51
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Wolff G, Melia CE, Snijder EJ, Bárcena M. Double-Membrane Vesicles as Platforms for Viral Replication. Trends Microbiol 2020; 28:1022-1033. [PMID: 32536523 PMCID: PMC7289118 DOI: 10.1016/j.tim.2020.05.009] [Citation(s) in RCA: 188] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/09/2020] [Accepted: 05/14/2020] [Indexed: 12/12/2022]
Abstract
Viruses, as obligate intracellular parasites, exploit cellular pathways and resources in a variety of fascinating ways. A striking example of this is the remodelling of intracellular membranes into specialized structures that support the replication of positive-sense ssRNA (+RNA) viruses infecting eukaryotes. These distinct forms of virus-induced structures include double-membrane vesicles (DMVs), found during viral infections as diverse and notorious as those of coronaviruses, enteroviruses, noroviruses, or hepatitis C virus. Our understanding of these DMVs has evolved over the past 15 years thanks to advances in imaging techniques and modern molecular biology tools. In this article, we review contemporary understanding of the biogenesis, structure, and function of virus-induced DMVs as well as the open questions posed by these intriguing structures.
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Affiliation(s)
- Georg Wolff
- Section Electron Microscopy, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Charlotte E Melia
- Section Electron Microscopy, Department of Cell and Chemical 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
| | - Montserrat Bárcena
- Section Electron Microscopy, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands.
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52
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Ren S, Ding C, Sun Y. Morphology Remodeling and Selective Autophagy of Intracellular Organelles during Viral Infections. Int J Mol Sci 2020; 21:ijms21103689. [PMID: 32456258 PMCID: PMC7279407 DOI: 10.3390/ijms21103689] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/14/2020] [Accepted: 05/21/2020] [Indexed: 12/17/2022] Open
Abstract
Viruses have evolved different strategies to hijack subcellular organelles during their life cycle to produce robust infectious progeny. Successful viral reproduction requires the precise assembly of progeny virions from viral genomes, structural proteins, and membrane components. Such spatial and temporal separation of assembly reactions depends on accurate coordination among intracellular compartmentalization in multiple organelles. Here, we overview the rearrangement and morphology remodeling of virus-triggered intracellular organelles. Focus is given to the quality control of intracellular organelles, the hijacking of the modified organelle membranes by viruses, morphology remodeling for viral replication, and degradation of intracellular organelles by virus-triggered selective autophagy. Understanding the functional reprogram and morphological remodeling in the virus-organelle interplay can provide new insights into the development of broad-spectrum antiviral strategies.
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Affiliation(s)
- Shanhui Ren
- Department of Avian Infectious Diseases, Shanghai Veterinary Research Institute. Chinese Academy of Agricultural Science, Shanghai 200241, China;
| | - Chan Ding
- Department of Avian Infectious Diseases, Shanghai Veterinary Research Institute. Chinese Academy of Agricultural Science, Shanghai 200241, China;
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, Yangzhou University, Yangzhou 225009, China
- Correspondence: (C.D.); (Y.S.); Tel.: +86-21-34293441 (C.D. & Y.S.); Fax: +86-21-54081818 (C.D. & Y.S.)
| | - Yingjie Sun
- Department of Avian Infectious Diseases, Shanghai Veterinary Research Institute. Chinese Academy of Agricultural Science, Shanghai 200241, China;
- Correspondence: (C.D.); (Y.S.); Tel.: +86-21-34293441 (C.D. & Y.S.); Fax: +86-21-54081818 (C.D. & Y.S.)
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53
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Caldas LA, Azevedo RC, da Silva JL, de Souza W. Microscopy analysis of Zika virus morphogenesis in mammalian cells. Sci Rep 2020; 10:8370. [PMID: 32433502 PMCID: PMC7239924 DOI: 10.1038/s41598-020-65409-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 05/04/2020] [Indexed: 12/13/2022] Open
Abstract
Zika virus (ZIKV) is an arbovirus that recently emerged in the Americas as an important pathogen mainly because of its expanded pathogenesis, and elevated tropism for neuronal cells, transposition across the placental barrier, and replication in reproductive tract cells. Thus, transmission modes are eventually independent of an invertebrate vector, which is an atypical behavior for the flavivirus genus and indicates the need to study the replication of this virus in different cell types. Although ZIKV became a target for public health programs, the interaction of this flavivirus with the infected cell is still poorly understood. Herein, we analyzed the main stages of virus morphogenesis in mammalian cells, from establishment of the viroplasm-like zone to viral release from infected cells, using super-resolution fluorescence microscopy and electron microscopy. In addition, we compared this with other host cell types and other members of the Flaviviridae family that present a similar dynamic.
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Affiliation(s)
- Lucio Ayres Caldas
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro. Av. Carlos Chagas Filho 373, Prédio CCS, Bloco C, subsolo, CEP:21941902, Cidade Universitária, Rio de Janeiro, RJ, Brazil. .,Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem. Avenida Carlos Chagas Filho 373. Centro de Ciências da Saúde (CCS), Bloco M, Unidade 3, Cidade Universitária, CEP:21941902, Rio de Janeiro, RJ, Brazil.
