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Kordys M, Urbanowicz A. 3D Puzzle at the Nanoscale-How do RNA Viruses Self-Assemble their Capsids into Perfectly Ordered Structures. Macromol Biosci 2024:e2400088. [PMID: 38864315 DOI: 10.1002/mabi.202400088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/03/2024] [Indexed: 06/13/2024]
Abstract
The phenomenon of RNA virus self-organization, first observed in the mid-20th century in tobacco mosaic virus, is the subject of extensive research. Efforts to comprehend this process intensify due to its potential for producing vaccines or antiviral compounds as well as nanocarriers and nanotemplates. However, direct observation of the self-assembly is hindered by its prevalence within infected host cells. One of the approaches involves in vitro and in silico research using model viruses featuring a ssRNA(+) genome enclosed within a capsid made up of a single type protein. While various pathways are proposed based on these studies, their relevance in vivo remains uncertain. On the other hand, the development of advanced microscopic methods provide insights into the events within living cells, where following viral infection, specialized compartments form to facilitate the creation of nascent virions. Intriguingly, a growing body of evidence indicates that the primary function of packaging signals in viral RNA is to effectively initiate the virion self-assembly. This is in contrast to earlier opinions suggesting a role in marking RNA for encapsidation. Another noteworthy observation is that many viruses undergo self-assembly within membraneless liquid organelles, which are specifically induced by viral proteins.
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Affiliation(s)
- Martyna Kordys
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego Str. 12/14, Poznan, 61-704, Poland
| | - Anna Urbanowicz
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego Str. 12/14, Poznan, 61-704, Poland
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2
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Uckeley ZM, Duboeuf M, Gu Y, Erny A, Mazelier M, Lüchtenborg C, Winter SL, Schad P, Mathieu C, Koch J, Boulant S, Chlanda P, Maisse C, Brügger B, Lozach PY. Glucosylceramide in bunyavirus particles is essential for virus binding to host cells. Cell Mol Life Sci 2024; 81:71. [PMID: 38300320 PMCID: PMC10834583 DOI: 10.1007/s00018-023-05103-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 12/08/2023] [Accepted: 12/21/2023] [Indexed: 02/02/2024]
Abstract
Hexosylceramides (HexCer) are implicated in the infection process of various pathogens. However, the molecular and cellular functions of HexCer in infectious cycles are poorly understood. Investigating the enveloped virus Uukuniemi (UUKV), a bunyavirus of the Phenuiviridae family, we performed a lipidomic analysis with mass spectrometry and determined the lipidome of both infected cells and derived virions. We found that UUKV alters the processing of HexCer to glycosphingolipids (GSL) in infected cells. The infection resulted in the overexpression of glucosylceramide (GlcCer) synthase (UGCG) and the specific accumulation of GlcCer and its subsequent incorporation into viral progeny. UUKV and several pathogenic bunyaviruses relied on GlcCer in the viral envelope for binding to various host cell types. Overall, our results indicate that GlcCer is a structural determinant of virions crucial for bunyavirus infectivity. This study also highlights the importance of glycolipids on virions in facilitating interactions with host cell receptors and infectious entry of enveloped viruses.
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Affiliation(s)
- Zina M Uckeley
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, 69120, Heidelberg, Germany
- Cluster of Excellence, CellNetworks, 69120, Heidelberg, Germany
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany
- Department for Molecular Genetics and Microbiology, University of Florida, Gainesville, USA
| | - Maëva Duboeuf
- Université Claude Bernard Lyon 1, INRAE, EPHE, IVPC UMR754, Team iWays, 69007, Lyon, France
| | - Yu Gu
- Université Claude Bernard Lyon 1, INRAE, EPHE, IVPC UMR754, Team iWays, 69007, Lyon, France
| | - Alexandra Erny
- Université Claude Bernard Lyon 1, INRAE, EPHE, IVPC UMR754, Team iWays, 69007, Lyon, France
| | - Magalie Mazelier
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, 69120, Heidelberg, Germany
- Cluster of Excellence, CellNetworks, 69120, Heidelberg, Germany
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | | | - Sophie L Winter
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, 69120, Heidelberg, Germany
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany
- Schaller Research Groups, Department of Infectious Diseases, Virology, Heidelberg University Hospital, Heidelberg, Germany
| | - Paulina Schad
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, 69120, Heidelberg, Germany
- Cluster of Excellence, CellNetworks, 69120, Heidelberg, Germany
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Cyrille Mathieu
- CIRI (Centre International de Recherche en Infectiologie), Team Neuro-Invasion, TROpism and VIRal Encephalitis, INSERM U1111, CNRS UMR5308, Université Claude Bernard Lyon 1, Ecole Normale Supérieure de Lyon, 69007, Lyon, France
| | - Jana Koch
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, 69120, Heidelberg, Germany
- Cluster of Excellence, CellNetworks, 69120, Heidelberg, Germany
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany
- Université Claude Bernard Lyon 1, INRAE, EPHE, IVPC UMR754, Team iWays, 69007, Lyon, France
| | - Steeve Boulant
- Department for Molecular Genetics and Microbiology, University of Florida, Gainesville, USA
| | - Petr Chlanda
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, 69120, Heidelberg, Germany
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany
- Schaller Research Groups, Department of Infectious Diseases, Virology, Heidelberg University Hospital, Heidelberg, Germany
| | - Carine Maisse
- Université Claude Bernard Lyon 1, INRAE, EPHE, IVPC UMR754, Team iWays, 69007, Lyon, France
| | - Britta Brügger
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Pierre-Yves Lozach
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, 69120, Heidelberg, Germany.
