-expressing or JEV-infected cells. Additionally, an upregulated replication level of JEV was shown upon KPNA3 or KPNA4 overexpression. These results suggest that JEV NS5 inhibits the induction of type I IFN by targeting KPNA3 and KPNA4.IMPORTANCE JEV is the major cause of viral encephalitis in South and Southeast Asia, with high mortality. However, the molecular mechanisms contributing to the severe pathogenesis are poorly understood. The ability of JEV to counteract the host innate immune response is potentially one of the mechanisms responsible for JEV virulence. Here we demonstrate the ability of JEV NS5 to interfere with the dsRNA-induced nuclear translocation of IRF3 and NF-κB by competitively inhibiting the interaction of IRF3 and NF-κB with nuclear transport proteins. Via this mechanism, JEV NS5 suppresses the induction of type I IFN and the antiviral response in host cells. These findings reveal a novel strategy for JEV to escape the host innate immune response and provide new insights into the pathogenesis of JEV.
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153
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Yun SI, Lee YM. Zika virus: An emerging flavivirus. J Microbiol 2017; 55:204-219. [PMID: 28243937 DOI: 10.1007/s12275-017-7063-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 02/15/2017] [Indexed: 01/18/2023]
Abstract
Zika virus (ZIKV) is a previously little-known flavivirus closely related to Japanese encephalitis, West Nile, dengue, and yellow fever viruses, all of which are primarily transmitted by blood-sucking mosquitoes. Since its discovery in Uganda in 1947, ZIKV has continued to expand its geographic range, from equatorial Africa and Asia to the Pacific Islands, then further afield to South and Central America and the Caribbean. Currently, ZIKV is actively circulating not only in much of Latin America and its neighbors but also in parts of the Pacific Islands and Southeast Asia. Although ZIKV infection generally causes only mild symptoms in some infected individuals, it is associated with a range of neuroimmunological disorders, including Guillain-Barré syndrome, meningoencephalitis, and myelitis. Recently, maternal ZIKV infection during pregnancy has been linked to neonatal malformations, resulting in various degrees of congenital abnormalities, microcephaly, and even abortion. Despite its emergence as an important public health problem, however, little is known about ZIKV biology, and neither vaccine nor drug is available to control ZIKV infection. This article provides a brief introduction to ZIKV with a major emphasis on its molecular virology, in order to help facilitate the development of diagnostics, therapeutics, and vaccines.
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Affiliation(s)
- Sang-Im Yun
- Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, UT, 84322-4815, USA
| | - Young-Min Lee
- Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, UT, 84322-4815, USA. .,Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, 84322-4815, USA.
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154
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Strating JR, van Kuppeveld FJ. Viral rewiring of cellular lipid metabolism to create membranous replication compartments. Curr Opin Cell Biol 2017; 47:24-33. [PMID: 28242560 PMCID: PMC7127510 DOI: 10.1016/j.ceb.2017.02.005] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Revised: 02/02/2017] [Accepted: 02/09/2017] [Indexed: 02/08/2023]
Abstract
Positive-strand RNA (+RNA) viruses (e.g. poliovirus, hepatitis C virus, dengue virus, SARS-coronavirus) remodel cellular membranes to form so-called viral replication compartments (VRCs), which are the sites where viral RNA genome replication takes place. To induce VRC formation, these viruses extensively rewire lipid metabolism. Disparate viruses have many commonalities as well as disparities in their interactions with the host lipidome and accumulate specific sets of lipids (sterols, glycerophospholipids, sphingolipids) at their VRCs. Recent years have seen an upsurge in studies investigating the role of lipids in +RNA virus replication, in particular of sterols, and uncovered that membrane contact sites and lipid transfer proteins are hijacked by viruses and play pivotal roles in VRC formation.
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Affiliation(s)
- Jeroen Rpm Strating
- Utrecht University, Faculty of Veterinary Medicine, Department of Infectious Diseases & Immunology, Division of Virology, Utrecht, The Netherlands.
| | - Frank Jm van Kuppeveld
- Utrecht University, Faculty of Veterinary Medicine, Department of Infectious Diseases & Immunology, Division of Virology, Utrecht, The Netherlands.
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155
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Lopez-Denman AJ, Mackenzie JM. The IMPORTance of the Nucleus during Flavivirus Replication. Viruses 2017; 9:v9010014. [PMID: 28106839 PMCID: PMC5294983 DOI: 10.3390/v9010014] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 12/24/2022] Open
Abstract
Flaviviruses are a large group of arboviruses of significant medical concern worldwide. With outbreaks a common occurrence, the need for efficient viral control is required more than ever. It is well understood that flaviviruses modulate the composition and structure of membranes in the cytoplasm that are crucial for efficient replication and evading immune detection. As the flavivirus genome consists of positive sense RNA, replication can occur wholly within the cytoplasm. What is becoming more evident is that some viral proteins also have the ability to translocate to the nucleus, with potential roles in replication and immune system perturbation. In this review, we discuss the current understanding of flavivirus nuclear localisation, and the function it has during flavivirus infection. We also describe-while closely related-the functional differences between similar viral proteins in their nuclear translocation.
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Affiliation(s)
- Adam J Lopez-Denman
- Department of Microbiology & Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Victoria 3010, Australia.
- Department of Physiology, Anatomy & Microbiology, La Trobe University, Melbourne 3086, Australia.
| | - Jason M Mackenzie
- Department of Microbiology & Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Victoria 3010, Australia.
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156
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Offerdahl DK, Dorward DW, Hansen BT, Bloom ME. Cytoarchitecture of Zika virus infection in human neuroblastoma and Aedes albopictus cell lines. Virology 2017; 501:54-62. [PMID: 27863275 PMCID: PMC5201448 DOI: 10.1016/j.virol.2016.11.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 10/28/2016] [Accepted: 11/02/2016] [Indexed: 01/22/2023]
Abstract
The Zika virus (ZIKV) pandemic is a global concern due to its role in the development of congenital anomalies of the central nervous system. This mosquito-borne flavivirus alternates between mammalian and mosquito hosts, but information about the biogenesis of ZIKV is limited. Using a human neuroblastoma cell line (SK-N-SH) and an Aedes albopictus mosquito cell line (C6/36), we characterized ZIKV infection by immunofluorescence, transmission electron microscopy (TEM), and electron tomography (ET) to better understand infection in these disparate host cells. ZIKV replicated well in both cell lines, but infected SK-N-SH cells suffered a lytic crisis. Flaviviruses scavenge host cell membranes to serve as replication platforms and ZIKV showed the hallmarks of this process. Via TEM, we identified virus particles and 60-100nm spherular vesicles. ET revealed these vesicular replication compartments contain smaller 20-30nm spherular structures. Our studies indicate that SK-N-SH and C6/36 cells are relevant models for viral cytoarchitecture study.
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Affiliation(s)
- Danielle K Offerdahl
- Laboratory of Virology, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT, United States
| | - David W Dorward
- Microscopy Unit, Research Technology Branch, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT, United States
| | - Bryan T Hansen
- Microscopy Unit, Research Technology Branch, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT, United States
| | - Marshall E Bloom
- Laboratory of Virology, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT, United States.
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157
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Phongphaew W, Kobayashi S, Sasaki M, Carr M, Hall WW, Orba Y, Sawa H. Valosin-containing protein (VCP/p97) plays a role in the replication of West Nile virus. Virus Res 2016; 228:114-123. [PMID: 27914931 PMCID: PMC7114552 DOI: 10.1016/j.virusres.2016.11.029] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 11/25/2016] [Accepted: 11/25/2016] [Indexed: 12/16/2022]
Abstract
Inhibition of VCP by chemical inhibitors decreased WNV infection in a dose-dependent manner. Knockdown of endogenous VCP level using siRNA suppressed WNV infection. Depletion of VCP levels suppressed WNV infection at the early stages of WNV replication cycle. Depletion of VCP levels lowered nascent WNV genomic RNA. VCP participates in early stages and viral genomic RNA replication.
Valosin-containing protein (VCP) is classified as a member of the type II AAA+ ATPase protein family. VCP functions in several cellular processes, including protein degradation, membrane fusion, vesicular trafficking and disassembly of stress granules. Moreover, VCP is considered to play a role in the replication of several viruses, albeit through different mechanisms. In the present study, we have investigated the role of VCP in West Nile virus (WNV) infection. Endogenous VCP expression was inhibited using either VCP inhibitors or by siRNA knockdown. It could be shown that the inhibition of endogenous VCP expression significantly inhibited WNV infection. The entry assay revealed that silencing of endogenous VCP caused a significant reduction in the expression levels of WNV-RNA compared to control siRNA-treated cells. This indicates that VCP may play a role in early steps either the binding or entry steps of the WNV life cycle. Using WNV virus like particles and WNV-DNA-based replicon, it could be demonstrated that perturbation of VCP expression decreased levels of newly synthesized WNV genomic RNA. These findings suggest that VCP is involved in early steps and during genome replication of the WNV life cycle.
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Affiliation(s)
- Wallaya Phongphaew
- Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan
| | - Shintaro Kobayashi
- Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan; Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, N18, W9, Kita-ku, Sapporo 001-0020, Japan
| | - Michihito Sasaki
- Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan
| | - Michael Carr
- Global Institution for Collaborative Researches and Education (GI-CoRE), Global Station for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan; National Virus Reference Laboratory, University College Dublin, Belfield, Dublin 4, Ireland
| | - William W Hall
- Global Institution for Collaborative Researches and Education (GI-CoRE), Global Station for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan; Center for Research in Infectious Diseases, University College of Dublin, Belfield, Dublin 4, Dublin, Ireland; Global Virus Network (GVN), The Institute of Human Virology, University of Maryland, 22S. Greene Street, Baltimore, MD 21201, USA
| | - Yasuko Orba
- Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan
| | - Hirofumi Sawa
- Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan; Global Institution for Collaborative Researches and Education (GI-CoRE), Global Station for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan; Global Virus Network (GVN), The Institute of Human Virology, University of Maryland, 22S. Greene Street, Baltimore, MD 21201, USA.
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158
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Miyamura T, Lemon SM, Walker CM, Wakita T. The HCV Replicase Complex and Viral RNA Synthesis. HEPATITIS C VIRUS I 2016. [PMCID: PMC7122888 DOI: 10.1007/978-4-431-56098-2_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Replication of hepatitis C virus (HCV) is tightly linked to membrane alterations designated the membranous web, harboring the viral replicase complex. In this chapter we describe the morphology and 3D architecture of the HCV-induced replication organelles, mainly consisting of double membrane vesicles, which are generated by a concerted action of the nonstructural proteins NS3 to NS5B. Recent studies have furthermore identified a number of host cell proteins and lipids contributing to the biogenesis of the membranous web, which are discussed in this chapter. Viral RNA synthesis is tightly associated with these membrane alterations and mainly driven by the viral RNA dependent RNA polymerase NS5B. We summarize our current knowledge of the structure and function of NS5B, the role of cis-acting replication elements at the termini of the genome in regulating RNA synthesis and the contribution of additional viral and host factors to viral RNA synthesis, which is still ill defined.