| | - Renata Campos Azevedo
- Laboratório de Interação Vírus-Célula, Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro. Av. Carlos Chagas Filho 373, Prédio CCS, Bloco I, subsolo, CEP:21941902, Cidade Universitária, Rio de Janeiro, RJ, Brazil
| | - Jerson Lima da Silva
- Instituto de Bioquímica Médica Leopoldo de Meis, Laboratório de Termodinâmica de Proteínas e Estruturas Virais Gregório Weber, Universidade Federal do Rio de Janeiro. Av. Carlos Chagas Filho 373, Prédio CCS, Bloco E, sala 10, Cidade Universitária, CEP:21941902, Rio de Janeiro, RJ, Brazil
| | - Wanderley de Souza
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro. Av. Carlos Chagas Filho 373, Prédio CCS, Bloco C, subsolo, CEP:21941902, Cidade Universitária, Rio de Janeiro, RJ, Brazil.,Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem. Avenida Carlos Chagas Filho 373. Centro de Ciências da Saúde (CCS), Bloco M, Unidade 3, Cidade Universitária, CEP:21941902, Rio de Janeiro, RJ, Brazil
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54
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Beren C, Cui Y, Chakravarty A, Yang X, Rao ALN, Knobler CM, Zhou ZH, Gelbart WM. Genome organization and interaction with capsid protein in a multipartite RNA virus. Proc Natl Acad Sci U S A 2020; 117:10673-10680. [PMID: 32358197 PMCID: PMC7245085 DOI: 10.1073/pnas.1915078117] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We report the asymmetric reconstruction of the single-stranded RNA (ssRNA) content in one of the three otherwise identical virions of a multipartite RNA virus, brome mosaic virus (BMV). We exploit a sample consisting exclusively of particles with the same RNA content-specifically, RNAs 3 and 4-assembled in planta by agrobacterium-mediated transient expression. We find that the interior of the particle is nearly empty, with most of the RNA genome situated at the capsid shell. However, this density is disordered in the sense that the RNA is not associated with any particular structure but rather, with an ensemble of secondary/tertiary structures that interact with the capsid protein. Our results illustrate a fundamental difference between the ssRNA organization in the multipartite BMV viral capsid and the monopartite bacteriophages MS2 and Qβ for which a dominant RNA conformation is found inside the assembled viral capsids, with RNA density conserved even at the center of the particle. This can be understood in the context of the differing demands on their respective lifecycles: BMV must package separately each of several different RNA molecules and has been shown to replicate and package them in isolated, membrane-bound, cytoplasmic complexes, whereas the bacteriophages exploit sequence-specific "packaging signals" throughout the viral RNA to package their monopartite genomes.
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Affiliation(s)
- Christian Beren
- Department of Chemistry & Biochemistry, University of California, Los Angeles, CA 90095
| | - Yanxiang Cui
- California NanoSystems Institute, University of California, Los Angeles, CA 90095
| | - Antara Chakravarty
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521
| | - Xue Yang
- California NanoSystems Institute, University of California, Los Angeles, CA 90095
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, CA 90095
| | - A L N Rao
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521;
| | - Charles M Knobler
- Department of Chemistry & Biochemistry, University of California, Los Angeles, CA 90095
| | - Z Hong Zhou
- California NanoSystems Institute, University of California, Los Angeles, CA 90095;
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, CA 90095
| | - William M Gelbart
- Department of Chemistry & Biochemistry, University of California, Los Angeles, CA 90095;
- California NanoSystems Institute, University of California, Los Angeles, CA 90095
- Molecular Biology Institute, University of California, Los Angeles, CA 90095
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55
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Sun R, Zhang S, Zheng L, Qu F. Translation-Independent Roles of RNA Secondary Structures within the Replication Protein Coding Region of Turnip Crinkle Virus. Viruses 2020; 12:v12030350. [PMID: 32235750 PMCID: PMC7150753 DOI: 10.3390/v12030350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 03/12/2020] [Accepted: 03/20/2020] [Indexed: 01/20/2023] Open
Abstract
RNA secondary structures play diverse roles in positive-sense (+) RNA virus infections, but those located with the replication protein coding sequence can be difficult to investigate. Structures that regulate the translation of replication proteins pose particular challenges, as their potential involvement in post-translational steps cannot be easily discerned independent of their roles in regulating translation. In the current study, we attempted to overcome these difficulties by providing viral replication proteins in trans. Specifically, we modified the plant-infecting turnip crinkle virus (TCV) into variants that are unable to translate one (p88) or both (p28 and p88) replication proteins, and complemented their replication with the corresponding replication protein(s) produced from separate, non-replicating constructs. This approach permitted us to re-examine the p28/p88 coding region for potential RNA elements needed for TCV replication. We found that, while more than a third of the p88 coding sequence could be deleted without substantially affecting viral RNA levels, two relatively small regions, known as RSE and IRE, were essential for robust accumulation of TCV genomic RNA, but not subgenomic RNAs. In particular, the RSE element, found previously to be required for regulating the translational read-through of p28 stop codon to produce p88, contained sub-elements needed for efficient replication of the TCV genome. Application of this new approach in other viruses could reveal novel RNA secondary structures vital for viral multiplication.
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Affiliation(s)
| | | | | | - Feng Qu
- Correspondence: ; Tel.: +1-330-263-3835
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56
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Dinan AM, Lukhovitskaya NI, Olendraite I, Firth AE. A case for a negative-strand coding sequence in a group of positive-sense RNA viruses. Virus Evol 2020; 6:veaa007. [PMID: 32064120 PMCID: PMC7010960 DOI: 10.1093/ve/veaa007] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Positive-sense single-stranded RNA viruses form the largest and most diverse group of eukaryote-infecting viruses. Their genomes comprise one or more segments of coding-sense RNA that function directly as messenger RNAs upon release into the cytoplasm of infected cells. Positive-sense RNA viruses are generally accepted to encode proteins solely on the positive strand. However, we previously identified a surprisingly long (∼1,000-codon) open reading frame (ORF) on the negative strand of some members of the family Narnaviridae which, together with RNA bacteriophages of the family Leviviridae, form a sister group to all other positive-sense RNA viruses. Here, we completed the genomes of three mosquito-associated narnaviruses, all of which have the long reverse-frame ORF. We systematically identified narnaviral sequences in public data sets from a wide range of sources, including arthropod, fungal, and plant transcriptomic data sets. Long reverse-frame ORFs are widespread in one clade of narnaviruses, where they frequently occupy >95 per cent of the genome. The reverse-frame ORFs correspond to a specific avoidance of CUA, UUA, and UCA codons (i.e. stop codon reverse complements) in the forward-frame RNA-dependent RNA polymerase ORF. However, absence of these codons cannot be explained by other factors such as inability to decode these codons or GC3 bias. Together with other analyses, we provide the strongest evidence yet of coding capacity on the negative strand of a positive-sense RNA virus. As these ORFs comprise some of the longest known overlapping genes, their study may be of broad relevance to understanding overlapping gene evolution and de novo origin of genes.