- Cluster of Excellence, CellNetworks, 69120, Heidelberg, Germany.
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany.
- Université Claude Bernard Lyon 1, INRAE, EPHE, IVPC UMR754, Team iWays, 69007, Lyon, France.
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3
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Sachse M, Fernández-Sánchez SY, Tenorio R, de Castro IF, Risco C. Imaging Bunyavirus Infections by Transmission Electron Microscopy: Conventional Sample Preparation vs High-Pressure Freezing and Freeze-Substitution. Methods Mol Biol 2024; 2824:241-258. [PMID: 39039417 DOI: 10.1007/978-1-0716-3926-9_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Transmission electron microscopy significantly contributed to unveil the course of virus entry, replication, morphogenesis, and egress. For these studies, the most widely used approach is imaging ultrathin sections of virus-infected cells embedded in a plastic resin that is transparent to electrons. Before infiltration in a resin, cells must be processed to stabilize their components under the observation conditions in an electron microscope, such as high vacuum and irradiation with electrons. For conventional sample preparation, chemical fixation and dehydration are followed by infiltration in the resin and polymerization to produce a hard block that can be sectioned with an ultramicrotome. Another method that provides a superior preservation of cell components is high-pressure freezing (HPF) followed by freeze substitution (FS) before resin infiltration and polymerization. This chapter describes both procedures with cells infected with Bunyamwera virus (BUNV), a well characterized member of the Bunyavirales, and compares the morphological details of different viral structures imaged in the two types of samples. Advantages, disadvantages, and applications of conventional processing and HPF/FS are also presented and discussed.
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Affiliation(s)
- Martin Sachse
- Centro Nacional de Microbiología/ISCIII, Madrid, Spain.
| | - Sara Y Fernández-Sánchez
- Cell Structure Lab, Centro Nacional de Biotecnología, CNB - CSIC, Campus de Cantoblanco, Madrid, Spain
| | - Raquel Tenorio
- Cell Structure Lab, Centro Nacional de Biotecnología, CNB - CSIC, Campus de Cantoblanco, Madrid, Spain
| | | | - Cristina Risco
- Cell Structure Lab, Centro Nacional de Biotecnología, CNB - CSIC, Campus de Cantoblanco, Madrid, Spain.
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4
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Yvon M, German TL, Ullman DE, Dasgupta R, Parker MH, Ben-Mahmoud S, Verdin E, Gognalons P, Ancelin A, Laï Kee Him J, Girard J, Vernerey MS, Fernandez E, Filloux D, Roumagnac P, Bron P, Michalakis Y, Blanc S. The genome of a bunyavirus cannot be defined at the level of the viral particle but only at the scale of the viral population. Proc Natl Acad Sci U S A 2023; 120:e2309412120. [PMID: 37983500 PMCID: PMC10691328 DOI: 10.1073/pnas.2309412120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 10/21/2023] [Indexed: 11/22/2023] Open
Abstract
Bunyaviruses are enveloped negative or ambisense single-stranded RNA viruses with a genome divided into several segments. The canonical view depicts each viral particle packaging one copy of each genomic segment in one polarity named the viral strand. Several opposing observations revealed nonequal ratios of the segments, uneven number of segments per virion, and even packaging of viral complementary strands. Unfortunately, these observations result from studies often addressing other questions, on distinct viral species, and not using accurate quantitative methods. Hence, what RNA segments and strands are packaged as the genome of any bunyavirus remains largely ambiguous. We addressed this issue by first investigating the virion size distribution and RNA content in populations of the tomato spotted wilt virus (TSWV) using microscopy and tomography. These revealed heterogeneity in viral particle volume and amount of RNA content, with a surprising lack of correlation between the two. Then, the ratios of all genomic segments and strands were established using RNA sequencing and qRT-PCR. Within virions, both plus and minus strands (but no mRNA) are packaged for each of the three L, M, and S segments, in reproducible nonequimolar proportions determined by those in total cell extracts. These results show that virions differ in their genomic content but together build up a highly reproducible genetic composition of the viral population. This resembles the genome formula described for multipartite viruses, with which some species of the order Bunyavirales may share some aspects of the way of life, particularly emerging properties at a supravirion scale.
