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Stass R, Ng WM, Kim YC, Huiskonen JT. Structures of enveloped virions determined by cryogenic electron microscopy and tomography. Adv Virus Res 2019; 105:35-71. [PMID: 31522708 PMCID: PMC7112279 DOI: 10.1016/bs.aivir.2019.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Enveloped viruses enclose their genomes inside a lipid bilayer which is decorated by membrane proteins that mediate virus entry. These viruses display a wide range of sizes, morphologies and symmetries. Spherical viruses are often isometric and their envelope proteins follow icosahedral symmetry. Filamentous and pleomorphic viruses lack such global symmetry but their surface proteins may display locally ordered assemblies. Determining the structures of enveloped viruses, including the envelope proteins and their protein-protein interactions on the viral surface, is of paramount importance. These structures can reveal how the virions are assembled and released by budding from the infected host cell, how the progeny virions infect new cells by membrane fusion, and how antibodies bind surface epitopes to block infection. In this chapter, we discuss the uses of cryogenic electron microscopy (cryo-EM) in elucidating structures of enveloped virions. Starting from a detailed outline of data collection and processing strategies, we highlight how cryo-EM has been successfully utilized to provide unique insights into enveloped virus entry, assembly, and neutralization.
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Affiliation(s)
- Robert Stass
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Weng M Ng
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Young Chan Kim
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Juha T Huiskonen
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom; Helsinki Institute of Life Science HiLIFE and Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
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Ke Z, Strauss JD, Hampton CM, Brindley MA, Dillard RS, Leon F, Lamb KM, Plemper RK, Wright ER. Promotion of virus assembly and organization by the measles virus matrix protein. Nat Commun 2018; 9:1736. [PMID: 29712906 PMCID: PMC5928126 DOI: 10.1038/s41467-018-04058-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 03/29/2018] [Indexed: 12/05/2022] Open
Abstract
Measles virus (MeV) remains a major human pathogen, but there are presently no licensed antivirals to treat MeV or other paramyxoviruses. Here, we use cryo-electron tomography (cryo-ET) to elucidate the principles governing paramyxovirus assembly in MeV-infected human cells. The three-dimensional (3D) arrangement of the MeV structural proteins including the surface glycoproteins (F and H), matrix protein (M), and the ribonucleoprotein complex (RNP) are characterized at stages of virus assembly and budding, and in released virus particles. The M protein is observed as an organized two-dimensional (2D) paracrystalline array associated with the membrane. A two-layered F–M lattice is revealed suggesting that interactions between F and M may coordinate processes essential for MeV assembly. The RNP complex remains associated with and in close proximity to the M lattice. In this model, the M lattice facilitates the well-ordered incorporation and concentration of the surface glycoproteins and the RNP at sites of virus assembly. Virus assembly is technically challenging to study. Here the authors use cryo-electron tomography of measles virus-infected human cells to determine native-state virus structure and they locate well-ordered M lattices that organize viral glycoproteins, RNP, and drive assembly.
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Affiliation(s)
- Zunlong Ke
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Joshua D Strauss
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Cheri M Hampton
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Melinda A Brindley
- Department of Infectious Diseases, Department of Population Health and Center for Vaccines and Immunology, University of Georgia, Athens, GA, 30602, USA.,Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, 30303, USA
| | - Rebecca S Dillard
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Fredrick Leon
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Kristen M Lamb
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Richard K Plemper
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, 30303, USA.
| | - Elizabeth R Wright
- Division of Infectious Diseases, Department of Pediatrics, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA. .,Robert P. Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, GA, 30322, USA.
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Measles virus nonstructural C protein modulates viral RNA polymerase activity by interacting with host protein SHCBP1. J Virol 2013; 87:9633-42. [PMID: 23804634 DOI: 10.1128/jvi.00714-13] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Most viruses possess strategies to circumvent host immune responses. The measles virus (MV) nonstructural C protein suppresses the interferon response, thereby allowing efficient viral growth, but its detailed mechanism has been unknown. We identified Shc Src homology 2 domain-binding protein 1 (SHCBP1) as one of the host proteins interacting with the C protein. Knockdown of SHCBP1 using a short-hairpin RNA greatly reduced MV growth. SHCBP1 was found to be required for viral RNA synthesis in the minigenome assay and to bind to the MV phosphoprotein, a subunit of the viral RNA polymerase. A stretch of 12 amino acid residues in the C protein were sufficient for SHCBP1 binding, and the peptide containing these 12 residues could suppress MV RNA synthesis, like the full-length C protein. The central region of SHCBP1 was found to bind to the C protein, as well as the phosphoprotein, but the two viral proteins did not compete for SHCBP1 binding. Our results indicate that the C protein modulates MV RNA polymerase activity by binding to the host protein SHCBP1. SHCBP1 may be exploited as a target of antiviral compounds.