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Affiliation(s)
- Adam M Dinan
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Nina I Lukhovitskaya
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Ingrida Olendraite
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Andrew E Firth
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
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57
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Neufeldt CJ, Cortese M, Acosta EG, Bartenschlager R. Rewiring cellular networks by members of the Flaviviridae family. Nat Rev Microbiol 2019; 16:125-142. [PMID: 29430005 PMCID: PMC7097628 DOI: 10.1038/nrmicro.2017.170] [Citation(s) in RCA: 230] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Members of the Flaviviridae virus family comprise a large group of enveloped viruses with a single-strand RNA genome of positive polarity. Several genera belong to this family, including the Hepacivirus genus, of which hepatitis C virus (HCV) is the prototype member, and the Flavivirus genus, which contains both dengue virus and Zika virus. Viruses of these genera differ in many respects, such as the mode of transmission or the course of infection, which is either predominantly persistent in the case of HCV or acutely self-limiting in the case of flaviviruses. Although the fundamental replication strategy of Flaviviridae members is similar, during the past few years, important differences have been discovered, including the way in which these viruses exploit cellular resources to facilitate viral propagation. These differences might be responsible, at least in part, for the various biological properties of these viruses, thus offering the possibility to learn from comparisons. In this Review, we discuss the current understanding of how Flaviviridae viruses manipulate and usurp cellular pathways in infected cells. Specifically, we focus on comparing strategies employed by flaviviruses with those employed by hepaciviruses, and we discuss the importance of these interactions in the context of viral replication and antiviral therapies.
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Affiliation(s)
- Christopher J Neufeldt
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Mirko Cortese
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Eliana G Acosta
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany.,German Center for Infection Research, Heidelberg Partner Site, 69120 Heidelberg, Germany
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58
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Obr M, Schur FKM. Structural analysis of pleomorphic and asymmetric viruses using cryo-electron tomography and subtomogram averaging. Adv Virus Res 2019; 105:117-159. [PMID: 31522703 DOI: 10.1016/bs.aivir.2019.07.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Describing the protein interactions that form pleomorphic and asymmetric viruses represents a considerable challenge to most structural biology techniques, including X-ray crystallography and single particle cryo-electron microscopy. Obtaining a detailed understanding of these interactions is nevertheless important, considering the number of relevant human pathogens that do not follow strict icosahedral or helical symmetry. Cryo-electron tomography and subtomogram averaging methods provide structural insights into complex biological environments and are well suited to go beyond structures of perfectly symmetric viruses. This chapter discusses recent developments showing that cryo-ET and subtomogram averaging can provide high-resolution insights into hitherto unknown structural features of pleomorphic and asymmetric virus particles. It also describes how these methods have significantly added to our understanding of retrovirus capsid assemblies in immature and mature viruses. Additional examples of irregular viruses and their associated proteins, whose structures have been studied via cryo-ET and subtomogram averaging, further support the versatility of these methods.
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Affiliation(s)
- Martin Obr
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Florian K M Schur
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria.
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59
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Otegui MS, Pennington JG. Electron tomography in plant cell biology. Microscopy (Oxf) 2019; 68:69-79. [PMID: 30452668 DOI: 10.1093/jmicro/dfy133] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/15/2018] [Accepted: 10/31/2018] [Indexed: 12/11/2022] Open
Abstract
Electron tomography (ET) approaches are based on the imaging of a biological specimen at different tilt angles by transmission electron microscopy (TEM). ET can be applied to both plastic-embedded and frozen samples. Technological advancements in TEM, direct electron detection, automated image collection, and imaging processing algorithms allow for 2-7-nm scale axial resolution in tomographic reconstructions of cells and organelles. In this review, we discussed the application of ET in plant cell biology and new opportunities for imaging plant cells by cryo-ET and other 3D electron microscopy approaches.
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Affiliation(s)
- Marisa S Otegui
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison WI, USA.,Laboratory of Molecular and Cellular Biology, University of Wisconsin-Madison, 1525 Linden Drive, Madison WI, USA.,Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison WI, USA
| | - Jannice G Pennington
- Institute for Molecular Virology, University of Wisconsin-Madison, 1525 Linden Drive, Madison WI, USA.,Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, USA
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60
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New Phylogenetic Grouping of Positive-Sense RNA Viruses Is Concordant with Replication Complex Morphology. mBio 2019; 10:mBio.01402-19. [PMID: 31363030 PMCID: PMC6667620 DOI: 10.1128/mbio.01402-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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61
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A Transgenic Flock House Virus Replicon Reveals an RNAi Independent Antiviral Mechanism Acting in Drosophila Follicular Somatic Cells. G3-GENES GENOMES GENETICS 2019; 9:403-412. [PMID: 30530643 PMCID: PMC6385967 DOI: 10.1534/g3.118.200872] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The small interfering RNA (siRNA) pathway is the main and best studied invertebrate antiviral response. Other poorly characterized protein based antiviral mechanisms also contribute to the control of viral replication in insects. In addition, it remains unclear whether tissue specific factors contribute to RNA and protein-based antiviral immunity mechanisms. In vivo screens to identify such factors are challenging and time consuming. In addition, the scored phenotype is usually limited to survival and/or viral load. Transgenic viral replicons are valuable tools to overcome these limitations and screen for novel antiviral factors. Here we describe transgenic Drosophila melanogaster lines encoding a Flock House Virus-derived replicon (FHV∆B2eGFP), expressing GFP as a reporter of viral replication. This replicon is efficiently controlled by the siRNA pathway in most somatic tissues, with GFP fluorescence providing a reliable marker for the activity of antiviral RNAi. Interestingly, in follicular somatic cells (FSC) of ovaries, this replicon is still partially repressed in an siRNA independent manner. We did not detect replicon derived Piwi-interacting RNAs in FSCs and identified 31 differentially expressed genes between restrictive and permissive FSCs. Altogether, our results uncovered a yet unidentified RNAi-independent mechanism controlling FHV replication in FSCs of ovaries and validate the FHV∆B2eGFP replicon as a tool to screen for novel tissue specific antiviral mechanisms.