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Affiliation(s)
- Michel Yvon
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
| | - Thomas L. German
- Department of Entomology, University of Wisconsin, Wisconsin53706, Madison
| | - Diane E. Ullman
- Department of Entomology and Nematology, University of California, California95616, Davis
| | - Ranjit Dasgupta
- Department of Entomology, University of Wisconsin, Wisconsin53706, Madison
| | - Maxwell H. Parker
- Department of Entomology, University of Wisconsin, Wisconsin53706, Madison
| | - Sulley Ben-Mahmoud
- Department of Entomology and Nematology, University of California, California95616, Davis
| | - Eric Verdin
- Pathologie végétale, INRAE, Avignon84143, France
| | | | - Aurélie Ancelin
- CBS, Univ Montpellier, CNRS, INSERM, Montpellier34090, France
| | | | - Justine Girard
- CBS, Univ Montpellier, CNRS, INSERM, Montpellier34090, France
| | | | - Emmanuel Fernandez
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
| | - Denis Filloux
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
| | - Philippe Roumagnac
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
| | - Patrick Bron
- CBS, Univ Montpellier, CNRS, INSERM, Montpellier34090, France
| | | | - Stéphane Blanc
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
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5
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Du S, Peng R, Xu W, Qu X, Wang Y, Wang J, Li L, Tian M, Guan Y, Wang J, Wang G, Li H, Deng L, Shi X, Ma Y, Liu F, Sun M, Wei Z, Jin N, Liu W, Qi J, Liu Q, Liao M, Li C. Cryo-EM structure of severe fever with thrombocytopenia syndrome virus. Nat Commun 2023; 14:6333. [PMID: 37816705 PMCID: PMC10564799 DOI: 10.1038/s41467-023-41804-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 09/19/2023] [Indexed: 10/12/2023] Open
Abstract
The severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne human-infecting bunyavirus, which utilizes two envelope glycoproteins, Gn and Gc, to enter host cells. However, the structure and organization of these glycoproteins on virion surface are not yet known. Here we describe the structure of SFTSV determined by single particle reconstruction, which allows mechanistic insights into bunyavirus assembly at near-atomic resolution. The SFTSV Gn and Gc proteins exist as heterodimers and further assemble into pentameric and hexameric peplomers, shielding the Gc fusion loops by both intra- and inter-heterodimer interactions. Individual peplomers are associated mainly through the ectodomains, in which the highly conserved glycans on N914 of Gc play a crucial role. This elaborate assembly stabilizes Gc in the metastable prefusion conformation and creates some cryptic epitopes that are only accessible in the intermediate states during virus entry. These findings provide an important basis for developing vaccines and therapeutic drugs.
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Affiliation(s)
- Shouwen Du
- Key Laboratory of Livestock Disease Prevention of Guangdong Province, Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- The First Affiliated Hospital (Shenzhen People's Hospital), Southern University of Science and Technology, Shenzhen, China
- Department of Infectious Diseases and Center for Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, The First Hospital of Jilin University, Changchun, China
| | - Ruchao Peng
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Wang Xu
- Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Xiaoyun Qu
- Key Laboratory of Livestock Disease Prevention of Guangdong Province, Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, China
| | - Yuhang Wang
- The First Affiliated Hospital (Shenzhen People's Hospital), Southern University of Science and Technology, Shenzhen, China
| | - Jiamin Wang
- Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Letian Li
- Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Mingyao Tian
- Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Yudong Guan
- The First Affiliated Hospital (Shenzhen People's Hospital), Southern University of Science and Technology, Shenzhen, China
| | - Jigang Wang
- The First Affiliated Hospital (Shenzhen People's Hospital), Southern University of Science and Technology, Shenzhen, China
| | - Guoqing Wang
- Department of Infectious Diseases and Center for Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, The First Hospital of Jilin University, Changchun, China
| | - Hao Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Lingcong Deng
- Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Xiaoshuang Shi
- Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Yidan Ma
- Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Fengting Liu
- The First Affiliated Hospital (Shenzhen People's Hospital), Southern University of Science and Technology, Shenzhen, China
| | - Minhua Sun
- Key Laboratory of Livestock Disease Prevention of Guangdong Province, Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Zhengkai Wei
- Key Laboratory of Livestock Disease Prevention of Guangdong Province, Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Ningyi Jin
- Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Wei Liu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
| | - Jianxun Qi
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China.
| | - Quan Liu
- Key Laboratory of Livestock Disease Prevention of Guangdong Province, Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China.
- Department of Infectious Diseases and Center for Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, The First Hospital of Jilin University, Changchun, China.
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Institute of Zoology, Guangdong Academy of Sciences, Foshan University, Foshan, China.
| | - Ming Liao
- Key Laboratory of Livestock Disease Prevention of Guangdong Province, Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China.
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, China.
| | - Chang Li
- Department of Infectious Diseases and Center for Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, The First Hospital of Jilin University, Changchun, China.
- Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China.
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6
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Koch J, Xin Q, Obr M, Schäfer A, Rolfs N, Anagho HA, Kudulyte A, Woltereck L, Kummer S, Campos J, Uckeley ZM, Bell-Sakyi L, Kräusslich HG, Schur FKM, Acuna C, Lozach PY. The phenuivirus Toscana virus makes an atypical use of vacuolar acidity to enter host cells. PLoS Pathog 2023; 19:e1011562. [PMID: 37578957 PMCID: PMC10449198 DOI: 10.1371/journal.ppat.1011562] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 08/24/2023] [Accepted: 07/17/2023] [Indexed: 08/16/2023] Open
Abstract
Toscana virus is a major cause of arboviral disease in humans in the Mediterranean basin during summer. However, early virus-host cell interactions and entry mechanisms remain poorly characterized. Investigating iPSC-derived human neurons and cell lines, we found that virus binding to the cell surface was specific, and 50% of bound virions were endocytosed within 10 min. Virions entered Rab5a+ early endosomes and, subsequently, Rab7a+ and LAMP-1+ late endosomal compartments. Penetration required intact late endosomes and occurred within 30 min following internalization. Virus entry relied on vacuolar acidification, with an optimal pH for viral membrane fusion at pH 5.5. The pH threshold increased to 5.8 with longer pre-exposure of virions to the slightly acidic pH in early endosomes. Strikingly, the particles remained infectious after entering late endosomes with a pH below the fusion threshold. Overall, our study establishes Toscana virus as a late-penetrating virus and reveals an atypical use of vacuolar acidity by this virus to enter host cells.