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Shu Y, Habchi J, Costanzo S, Padilla A, Brunel J, Gerlier D, Oglesbee M, Longhi S. Plasticity in structural and functional interactions between the phosphoprotein and nucleoprotein of measles virus. J Biol Chem 2012; 287:11951-67. [PMID: 22318731 DOI: 10.1074/jbc.m111.333088] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The measles virus (MeV) phosphoprotein (P) tethers the polymerase to the nucleocapsid template for transcription and genome replication. Binding of P to nucleocapsid is mediated by the X domain of P (XD) and a conserved sequence (Box-2) within the C-terminal domain of the nucleoprotein (N(TAIL)). XD binding induces N(TAIL) α-helical folding, which in turn has been proposed to stabilize the polymerase-nucleocapsid complex, with cycles of binding and release required for transcription and genome replication. The current work directly assessed the relationships among XD-induced N(TAIL) folding, XD-N(TAIL) binding affinity, and polymerase activity. Amino acid substitutions that abolished XD-induced N(TAIL) α-helical folding were created within Box-2 of Edmonston MeV N(TAIL). Polymerase activity in minireplicons was maintained despite a 35-fold decrease in XD-N(TAIL) binding affinity or reduction/loss of XD-induced N(TAIL) alpha-helical folding. Recombinant infectious virus was recovered for all mutants, and transcriptase elongation rates remained within a 1.7-fold range of parent virus. Box-2 mutations did however impose a significant cost to infectivity, reflected in an increase in the amount of input genome required to match the infectivity of parent virus. Diminished infectivity could not be attributed to changes in virion protein composition or production of defective interfering particles, where changes from parent virus were within a 3-fold range. The results indicated that MeV polymerase activity, but not infectivity, tolerates amino acid changes in the XD-binding region of the nucleoprotein. Selectional pressure for conservation of the Box-2 sequence may thus reflect a role in assuring the fidelity of polymerase functions or the assembly of viral particles required for optimal infectivity.
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Affiliation(s)
- Yaoling Shu
- Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio 43210, USA
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Electron cryotomography of measles virus reveals how matrix protein coats the ribonucleocapsid within intact virions. Proc Natl Acad Sci U S A 2011; 108:18085-90. [PMID: 22025713 DOI: 10.1073/pnas.1105770108] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Measles virus is a highly infectious, enveloped, pleomorphic virus. We combined electron cryotomography with subvolume averaging and immunosorbent electron microscopy to characterize the 3D ultrastructure of the virion. We show that the matrix protein forms helices coating the helical ribonucleocapsid rather than coating the inner leaflet of the membrane, as previously thought. The ribonucleocapsid is folded into tight bundles through matrix-matrix interactions. The implications for virus assembly are that the matrix already tightly interacts with the ribonucleocapsid in the cytoplasm, providing a structural basis for the previously observed regulation of RNA transcription by the matrix protein. Next, the matrix-covered ribonucleocapsids are transported to the plasma membrane, where the matrix interacts with the envelope glycoproteins during budding. These results are relevant to the nucleocapsid organization and budding of other paramyxoviruses, where isolated matrix has been observed to form helices.