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Affiliation(s)
- Tatsuo Miyamura
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
| | - Stanley M. Lemon
- Departments of Medicine and Microbiology & Immunology , The University of North Carolina, Chapel Hill, North Carolina USA
| | - Christopher M. Walker
- Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio USA
| | - Takaji Wakita
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
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159
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Abstract
Replication of positive-strand RNA viruses occurs in tight association with reorganized host cell membranes. In a concerted fashion, viral and cellular factors generate distinct organelle-like structures, designated viral replication factories. These virus-induced compartments promote highly efficient genome replication, allow spatiotemporal coordination of the different steps of the viral replication cycle, and protect viral RNA from the hostile cytoplasmic environment. The combined use of ultrastructural and functional studies has greatly increased our understanding of the architecture and biogenesis of viral replication factories. Here, we review common concepts and distinct differences in replication organelle morphology and biogenesis within the Flaviviridae family, exemplified by dengue virus and hepatitis C virus. We discuss recent progress made in our understanding of the complex interplay between viral determinants and subverted cellular membrane homeostasis in biogenesis and maintenance of replication factories of this virus family.
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Affiliation(s)
- David Paul
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, 69120 Heidelberg, Germany; ,
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, 69120 Heidelberg, Germany; , .,Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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160
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Gack MU, Diamond MS. Innate immune escape by Dengue and West Nile viruses. Curr Opin Virol 2016; 20:119-128. [PMID: 27792906 DOI: 10.1016/j.coviro.2016.09.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 09/15/2016] [Accepted: 09/27/2016] [Indexed: 12/28/2022]
Abstract
Dengue (DENV) and West Nile (WNV) viruses are mosquito-transmitted flaviviruses that cause significant morbidity and mortality worldwide. Disease severity and pathogenesis of DENV and WNV infections in humans depend on many factors, including pre-existing immunity, strain virulence, host genetics and virus-host interactions. Among the flavivirus-host interactions, viral evasion of type I interferon (IFN)-mediated innate immunity has a critical role in modulating pathogenesis. DENV and WNV have evolved effective strategies to evade immune surveillance pathways that lead to IFN induction and to block signaling downstream of the IFN-α/β receptor. Here, we discuss recent advances in our understanding of the molecular mechanisms by which DENV and WNV antagonize the type I IFN response in human cells.
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Affiliation(s)
- Michaela U Gack
- Department of Microbiology, The University of Chicago, Chicago, IL, 60637, USA.
| | - Michael S Diamond
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St. Louis, MO 63110, USA
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161
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Martín-Acebes MA, Vázquez-Calvo Á, Saiz JC. Lipids and flaviviruses, present and future perspectives for the control of dengue, Zika, and West Nile viruses. Prog Lipid Res 2016; 64:123-137. [PMID: 27702593 DOI: 10.1016/j.plipres.2016.09.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 08/17/2016] [Accepted: 09/16/2016] [Indexed: 02/06/2023]
Abstract
Flaviviruses are emerging arthropod-borne pathogens that cause life-threatening diseases such as yellow fever, dengue, West Nile encephalitis, tick-borne encephalitis, Kyasanur Forest disease, tick-borne encephalitis, or Zika disease. This viral genus groups >50 viral species of small enveloped plus strand RNA virus that are phylogenetically closely related to hepatitis C virus. Importantly, the flavivirus life cycle is intimately associated to host cell lipids. Along this line, flaviviruses rearrange intracellular membranes from the endoplasmic-reticulum of the infected cells to develop adequate platforms for viral replication and particle biogenesis. Moreover, flaviviruses dramatically orchestrate a profound reorganization of the host cell lipid metabolism to create a favorable environment for viral multiplication. Consistently, recent work has shown the importance of specific lipid classes in flavivirus infections. For instances, fatty acid synthesis is linked to viral replication, phosphatidylserine and phosphatidylethanolamine are involved on the entry of flaviviruses, sphingolipids (ceramide and sphingomyelin) play a key role on virus assembly and pathogenesis, and cholesterol is essential for innate immunity evasion in flavivirus-infected cells. Here, we revise the current knowledge on the interactions of the flaviviruses with the cellular lipid metabolism to identify potential targets for future antiviral development aimed to combat these relevant health-threatening pathogens.
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Affiliation(s)
- Miguel A Martín-Acebes
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Carretera de A Coruña km 7.5, 28040 Madrid, Spain.
| | - Ángela Vázquez-Calvo
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Carretera de A Coruña km 7.5, 28040 Madrid, Spain
| | - Juan-Carlos Saiz
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Carretera de A Coruña km 7.5, 28040 Madrid, Spain
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162
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Liu ZY, Li XF, Jiang T, Deng YQ, Ye Q, Zhao H, Yu JY, Qin CF. Viral RNA switch mediates the dynamic control of flavivirus replicase recruitment by genome cyclization. eLife 2016; 5. [PMID: 27692070 PMCID: PMC5101012 DOI: 10.7554/elife.17636] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 09/30/2016] [Indexed: 12/23/2022] Open
Abstract
Viral replicase recruitment and long-range RNA interactions are essential for RNA virus replication, yet the mechanism of their interplay remains elusive. Flaviviruses include numerous important human pathogens, e.g., dengue virus (DENV) and Zika virus (ZIKV). Here, we revealed a highly conserved, conformation-tunable cis-acting element named 5′-UAR-flanking stem (UFS) in the flavivirus genomic 5′ terminus. We demonstrated that the UFS was critical for efficient NS5 recruitment and viral RNA synthesis in different flaviviruses. Interestingly, stabilization of the DENV UFS impaired both genome cyclization and vRNA replication. Moreover, the UFS unwound in response to genome cyclization, leading to the decreased affinity of NS5 for the viral 5′ end. Thus, we propose that the UFS is switched by genome cyclization to regulate dynamic RdRp binding for vRNA replication. This study demonstrates that the UFS enables communication between flavivirus genome cyclization and RdRp recruitment, highlighting the presence of switch-like mechanisms among RNA viruses. DOI:http://dx.doi.org/10.7554/eLife.17636.001 Flaviviruses include a large family of viruses that are harmful to human health, such as dengue virus, West Nile virus and Zika virus. Understanding the details of the life cycle of these viruses is important for better controlling and treating the diseases that they cause. The genetic information of flaviviruses is stored in single-stranded molecules of RNA. To form new copies of a virus, the RNA must be replicated in a process that involves two critical steps. First, an enzyme called viral RNA polymerase NS5 must be recruited to a specific end of the RNA strand (known as the 5′ end). Then, the ends of the RNA strand bind together to form a circular loop. However, little is known about whether these two processes are linked, or how they are regulated. Using bioinformatics, biochemical and reverse genetics approaches, Liu et al. have now identified a new section of RNA in the 5′ end of the flavivirus RNA, named the 5′-UAR-flanking stem (or UFS for short), which is critical for viral replication. The UFS plays an important role in efficiently recruiting the NS5 viral RNA polymerase to the 5′ end of the flavivirus RNA. After the RNA forms a circle, the UFS unwinds. This makes the NS5 polymerase less likely to bind to the 5′ end of the RNA. Stabilizing the structure of the UFS impairs the ability of the RNA strand to form a circle, and hence reduces the ability of the RNA to replicate. Thus, the UFS links and enables communication between the processes that form the flavivirus RNA into a circle and that recruit the viral RNA polymerase to the RNA. The structural basis of the interaction between the flavivirus RNA 5′ end, including the UFS element, and the viral RNA polymerase now deserves further investigation. It will be also important to explore whether other types of viruses regulate their replication via a similar mechanism. DOI:http://dx.doi.org/10.7554/eLife.17636.002
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Affiliation(s)
- Zhong-Yu Liu
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China.,State Key Laboratory of Pathogen and Biosecurity, Beijing, China
| | - Xiao-Feng Li
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China.,State Key Laboratory of Pathogen and Biosecurity, Beijing, China
| | - Tao Jiang
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China.,State Key Laboratory of Pathogen and Biosecurity, Beijing, China
| | - Yong-Qiang Deng
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China.,State Key Laboratory of Pathogen and Biosecurity, Beijing, China
| | - Qing Ye
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Hui Zhao
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jiu-Yang Yu
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Cheng-Feng Qin
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China.,State Key Laboratory of Pathogen and Biosecurity, Beijing, China
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163
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Maximova OA, Bernbaum JG, Pletnev AG. West Nile Virus Spreads Transsynaptically within the Pathways of Motor Control: Anatomical and Ultrastructural Mapping of Neuronal Virus Infection in the Primate Central Nervous System. PLoS Negl Trop Dis 2016; 10:e0004980. [PMID: 27617450 PMCID: PMC5019496 DOI: 10.1371/journal.pntd.0004980] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/15/2016] [Indexed: 02/06/2023] Open
Abstract
Background During recent West Nile virus (WNV) outbreaks in the US, half of the reported cases were classified as neuroinvasive disease. WNV neuroinvasion is proposed to follow two major routes: hematogenous and/or axonal transport along the peripheral nerves. How virus spreads once within the central nervous system (CNS) remains unknown. Methodology/Principal Findings Using immunohistochemistry, we examined the expression of viral antigens in the CNS of rhesus monkeys that were intrathalamically inoculated with a wild-type WNV. The localization of WNV within the CNS was mapped to specific neuronal groups and anatomical structures. The neurological functions related to structures containing WNV-labeled neurons were reviewed and summarized. Intraneuronal localization of WNV was investigated by electron microscopy. The known anatomical connectivity of WNV-labeled neurons was used to reconstruct the directionality of WNV spread within the CNS using a connectogram design. Anatomical mapping revealed that all structures identified as containing WNV-labeled neurons belonged to the pathways of motor control. Ultrastructurally, virions were found predominantly within vesicular structures (including autophagosomes) in close vicinity to the axodendritic synapses, either at pre- or post-synaptic positions (axonal terminals and dendritic spines, respectively), strongly indicating transsynaptic spread of the virus between connected neurons. Neuronal connectivity-based reconstruction of the directionality of transsynaptic virus spread suggests that, within the CNS, WNV can utilize both anterograde and retrograde axonal transport to infect connected neurons. Conclusions/Significance This study offers a new insight into the neuropathogenesis of WNV infection in a primate model that closely mimics WNV encephalomyelitis in humans. We show that within the primate CNS, WNV primarily infects the anatomical structures and pathways responsible for the control of movement. Our findings also suggest that WNV most likely propagates within the CNS transsynaptically, by both, anterograde and retrograde axonal transport. West Nile virus (WNV) is a mosquito-borne neurotropic flavivirus that has emerged as a human pathogen of global scale. During recent WNV outbreaks in the US, half of the reported human cases were classified as neuroinvasive disease. Although much research has been done, there are still gaps in our understanding of WNV neuropathogenesis. While WNV neuroinvasion is proposed to occur by the hematogenous route and/or by axonal transport along the peripheral nerves, how virus spreads once within the central nervous system (CNS) remains unknown. In this study, we examined the expression of viral antigens in the CNS of monkeys that were intrathalamically inoculated with WNV. Next, we mapped the localization of WNV-infected neurons to specific anatomical structures, identified the intraneuronal localizations of WNV particles and investigated the role of neuronal connectivity in the spread of WNV within the CNS. Our results revealed that all structures containing WNV-labeled neurons belonged to the pathways of motor control. Virions were found in close vicinity to the axodendritic synapses, strongly indicating transsynaptic spread of the virus. Neuronal connectivity-based reconstruction of the directionality of transsynaptic virus spread suggests that, within the CNS, WNV can utilize both anterograde and retrograde axonal transport to infect connected neurons.