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Affiliation(s)
- Jana Koch
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
- CellNetworks–Cluster of Excellence, Heidelberg, Germany
- Univ. Lyon, INRAE, EPHE, IVPC, Lyon, France
| | - Qilin Xin
- Univ. Lyon, INRAE, EPHE, IVPC, Lyon, France
| | - Martin Obr
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Alicia Schäfer
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
- CellNetworks–Cluster of Excellence, Heidelberg, Germany
| | - Nina Rolfs
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
- CellNetworks–Cluster of Excellence, Heidelberg, Germany
| | - Holda A. Anagho
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
- CellNetworks–Cluster of Excellence, Heidelberg, Germany
| | - Aiste Kudulyte
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
- CellNetworks–Cluster of Excellence, Heidelberg, Germany
| | - Lea Woltereck
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
- CellNetworks–Cluster of Excellence, Heidelberg, Germany
| | - Susann Kummer
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
| | - Joaquin Campos
- Chica and Heinz Schaller Research Group, Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Zina M. Uckeley
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
- CellNetworks–Cluster of Excellence, Heidelberg, Germany
| | - Lesley Bell-Sakyi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United-Kingdom
| | - Hans-Georg Kräusslich
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
| | - Florian KM. Schur
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Claudio Acuna
- Chica and Heinz Schaller Research Group, Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Pierre-Yves Lozach
- Center for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, Heidelberg, Germany
- CellNetworks–Cluster of Excellence, Heidelberg, Germany
- Univ. Lyon, INRAE, EPHE, IVPC, Lyon, France
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7
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Barker J, daSilva LLP, Crump CM. Mechanisms of bunyavirus morphogenesis and egress. J Gen Virol 2023; 104. [PMID: 37083579 DOI: 10.1099/jgv.0.001845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023] Open
Abstract
Unlike many segmented negative-sense RNA viruses, most members of the Bunyavirales bud at Golgi membranes, as opposed to the plasma membrane. Central players in this assembly process are the envelope glycoproteins, Gn and Gc, which upon translation undergo proteolytic processing, glycosylation and trafficking to the Golgi, where they interact with ribonucleoprotein genome segments and bud into Golgi-derived compartments. The processes involved in genome packaging during virion assembly can lead to the generation of reassorted viruses, if a cell is co-infected with two different bunyaviruses, due to mismatching of viral genome segment packaging. This can lead to viruses with high pathogenic potential, as demonstrated by the emergence of Schmallenberg virus. This review focuses on the assembly pathways of tri-segmented bunyaviruses, highlighting some areas in need of further research to understand these important pathogens with zoonotic potential.
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Affiliation(s)
- Jake Barker
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK
| | - Luis L P daSilva
- Departamento de Biologia Celular e Molecular, Centro de Pesquisa em Virologia, Faculdade de Medicina de Ribeirão Preto, University of São Paulo, State of São Paulo, Brazil
| | - Colin M Crump
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK
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8
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Abstract
Viral fusion glycoproteins catalyze membrane fusion during viral entry. Unlike most enzymes, however, they lack a conventional active site in which formation or scission of a specific covalent bond is catalyzed. Instead, they drive the membrane fusion reaction by cojoining highly regulated changes in conformation to membrane deformation. Despite the challenges in applying inhibitor design approaches to these proteins, recent advances in knowledge of the structures and mechanisms of viral fusogens have enabled the development of small-molecule inhibitors of both class I and class II viral fusion proteins. Here, we review well-validated inhibitors, including their discovery, targets, and mechanism(s) of action, while highlighting mechanistic similarities and differences. Together, these examples make a compelling case for small-molecule inhibitors as tools for probing the mechanisms of viral glycoprotein-mediated fusion and for viral glycoproteins as druggable targets.
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Affiliation(s)
- Han-Yuan Liu
- Department of Microbiology and Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
- Current affiliation: Department of Microbiology and Immunology, Stanford University School of Medicine, Palo Alto, California 94305, USA;
| | - Priscilla L Yang
- Department of Microbiology and Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
- Current affiliation: Department of Microbiology and Immunology, Stanford University School of Medicine, Palo Alto, California 94305, USA;
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9
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Meier K, Thorkelsson SR, Quemin ERJ, Rosenthal M. Hantavirus Replication Cycle-An Updated Structural Virology Perspective. Viruses 2021; 13:1561. [PMID: 34452426 PMCID: PMC8402763 DOI: 10.3390/v13081561] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 11/17/2022] Open
Abstract
Hantaviruses infect a wide range of hosts including insectivores and rodents and can also cause zoonotic infections in humans, which can lead to severe disease with possible fatal outcomes. Hantavirus outbreaks are usually linked to the population dynamics of the host animals and their habitats being in close proximity to humans, which is becoming increasingly important in a globalized world. Currently there is neither an approved vaccine nor a specific and effective antiviral treatment available for use in humans. Hantaviruses belong to the order Bunyavirales with a tri-segmented negative-sense RNA genome. They encode only five viral proteins and replicate and transcribe their genome in the cytoplasm of infected cells. However, many details of the viral amplification cycle are still unknown. In recent years, structural biology methods such as cryo-electron tomography, cryo-electron microscopy, and crystallography have contributed essentially to our understanding of virus entry by membrane fusion as well as genome encapsidation by the nucleoprotein. In this review, we provide an update on the hantavirus replication cycle with a special focus on structural virology aspects.