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Wyss-Fluehmann G, Zurbriggen A, Vandevelde M, Plattet P. Canine distemper virus persistence in demyelinating encephalitis by swift intracellular cell-to-cell spread in astrocytes is controlled by the viral attachment protein. Acta Neuropathol 2010; 119:617-30. [PMID: 20119836 PMCID: PMC2849939 DOI: 10.1007/s00401-010-0644-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 01/14/2010] [Accepted: 01/19/2010] [Indexed: 12/15/2022]
Abstract
The mechanism of viral persistence, the driving force behind the chronic progression of inflammatory demyelination in canine distemper virus (CDV) infection, is associated with non-cytolytic viral cell-to-cell spread. Here, we studied the molecular mechanisms of viral spread of a recombinant fluorescent protein-expressing virulent CDV in primary canine astrocyte cultures. Time-lapse video microscopy documented that CDV spread was very efficient using cell processes contacting remote target cells. Strikingly, CDV transmission to remote cells could occur in less than 6 h, suggesting that a complete viral cycle with production of extracellular free particles was not essential in enabling CDV to spread in glial cells. Titration experiments and electron microscopy confirmed a very low CDV particle production despite higher titers of membrane-associated viruses. Interestingly, confocal laser microscopy and lentivirus transduction indicated expression and functionality of the viral fusion machinery, consisting of the viral fusion (F) and attachment (H) glycoproteins, at the cell surface. Importantly, using a single-cycle infectious recombinant H-knockout, H-complemented virus, we demonstrated that H, and thus potentially the viral fusion complex, was necessary to enable CDV spread. Furthermore, since we could not detect CD150/SLAM expression in brain cells, the presence of a yet non-identified glial receptor for CDV was suggested. Altogether, our findings indicate that persistence in CDV infection results from intracellular cell-to-cell transmission requiring the CDV-H protein. Viral transfer, happening selectively at the tip of astrocytic processes, may help the virus to cover long distances in the astroglial network, “outrunning” the host’s immune response in demyelinating plaques, thus continuously eliciting new lesions.
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Affiliation(s)
- Gaby Wyss-Fluehmann
- Division of Neurology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Andreas Zurbriggen
- Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3001 Bern, Switzerland
| | - Marc Vandevelde
- Division of Neurology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Philippe Plattet
- Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3001 Bern, Switzerland
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Mosquera JA, Hernandez JP, Valero N, Espina LM, Añez GJ. Ultrastructural studies on dengue virus type 2 infection of cultured human monocytes. Virol J 2005; 2:26. [PMID: 15801983 PMCID: PMC1082913 DOI: 10.1186/1743-422x-2-26] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2005] [Accepted: 03/31/2005] [Indexed: 12/04/2022] Open
Abstract
Background Early interaction of dengue virus and monocyte/macrophages could be an important feature for virus dissemination after its initial entry via the mosquito vector. Since ultrastructural analysis of this interaction has not been reported, dengue type 2 (DEN2) virus-infected human monocyte cultures were studied at 1, 2, 4 and 6 hours after infection. Results Typical dengue particles and fuzzy coated viral particles were 35 to 42 nm and 74 to 85 nm respectively. Viruses were engulfed by phagocytosis and macropicnocytosis leading to huge vacuoles and phagosomes inside the monocytes. Interaction of monocytes with DEN2 virus induced apoptosis, characterized by nuclear condensation and fragmentation, cellular shrinkage, blebbing and budding phenomena and phagocytosis of apoptotic cells by neighboring monocytes. This finding was confirmed by TUNEL. Ultrastructural features associated to DEN2 virus replication were not observed. Conclusion These data suggest that clearance of the virus by monocytes and cellular death are the main features during the initial interaction of DEN2 virus and monocytes and this could be important in the rapid elimination of the virus after infection by mosquito vector.
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Affiliation(s)
- Jesus A Mosquera
- Seccion de Inmunologia y Biologia Celular, Instituto de Investigaciones Clinicas "Dr. Americo Negrette". Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela
| | - Juan Pablo Hernandez
- Instituto de Investigaciones Biologicas. Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela
| | - Nereida Valero
- Seccion de Virologia, Instituto de Investigaciones Clinicas "Dr. Americo Negrette". Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela
| | - Luz Marina Espina
- Seccion de Virologia, Instituto de Investigaciones Clinicas "Dr. Americo Negrette". Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela
| | - German J Añez
- Seccion de Virologia, Instituto de Investigaciones Clinicas "Dr. Americo Negrette". Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela
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Alldinger S, Baumgärtner W, Orvell C. Restricted expression of viral surface proteins in canine distemper encephalitis. Acta Neuropathol 1993; 85:635-45. [PMID: 7687812 DOI: 10.1007/bf00334674] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Sixteen dogs with naturally occurring acute and chronic canine distemper virus (CDV) encephalitis were examined immunohistochemically for the presence of the five major CDV-specific proteins in the central nervous system. Monoclonal antibodies (mAbs) directed against two, three, four and five epitopes of the nucleo- (N), phospho- (P), fusion (F), and hemagglutinin (H) protein, respectively, and a polyclonal monospecific antibody recognizing the matrix (M) protein were used. Both core proteins and their epitopes, three F protein epitopes and the M protein were demonstrated in all animals examined. A fourth F protein epitope was found only in 13 animals. The H-2 and H-3 epitope of the H protein were detected in 15, the H-1 and H-5 epitope in 14, and the H-4 epitope in 3 animals. All viral proteins were observed in the same types of brain cells including neurons and astrocytes. The N and P protein were demonstrated in nucleus, cytoplasm and cell processes, whereas M, H and F protein were observed in the cytoplasm only and rarely in cell processes. In addition, the M protein was detected occasionally in the nucleus of neurons and reactive astrocytes. Intralesional distribution of CDV-specific proteins varied between core and surface proteins. In acute and subacute lesions without associated inflammation, expression of the M, H and F protein was only slightly diminished compared to the N and P protein. However, plaques with severe inflammation were either devoid of viral antigen or exhibited N- and P protein-specific immunoreactivity exclusively at the periphery, whereas expression of surface proteins was severely reduced or absent. These results are suggestive of restricted synthesis of CDV envelope proteins in acute, and more prominent in chronic, distemper encephalitis.