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Affiliation(s)
- Olga A. Maximova
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (OAM); (AGP)
| | - John G. Bernbaum
- Office of the Chief Scientist, Integrated Research Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, Maryland, United States of America
| | - Alexander G. Pletnev
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (OAM); (AGP)
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164
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Valadão ALC, Aguiar RS, de Arruda LB. Interplay between Inflammation and Cellular Stress Triggered by Flaviviridae Viruses. Front Microbiol 2016; 7:1233. [PMID: 27610098 PMCID: PMC4996823 DOI: 10.3389/fmicb.2016.01233] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 07/25/2016] [Indexed: 12/15/2022] Open
Abstract
The Flaviviridae family comprises several human pathogens, including Dengue, Zika, Yellow Fever, West Nile, Japanese Encephalitis viruses, and Hepatitis C Virus. Those are enveloped, single-stranded positive sense RNA viruses, which replicate mostly in intracellular compartments associated to endoplasmic reticulum (ER) and Golgi complex. Virus replication results in abundant viral RNAs and proteins, which are recognized by cellular mechanisms evolved to prevent virus infection, resulting in inflammation and stress responses. Virus RNA molecules are sensed by Toll-like receptors (TLRs), RIG-I-like receptors (RIG-I and MDA5) and RNA-dependent protein kinases (PKR), inducing the production of inflammatory mediators and interferons. Simultaneously, the synthesis of virus RNA and proteins are distinguished in different compartments such as mitochondria, ER and cytoplasmic granules, triggering intracellular stress pathways, including oxidative stress, unfolded protein response pathway, and stress granules assembly. Here, we review the new findings that connect the inflammatory pathways to cellular stress sensors and the strategies of Flaviviridae members to counteract these cellular mechanisms and escape immune response.
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Affiliation(s)
- Ana L C Valadão
- Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | - Renato S Aguiar
- Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | - Luciana B de Arruda
- Departamento de Virologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
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Abstract
Dengue virus affects hundreds of millions of people each year around the world, causing a tremendous social and economic impact on affected countries. The aim of this review is to summarize our current knowledge of the functions, structure, and interactions of the viral capsid protein. The primary role of capsid is to package the viral genome. There are two processes linked to this function: the recruitment of the viral RNA during assembly and the release of the genome during infection. Although particle assembly takes place on endoplasmic reticulum membranes, capsid localizes in nucleoli and lipid droplets. Why capsid accumulates in these locations during infection remains unknown. In this review, we describe available data and discuss new ideas on dengue virus capsid functions and interactions. We believe that a deeper understanding of how the capsid protein works during infection will create opportunities for novel antiviral strategies, which are urgently needed to control dengue virus infections.
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Affiliation(s)
- Laura A Byk
- Fundación Instituto Leloir-National Research Council for Science and Technology (CONICET), Buenos Aires 1405, Argentina;
| | - Andrea V Gamarnik
- Fundación Instituto Leloir-National Research Council for Science and Technology (CONICET), Buenos Aires 1405, Argentina;
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166
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Flavivirus modulation of cellular metabolism. Curr Opin Virol 2016; 19:7-10. [PMID: 27280383 DOI: 10.1016/j.coviro.2016.05.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 05/16/2016] [Accepted: 05/23/2016] [Indexed: 02/07/2023]
Abstract
Over the last decade, we have begun to appreciate how flaviviruses manipulate cellular metabolism to establish an optimal environment for their replication. These metabolic changes include the stimulation of glycolysis, in addition to lipid anabolic and catabolic pathways. These processes are thought to promote an energetically favorable state, in addition to modifying membrane lipid composition for viral replication and virion envelopment. Importantly, many of these processes can be pharmacologically inhibited as successful antiviral strategies, at least in cell culture. In this review, we discuss the mechanisms by which flaviviruses alter cellular metabolism, remaining questions, and opportunities for therapeutic development.
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167
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Endoplasmic Reticulum: The Favorite Intracellular Niche for Viral Replication and Assembly. Viruses 2016; 8:v8060160. [PMID: 27338443 PMCID: PMC4926180 DOI: 10.3390/v8060160] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 05/23/2016] [Accepted: 05/26/2016] [Indexed: 02/07/2023] Open
Abstract
The endoplasmic reticulum (ER) is the largest intracellular organelle. It forms a complex network of continuous sheets and tubules, extending from the nuclear envelope (NE) to the plasma membrane. This network is frequently perturbed by positive-strand RNA viruses utilizing the ER to create membranous replication factories (RFs), where amplification of their genomes occurs. In addition, many enveloped viruses assemble progeny virions in association with ER membranes, and viruses replicating in the nucleus need to overcome the NE barrier, requiring transient changes of the NE morphology. This review first summarizes some key aspects of ER morphology and then focuses on the exploitation of the ER by viruses for the sake of promoting the different steps of their replication cycles.
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168
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Shulla A, Randall G. (+) RNA virus replication compartments: a safe home for (most) viral replication. Curr Opin Microbiol 2016; 32:82-88. [PMID: 27253151 PMCID: PMC4983521 DOI: 10.1016/j.mib.2016.05.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 05/03/2016] [Indexed: 12/19/2022]
Abstract
(+) RNA virus replication compartments form two structural classes. Both classes of replication compartments use cellular membrane curvature proteins. Both classes of replication compartments manipulate de novo lipid synthesis. Some double membrane vesicles use cellular lipid kinases and transfer proteins. Limited transient replication may occur before replication compartment formation.
This review describes recent advances in our understanding of the mechanisms by which (+) RNA viruses establish their replication niche.
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Affiliation(s)
- Ana Shulla
- Department of Microbiology, The University of Chicago, Chicago, IL 60637, United States
| | - Glenn Randall
- Department of Microbiology, The University of Chicago, Chicago, IL 60637, United States.
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A Proline-Rich N-Terminal Region of the Dengue Virus NS3 Is Crucial for Infectious Particle Production. J Virol 2016; 90:5451-61. [PMID: 27009958 DOI: 10.1128/jvi.00206-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/17/2016] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Dengue virus is currently the most important insect-borne viral human pathogen. Viral nonstructural protein 3 (NS3) is a key component of the viral replication machinery that performs multiple functions during viral replication and participates in antiviral evasion. Using dengue virus infectious clones and reporter systems to dissect each step of the viral life cycle, we examined the requirements of different domains of NS3 on viral particle assembly. A thorough site-directed mutagenesis study based on solvent-accessible surface areas of NS3 revealed that, in addition to being essential for RNA replication, different domains of dengue virus NS3 are critically required for production of infectious viral particles. Unexpectedly, point mutations in the protease, interdomain linker, or helicase domain were sufficient to abolish infectious particle formation without affecting translation, polyprotein processing, or RNA replication. In particular, we identified a novel proline-rich N-terminal unstructured region of NS3 that contains several amino acid residues involved in infectious particle formation. We also showed a new role for the interdomain linker of NS3 in virion assembly. In conclusion, we present a comprehensive genetic map of novel NS3 determinants for viral particle assembly. Importantly, our results provide evidence of a central role of NS3 in the coordination of both dengue virus RNA replication and particle formation. IMPORTANCE Dengue virus is an important human pathogen, and its prominence is expanding globally; however, basic aspects of its biology are still unclear, hindering the development of effective therapeutic and prophylactic treatments. Little is known about the initial steps of dengue and other flavivirus particle assembly. This process involves a complex interplay between viral and cellular components, making it an attractive antiviral target. Unpredictably, we identified spatially separated regions of the large NS3 viral protein as determinants for dengue virus particle assembly. NS3 is a multifunctional enzyme that participates in different steps of the viral life cycle. Using reporter systems to dissect different viral processes, we identified a novel N-terminal unstructured region of the NS3 protein as crucial for production of viral particles. Based on our findings, we propose new ideas that include NS3 as a possible scaffold for the viral assembly process.
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170
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van der Hoeven B, Oudshoorn D, Koster AJ, Snijder EJ, Kikkert M, Bárcena M. Biogenesis and architecture of arterivirus replication organelles. Virus Res 2016; 220:70-90. [PMID: 27071852 PMCID: PMC7111217 DOI: 10.1016/j.virusres.2016.04.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 04/01/2016] [Indexed: 02/06/2023]
Abstract
Arterivirus RNA synthesis presumably is associated with double-membrane vesicles (DMVs). Putative intermediates in DMV formation were detected in infected cells. Arterivirus-induced DMVs form a highly interconnected reticulovesicular network (RVN). Expression of the nsp2-3 replicase polyprotein fragment induces a comparable RVN. Nsp2-7 expression results in smaller DMVs, closer in size to DMVs found in infection.
All eukaryotic positive-stranded RNA (+RNA) viruses appropriate host cell membranes and transform them into replication organelles, specialized micro-environments that are thought to support viral RNA synthesis. Arteriviruses (order Nidovirales) belong to the subset of +RNA viruses that induce double-membrane vesicles (DMVs), similar to the structures induced by e.g. coronaviruses, picornaviruses and hepatitis C virus. In the last years, electron tomography has revealed substantial differences between the structures induced by these different virus groups. Arterivirus-induced DMVs appear to be closed compartments that are continuous with endoplasmic reticulum membranes, thus forming an extensive reticulovesicular network (RVN) of intriguing complexity. This RVN is remarkably similar to that described for the distantly related coronaviruses (also order Nidovirales) and sets them apart from other DMV-inducing viruses analysed to date. We review here the current knowledge and open questions on arterivirus replication organelles and discuss them in the light of the latest studies on other DMV-inducing viruses, particularly coronaviruses. Using the equine arteritis virus (EAV) model system and electron tomography, we present new data regarding the biogenesis of arterivirus-induced DMVs and uncover numerous putative intermediates in DMV formation. We generated cell lines that can be induced to express specific EAV replicase proteins and showed that DMVs induced by the transmembrane proteins nsp2 and nsp3 form an RVN and are comparable in topology and architecture to those formed during viral infection. Co-expression of the third EAV transmembrane protein (nsp5), expressed as part of a self-cleaving polypeptide that mimics viral polyprotein processing in infected cells, led to the formation of DMVs whose size was more homogenous and closer to what is observed upon EAV infection, suggesting a regulatory role for nsp5 in modulating membrane curvature and DMV formation.
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Affiliation(s)
- Barbara van der Hoeven
- Electron Microscopy Section, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Diede Oudshoorn
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Abraham J Koster
- Electron Microscopy Section, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Eric J Snijder
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marjolein Kikkert
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands.
| | - Montserrat Bárcena
- Electron Microscopy Section, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
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171
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Mlakar J, Korva M, Tul N, Popović M, Poljšak-Prijatelj M, Mraz J, Kolenc M, Resman Rus K, Vesnaver Vipotnik T, Fabjan Vodušek V, Vizjak A, Pižem J, Petrovec M, Avšič Županc T. Zika Virus Associated with Microcephaly. N Engl J Med 2016; 374:951-8. [PMID: 26862926 DOI: 10.1056/nejmoa1600651] [Citation(s) in RCA: 1859] [Impact Index Per Article: 232.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A widespread epidemic of Zika virus (ZIKV) infection was reported in 2015 in South and Central America and the Caribbean. A major concern associated with this infection is the apparent increased incidence of microcephaly in fetuses born to mothers infected with ZIKV. In this report, we describe the case of an expectant mother who had a febrile illness with rash at the end of the first trimester of pregnancy while she was living in Brazil. Ultrasonography performed at 29 weeks of gestation revealed microcephaly with calcifications in the fetal brain and placenta. After the mother requested termination of the pregnancy, a fetal autopsy was performed. Micrencephaly (an abnormally small brain) was observed, with almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications in the cortex and subcortical white matter, with associated cortical displacement and mild focal inflammation. ZIKV was found in the fetal brain tissue on reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay, with consistent findings on electron microscopy. The complete genome of ZIKV was recovered from the fetal brain.