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Affiliation(s)
- Kristina Meier
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany;
| | - Sigurdur R. Thorkelsson
- Centre for Structural Systems Biology, Leibniz Institute for Experimental Virology, University of Hamburg, 22607 Hamburg, Germany;
| | - Emmanuelle R. J. Quemin
- Centre for Structural Systems Biology, Leibniz Institute for Experimental Virology, University of Hamburg, 22607 Hamburg, Germany;
| | - Maria Rosenthal
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany;
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, 22525 Hamburg, Germany
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10
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Bermúdez-Méndez E, Katrukha EA, Spruit CM, Kortekaas J, Wichgers Schreur PJ. Visualizing the ribonucleoprotein content of single bunyavirus virions reveals more efficient genome packaging in the arthropod host. Commun Biol 2021; 4:345. [PMID: 33753850 PMCID: PMC7985392 DOI: 10.1038/s42003-021-01821-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 02/09/2021] [Indexed: 01/31/2023] Open
Abstract
Bunyaviruses have a genome that is divided over multiple segments. Genome segmentation complicates the generation of progeny virus, since each newly formed virus particle should preferably contain a full set of genome segments in order to disseminate efficiently within and between hosts. Here, we combine immunofluorescence and fluorescence in situ hybridization techniques to simultaneously visualize bunyavirus progeny virions and their genomic content at single-molecule resolution in the context of singly infected cells. Using Rift Valley fever virus and Schmallenberg virus as prototype tri-segmented bunyaviruses, we show that bunyavirus genome packaging is influenced by the intracellular viral genome content of individual cells, which results in greatly variable packaging efficiencies within a cell population. We further show that bunyavirus genome packaging is more efficient in insect cells compared to mammalian cells and provide new insights on the possibility that incomplete particles may contribute to bunyavirus spread as well.
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Affiliation(s)
- Erick Bermúdez-Méndez
- Department of Virology, Wageningen Bioveterinary Research, Lelystad, The Netherlands
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Eugene A Katrukha
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Cindy M Spruit
- Department of Virology, Wageningen Bioveterinary Research, Lelystad, The Netherlands
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Jeroen Kortekaas
- Department of Virology, Wageningen Bioveterinary Research, Lelystad, The Netherlands
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
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11
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Hulswit RJG, Paesen GC, Bowden TA, Shi X. Recent Advances in Bunyavirus Glycoprotein Research: Precursor Processing, Receptor Binding and Structure. Viruses 2021; 13:353. [PMID: 33672327 PMCID: PMC7926653 DOI: 10.3390/v13020353] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/13/2021] [Accepted: 02/15/2021] [Indexed: 01/04/2023] Open
Abstract
The Bunyavirales order accommodates related viruses (bunyaviruses) with segmented, linear, single-stranded, negative- or ambi-sense RNA genomes. Their glycoproteins form capsomeric projections or spikes on the virion surface and play a crucial role in virus entry, assembly, morphogenesis. Bunyavirus glycoproteins are encoded by a single RNA segment as a polyprotein precursor that is co- and post-translationally cleaved by host cell enzymes to yield two mature glycoproteins, Gn and Gc (or GP1 and GP2 in arenaviruses). These glycoproteins undergo extensive N-linked glycosylation and despite their cleavage, remain associated to the virion to form an integral transmembrane glycoprotein complex. This review summarizes recent advances in our understanding of the molecular biology of bunyavirus glycoproteins, including their processing, structure, and known interactions with host factors that facilitate cell entry.
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Affiliation(s)
- Ruben J. G. Hulswit
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (R.J.G.H.); (G.C.P.)
| | - Guido C. Paesen
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (R.J.G.H.); (G.C.P.)
| | - Thomas A. Bowden
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (R.J.G.H.); (G.C.P.)
| | - Xiaohong Shi
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G61 1QH, UK
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12
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Entry of Phenuiviruses into Mammalian Host Cells. Viruses 2021; 13:v13020299. [PMID: 33672975 PMCID: PMC7918600 DOI: 10.3390/v13020299] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 02/08/2021] [Accepted: 02/11/2021] [Indexed: 12/22/2022] Open
Abstract
Phenuiviridae is a large family of arthropod-borne viruses with over 100 species worldwide. Several cause severe diseases in both humans and livestock. Global warming and the apparent geographical expansion of arthropod vectors are good reasons to seriously consider these viruses potential agents of emerging diseases. With an increasing frequency and number of epidemics, some phenuiviruses represent a global threat to public and veterinary health. This review focuses on the early stage of phenuivirus infection in mammalian host cells. We address current knowledge on each step of the cell entry process, from virus binding to penetration into the cytosol. Virus receptors, endocytosis, and fusion mechanisms are discussed in light of the most recent progress on the entry of banda-, phlebo-, and uukuviruses, which together constitute the three prominent genera in the Phenuiviridae family.