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62
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Richert-Pöggeler KR, Franzke K, Hipp K, Kleespies RG. Electron Microscopy Methods for Virus Diagnosis and High Resolution Analysis of Viruses. Front Microbiol 2019; 9:3255. [PMID: 30666247 PMCID: PMC6330349 DOI: 10.3389/fmicb.2018.03255] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 12/14/2018] [Indexed: 01/29/2023] Open
Abstract
The term "virosphere" describes both the space where viruses are found and the space they influence, and can extend to their impact on the environment, highlighting the complexity of the interactions involved. Studying the biology of viruses and the etiology of virus disease is crucial to the prevention of viral disease, efficient and reliable virus diagnosis, and virus control. Electron microscopy (EM) is an essential tool in the detection and analysis of virus replication. New EM methods and ongoing technical improvements offer a broad spectrum of applications, allowing in-depth investigation of viral impact on not only the host but also the environment. Indeed, using the most up-to-date electron cryomicroscopy methods, such investigations are now close to atomic resolution. In combination with bioinformatics, the transition from 2D imaging to 3D remodeling allows structural and functional analyses that extend and augment our knowledge of the astonishing diversity in virus structure and lifestyle. In combination with confocal laser scanning microscopy, EM enables live imaging of cells and tissues with high-resolution analysis. Here, we describe the pivotal role played by EM in the study of viruses, from structural analysis to the biological relevance of the viral metagenome (virome).
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Affiliation(s)
- Katja R. Richert-Pöggeler
- Federal Research Center for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn Institute, Braunschweig, Germany
| | - Kati Franzke
- Institute of Infectiology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Katharina Hipp
- Electron Microscopy Facility, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Regina G. Kleespies
- Federal Research Centre for Cultivated Plants, Institute for Biological Control, Julius Kühn Institute, Darmstadt, Germany
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63
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Robinson M, Schor S, Barouch-Bentov R, Einav S. Viral journeys on the intracellular highways. Cell Mol Life Sci 2018; 75:3693-3714. [PMID: 30043139 PMCID: PMC6151136 DOI: 10.1007/s00018-018-2882-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/01/2018] [Accepted: 07/19/2018] [Indexed: 12/24/2022]
Abstract
Viruses are obligate intracellular pathogens that are dependent on cellular machineries for their replication. Recent technological breakthroughs have facilitated reliable identification of host factors required for viral infections and better characterization of the virus-host interplay. While these studies have revealed cellular machineries that are uniquely required by individual viruses, accumulating data also indicate the presence of broadly required mechanisms. Among these overlapping cellular functions are components of intracellular membrane trafficking pathways. Here, we review recent discoveries focused on how viruses exploit intracellular membrane trafficking pathways to promote various stages of their life cycle, with an emphasis on cellular factors that are usurped by a broad range of viruses. We describe broadly required components of the endocytic and secretory pathways, the Endosomal Sorting Complexes Required for Transport pathway, and the autophagy pathway. Identification of such overlapping host functions offers new opportunities to develop broad-spectrum host-targeted antiviral strategies.
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Affiliation(s)
- Makeda Robinson
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Lane Building, Rm L127, Stanford, CA, 94305, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Stanford Schor
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Lane Building, Rm L127, Stanford, CA, 94305, USA
| | - Rina Barouch-Bentov
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Lane Building, Rm L127, Stanford, CA, 94305, USA
| | - Shirit Einav
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Lane Building, Rm L127, Stanford, CA, 94305, USA.
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.
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64
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The RNA Capping Enzyme Domain in Protein A is Essential for Flock House Virus Replication. Viruses 2018; 10:v10090483. [PMID: 30205593 PMCID: PMC6165433 DOI: 10.3390/v10090483] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 09/05/2018] [Accepted: 09/05/2018] [Indexed: 01/18/2023] Open
Abstract
The nodavirus flock house virus (FHV) and the alphavirus Semliki Forest virus (SFV) show evolutionarily intriguing similarities in their replication complexes and RNA capping enzymes. In this study, we first established an efficient FHV trans-replication system in mammalian cells, which disjoins protein expression from viral RNA synthesis. Following transfection, FHV replicase protein A was associated with mitochondria, whose outer surface displayed pouch-like invaginations with a ‘neck’ structure opening towards the cytoplasm. In mitochondrial pellets from transfected cells, high-level synthesis of both genomic and subgenomic RNA was detected in vitro and the newly synthesized RNA was of positive polarity. Secondly, we initiated the study of the putative RNA capping enzyme domain in protein A by mutating the conserved amino acids H93, R100, D141, and W215. RNA replication was abolished for all mutants inside cells and in vitro except for W215A, which showed reduced replication. Transfection of capped RNA template did not rescue the replication activity of the mutants. Comparing the efficiency of SFV and FHV trans-replication systems, the FHV system appeared to produce more RNA. Using fluorescent marker proteins, we demonstrated that both systems could replicate in the same cell. This work may facilitate the comparative analysis of FHV and SFV replication.
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65
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Navarro PP, Stahlberg H, Castaño-Díez D. Protocols for Subtomogram Averaging of Membrane Proteins in the Dynamo Software Package. Front Mol Biosci 2018; 5:82. [PMID: 30234127 PMCID: PMC6131572 DOI: 10.3389/fmolb.2018.00082] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/13/2018] [Indexed: 11/13/2022] Open
Abstract
Cryo-electron tomography allows low-resolution three-dimensional (3D) viewing of cellular organelles and macromolecular complexes present as multiple copies within a tomogram. These structures are computationally extracted and averaged in order to obtain high-resolution 3D structures, and provide a map of their spatial distribution and interaction with their biological microenvironment. To do so, we apply the user-friendly Dynamo software package on a tomographic data set. Dynamo acts as a modular toolbox adaptable to different biological scenarios, allowing a custom designed pipeline for subtomogram averaging. Here, we use as a textbook example the mitochondrial docking site of the positive-strand RNA Flock house nodavirus (FHV) to describe how Dynamo coordinates several basic steps in the subtomogram averaging workflow. Our framework covers specific strategies to deal with additional issues in subtomogram averaging as tomographic data management, 3D surface visualization, automatic assignment of asymmetry and inherent loss of Fourier information in presence of preferential views.