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Affiliation(s)
- Jernej Mlakar
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Misa Korva
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Nataša Tul
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Mara Popović
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Mateja Poljšak-Prijatelj
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Jerica Mraz
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Marko Kolenc
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Katarina Resman Rus
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Tina Vesnaver Vipotnik
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Vesna Fabjan Vodušek
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Alenka Vizjak
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Jože Pižem
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Miroslav Petrovec
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
| | - Tatjana Avšič Županc
- From the Institute of Pathology, Faculty of Medicine (J. Mlakar, M. Popović, J. Mraz, A.V., J.P.), and the Institute of Microbiology and Immunology, Faculty of Medicine (M. Korva, M.P.-P., M. Kolenc, K.R.R., M. Petrovec, T.A.Z.), University of Ljubljana, and the Department of Perinatology, Division of Gynecology and Obstetrics (N.T., V.F.V.), and the Institute of Radiology (T.V.V.), University Medical Center Ljubljana - all in Ljubljana, Slovenia
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Blázquez AB, Martín-Acebes MA, Saiz JC. Inhibition of West Nile Virus Multiplication in Cell Culture by Anti-Parkinsonian Drugs. Front Microbiol 2016; 7:296. [PMID: 27014219 PMCID: PMC4779909 DOI: 10.3389/fmicb.2016.00296] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 02/23/2016] [Indexed: 12/14/2022] Open
Abstract
West Nile virus (WNV) is a mosquito-borne flavivirus maintained in a transmission cycle between mosquitoes and birds, but it can also infect other vertebrates, including humans, in which it can cause neuroinvasive diseases. To date, no licensed vaccine or therapy for human use against this pathogen is yet available. A recent approach to search for new antiviral agent candidates is the assessment of long-used drugs commonly administered by clinicians to treat human disorders in drug antiviral development. In this regard, as patients with West Nile encephalitis frequently develop symptoms and features of parkinsonism, and cellular factors altered in parkinsonism, such as alpha-synuclein, have been shown to play a role on WNV infection, we have assessed the effect of four drugs (L-dopa, Selegiline, Isatin, and Amantadine), that are used as therapy for Parkinson's disease in the inhibition of WNV multiplication. L-dopa, Isatin, and Amantadine treatments significantly reduced the production of infectious virus in all cell types tested, but only Amantadine reduced viral RNA levels. These results point to antiparkinsonian drugs as possible therapeutic candidates for the development of antiviral strategies against WNV infection.
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Affiliation(s)
- Ana B Blázquez
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain
| | - Miguel A Martín-Acebes
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain
| | - Juan-Carlos Saiz
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain
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Farhat R, Séron K, Ferlin J, Fénéant L, Belouzard S, Goueslain L, Jackson CL, Dubuisson J, Rouillé Y. Identification of class II ADP-ribosylation factors as cellular factors required for hepatitis C virus replication. Cell Microbiol 2016; 18:1121-33. [PMID: 26814617 DOI: 10.1111/cmi.12572] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 01/12/2016] [Accepted: 01/21/2016] [Indexed: 12/21/2022]
Abstract
GBF1 is a host factor required for hepatitis C virus (HCV) replication. GBF1 functions as a guanine nucleotide exchange factor for G-proteins of the Arf family, which regulate membrane dynamics in the early secretory pathway and the metabolism of cytoplasmic lipid droplets. Here we established that the Arf-guanine nucleotide exchange factor activity of GBF1 is critical for its function in HCV replication, indicating that it promotes viral replication by activating one or more Arf family members. Arf involvement was confirmed with the use of two dominant negative Arf1 mutants. However, siRNA-mediated depletion of Arf1, Arf3 (class I Arfs), Arf4 or Arf5 (class II Arfs), which potentially interact with GBF1, did not significantly inhibit HCV infection. In contrast, the simultaneous depletion of both Arf4 and Arf5, but not of any other Arf pair, imposed a significant inhibition of HCV infection. Interestingly, the simultaneous depletion of both Arf4 and Arf5 had no impact on the activity of the secretory pathway and induced a compaction of the Golgi and an accumulation of lipid droplets. A similar phenotype of lipid droplet accumulation was also observed when GBF1 was inhibited by brefeldin A. In contrast, the simultaneous depletion of both Arf1 and Arf4 resulted in secretion inhibition and Golgi scattering, two actions reminiscent of GBF1 inhibition. We conclude that GBF1 could regulate different metabolic pathways through the activation of different pairs of Arf proteins.
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Affiliation(s)
- Rayan Farhat
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204, CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Karin Séron
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204, CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Juliette Ferlin
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204, CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Lucie Fénéant
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204, CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Sandrine Belouzard
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204, CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Lucie Goueslain
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204, CIIL - Center for Infection and Immunity of Lille, Lille, France.,Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Catherine L Jackson
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Jean Dubuisson
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204, CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Yves Rouillé
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204, CIIL - Center for Infection and Immunity of Lille, Lille, France
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174
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Klema VJ, Ye M, Hindupur A, Teramoto T, Gottipati K, Padmanabhan R, Choi KH. Dengue Virus Nonstructural Protein 5 (NS5) Assembles into a Dimer with a Unique Methyltransferase and Polymerase Interface. PLoS Pathog 2016; 12:e1005451. [PMID: 26895240 PMCID: PMC4760774 DOI: 10.1371/journal.ppat.1005451] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 01/22/2016] [Indexed: 01/07/2023] Open
Abstract
Flavivirus nonstructural protein 5 (NS5) consists of methyltransferase (MTase) and RNA-dependent RNA polymerase (RdRp) domains, which catalyze 5'-RNA capping/methylation and RNA synthesis, respectively, during viral genome replication. Although the crystal structure of flavivirus NS5 is known, no data about the quaternary organization of the functional enzyme are available. We report the crystal structure of dengue virus full-length NS5, where eight molecules of NS5 are arranged as four independent dimers in the crystallographic asymmetric unit. The relative orientation of each monomer within the dimer, as well as the orientations of the MTase and RdRp domains within each monomer, is conserved, suggesting that these structural arrangements represent the biologically relevant conformation and assembly of this multi-functional enzyme. Essential interactions between MTase and RdRp domains are maintained in the NS5 dimer via inter-molecular interactions, providing evidence that flavivirus NS5 can adopt multiple conformations while preserving necessary interactions between the MTase and RdRp domains. Furthermore, many NS5 residues that reduce viral replication are located at either the inter-domain interface within a monomer or at the inter-molecular interface within the dimer. Hence the X-ray structure of NS5 presented here suggests that MTase and RdRp activities could be coordinated as a dimer during viral genome replication.
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Affiliation(s)
- Valerie J. Klema
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Mengyi Ye
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Aditya Hindupur
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Tadahisa Teramoto
- Department of Microbiology and Immunology, Georgetown University School of Medicine, Washington, D.C., United States of America
| | - Keerthi Gottipati
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Radhakrishnan Padmanabhan
- Department of Microbiology and Immunology, Georgetown University School of Medicine, Washington, D.C., United States of America
| | - Kyung H. Choi
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
- * E-mail:
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175
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Neufeldt CJ, Joyce MA, Van Buuren N, Levin A, Kirkegaard K, Gale Jr. M, Tyrrell DLJ, Wozniak RW. The Hepatitis C Virus-Induced Membranous Web and Associated Nuclear Transport Machinery Limit Access of Pattern Recognition Receptors to Viral Replication Sites. PLoS Pathog 2016; 12:e1005428. [PMID: 26863439 PMCID: PMC4749181 DOI: 10.1371/journal.ppat.1005428] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 01/10/2016] [Indexed: 12/25/2022] Open
Abstract
Hepatitis C virus (HCV) is a positive-strand RNA virus of the Flaviviridae family and a major cause of liver disease worldwide. HCV replicates in the cytoplasm, and the synthesis of viral proteins induces extensive rearrangements of host cell membranes producing structures, collectively termed the membranous web (MW). The MW contains the sites of viral replication and assembly, and we have identified distinct membrane fractions derived from HCV-infected cells that contain replication and assembly complexes enriched for viral RNA and infectious virus, respectively. The complex membrane structure of the MW is thought to protect the viral genome limiting its interactions with cytoplasmic pattern recognition receptors (PRRs) and thereby preventing activation of cellular innate immune responses. Here we show that PRRs, including RIG-I and MDA5, and ribosomes are excluded from viral replication and assembly centers within the MW. Furthermore, we present evidence that components of the nuclear transport machinery regulate access of proteins to MW compartments. We show that the restricted assess of RIG-I to the MW can be overcome by the addition of a nuclear localization signal sequence, and that expression of a NLS-RIG-I construct leads to increased immune activation and the inhibition of viral replication. Hepatitis C virus (HCV) is a positive-strand RNA virus and it is a major cause of liver disease worldwide affecting more than 170 million individuals. Infection of cells with HCV leads to rearrangement of cytoplasmic host cell membranes and the formation of the membranous web (MW) containing viral replication and assembly complexes. The MW is thought to function in concentrating viral components, regulating virus replication, and immune evasion. Our analysis has provided new insight into the organization of the MW and the mechanisms that contribute to the formation and maintenance of distinct compartments within the MW. We show that the MW limits access of host cell innate immune receptors to sites of viral replication and assembly. Moreover, we show that components of the nuclear transport machinery, normally involved in regulating traffic between the cytoplasm and the nucleus, have a role in limiting immune receptor access to compartments within the MW. These findings provide important insights in how HCV, and likely other positive-strand RNA viruses, organize their replication factories and evaded recognition by host cell immune receptors.
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Affiliation(s)
- Christopher J. Neufeldt
- Department of Cell Biology University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
- Li Ka Shing Institute of Virology, Edmonton, Alberta, Canada
| | - Michael A. Joyce
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
- Li Ka Shing Institute of Virology, Edmonton, Alberta, Canada
| | - Nicholas Van Buuren
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Aviad Levin
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
- Li Ka Shing Institute of Virology, Edmonton, Alberta, Canada
| | - Karla Kirkegaard
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Michael Gale Jr.
- Department of Immunology, University of Washington, Seattle, Washington, United States of America
| | - D. Lorne J. Tyrrell
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
- Li Ka Shing Institute of Virology, Edmonton, Alberta, Canada
- * E-mail: (RWW); (DLJT)
| | - Richard W. Wozniak
- Department of Cell Biology University of Alberta, Edmonton, Alberta, Canada
- Li Ka Shing Institute of Virology, Edmonton, Alberta, Canada
- * E-mail: (RWW); (DLJT)
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176
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Kobayashi S, Suzuki T, Kawaguchi A, Phongphaew W, Yoshii K, Iwano T, Harada A, Kariwa H, Orba Y, Sawa H. Rab8b Regulates Transport of West Nile Virus Particles from Recycling Endosomes. J Biol Chem 2016; 291:6559-68. [PMID: 26817838 DOI: 10.1074/jbc.m115.712760] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Indexed: 01/09/2023] Open
Abstract
West Nile virus (WNV) particles assemble at and bud into the endoplasmic reticulum (ER) and are secreted from infected cells through the secretory pathway. However, the host factor related to these steps is not fully understood. Rab proteins, belonging to the Ras superfamily, play essential roles in regulating many aspects of vesicular trafficking. In this study, we sought to determine which Rab proteins are involved in intracellular trafficking of nascent WNV particles. RNAi analysis revealed that Rab8b plays a role in WNV particle release. We found that Rab8 and WNV antigen were colocalized in WNV-infected human neuroblastoma cells, and that WNV infection enhanced Rab8 expression in the cells. In addition, the amount of WNV particles in the supernatant of Rab8b-deficient cells was significantly decreased compared with that of wild-type cells. We also demonstrated that WNV particles accumulated in the recycling endosomes in WNV-infected cells. In summary, these results suggest that Rab8b is involved in trafficking of WNV particles from recycling endosomes to the plasma membrane.