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13
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Bruinsma RF, Wuite GJL, Roos WH. Physics of viral dynamics. NATURE REVIEWS. PHYSICS 2021; 3:76-91. [PMID: 33728406 PMCID: PMC7802615 DOI: 10.1038/s42254-020-00267-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/20/2020] [Indexed: 05/12/2023]
Abstract
Viral capsids are often regarded as inert structural units, but in actuality they display fascinating dynamics during different stages of their life cycle. With the advent of single-particle approaches and high-resolution techniques, it is now possible to scrutinize viral dynamics during and after their assembly and during the subsequent development pathway into infectious viruses. In this Review, the focus is on the dynamical properties of viruses, the different physical virology techniques that are being used to study them, and the physical concepts that have been developed to describe viral dynamics.
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Affiliation(s)
- Robijn F. Bruinsma
- Department of Physics and Astronomy, University of California, Los Angeles, California, USA
| | - Gijs J. L. Wuite
- Fysica van levende systemen, Vrije Universiteit, Amsterdam, the Netherlands
| | - Wouter H. Roos
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Groningen, the Netherlands
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14
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Singh AR, Košmrlj A, Bruinsma R. Finite Temperature Phase Behavior of Viral Capsids as Oriented Particle Shells. PHYSICAL REVIEW LETTERS 2020; 124:158101. [PMID: 32357054 PMCID: PMC7219451 DOI: 10.1103/physrevlett.124.158101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 03/16/2020] [Indexed: 05/02/2023]
Abstract
A general phase plot is proposed for discrete particle shells that allows for thermal fluctuations of the shell geometry and of the inter-particle connectivities. The phase plot contains a first-order melting transition, a buckling transition, and a collapse transition and is used to interpret the thermodynamics of microbiological shells.
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Affiliation(s)
- Amit R Singh
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Currently at Department of Mechanical Engineering, Birla Institute of Technology and Science, Pilani, Rajasthan 333031, India
| | - Andrej Košmrlj
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08540, USA
- Princeton Institute for the Science and Technology of Materials (PRISM), Princeton University, Princeton, New Jersey 08544, USA
| | - Robijn Bruinsma
- Departments of Physics and Astronomy, and Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
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15
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Uckeley ZM, Moeller R, Kühn LI, Nilsson E, Robens C, Lasswitz L, Lindqvist R, Lenman A, Passos V, Voss Y, Sommerauer C, Kampmann M, Goffinet C, Meissner F, Överby AK, Lozach PY, Gerold G. Quantitative Proteomics of Uukuniemi Virus-host Cell Interactions Reveals GBF1 as Proviral Host Factor for Phleboviruses. Mol Cell Proteomics 2019; 18:2401-2417. [PMID: 31570497 PMCID: PMC6885706 DOI: 10.1074/mcp.ra119.001631] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/15/2019] [Indexed: 12/20/2022] Open
Abstract
Novel tick-borne phleboviruses in the Phenuiviridae family, which are highly pathogenic in humans and all closely related to Uukuniemi virus (UUKV), have recently emerged on different continents. How phleboviruses assemble, bud, and exit cells remains largely elusive. Here, we performed high-resolution, label-free mass spectrometry analysis of UUKV immunoprecipitated from cell lysates and identified 39 cellular partners interacting with the viral envelope glycoproteins. The importance of these host factors for UUKV infection was validated by silencing each host factor by RNA interference. This revealed Golgi-specific brefeldin A-resistance guanine nucleotide exchange factor 1 (GBF1), a guanine nucleotide exchange factor resident in the Golgi, as a critical host factor required for the UUKV life cycle. An inhibitor of GBF1, Golgicide A, confirmed the role of the cellular factor in UUKV infection. We could pinpoint the GBF1 requirement to UUKV replication and particle assembly. When the investigation was extended to viruses from various positive and negative RNA viral families, we found that not only phleboviruses rely on GBF1 for infection, but also Flavi-, Corona-, Rhabdo-, and Togaviridae In contrast, silencing or blocking GBF1 did not abrogate infection by the human adenovirus serotype 5 and immunodeficiency retrovirus type 1, the replication of both requires nuclear steps. Together our results indicate that UUKV relies on GBF1 for viral replication, assembly and egress. This study also highlights the proviral activity of GBF1 in the infection by a broad range of important zoonotic RNA viruses.
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Affiliation(s)
- Zina M Uckeley
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany; CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Rebecca Moeller
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Lars I Kühn
- Experimental Systems Immunology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Emma Nilsson
- Division of Virology, Department of Clinical Microbiology, and Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Claudia Robens
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Lisa Lasswitz
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Richard Lindqvist
- Division of Virology, Department of Clinical Microbiology, and Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Annasara Lenman
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Vania Passos
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Instituto De Ciências Biomédicas Abel Salazar, Universidade Do Porto, Porto, Portugal
| | - Yannik Voss
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Christian Sommerauer
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Martin Kampmann
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Christine Goffinet
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Institute of Virology, Charité, Universitätsmedizin Berlin, Berlin, Germany and Berlin Institute of Health (BIH), Berlin, Germany
| | - Felix Meissner
- Experimental Systems Immunology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Anna K Överby
- Division of Virology, Department of Clinical Microbiology, and Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Pierre-Yves Lozach
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany; IVPC UMR754, INRA, Univ. Lyon, EPHE, 50 Av. Tony Garnier, 69007 Lyon, France.
| | - Gisa Gerold
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Department of Clinical Microbiology, Virology & Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, SE-90185 Umeå, Sweden.