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Affiliation(s)
- S Alldinger
- Institut für Veterinär-Pathologie, Justus-Liebig-Universität, Giessen, Germany
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Bohn W, Ciampor F, Rutter R, Mannweiler K. Localization of nucleocapsid associated polypeptides in measles virus-infected cells by immunogold labelling after resin embedding. Arch Virol 1990; 114:53-64. [PMID: 2222190 DOI: 10.1007/bf01311011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The nucleo-, phospho- and matrix protein of measles virus were localized at high resolution within infected cells by use of post-embedding immunogold labelling techniques. In general, labelling with monospecific antibodies as well as with a polyvalent rabbit anti-measles hyperimmune antiserum revealed measles virus polypeptides to be distributed non-randomly within infected cells with the label largely confined to specific sites, namely inclusions of nucleocapsids and assembled virus structures at the plasma membrane. Immunogold double labelling indicated that the phosphoprotein strictly co-localized with the nucleoprotein in cytoplasmic inclusions of nucleocapsids and in budding virions, whereas intranuclear inclusions of nucleocapsids were devoid of phosphoprotein labelling. Antibodies to the matrix protein clearly labelled assembled virus structures at the plasma membrane but exhibited no significant cytoplasmic or intranuclear reaction. The data indicate that the composition of nucleocapsids varies with the cellular compartment with which they are associated, supporting the view of a rapid assembly of paramyxovirus nucleocapsid polypeptides, and emphasize the proposed selective role of the matrix protein in virus assembly and budding at the plasma membrane.
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Affiliation(s)
- W Bohn
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Hamburg, Federal Republic of Germany
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Brown HR, Goller NL, Thormar H, Rudelli R, Tourtellotte WW, Shapshak P, Boostanfar R, Wisniewski HM. Measles virus matrix protein gene expression in a subacute sclerosing panencephalitis patient brain and virus isolate demonstrated by cDNA hybridization and immunocytochemistry. Acta Neuropathol 1987; 75:123-30. [PMID: 3324622 DOI: 10.1007/bf00687072] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Subacute sclerosing panencephalitis (SSPE) is a rare, fatal disease of children caused by a persistent measles virus infection of the central nervous system. A defect in synthesis of measles virus matrix (M) protein may be a factor in virus persistence in the brain. This study details attempts to detect expression of M protein in the brain of an SSPE patient, in the cell-associated virus isolated from this brain, and in brains of ferrets inoculated with the isolate. In situ hybridization with a tritiated cloned cDNA probe was used to search for RNA encoding M protein. Immunostaining with monospecific antiserum and the avidin-biotin-peroxidase technique was done to locate the polypeptide. The data obtained indicate that although nucleotide sequences coding for M protein were detected in the patient and ferret brains, expression of M protein in these tissues could not be detected. In the culture SSPE virus isolate, the results were the same until the infected cells were examined by electron microscopy and a very limited expression of M protein was revealed. This suggests either diminished synthesis and/or rapid degradation of M protein in this cell-associated virus strain.
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Affiliation(s)
- H R Brown
- New York State Office of Mental Retardation and Developmental Disabilities, Institute for Basic Research, Staten Island 10314
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