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Affiliation(s)
- Shintaro Kobayashi
- From the Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan, Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, N18, W9, Kita-ku, Sapporo 060-0818, Japan
| | - Tadaki Suzuki
- Department of Pathology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-Ku, Tokyo 162-8640, Japan
| | - Akira Kawaguchi
- From the Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan
| | - Wallaya Phongphaew
- From the Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan
| | - Kentaro Yoshii
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, N18, W9, Kita-ku, Sapporo 060-0818, Japan
| | - Tomohiko Iwano
- Department of Anatomy and Cell Biology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimo-Kateau, Chuo, Yamanashi 409-3898, Japan
| | - Akihiro Harada
- Department of Cell Biology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan, and
| | - Hiroaki Kariwa
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, N18, W9, Kita-ku, Sapporo 060-0818, Japan
| | - Yasuko Orba
- From the Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan
| | - Hirofumi Sawa
- From the Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan, Global Institution for Collaborative Research and Education (GI-CoRE) and Global Virus Network (GVN), Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan
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177
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Martín-Acebes MA, Gabandé-Rodríguez E, García-Cabrero AM, Sánchez MP, Ledesma MD, Sobrino F, Saiz JC. Host sphingomyelin increases West Nile virus infection in vivo. J Lipid Res 2016; 57:422-32. [PMID: 26764042 DOI: 10.1194/jlr.m064212] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Indexed: 12/16/2022] Open
Abstract
Flaviviruses, such as the dengue virus and the West Nile virus (WNV), are arthropod-borne viruses that represent a global health problem. The flavivirus lifecycle is intimately connected to cellular lipids. Among the lipids co-opted by flaviviruses, we have focused on SM, an important component of cellular membranes particularly enriched in the nervous system. After infection with the neurotropic WNV, mice deficient in acid sphingomyelinase (ASM), which accumulate high levels of SM in their tissues, displayed exacerbated infection. In addition, WNV multiplication was enhanced in cells from human patients with Niemann-Pick type A, a disease caused by a deficiency of ASM activity resulting in SM accumulation. Furthermore, the addition of SM to cultured cells also increased WNV infection, whereas treatment with pharmacological inhibitors of SM synthesis reduced WNV infection. Confocal microscopy analyses confirmed the association of SM with viral replication sites within infected cells. Our results unveil that SM metabolism regulates flavivirus infection in vivo and propose SM as a suitable target for antiviral design against WNV.
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Affiliation(s)
- Miguel A Martín-Acebes
- Departments of Virology and Microbiology Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Madrid 28049, Spain Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid 28040, Spain
| | | | - Ana M García-Cabrero
- Laboratory of Neurology, Instituto de Investigación Sanitaria Fundación Jiménez Díaz, Madrid 28040, Spain
| | - Marina P Sánchez
- Laboratory of Neurology, Instituto de Investigación Sanitaria Fundación Jiménez Díaz, Madrid 28040, Spain
| | - María Dolores Ledesma
- Molecular Neurobiology, Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Madrid 28049, Spain
| | - Francisco Sobrino
- Departments of Virology and Microbiology Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Madrid 28049, Spain
| | - Juan-Carlos Saiz
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid 28040, Spain
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178
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Yun SI, Song BH, Kim JK, Lee YM. Bacterial Artificial Chromosomes: A Functional Genomics Tool for the Study of Positive-strand RNA Viruses. J Vis Exp 2015:e53164. [PMID: 26780115 PMCID: PMC4780872 DOI: 10.3791/53164] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Reverse genetics, an approach to rescue infectious virus entirely from a cloned cDNA, has revolutionized the field of positive-strand RNA viruses, whose genomes have the same polarity as cellular mRNA. The cDNA-based reverse genetics system is a seminal method that enables direct manipulation of the viral genomic RNA, thereby generating recombinant viruses for molecular and genetic studies of both viral RNA elements and gene products in viral replication and pathogenesis. It also provides a valuable platform that allows the development of genetically defined vaccines and viral vectors for the delivery of foreign genes. For many positive-strand RNA viruses such as Japanese encephalitis virus (JEV), however, the cloned cDNAs are unstable, posing a major obstacle to the construction and propagation of the functional cDNA. Here, the present report describes the strategic considerations in creating and amplifying a genetically stable full-length infectious JEV cDNA as a bacterial artificial chromosome (BAC) using the following general experimental procedures: viral RNA isolation, cDNA synthesis, cDNA subcloning and modification, assembly of a full-length cDNA, cDNA linearization, in vitro RNA synthesis, and virus recovery. This protocol provides a general methodology applicable to cloning full-length cDNA for a range of positive-strand RNA viruses, particularly those with a genome of >10 kb in length, into a BAC vector, from which infectious RNAs can be transcribed in vitro with a bacteriophage RNA polymerase.
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Affiliation(s)
- Sang-Im Yun
- Department of Animal, Dairy, and Veterinary Sciences, Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University
| | - Byung-Hak Song
- Department of Animal, Dairy, and Veterinary Sciences, Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University
| | - Jin-Kyoung Kim
- Department of Animal, Dairy, and Veterinary Sciences, Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University
| | - Young-Min Lee
- Department of Animal, Dairy, and Veterinary Sciences, Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University;
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179
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A Single Amino Acid Substitution in the M Protein Attenuates Japanese Encephalitis Virus in Mammalian Hosts. J Virol 2015; 90:2676-89. [PMID: 26656690 DOI: 10.1128/jvi.01176-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 11/30/2015] [Indexed: 02/04/2023] Open
Abstract
UNLABELLED Japanese encephalitis virus (JEV) membrane (M) protein plays important structural roles in the processes of fusion and maturation of progeny virus during cellular infection. The M protein is anchored in the viral membrane, and its ectodomain is composed of a flexible N-terminal loop and a perimembrane helix. In this study, we performed site-directed mutagenesis on residue 36 of JEV M protein and showed that the resulting mutation had little or no effect on the entry process but greatly affected virus assembly in mammalian cells. Interestingly, this mutant virus had a host-dependent phenotype and could develop a wild-type infection in insect cells. Experiments performed on infectious virus as well as in a virus-like particle (VLP) system indicate that the JEV mutant expresses structural proteins but fails to form infectious particles in mammalian cells. Using a mouse model for JEV pathogenesis, we showed that the mutation conferred complete attenuation in vivo. The production of JEV neutralizing antibodies in challenged mice was indicative of the immunogenicity of the mutant virus in vivo. Together, our results indicate that the introduction of a single mutation in the M protein, while being tolerated in insect cells, strongly impacts JEV infection in mammalian hosts. IMPORTANCE JEV is a mosquito-transmitted flavivirus and is a medically important pathogen in Asia. The M protein is thought to be important for accommodating the structural rearrangements undergone by the virion during viral assembly and may play additional roles in the JEV infectious cycle. In the present study, we show that a sole mutation in the M protein impairs the JEV infection cycle in mammalian hosts but not in mosquito cells. This finding highlights differences in flavivirus assembly pathways among hosts. Moreover, infection of mice indicated that the mutant was completely attenuated and triggered a strong immune response to JEV, thus providing new insights for further development of JEV vaccines.
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180
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Viral Infection at High Magnification: 3D Electron Microscopy Methods to Analyze the Architecture of Infected Cells. Viruses 2015; 7:6316-45. [PMID: 26633469 PMCID: PMC4690864 DOI: 10.3390/v7122940] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 10/16/2015] [Accepted: 11/16/2015] [Indexed: 02/06/2023] Open
Abstract
As obligate intracellular parasites, viruses need to hijack their cellular hosts and reprogram their machineries in order to replicate their genomes and produce new virions. For the direct visualization of the different steps of a viral life cycle (attachment, entry, replication, assembly and egress) electron microscopy (EM) methods are extremely helpful. While conventional EM has given important information about virus-host cell interactions, the development of three-dimensional EM (3D-EM) approaches provides unprecedented insights into how viruses remodel the intracellular architecture of the host cell. During the last years several 3D-EM methods have been developed. Here we will provide a description of the main approaches and examples of innovative applications.
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181
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Modification of the Host Cell Lipid Metabolism Induced by Hypolipidemic Drugs Targeting the Acetyl Coenzyme A Carboxylase Impairs West Nile Virus Replication. Antimicrob Agents Chemother 2015; 60:307-15. [PMID: 26503654 DOI: 10.1128/aac.01578-15] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/19/2015] [Indexed: 01/26/2023] Open
Abstract
West Nile virus (WNV) is a neurotropic flavivirus transmitted by the bite of mosquitoes that causes meningitis and encephalitis in humans, horses, and birds. Several studies have highlighted that flavivirus infection is highly dependent on cellular lipids for virus replication and infectious particle biogenesis. The first steps of lipid synthesis involve the carboxylation of acetyl coenzyme A (acetyl-CoA) to malonyl-CoA that is catalyzed by the acetyl-CoA carboxylase (ACC). This makes ACC a key enzyme of lipid synthesis that is currently being evaluated as a therapeutic target for different disorders, including cancers, obesity, diabetes, and viral infections. We have analyzed the effect of the ACC inhibitor 5-(tetradecyloxy)-2-furoic acid (TOFA) on infection by WNV. Lipidomic analysis of TOFA-treated cells confirmed that this drug reduced the cellular content of multiple lipids, including those directly implicated in the flavivirus life cycle (glycerophospholipids, sphingolipids, and cholesterol). Treatment with TOFA significantly inhibited the multiplication of WNV in a dose-dependent manner. Further analysis of the antiviral effect of this drug showed that the inhibitory effect was related to a reduction of viral replication. Furthermore, treatment with another ACC inhibitor, 3,3,14,14-tetramethylhexadecanedioic acid (MEDICA 16), also inhibited WNV infection. Interestingly, TOFA and MEDICA 16 also reduced the multiplication of Usutu virus (USUV), a WNV-related flavivirus. These results point to the ACC as a druggable cellular target suitable for antiviral development against WNV and other flaviviruses.
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182
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Herweg JA, Pons V, Becher D, Hecker M, Krohne G, Barbier J, Berger H, Rudel T, Mehlitz A. Proteomic analysis of the Simkania-containing vacuole: the central role of retrograde transport. Mol Microbiol 2015; 99:151-71. [PMID: 26374382 DOI: 10.1111/mmi.13222] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2015] [Indexed: 01/25/2023]
Abstract
Simkania negevensis is an obligate intracellular bacterial pathogen that grows in amoeba or human cells within a membrane-bound vacuole forming endoplasmic reticulum (ER) contact sites. The membrane of this Simkania-containing vacuole (SnCV) is a critical host-pathogen interface whose origin and molecular interactions with cellular organelles remain poorly defined. We performed proteomic analysis of purified ER-SnCV-membranes using label free LC-MS(2) to define the pathogen-containing organelle composition. Of the 1,178 proteins of human and 302 proteins of Simkania origin identified by this strategy, 51 host cell proteins were enriched or depleted by infection and 57 proteins were associated with host endosomal transport pathways. Chemical inhibitors that selectively interfere with trafficking at the early endosome-to-trans-Golgi network (TGN) interface (retrograde transport) affected SnCV formation, morphology and lipid transport. Our data demonstrate that Simkania exploits early endosome-to-TGN transport for nutrient acquisition and growth.