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Affiliation(s)
- Paula P Navarro
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Basel, Switzerland
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Basel, Switzerland
| | - Daniel Castaño-Díez
- BioEM Lab, Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Basel, Switzerland
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66
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Jin J, Galaz-Montoya JG, Sherman MB, Sun SY, Goldsmith CS, O'Toole ET, Ackerman L, Carlson LA, Weaver SC, Chiu W, Simmons G. Neutralizing Antibodies Inhibit Chikungunya Virus Budding at the Plasma Membrane. Cell Host Microbe 2018; 24:417-428.e5. [PMID: 30146390 DOI: 10.1016/j.chom.2018.07.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/05/2018] [Accepted: 07/26/2018] [Indexed: 01/29/2023]
Abstract
Neutralizing antibodies (NAbs) are traditionally thought to inhibit virus infection by preventing virion entry into target cells. In addition, antibodies can engage Fc receptors (FcRs) on immune cells to activate antiviral responses. We describe a mechanism by which NAbs inhibit chikungunya virus (CHIKV), the most common alphavirus infecting humans, by preventing virus budding from infected human cells and activating IgG-specific Fcγ receptors. NAbs bind to CHIKV glycoproteins on the infected cell surface and induce glycoprotein coalescence, preventing budding of nascent virions and leaving structurally heterogeneous nucleocapsids arrested in the cytosol. Furthermore, NAbs induce clustering of CHIKV replication spherules at sites of budding blockage. Functionally, these densely packed glycoprotein-NAb complexes on infected cells activate Fcγ receptors, inducing a strong, antibody-dependent, cell-mediated cytotoxicity response from immune effector cells. Our findings describe a triply functional antiviral pathway for NAbs that might be broadly applicable across virus-host systems, suggesting avenues for therapeutic innovation through antibody design.
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Affiliation(s)
- Jing Jin
- Blood Systems Research Institute, San Francisco, CA 94118, USA; Department of Pathology and Laboratory Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
| | - Jesús G Galaz-Montoya
- Departments of Bioengineering, Microbiology and Immunology, and Photon Science, James H. Clark Center, Stanford University, Stanford, CA 94305, USA
| | - Michael B Sherman
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Stella Y Sun
- Departments of Bioengineering, Microbiology and Immunology, and Photon Science, James H. Clark Center, Stanford University, Stanford, CA 94305, USA
| | - Cynthia S Goldsmith
- Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Eileen T O'Toole
- Boulder Laboratory for 3-D Electron Microscopy of Cells, Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Larry Ackerman
- Department of Anatomy, University of California San Francisco, San Francisco, CA 94143, USA
| | - Lars-Anders Carlson
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 901 87, Sweden
| | - Scott C Weaver
- Institute for Human Infections and Immunity and Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Wah Chiu
- Departments of Bioengineering, Microbiology and Immunology, and Photon Science, James H. Clark Center, Stanford University, Stanford, CA 94305, USA
| | - Graham Simmons
- Blood Systems Research Institute, San Francisco, CA 94118, USA; Department of Pathology and Laboratory Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
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67
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Infectious Bursal Disease Virus Hijacks Endosomal Membranes as the Scaffolding Structure for Viral Replication. J Virol 2018. [PMID: 29540593 DOI: 10.1128/jvi.01964-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Birnaviruses are unconventional members of the group of double-stranded RNA (dsRNA) viruses that are characterized by the lack of a transcriptionally active inner core. Instead, the birnaviral particles organize their genome in ribonucleoprotein complexes (RNPs) composed by dsRNA segments, the dsRNA-binding VP3 protein, and the virally encoded RNA-dependent RNA polymerase (RdRp). This and other structural features suggest that birnaviruses may follow a completely different replication program from that followed by members of the Reoviridae family, supporting the hypothesis that birnaviruses are the evolutionary link between single-stranded positive RNA (+ssRNA) and dsRNA viruses. Here we demonstrate that infectious bursal disease virus (IBDV), a prototypical member of the Birnaviridae family, hijacks endosomal membranes of infected cells through the interaction of a viral protein, VP3, with the phospholipids on the cytosolic leaflet of these compartments for replication. Employing a mutagenesis approach, we demonstrated that VP3 domain PATCH 2 (P2) mediates the association of VP3 with the endosomal membranes. To determine the role of VP3 P2 in the context of the virus replication cycle, we used avian cells stably overexpressing VP3 P2 for IBDV infection. Importantly, the intra- and extracellular virus yields, as well as the intracellular levels of VP2 viral capsid protein, were significantly diminished in cells stably overexpressing VP3 P2. Together, our results indicate that the association of VP3 with endosomes has a relevant role in the IBDV replication cycle. This report provides direct experimental evidence for membranous compartments such as endosomes being required by a dsRNA virus for its replication. The results also support the previously proposed role of birnaviruses as an evolutionary link between +ssRNA and dsRNA viruses.IMPORTANCE Infectious bursal disease (IBD; also called Gumboro disease) is an acute, highly contagious immunosuppressive disease that affects young chickens and spreads worldwide. The etiological agent of IBD is infectious bursal disease virus (IBDV). This virus destroys the central immune organ (bursa of Fabricius), resulting in immunosuppression and reduced responses of chickens to vaccines, which increase their susceptibility to other pathogens. IBDV is a member of Birnaviridae family, which comprises unconventional members of dsRNA viruses, whose replication strategy has been scarcely studied. In this report we show that IBDV hijacks the endosomes of the infected cells for establishing viral replication complexes via the association of the ribonucleoprotein complex component VP3 with the phospholipids in the cytosolic leaflet of endosomal membranes. We show that this interaction is mediated by the VP3 PATCH 2 domain and demonstrate its relevant role in the context of viral infection.