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16
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Li X, Yang Y, Wang R, Liu G, Liu X, Liu C, Deng Y, Bai Z. Quality by Design-Driven Process Development of Severe Fever With Thrombocytopenia Syndrome Vaccine. J Pharm Sci 2019; 108:3785-3791. [PMID: 31521642 DOI: 10.1016/j.xphs.2019.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 08/20/2019] [Accepted: 09/06/2019] [Indexed: 10/26/2022]
Abstract
Owing to the biological activity of the vaccine, the complicated production process, sterility, and uniformity of the product, the producing process of the vaccine is complicated and the product quality hard to control. In recent years, with the development of basic science such as cell biology, molecular biology, and metabolic engineering, bioprocess engineering research has developed rapidly. Therefore, U.S. Food and Drug Administration and European Medicines Agency conduct stringent control over the development of biomedical process engineering and product quality. This case study describes an example of Quality by Design-driven process development for manufacturing a human vaccine produced with Vero cells. Cell density in harvest fermentation broth and antigenic titer were chosen as 2 critical quality attributes. The study through 3 rounds design of experiment revealed that H2O2 and cell boost 4 had a significant effect on antigenic titer. Ethanolamine had significant improvement in the final concentration of cells. Through the Monte Carlo simulation, the design spaces and control space of process parameters were determined. A successful validation in a bioreactor was executed to verify the results of a spinner flask. Our investigation presents a successful case of Quality by Design principle, which encourages other researchers to combine the methodology into other biopharmaceutical manufacturing process.
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Affiliation(s)
- Xinran Li
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
| | - Yankun Yang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, China.
| | - Rongbin Wang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
| | - Guoqiang Liu
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
| | - Xiuxia Liu
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, China
| | - Chunli Liu
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, China
| | - Yu Deng
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, China
| | - Zhonghu Bai
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, China.
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17
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Parvate A, Williams EP, Taylor MK, Chu YK, Lanman J, Saphire EO, Jonsson CB. Diverse Morphology and Structural Features of Old and New World Hantaviruses. Viruses 2019; 11:E862. [PMID: 31527500 PMCID: PMC6783877 DOI: 10.3390/v11090862] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/01/2019] [Accepted: 09/12/2019] [Indexed: 02/07/2023] Open
Abstract
To further understanding of the structure and morphology of the Orthohantavirus, family Hantaviridae, we have employed cryo-electron microscopy (cryo-EM) for three New World hantaviruses: Andes (ANDV), Sin Nombre (SNV), and Black Creek Canal (BCCV). Building upon our prior cryo-EM and cryo-tomography study of the Old World hantavirus, Hantaan virus (HTNV), we have expanded our studies to examine the entire virion population present in cell culture supernatant. Hence, in contrast to the prior cryo-EM/ET studies in which we used a polyethylene precipitation, a sucrose gradient, and a sucrose cushion, we used two sucrose cushions. We inactivated the material after the first cushion. We tested the method using HTNV which has a known cryo-EM structure and observed equivalent results. Therefore, we used this method to assess the particle distribution of the New World hantaviruses by cryo-EM. Cryo-EM images showed a diverse range of sizes and morphologies for the New World viruses that we classified as round, tubular, and irregular. Strikingly, BCCV virions were mostly tubular. These first cryo-EM images of the New World Orthohantavirus confirm prior EM observations that noted tubular projections of SNV at the plasma membrane during virion morphogenesis but were not confirmed. These findings underscore the need for further investigation of virion morphogenesis of the Orthohantavirus.
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Affiliation(s)
- Amar Parvate
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47906, USA; (A.P.)
| | - Evan P. Williams
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA, (M.K.T.)
| | - Mariah K. Taylor
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA, (M.K.T.)
| | - Yong-Kyu Chu
- Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville, Louisville, KY 40202, USA;
| | - Jason Lanman
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47906, USA; (A.P.)
| | | | - Colleen B. Jonsson
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA, (M.K.T.)
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18
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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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19
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Chen Y, Dessau M, Rotenberg D, Rasmussen DA, Whitfield AE. Entry of bunyaviruses into plants and vectors. Adv Virus Res 2019; 104:65-96. [PMID: 31439153 DOI: 10.1016/bs.aivir.2019.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The majority of plant-infecting viruses are transmitted by arthropod vectors that deliver them directly into a living plant cell. There are diverse mechanisms of transmission ranging from direct binding to the insect stylet (non-persistent transmission) to persistent-propagative transmission in which the virus replicates in the insect vector. Despite this diversity in interactions, most arthropods that serve as efficient vectors have feeding strategies that enable them to deliver the virus into the plant cell without extensive damage to the plant and thus effectively inoculate the plant. As such, the primary virus entry mechanism for plant viruses is mediated by the biological vector. Remarkably, viruses that are transmitted in a propagative manner (bunyaviruses, rhabdoviruses, and reoviruses) have developed an ability to replicate in hosts from two kingdoms. Viruses in the order Bunyavirales are of emerging importance and with the advent of new sequencing technologies, we are getting unprecedented glimpses into the diversity of these viruses. Plant-infecting bunyaviruses are transmitted in a persistent, propagative manner must enter two unique types of host cells, plant and insect. In the insect phase of the virus life cycle, the propagative viruses likely use typical cellular entry strategies to traverse cell membranes. In this review, we highlight the transmission and entry strategies of three genera of plant-infecting bunyaviruses: orthotospoviruses, tenuiviruses, and emaraviruses.