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Affiliation(s)
- Jo-Ana Herweg
- Department of Microbiology, University of Würzburg, Biocenter, Am Hubland, D-97074, Würzburg, Germany
| | - Valérie Pons
- DSV, iBiTec-S, LabEx LERMIT, CEA, F-91191, Gif sur Yvette, France
| | - Dörte Becher
- Department of Microbial Proteomics, University of Greifswald, Institute of Microbiology, Friedrich-Ludwig-Jahn-Straße 15, D-17487, Greifswald, Germany
| | - Michael Hecker
- Microbial Physiology/Molecular Biology, University of Greifswald, Institute of Microbiology, Friedrich-Ludwig-Jahn-Straße 15, D-17487, Greifswald, Germany
| | - Georg Krohne
- Division of Electron Microscopy, University of Würzburg, Biocenter, Am Hubland, D-97074, Würzburg, Germany
| | - Julien Barbier
- DSV, iBiTec-S, LabEx LERMIT, CEA, F-91191, Gif sur Yvette, France
| | - Hilmar Berger
- Department of Molecular Biology, Max-Planck-Institute for Infection Biology, Charitéplatz 1, D-10117, Berlin, Germany
| | - Thomas Rudel
- Department of Microbiology, University of Würzburg, Biocenter, Am Hubland, D-97074, Würzburg, Germany
| | - Adrian Mehlitz
- Department of Microbiology, University of Würzburg, Biocenter, Am Hubland, D-97074, Würzburg, Germany.,Department of Molecular Biology, Max-Planck-Institute for Infection Biology, Charitéplatz 1, D-10117, Berlin, Germany
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183
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Fu Q, Inankur B, Yin J, Striker R, Lan Q. Sterol Carrier Protein 2, a Critical Host Factor for Dengue Virus Infection, Alters the Cholesterol Distribution in Mosquito Aag2 Cells. JOURNAL OF MEDICAL ENTOMOLOGY 2015; 52:1124-1134. [PMID: 26336241 DOI: 10.1093/jme/tjv101] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 06/24/2015] [Indexed: 06/05/2023]
Abstract
Host factors that enable dengue virus (DENV) to propagate in the mosquito host cells are unclear. It is known that cellular cholesterol plays an important role in the life cycle of DENV in human host cells but unknown if the lipid requirements differ for mosquito versus mammalian. In mosquito Aedes aegypti, sterol carrier protein 2 (SCP-2) is critical for cellular cholesterol homeostasis. In this study, we identified SCP-2 as a critical host factor for DENV production in mosquito Aag2 cells. Treatment with a small molecule commonly referred to as SCPI-1, (N-(4-{[4-(3,4-dichlorophenyl)-1,3-thiazol-2-yl]amino}phenyl)acetamide hydrobromide, a known inhibitor of SCP-2, or knockdown of SCP-2 dramatically repressed the virus production in mosquito but not mammalian cells. We showed that the intracellular cholesterol distribution in mosquito cells was altered by SCP-2 inhibitor treatment, suggesting that SCP-2-mediated cholesterol trafficking pathway is important for DENV viral production. A comparison of the effect of SCP-2 on mosquito and human cells suggests that SCPI-1 treatment decreases cholesterol in both cell lines, but this decrease in cholesterol only leads to a decline in viral titer in mosquito host cells, perhaps, owing to a more drastic effect on perinuclear cholesterol storages in mosquito cells that was absent in human cells. SCP-2 had no inhibitory effect on another enveloped RNA virus grown in mosquito cells, suggesting that SCP-2 does not have a generalized anti-cellular or antiviral effect. Our cell culture results imply that SCP-2 may play a limiting role in mosquito-dengue vector competence.
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Affiliation(s)
- Qiang Fu
- Department of Entomology, University of Wisconsin-Madison, WI.
| | - Bahar Inankur
- Chemical and Biological Engineering Department, University of Wisconsin-Madison, WI
| | - John Yin
- Chemical and Biological Engineering Department, University of Wisconsin-Madison, WI
| | - Rob Striker
- Department of Medicine, University of Wisconsin-Madison, WI
| | - Que Lan
- Department of Entomology, University of Wisconsin-Madison, WI. Deceased
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184
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Klema VJ, Padmanabhan R, Choi KH. Flaviviral Replication Complex: Coordination between RNA Synthesis and 5'-RNA Capping. Viruses 2015; 7:4640-56. [PMID: 26287232 PMCID: PMC4576198 DOI: 10.3390/v7082837] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 07/30/2015] [Accepted: 08/04/2015] [Indexed: 12/28/2022] Open
Abstract
Genome replication in flavivirus requires (-) strand RNA synthesis, (+) strand RNA synthesis, and 51-RNA capping and methylation. To carry out viral genome replication, flavivirus assembles a replication complex, consisting of both viral and host proteins, on the cytoplasmic side of the endoplasmic reticulum (ER) membrane. Two major components of the replication complex are the viral non-structural (NS) proteins NS3 and NS5. Together they possess all the enzymatic activities required for genome replication, yet how these activities are coordinated during genome replication is not clear. We provide an overview of the flaviviral genome replication process, the membrane-bound replication complex, and recent crystal structures of full-length NS5. We propose a model of how NS3 and NS5 coordinate their activities in the individual steps of (-) RNA synthesis, (+) RNA synthesis, and 51-RNA capping and methylation.
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Affiliation(s)
- Valerie J Klema
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, TX 77555-0647, USA.
| | - Radhakrishnan Padmanabhan
- Department of Microbiology and Immunology, Georgetown University School of Medicine, Washington, DC 20057, USA.
| | - Kyung H Choi
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, TX 77555-0647, USA.
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185
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Reid CR, Airo AM, Hobman TC. The Virus-Host Interplay: Biogenesis of +RNA Replication Complexes. Viruses 2015; 7:4385-413. [PMID: 26287230 PMCID: PMC4576186 DOI: 10.3390/v7082825] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/21/2015] [Accepted: 07/24/2015] [Indexed: 12/22/2022] Open
Abstract
Positive-strand RNA (+RNA) viruses are an important group of human and animal pathogens that have significant global health and economic impacts. Notable members include West Nile virus, Dengue virus, Chikungunya, Severe acute respiratory syndrome (SARS) Coronavirus and enteroviruses of the Picornaviridae family.Unfortunately, prophylactic and therapeutic treatments against these pathogens are limited. +RNA viruses have limited coding capacity and thus rely extensively on host factors for successful infection and propagation. A common feature among these viruses is their ability to dramatically modify cellular membranes to serve as platforms for genome replication and assembly of new virions. These viral replication complexes (VRCs) serve two main functions: To increase replication efficiency by concentrating critical factors and to protect the viral genome from host anti-viral systems. This review summarizes current knowledge of critical host factors recruited to or demonstrated to be involved in the biogenesis and stabilization of +RNA virus VRCs.
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Affiliation(s)
- Colleen R Reid
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2E1, Canada.
| | - Adriana M Airo
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2E1, Canada.
| | - Tom C Hobman
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2E1, Canada.
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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186
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Aktepe TE, Pham H, Mackenzie JM. Differential utilisation of ceramide during replication of the flaviviruses West Nile and dengue virus. Virology 2015; 484:241-250. [PMID: 26122470 DOI: 10.1016/j.virol.2015.06.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 04/05/2015] [Accepted: 06/12/2015] [Indexed: 01/22/2023]
Abstract
It is well established that +ssRNA viruses manipulate cellular lipid homoeostasis and distribution to facilitate efficient replication. Here, we show that the cellular lipid ceramide is redistributed to the West Nile virus strain Kunjin virus (WNVKUN) replication complex (RC) but not to the dengue virus serotype 2 strain New Guinea C (DENVNGC) RC. We show that prolonged chemical inhibition of serine palmitoyltransferase with myriocin had a significant deleterious effect on WNVKUN replication but enhanced DENVNGC replication. Additionally, inhibition of ceramide synthase with Fumonisin B1 had a detrimental effect on WNVKUN replication and release of infectious virus particles but contrastingly an enhancing effect on DENVNGC replication and virus production. These observations suggest that ceramide production via the de novo and salvage pathway is a requirement for WNVKUN replication but inhibitory for DENVNGC replication. Thus, although these two viruses are from the same genus, they have a differential ceramide requirement for replication.
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Affiliation(s)
- Turgut E Aktepe
- Department of Microbiology and Immunology, University of Melbourne, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Helen Pham
- Department of Microbiology, La Trobe University, Melbourne, VIC, Australia
| | - Jason M Mackenzie
- Department of Microbiology and Immunology, University of Melbourne, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.
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187
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Bílý T, Palus M, Eyer L, Elsterová J, Vancová M, Růžek D. Electron Tomography Analysis of Tick-Borne Encephalitis Virus Infection in Human Neurons. Sci Rep 2015; 5:10745. [PMID: 26073783 PMCID: PMC4466586 DOI: 10.1038/srep10745] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 04/29/2015] [Indexed: 12/30/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) causes serious, potentially fatal neurological infections that affect humans in endemic regions of Europe and Asia. Neurons are the primary target for TBEV infection in the central nervous system. However, knowledge about this viral infection and virus-induced neuronal injury is fragmental. Here, we directly examined the pathology that occurs after TBEV infection in human primary neurons. We exploited the advantages of advanced high-pressure freezing and freeze-substitution techniques to achieve optimal preservation of infected cell architecture. Electron tomographic (ET) reconstructions elucidated high-resolution 3D images of the proliferating endoplasmic reticulum, and individual tubule-like structures of different diameters in the endoplasmic reticulum cisternae of single cells. ET revealed direct connections between the tubule-like structures and viral particles in the endoplasmic reticulum. Furthermore, ET showed connections between cellular microtubules and vacuoles that harbored the TBEV virions in neuronal extensions. This study was the first to characterize the 3D topographical organization of membranous whorls and autophagic vacuoles in TBEV-infected human neurons. The functional importance of autophagy during TBEV replication was studied in human neuroblastoma cells; stimulation of autophagy resulted in significantly increased dose-dependent TBEV production, whereas the inhibition of autophagy showed a profound, dose-dependent decrease of the yield of infectious virus.
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Affiliation(s)
- Tomáš Bílý
- 1] Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic [2] Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Martin Palus
- 1] Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic [2] Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic [3] Department of Virology, Veterinary Research Institute, Hudcova 70, CZ-62100 Brno, Czech Republic
| | - Luděk Eyer
- Department of Virology, Veterinary Research Institute, Hudcova 70, CZ-62100 Brno, Czech Republic
| | - Jana Elsterová
- 1] Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic [2] Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic [3] Department of Virology, Veterinary Research Institute, Hudcova 70, CZ-62100 Brno, Czech Republic
| | - Marie Vancová
- 1] Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic [2] Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Daniel Růžek
- 1] Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic [2] Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic [3] Department of Virology, Veterinary Research Institute, Hudcova 70, CZ-62100 Brno, Czech Republic
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188
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The Emerging Roles of Viroporins in ER Stress Response and Autophagy Induction during Virus Infection. Viruses 2015; 7:2834-57. [PMID: 26053926 PMCID: PMC4488716 DOI: 10.3390/v7062749] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 05/27/2015] [Accepted: 05/29/2015] [Indexed: 01/14/2023] Open
Abstract
Viroporins are small hydrophobic viral proteins that oligomerize to form aqueous pores on cellular membranes. Studies in recent years have demonstrated that viroporins serve important functions during virus replication and contribute to viral pathogenicity. A number of viroporins have also been shown to localize to the endoplasmic reticulum (ER) and/or its associated membranous organelles. In fact, replication of most RNA viruses is closely linked to the ER, and has been found to cause ER stress in the infected cells. On the other hand, autophagy is an evolutionarily conserved "self-eating" mechanism that is also observed in cells infected with RNA viruses. Both ER stress and autophagy are also known to modulate a wide variety of signaling pathways including pro-inflammatory and innate immune response, thereby constituting a major aspect of host-virus interactions. In this review, the potential involvement of viroporins in virus-induced ER stress and autophagy will be discussed.