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68
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Barrows NJ, Campos RK, Liao KC, Prasanth KR, Soto-Acosta R, Yeh SC, Schott-Lerner G, Pompon J, Sessions OM, Bradrick SS, Garcia-Blanco MA. Biochemistry and Molecular Biology of Flaviviruses. Chem Rev 2018; 118:4448-4482. [PMID: 29652486 DOI: 10.1021/acs.chemrev.7b00719] [Citation(s) in RCA: 193] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Flaviviruses, such as dengue, Japanese encephalitis, tick-borne encephalitis, West Nile, yellow fever, and Zika viruses, are critically important human pathogens that sicken a staggeringly high number of humans every year. Most of these pathogens are transmitted by mosquitos, and not surprisingly, as the earth warms and human populations grow and move, their geographic reach is increasing. Flaviviruses are simple RNA-protein machines that carry out protein synthesis, genome replication, and virion packaging in close association with cellular lipid membranes. In this review, we examine the molecular biology of flaviviruses touching on the structure and function of viral components and how these interact with host factors. The latter are functionally divided into pro-viral and antiviral factors, both of which, not surprisingly, include many RNA binding proteins. In the interface between the virus and the hosts we highlight the role of a noncoding RNA produced by flaviviruses to impair antiviral host immune responses. Throughout the review, we highlight areas of intense investigation, or a need for it, and potential targets and tools to consider in the important battle against pathogenic flaviviruses.
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Affiliation(s)
- Nicholas J Barrows
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States.,Department of Molecular Genetics and Microbiology , Duke University , Durham , North Carolina 27710 , United States
| | - Rafael K Campos
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States.,Department of Molecular Genetics and Microbiology , Duke University , Durham , North Carolina 27710 , United States
| | - Kuo-Chieh Liao
- Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore
| | - K Reddisiva Prasanth
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States
| | - Ruben Soto-Acosta
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States
| | - Shih-Chia Yeh
- Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore
| | - Geraldine Schott-Lerner
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States
| | - Julien Pompon
- Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore.,MIVEGEC, IRD, CNRS, Université de Montpellier , Montpellier 34090 , France
| | - October M Sessions
- Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore
| | - Shelton S Bradrick
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States
| | - Mariano A Garcia-Blanco
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States.,Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore
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69
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Purification of Highly Active Alphavirus Replication Complexes Demonstrates Altered Fractionation of Multiple Cellular Membranes. J Virol 2018; 92:JVI.01852-17. [PMID: 29367248 DOI: 10.1128/jvi.01852-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/17/2018] [Indexed: 01/26/2023] Open
Abstract
Positive-strand RNA viruses replicate their genomes in membrane-associated structures; alphaviruses and many other groups induce membrane invaginations called spherules. Here, we established a protocol to purify these membranous replication complexes (RCs) from cells infected with Semliki Forest virus (SFV). We isolated SFV spherules located on the plasma membrane and further purified them using two consecutive density gradients. This revealed that SFV infection strongly modifies cellular membranes. We removed soluble proteins, the Golgi membranes, and most of the mitochondria, but plasma membrane, endoplasmic reticulum (ER), and late endosome markers were retained in the membrane fraction that contained viral RNA synthesizing activity, replicase proteins, and minus- and plus-strand RNA. Electron microscopy revealed that the purified membranes displayed spherule-like structures with a narrow neck. This membrane enrichment was specific to viral replication, as such a distribution of membrane markers was only observed after infection. Besides the plasma membrane, SFV infection remodeled the ER, and the cofractionation of the RC-carrying plasma membrane and ER suggests that SFV recruits ER proteins or membrane to the site of replication. The purified RCs were highly active in synthesizing both genomic and subgenomic RNA. Detergent solubilization destroyed the replication activity, demonstrating that the membrane association of the complex is essential. Most of the newly made RNA was in double-stranded replicative molecules, but the purified complexes also produced single-stranded RNA as well as released newly made RNA. This indicates that the purification established here maintained the functionality of RCs and thus enables further structural and functional studies of active RCs.IMPORTANCE Similar to all positive-strand RNA viruses, the arthropod-borne alphaviruses induce membranous genome factories, but little is known about the arrangement of viral replicase proteins and the presence of host proteins in these replication complexes. To improve our knowledge of alphavirus RNA-synthesizing complexes, we isolated and purified them from infected mammalian cells. Detection of viral RNA and in vitro replication assays revealed that these complexes are abundant and highly active when located on the plasma membrane. After multiple purification steps, they remain functional in synthesizing and releasing viral RNA. Besides the plasma membrane, markers for the endoplasmic reticulum and late endosomes were enriched with the replication complexes, demonstrating that alphavirus infection modified cellular membranes beyond inducing replication spherules on the plasma membrane. We have developed here a gentle purification method to obtain large quantities of highly active replication complexes, and similar methods can be applied to other positive-strand RNA viruses.
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70
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Cyrklaff M, Frischknecht F, Kudryashev M. Functional insights into pathogen biology from 3D electron microscopy. FEMS Microbiol Rev 2018; 41:828-853. [PMID: 28962014 DOI: 10.1093/femsre/fux041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 07/25/2017] [Indexed: 01/10/2023] Open
Abstract
In recent years, novel imaging approaches revolutionised our understanding of the cellular and molecular biology of microorganisms. These include advances in fluorescent probes, dynamic live cell imaging, superresolution light and electron microscopy. Currently, a major transition in the experimental approach shifts electron microscopy studies from a complementary technique to a method of choice for structural and functional analysis. Here we review functional insights into the molecular architecture of viruses, bacteria and parasites as well as interactions with their respective host cells gained from studies using cryogenic electron tomography and related methodologies.