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189
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Cao X, Jin X, Zhang X, Li Y, Wang C, Wang X, Hong J, Wang X, Li D, Zhang Y. Morphogenesis of Endoplasmic Reticulum Membrane-Invaginated Vesicles during Beet Black Scorch Virus Infection: Role of Auxiliary Replication Protein and New Implications of Three-Dimensional Architecture. J Virol 2015; 89:6184-95. [PMID: 25833056 PMCID: PMC4474299 DOI: 10.1128/jvi.00401-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/25/2015] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED All well-characterized positive-strand RNA viruses[(+)RNA viruses] induce the formation of host membrane-bound viral replication complexes (VRCs), yet the underlying mechanism and machinery for VRC formation remain elusive. We report here the biogenesis and topology of the Beet black scorch virus (BBSV) replication complex. Distinct cytopathological changes typical of endoplasmic reticulum (ER) aggregation and vesiculation were observed in BBSV-infected Nicotiana benthamiana cells. Immunogold labeling of the auxiliary replication protein p23 and double-stranded RNA (dsRNA) revealed that the ER-derived membranous spherules provide the site for BBSV replication. Further studies indicated that p23 plays a crucial role in mediating the ER rearrangement. Three-dimensional electron tomographic analysis revealed the formation of multiple ER-originated vesicle packets. Each vesicle packet enclosed a few to hundreds of independent spherules that were invaginations of the ER membranes into the lumen. Strikingly, these vesicle packets were connected to each other via tubules, a rearrangement event that is rare among other virus-induced membrane reorganizations. Fibrillar contents within the spherules were also reconstructed by electron tomography, which showed diverse structures. Our results provide the first, to our knowledge, three-dimensional ultrastructural analysis of membrane-bound VRCs of a plant (+)RNA virus and should help to achieve a better mechanistic understanding of the organization and microenvironment of plant (+)RNA virus replication complexes. IMPORTANCE Assembly of virus replication complexes for all known positive-strand RNA viruses depends on the extensive remodeling of host intracellular membranes. Beet black scorch virus, a necrovirus in the family Tombusviridae, invaginates the endoplasmic reticulum (ER) membranes to form spherules in infected cells. Double-stranded RNAs, the viral replication intermediate, and the viral auxiliary replication protein p23 are all localized within such viral spherules, indicating that these are the sites for generating progeny viral RNAs. Furthermore, the BBSV p23 protein could to some extent reorganize the ER when transiently expressed in N. benthamiana. Electron tomographic analysis resolves the three-dimensional (3D) architecture of such spherules, which are connected to the cytoplasm via a neck-like structure. Strikingly, different numbers of spherules are enclosed in ER-originated vesicle packets that are connected to each other via tubule-like structures. Our results have significant implications for further understanding the mechanisms underlying the replication of positive-strand RNA viruses.
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Affiliation(s)
- Xiuling Cao
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China
| | - Xuejiao Jin
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China
| | - Xiaofeng Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China
| | - Ying Li
- Branch of China National Center for Protein Sciences, Tsinghua University, Beijing, People's Republic of China
| | - Chunyan Wang
- Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
| | - Xianbing Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China
| | - Jian Hong
- Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
| | - Xiaofeng Wang
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech University, Blacksburg, Virginia, USA
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China
| | - Yongliang Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China
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190
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Takamatsu Y, Uchida L, Morita K. Delayed IFN response differentiates replication of West Nile virus and Japanese encephalitis virus in human neuroblastoma and glioblastoma cells. J Gen Virol 2015; 96:2194-2199. [PMID: 25920530 DOI: 10.1099/vir.0.000168] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
West Nile virus (WNV) and Japanese encephalitis virus (JEV) are important causes of human encephalitis cases, which result in a high mortality ratio and neurological sequelae after recovery. Understanding the mechanism of neuropathogenicity in these viral infections is important for the development of specific antiviral therapy. Here, we focused on human-derived neuronal and glial cells to understand the cellular responses against WNV and JEV infection. It was demonstrated that early IFN-β induction regulated virus replication in glioblastoma tbl98G cells, whereas delayed IFN-β induction resulted in efficient virus replication in neuroblastoma SK-N-SH cells. Moreover, the concealing of viral dsRNA in the intracellular membrane resulted in the delayed IFN response in SK-N-SH cells. These results, which showed different IFN responses between human neuronal and glial cells after WNV or JEV infection, are expected to contribute to our understanding of the molecular mechanisms for neuropathology in these viral infections.
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Affiliation(s)
- Yuki Takamatsu
- Department of Virology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Leo Uchida
- Department of Virology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Kouichi Morita
- Department of Virology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
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191
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Kim JK, Kim JM, Song BH, Yun SI, Yun GN, Byun SJ, Lee YM. Profiling of viral proteins expressed from the genomic RNA of Japanese encephalitis virus using a panel of 15 region-specific polyclonal rabbit antisera: implications for viral gene expression. PLoS One 2015; 10:e0124318. [PMID: 25915765 PMCID: PMC4410938 DOI: 10.1371/journal.pone.0124318] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 02/27/2015] [Indexed: 12/16/2022] Open
Abstract
Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, is closely related to West Nile (WN), yellow fever (YF), and dengue (DEN) viruses. Its plus-strand genomic RNA carries a single open reading frame encoding a polyprotein that is cleaved into three structural (C, prM/M, and E) and at least seven nonstructural (NS1/NS1', NS2A, NS2B, NS3, NS4A, NS4B, and NS5) proteins, based on previous work with WNV, YFV, and DENV. Here, we aimed to profile experimentally all the viral proteins found in JEV-infected cells. We generated a collection of 15 JEV-specific polyclonal antisera covering all parts of the viral protein-coding regions, by immunizing rabbits with 14 bacterially expressed glutathione-S-transferase fusion proteins (for all nine viral proteins except NS2B) or with a chemically synthesized oligopeptide (for NS2B). In total lysates of JEV-infected BHK-21 cells, immunoblotting with these antisera revealed: (i) three mature structural proteins (~12-kDa C, ~8-kDa M, and ~53-kDa E), a precursor of M (~24-kDa prM) and three other M-related proteins (~10-14 kDa); (ii) the predicted ~45-kDa NS1 and its frameshift product, ~58-kDa NS1', with no evidence of the predicted ~25-kDa NS2A; (iii) the predicted but hardly detectable ~14-kDa NS2B and an unexpected but predominant ~12-kDa NS2B-related protein; (iv) the predicted ~69-kDa NS3 plus two major cleavage products (~34-kDa NS3N-term and ~35-kDa NS3C-term), together with at least nine minor proteins of ~16-52 kDa; (v) the predicted ~14-kDa NS4A; (vi) two NS4B-related proteins (~27-kDa NS4B and ~25-kDa NS4B'); and (vii) the predicted ~103-kDa NS5 plus at least three other NS5-related proteins (~15 kDa, ~27 kDa, and ~90 kDa). Combining these data with confocal microscopic imaging of the proteins' intracellular localization, our study is the first to provide a solid foundation for the study of JEV gene expression, which is crucial for elucidating the regulatory mechanisms of JEV genome replication and pathobiology.
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Affiliation(s)
- Jin-Kyoung Kim
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, United States of America
| | - Jeong-Min Kim
- Department of Microbiology, College of Medicine, Chungbuk National University, Cheongju, South Korea
| | - Byung-Hak Song
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, United States of America
| | - Sang-Im Yun
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, United States of America
| | - Gil-Nam Yun
- Department of Microbiology, College of Medicine, Chungbuk National University, Cheongju, South Korea
| | - Sung-June Byun
- Animal Biotechnology Division, Korea National Institute of Animal Science, Suwon, South Korea
| | - Young-Min Lee
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, United States of America
- * E-mail:
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192
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Hellström K, Vihinen H, Kallio K, Jokitalo E, Ahola T. Correlative light and electron microscopy enables viral replication studies at the ultrastructural level. Methods 2015; 90:49-56. [PMID: 25916619 DOI: 10.1016/j.ymeth.2015.04.019] [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: 02/25/2015] [Revised: 04/15/2015] [Accepted: 04/17/2015] [Indexed: 02/06/2023] Open
Abstract
Electron microscopy (EM) is a powerful tool to study structural changes within cells caused e.g. by ectopic protein expression, gene silencing or virus infection. Correlative light and electron microscopy (CLEM) has proven to be useful in cases when it is problematic to identify a particular cell among a majority of unaffected cells at the EM level. In this technique the cells of interest are first identified by fluorescence microscopy and then further processed for EM. CLEM has become crucial when studying positive-strand RNA virus replication, as it takes place in nanoscale replication sites on specific cellular membranes. Here we have employed CLEM for Semliki Forest virus (SFV) replication studies both by transfecting viral replication components to cells or by infecting different cell types. For the transfection-based system, we developed an RNA template that can be detected in the cells even in the absence of replication and thus allows exploration of lethal mutations in viral proteins. In infected mammalian and mosquito cells, we were able to find replication-positive cells by using a fluorescently labeled viral protein even in the cases of low infection efficiency. The fluorescent region within these cells was shown to correspond to an area rich in modified membranes. These results show that CLEM is a valuable technique for studying virus replication and membrane modifications at the ultrastructural level.
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Affiliation(s)
- Kirsi Hellström
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Helena Vihinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Katri Kallio
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Tero Ahola
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
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193
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Coccia EM, Battistini A. Early IFN type I response: Learning from microbial evasion strategies. Semin Immunol 2015; 27:85-101. [PMID: 25869307 PMCID: PMC7129383 DOI: 10.1016/j.smim.2015.03.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 03/10/2015] [Indexed: 12/12/2022]
Abstract
Type I interferon (IFN) comprises a class of cytokines first discovered more than 50 years ago and initially characterized for their ability to interfere with viral replication and restrict locally viral propagation. As such, their induction downstream of germ-line encoded pattern recognition receptors (PRRs) upon recognition of pathogen-associated molecular patterns (PAMPs) is a hallmark of the host antiviral response. The acknowledgment that several PAMPs, not just of viral origin, may induce IFN, pinpoints at these molecules as a first line of host defense against a number of invading pathogens. Acting in both autocrine and paracrine manner, IFN interferes with viral replication by inducing hundreds of different IFN-stimulated genes with both direct anti-pathogenic as well as immunomodulatory activities, therefore functioning as a bridge between innate and adaptive immunity. On the other hand an inverse interference to escape the IFN system is largely exploited by pathogens through a number of tactics and tricks aimed at evading, inhibiting or manipulating the IFN pathway, that result in progression of infection or establishment of chronic disease. In this review we discuss the interplay between the IFN system and some selected clinically important and challenging viruses and bacteria, highlighting the wide array of pathogen-triggered molecular mechanisms involved in evasion strategies.
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Affiliation(s)
- Eliana M Coccia
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, Rome 00161, Italy
| | - Angela Battistini
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, Rome 00161, Italy.