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Affiliation(s)
- Marek Cyrklaff
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Friedrich Frischknecht
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Mikhail Kudryashev
- Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt, Germany.,Buchmann Institute for Molecular Life Sciences, Goethe University of Frankfurt, Max-von-Laue Strasse 17, 60438 Frankfurt, Germany
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71
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Garcia-Ruiz H, Diaz A, Ahlquist P. Intermolecular RNA Recombination Occurs at Different Frequencies in Alternate Forms of Brome Mosaic Virus RNA Replication Compartments. Viruses 2018; 10:v10030131. [PMID: 29543718 PMCID: PMC5869524 DOI: 10.3390/v10030131] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/13/2018] [Accepted: 03/14/2018] [Indexed: 01/27/2023] Open
Abstract
Positive-strand RNA viruses replicate their genomes in membrane-bound replication compartments. Brome mosaic virus (BMV) replicates in vesicular invaginations of the endoplasmic reticulum membrane. BMV has served as a productive model system to study processes like virus-host interactions, RNA replication and recombination. Here we present multiple lines of evidence showing that the structure of the viral RNA replication compartments plays a fundamental role and that recruitment of parental RNAs to a common replication compartment is a limiting step in intermolecular RNA recombination. We show that a previously defined requirement for an RNA recruitment element on both parental RNAs is not to function as a preferred crossover site, but in order for individual RNAs to be recruited into the replication compartments. Moreover, modulating the form of the replication compartments from spherular vesicles (spherules) to more expansive membrane layers increased intermolecular RNA recombination frequency by 200- to 1000-fold. We propose that intermolecular RNA recombination requires parental RNAs to be recruited into replication compartments as monomers, and that recruitment of multiple RNAs into a contiguous space is much more common for layers than for spherules. These results could explain differences in recombination frequencies between viruses that replicate in association with smaller spherules versus larger double-membrane vesicles and convoluted membranes.
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Affiliation(s)
- Hernan Garcia-Ruiz
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA.
- Nebraska Center for Virology, Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68503, USA.
| | - Arturo Diaz
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA.
- Department of Biology, La Sierra University, Riverside, CA 92515, USA.
| | - Paul Ahlquist
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA.
- Howard Hughes Medical Institute and Morgridge Institute for Research, University of Wisconsin-Madison, MadisonWI 53706, USA.
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72
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Nonstructural Proteins of Alphavirus-Potential Targets for Drug Development. Viruses 2018; 10:v10020071. [PMID: 29425115 PMCID: PMC5850378 DOI: 10.3390/v10020071] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 02/02/2018] [Accepted: 02/06/2018] [Indexed: 12/31/2022] Open
Abstract
Alphaviruses are enveloped, positive single-stranded RNA viruses, typically transmitted by arthropods. They often cause arthralgia or encephalitic diseases in infected humans and there is currently no targeted antiviral treatment available. The re-emergence of alphaviruses in Asia, Europe, and the Americas over the last decade, including chikungunya and o'nyong'nyong viruses, have intensified the search for selective inhibitors. In this review, we highlight key molecular determinants within the alphavirus replication complex that have been identified as viral targets, focusing on their structure and functionality in viral dissemination. We also summarize recent structural data of these viral targets and discuss how these could serve as templates to facilitate structure-based drug design and development of small molecule inhibitors.
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73
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Nishikiori M, Ahlquist P. Organelle luminal dependence of (+)strand RNA virus replication reveals a hidden druggable target. SCIENCE ADVANCES 2018; 4:eaap8258. [PMID: 29387794 PMCID: PMC5787378 DOI: 10.1126/sciadv.aap8258] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/19/2017] [Indexed: 05/08/2023]
Abstract
Positive-strand RNA viruses replicate their genomes in membrane-bounded cytoplasmic complexes. We show that endoplasmic reticulum (ER)-linked genomic RNA replication by brome mosaic virus (BMV), a well-studied member of the alphavirus superfamily, depends on the ER luminal thiol oxidase ERO1. We further show that BMV RNA replication protein 1a, a key protein for the formation and function of vesicular BMV RNA replication compartments on ER membranes, permeabilizes these membranes to release oxidizing potential from the ER lumen. Conserved amphipathic sequences in 1a are sufficient to permeabilize liposomes, and mutations in these sequences simultaneously block membrane permeabilization, formation of a disulfide-linked, oxidized 1a multimer, 1a's RNA capping function, and productive genome replication. These results reveal new transmembrane complexities in positive-strand RNA virus replication, show that-as previously reported for certain picornaviruses and flaviviruses-some alphavirus superfamily members encode viroporins, identify roles for such viroporins in genome replication, and provide a potential new foundation for broad-spectrum antivirals.
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Affiliation(s)
- Masaki Nishikiori
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - Paul Ahlquist
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, Madison, WI 53715, USA
- Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI 53706, USA
- Corresponding author.
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74
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Zhang XF, Zhang S, Guo Q, Sun R, Wei T, Qu F. A New Mechanistic Model for Viral Cross Protection and Superinfection Exclusion. FRONTIERS IN PLANT SCIENCE 2018; 9:40. [PMID: 29422912 PMCID: PMC5788904 DOI: 10.3389/fpls.2018.00040] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 01/09/2018] [Indexed: 05/05/2023]
Abstract
Plants pre-infected with a mild variant of a virus frequently become protected against more severe variants of the same virus through the cross protection phenomenon first discovered in 1929. Despite its widespread use in managing important plant virus diseases, the mechanism of cross protection remains poorly understood. Recent investigations in our labs, by analyzing the whole-plant dynamics of a turnip crinkle virus (TCV) population, coupled with cell biological interrogation of individual TCV variants, revealed possible novel mechanisms for cross protection and the closely related process of superinfection exclusion (SIE). Our new mechanistic model postulates that, for RNA viruses like TCV, SIE manifests a viral function that denies progeny viruses the chance of re-replicating their genomes in the cells of their "parents," and it collaterally targets highly homologous superinfecting viruses that are indistinguishable from progeny viruses. We further propose that SIE may be evolutionarily selected to maintain an optimal error frequency in progeny genomes. Although primarily based on observations made with TCV, this new model could be broadly applicable to other viruses as it provides a molecular basis for maintaining virus genome fidelity in the face of the error-prone nature of virus replication process.