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194
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Ambrose RL, Mackenzie JM. Conserved amino acids within the N-terminus of the West Nile virus NS4A protein contribute to virus replication, protein stability and membrane proliferation. Virology 2015; 481:95-106. [PMID: 25771497 DOI: 10.1016/j.virol.2015.02.045] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 02/16/2015] [Accepted: 02/19/2015] [Indexed: 11/19/2022]
Abstract
The West Nile virus strain Kunjin virus (WNVKUN) NS4A protein is a multifunctional protein involved in many aspects of the virus life-cycle and is a major component of the WNVKUN replication complex (RC). Previously we identified a conserved region in the C-terminus of NS4A regulating proteolytic processing and RC assembly, and now investigate key conserved residues in the N-terminus of NS4A and their contribution to WNVKUN replication. Mutation of P13 completely ablated replication, whereas, mutation of P48 and D49, near the first transmembrane helix, and G66 within the helix, showed variable defects in replication, virion secretion and membrane proliferation. Intriguingly, the P48 and G66 NS4A mutants resulted in specific proteasome depletion of NS4A that could in part be rescued with a proteasome inhibitor. Our results suggest that the N-terminus of NS4A contributes to correct folding and stability, essential for facilitating the essential roles of NS4A during replication.
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Affiliation(s)
- R L Ambrose
- Department of Microbiology and Immunology, University of Melbourne, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - J M Mackenzie
- Department of Microbiology and Immunology, University of Melbourne, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.
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195
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Kappes MA, Miller CL, Faaberg KS. Porcine reproductive and respiratory syndrome virus nonstructural protein 2 (nsp2) topology and selective isoform integration in artificial membranes. Virology 2015; 481:51-62. [PMID: 25768891 DOI: 10.1016/j.virol.2015.01.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 01/15/2015] [Accepted: 01/30/2015] [Indexed: 11/28/2022]
Abstract
The membrane insertion and topology of nonstructural protein 2 (nsp2) of porcine reproductive and respiratory syndrome virus (PRRSV) strain VR-2332 was assessed using a cell free translation system in the presence or absence of artificial membranes. Expression of PRRSV nsp2 in the absence of all other viral factors resulted in the genesis of both full-length nsp2 as well as a select number of C-terminal nsp2 isoforms. Addition of membranes to the translation stabilized the translation reaction, resulting in predominantly full-length nsp2 as assessed by immunoprecipitation. Analysis further showed full-length nsp2 strongly associates with membranes, along with two additional large nsp2 isoforms. Membrane integration of full-length nsp2 was confirmed through high-speed density fractionation, protection from protease digestion, and immunoprecipitation. The results demonstrated that nsp2 integrated into the membranes with an unexpected topology, where the amino (N)-terminal (cytoplasmic) and C-terminal (luminal) domains were orientated on opposite sides of the membrane surface.
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Affiliation(s)
- Matthew A Kappes
- Virus and Prion Research Unit, USDA-ARS-National Animal Disease Center, Ames, IA, USA; Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Cathy L Miller
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Kay S Faaberg
- Virus and Prion Research Unit, USDA-ARS-National Animal Disease Center, Ames, IA, USA.
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196
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Harak C, Lohmann V. Ultrastructure of the replication sites of positive-strand RNA viruses. Virology 2015; 479-480:418-33. [PMID: 25746936 PMCID: PMC7111692 DOI: 10.1016/j.virol.2015.02.029] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/06/2015] [Accepted: 02/16/2015] [Indexed: 12/13/2022]
Abstract
Positive strand RNA viruses replicate in the cytoplasm of infected cells and induce intracellular membranous compartments harboring the sites of viral RNA synthesis. These replication factories are supposed to concentrate the components of the replicase and to shield replication intermediates from the host cell innate immune defense. Virus induced membrane alterations are often generated in coordination with host factors and can be grouped into different morphotypes. Recent advances in conventional and electron microscopy have contributed greatly to our understanding of their biogenesis, but still many questions remain how viral proteins capture membranes and subvert host factors for their need. In this review, we will discuss different representatives of positive strand RNA viruses and their ways of hijacking cellular membranes to establish replication complexes. We will further focus on host cell factors that are critically involved in formation of these membranes and how they contribute to viral replication.
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Affiliation(s)
- Christian Harak
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - Volker Lohmann
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany.
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197
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O’Brien CA, Hobson-Peters J, Yam AWY, Colmant AMG, McLean BJ, Prow NA, Watterson D, Hall-Mendelin S, Warrilow D, Ng ML, Khromykh AA, Hall RA. Viral RNA intermediates as targets for detection and discovery of novel and emerging mosquito-borne viruses. PLoS Negl Trop Dis 2015; 9:e0003629. [PMID: 25799391 PMCID: PMC4370754 DOI: 10.1371/journal.pntd.0003629] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/19/2015] [Indexed: 12/15/2022] Open
Abstract
Mosquito-borne viruses encompass a range of virus families, comprising a number of significant human pathogens (e.g., dengue viruses, West Nile virus, Chikungunya virus). Virulent strains of these viruses are continually evolving and expanding their geographic range, thus rapid and sensitive screening assays are required to detect emerging viruses and monitor their prevalence and spread in mosquito populations. Double-stranded RNA (dsRNA) is produced during the replication of many of these viruses as either an intermediate in RNA replication (e.g., flaviviruses, togaviruses) or the double-stranded RNA genome (e.g., reoviruses). Detection and discovery of novel viruses from field and clinical samples usually relies on recognition of antigens or nucleotide sequences conserved within a virus genus or family. However, due to the wide antigenic and genetic variation within and between viral families, many novel or divergent species can be overlooked by these approaches. We have developed two monoclonal antibodies (mAbs) which show co-localised staining with proteins involved in viral RNA replication in immunofluorescence assay (IFA), suggesting specific reactivity to viral dsRNA. By assessing binding against a panel of synthetic dsRNA molecules, we have shown that these mAbs recognise dsRNA greater than 30 base pairs in length in a sequence-independent manner. IFA and enzyme-linked immunosorbent assay (ELISA) were employed to demonstrate detection of a panel of RNA viruses from several families, in a range of cell types. These mAbs, termed monoclonal antibodies to viral RNA intermediates in cells (MAVRIC), have now been incorporated into a high-throughput, economical ELISA-based screening system for the detection and discovery of viruses from mosquito populations. Our results have demonstrated that this simple system enables the efficient detection and isolation of a range of known and novel viruses in cells inoculated with field-caught mosquito samples, and represents a rapid, sequence-independent, and cost-effective approach to virus discovery.
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Affiliation(s)
- Caitlin A. O’Brien
- Australian Infectious Disease Research Centre, School of Chemical and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Jody Hobson-Peters
- Australian Infectious Disease Research Centre, School of Chemical and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Alice Wei Yee Yam
- Australian Infectious Disease Research Centre, School of Chemical and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Agathe M. G. Colmant
- Australian Infectious Disease Research Centre, School of Chemical and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Breeanna J. McLean
- Australian Infectious Disease Research Centre, School of Chemical and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Natalie A. Prow
- Australian Infectious Disease Research Centre, School of Chemical and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Daniel Watterson
- Australian Infectious Disease Research Centre, School of Chemical and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Sonja Hall-Mendelin
- Public Health Virology Laboratory, Forensic and Scientific Services, Department of Health, Archerfield, Queensland, Australia
| | - David Warrilow
- Public Health Virology Laboratory, Forensic and Scientific Services, Department of Health, Archerfield, Queensland, Australia
| | - Mah-Lee Ng
- Department of Microbiology, National University Health System, National University of Singapore, Singapore
| | - Alexander A. Khromykh
- Australian Infectious Disease Research Centre, School of Chemical and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Roy A. Hall
- Australian Infectious Disease Research Centre, School of Chemical and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
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198
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Pijlman GP. Enveloped virus-like particles as vaccines against pathogenic arboviruses. Biotechnol J 2015; 10:659-70. [DOI: 10.1002/biot.201400427] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 11/27/2014] [Accepted: 12/22/2014] [Indexed: 12/26/2022]
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199
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Blázquez AB, Martín-Acebes MA, Saiz JC. Amino acid substitutions in the non-structural proteins 4A or 4B modulate the induction of autophagy in West Nile virus infected cells independently of the activation of the unfolded protein response. Front Microbiol 2015; 5:797. [PMID: 25642225 PMCID: PMC4295549 DOI: 10.3389/fmicb.2014.00797] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 12/26/2014] [Indexed: 01/19/2023] Open
Abstract
West Nile virus (WNV) is a neurotropic mosquito-borne flavivirus responsible for outbreaks of meningitis and encephalitis. Whereas the activation of autophagy in cells infected with other flaviviruses is well known, the interaction of WNV with the autophagic pathway still remains unclear and there are reports describing opposite findings obtained even analyzing the same viral strain. To clarify this controversy, we first analyzed the induction of autophagic features in cells infected with a panel of WNV strains. WNV was determined to induce autophagy in a strain dependent manner. We observed that all WNV strains or isolates analyzed, except for the WNV NY99 used, upregulated the autophagic pathway in infected cells. Interestingly, a variant derived from this WNV NY99 isolated from a persistently infected mouse increased LC3 modification and aggregation. Genome sequencing of this variant revealed only two non-synonymous nucleotide substitutions when compared to parental NY99 strain. These nucleotide substitutions introduced one amino acid replacement in NS4A and other in NS4B. Using genetically engineered viruses we showed that introduction of only one of these replacements was sufficient to upregulate the autophagic pathway. Thus, in this work we have shown that naturally occurring point mutations in the viral non-structural proteins NS4A and NS4B confer WNV with the ability to induce the hallmarks of autophagy such as LC3 modification and aggregation. Even more, the differences on the induction of an autophagic response observed among WNV variants in infected cells did not correlate with alterations on the activation of the unfolded protein response (UPR), suggesting an uncoupling of UPR and autophagy during flavivirus infection. The findings here reported could help to improve the knowledge of the cellular processes involved on flavivirus–host cell interactions and contribute to the design of effective strategies to combat these pathogens.
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Affiliation(s)
- Ana-Belén Blázquez
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain
| | - Miguel A Martín-Acebes
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain ; Department of Virology and Microbiology, Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Madrid Spain
| | - Juan-Carlos Saiz
- Department of Biotechnology, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain
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200
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V'kovski P, Al-Mulla H, Thiel V, Neuman BW. New insights on the role of paired membrane structures in coronavirus replication. Virus Res 2014; 202:33-40. [PMID: 25550072 PMCID: PMC7114427 DOI: 10.1016/j.virusres.2014.12.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/16/2014] [Accepted: 12/18/2014] [Indexed: 12/22/2022]
Abstract
Coronavirus replication is tied to formation of double-membrane organelles (DMOs). DMO-making genes are conserved across the Nidovirales. Here, we interpret recent experiments on the role and importance of coronavirus DMOs.
The replication of coronaviruses, as in other positive-strand RNA viruses, is closely tied to the formation of membrane-bound replicative organelles inside infected cells. The proteins responsible for rearranging cellular membranes to form the organelles are conserved not just among the Coronaviridae family members, but across the order Nidovirales. Taken together, these observations suggest that the coronavirus replicative organelle plays an important role in viral replication, perhaps facilitating the production or protection of viral RNA. However, the exact nature of this role, and the specific contexts under which it is important have not been fully elucidated. Here, we collect and interpret the recent experimental evidence about the role and importance of membrane-bound organelles in coronavirus replication.
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Affiliation(s)
- Philip V'kovski
- Federal Institute of Virology and Immunology, Mittelhäusern, Bern, Switzerland; Graduate School for Biomedical Sciences, University of Bern, Switzerland
| | - Hawaa Al-Mulla
- School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom; University of Baghdad, College of Science, Baghdad, Iraq
| | - Volker Thiel
- Federal Institute of Virology and Immunology, Mittelhäusern, Bern, Switzerland; Vetsuisse Faculty, University of Bern, Bern, Switzerland.
| | - Benjamin W Neuman
- School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom.
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