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Affiliation(s)
- Xiao-Feng Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
- *Correspondence: Feng Qu, Xiao-Feng Zhang,
| | - Shaoyan Zhang
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, Ohio State University, Wooster, OH, United States
| | - Qin Guo
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, Ohio State University, Wooster, OH, United States
| | - Rong Sun
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, Ohio State University, Wooster, OH, United States
| | - Taiyun Wei
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Feng Qu
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, Ohio State University, Wooster, OH, United States
- *Correspondence: Feng Qu, Xiao-Feng Zhang,
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75
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Richert-Pöggeler KR, Franzke K, Hipp K, Kleespies RG. Electron Microscopy Methods for Virus Diagnosis and High Resolution Analysis of Viruses. Front Microbiol 2018. [PMID: 30666247 DOI: 10.3389/fmicb.2018.03255.ecollection] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023] Open
Abstract
The term "virosphere" describes both the space where viruses are found and the space they influence, and can extend to their impact on the environment, highlighting the complexity of the interactions involved. Studying the biology of viruses and the etiology of virus disease is crucial to the prevention of viral disease, efficient and reliable virus diagnosis, and virus control. Electron microscopy (EM) is an essential tool in the detection and analysis of virus replication. New EM methods and ongoing technical improvements offer a broad spectrum of applications, allowing in-depth investigation of viral impact on not only the host but also the environment. Indeed, using the most up-to-date electron cryomicroscopy methods, such investigations are now close to atomic resolution. In combination with bioinformatics, the transition from 2D imaging to 3D remodeling allows structural and functional analyses that extend and augment our knowledge of the astonishing diversity in virus structure and lifestyle. In combination with confocal laser scanning microscopy, EM enables live imaging of cells and tissues with high-resolution analysis. Here, we describe the pivotal role played by EM in the study of viruses, from structural analysis to the biological relevance of the viral metagenome (virome).
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Affiliation(s)
- Katja R Richert-Pöggeler
- Federal Research Center for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn Institute, Braunschweig, Germany
| | - Kati Franzke
- Institute of Infectiology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Katharina Hipp
- Electron Microscopy Facility, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Regina G Kleespies
- Federal Research Centre for Cultivated Plants, Institute for Biological Control, Julius Kühn Institute, Darmstadt, Germany
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76
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Jin X, Cao X, Wang X, Jiang J, Wan J, Laliberté JF, Zhang Y. Three-Dimensional Architecture and Biogenesis of Membrane Structures Associated with Plant Virus Replication. FRONTIERS IN PLANT SCIENCE 2018; 9:57. [PMID: 29441085 PMCID: PMC5797596 DOI: 10.3389/fpls.2018.00057] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 01/11/2018] [Indexed: 05/20/2023]
Abstract
Positive-sense (+) RNA viruses represent the most abundant group of viruses and are dependent on the host cell machinery to replicate. One remarkable feature that occurs after (+) RNA virus entry into cells is the remodeling of host endomembranes, leading to the formation of viral replication factories. Recently, rapid progress in three-dimensional (3D) imaging technologies, such as electron tomography (ET) and focused ion beam-scanning electron microscopy (FIB-SEM), has enabled researchers to visualize the novel membrane structures induced by viruses at high resolution. These 3D imaging technologies provide new mechanistic insights into the viral infection cycle. In this review, we summarize the latest reports on the cellular remodeling that occurs during plant virus infection; in particular, we focus on studies that provide 3D architectural information on viral replication factories. We also outline the mechanisms underlying the formation of these membranous structures and discuss possible future research directions.
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Affiliation(s)
- 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, China
| | - 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, China
| | - Xueting Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jun Jiang
- Institut National de la Recherche Scientifique—Institut Armand-Frappier, Laval, QC, Canada
| | - Juan Wan
- Institut National de la Recherche Scientifique—Institut Armand-Frappier, Laval, QC, Canada
| | - Jean-François Laliberté
- Institut National de la Recherche Scientifique—Institut Armand-Frappier, Laval, QC, Canada
- *Correspondence: Jean-François Laliberté
| | - 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, China
- Yongliang Zhang
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77
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Pietilä MK, Albulescu IC, Hemert MJV, Ahola T. Polyprotein Processing as a Determinant for in Vitro Activity of Semliki Forest Virus Replicase. Viruses 2017; 9:v9100292. [PMID: 28991178 PMCID: PMC5691643 DOI: 10.3390/v9100292] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 09/29/2017] [Accepted: 10/03/2017] [Indexed: 12/11/2022] Open
Abstract
Semliki Forest virus (SFV) is an arthropod-borne alphavirus that induces membrane invaginations (spherules) in host cells. These harbor the viral replication complexes (RC) that synthesize viral RNA. Alphaviruses have four replicase or nonstructural proteins (nsPs), nsP1-4, expressed as polyprotein P1234. An early RC, which synthesizes minus-strand RNA, is formed by the polyprotein P123 and the polymerase nsP4. Further proteolytic cleavage results in a late RC consisting of nsP1-4 and synthesizing plus strands. Here, we show that only the late RCs are highly active in RNA synthesis in vitro. Furthermore, we demonstrate that active RCs can be isolated from both virus-infected cells and cells transfected with the wild-type replicase in combination with a plasmid expressing a template RNA. When an uncleavable polyprotein P123 and polymerase nsP4 were expressed together with a template, high levels of minus-strand RNA were produced in cells, but RCs isolated from these cells were hardly active in vitro. Furthermore, we observed that the uncleavable polyprotein P123 and polymerase nsP4, which have previously been shown to form spherules even in the absence of the template, did not replicate an exogenous template. Consequently, we hypothesize that the replicase proteins were sequestered in spherules and were no longer able to recruit a template.
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Affiliation(s)
- Maija K Pietilä
- Department of Food and Environmental Sciences, University of Helsinki, Viikinkaari 9 PO Box 56, 00014 Helsinki, Finland.
| | - Irina C Albulescu
- Department of Medical Microbiology, Leiden University Medical Center PO Box 9600, 2300 RC, Leiden, The Netherlands.
| | - Martijn J van Hemert
- Department of Medical Microbiology, Leiden University Medical Center PO Box 9600, 2300 RC, Leiden, The Netherlands.
| | - Tero Ahola
- Department of Food and Environmental Sciences, University of Helsinki, Viikinkaari 9 PO Box 56, 00014 Helsinki, Finland.
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