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Affiliation(s)
- Yuting Chen
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
| | - Moshe Dessau
- Azrieli Faculty of Medicine, Bar Ilan University, Safed, Israel
| | - Dorith Rotenberg
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
| | - David A Rasmussen
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
| | - Anna E Whitfield
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States.
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20
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Tenuivirus utilizes its glycoprotein as a helper component to overcome insect midgut barriers for its circulative and propagative transmission. PLoS Pathog 2019; 15:e1007655. [PMID: 30921434 PMCID: PMC6456217 DOI: 10.1371/journal.ppat.1007655] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 04/09/2019] [Accepted: 02/24/2019] [Indexed: 12/31/2022] Open
Abstract
Many persistent transmitted plant viruses, including rice stripe virus (RSV), cause serious damage to crop production worldwide. Although many reports have indicated that a successful insect-mediated virus transmission depends on a proper interaction between the virus and its insect vector, the mechanism(s) controlling this interaction remained poorly understood. In this study, we used RSV and its small brown planthopper (SBPH) vector as a working model to elucidate the molecular mechanisms underlying the entrance of RSV virions into SBPH midgut cells for virus circulative and propagative transmission. We have determined that this non-enveloped tenuivirus uses its non-structural glycoprotein NSvc2 as a helper component to overcome the midgut barrier(s) for RSV replication and transmission. In the absence of this glycoprotein, purified RSV virions were unable to enter SBPH midgut cells. In the RSV-infected cells, this glycoprotein was processed into two mature proteins: an amino-terminal protein (NSvc2-N) and a carboxyl-terminal protein (NSvc2-C). Both NSvc2-N and NSvc2-C interact with RSV virions. Our results showed that the NSvc2-N could bind directly to the surface of midgut lumen via its N-glycosylation sites. Upon recognition, the midgut cells underwent endocytosis followed by compartmentalization of RSV virions and NSvc2 into early and then late endosomes. The NSvc2-C triggered cell membrane fusion via its highly conserved fusion loop motifs under the acidic condition inside the late endosomes, leading to the release of RSV virions from endosomes into cytosol. In summary, our results showed for the first time that a rice tenuivirus utilized its glycoprotein NSvc2 as a helper component to ensure a proper interaction between its virions and SBPH midgut cells for its circulative and propagative transmission. Over 75% of the known plant viruses are insect transmitted. Understanding how plant viruses interact with their insect vectors during virus transmission is a key step towards the successful management of plant viruses worldwide. Several models for the direct or indirect virus–insect vector interactions have been proposed for the non-persistent or semi-persistent virus transmissions. However, the mechanisms controlling the interactions between viruses and their insect vector midgut barriers are poorly understood. In this study, we demonstrated that the circulative and propagative transmitted rice stripe virus (RSV) utilized its glycoprotein NSvc2 as a helper component to ensure a specific interaction between its virions and SBPH midgut cells to overcome the midgut barriers inside this vector. This is the first report of a viral helper component mediated mechanism for persistent-propagative virus transmission. Our new findings and working model should expand our knowledge on the molecular mechanism(s) controlling the interaction between virus and its insect vector during virus circulative and propagative transmission in nature.
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Sperber HS, Welke RW, Petazzi RA, Bergmann R, Schade M, Shai Y, Chiantia S, Herrmann A, Schwarzer R. Self-association and subcellular localization of Puumala hantavirus envelope proteins. Sci Rep 2019; 9:707. [PMID: 30679542 PMCID: PMC6345964 DOI: 10.1038/s41598-018-36879-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/28/2018] [Indexed: 01/08/2023] Open
Abstract
Hantavirus assembly and budding are governed by the surface glycoproteins Gn and Gc. In this study, we investigated the glycoproteins of Puumala, the most abundant Hantavirus species in Europe, using fluorescently labeled wild-type constructs and cytoplasmic tail (CT) mutants. We analyzed their intracellular distribution, co-localization and oligomerization, applying comprehensive live, single-cell fluorescence techniques, including confocal microscopy, imaging flow cytometry, anisotropy imaging and Number&Brightness analysis. We demonstrate that Gc is significantly enriched in the Golgi apparatus in absence of other viral components, while Gn is mainly restricted to the endoplasmic reticulum (ER). Importantly, upon co-expression both glycoproteins were found in the Golgi apparatus. Furthermore, we show that an intact CT of Gc is necessary for efficient Golgi localization, while the CT of Gn influences protein stability. Finally, we found that Gn assembles into higher-order homo-oligomers, mainly dimers and tetramers, in the ER while Gc was present as mixture of monomers and dimers within the Golgi apparatus. Our findings suggest that PUUV Gc is the driving factor of the targeting of Gc and Gn to the Golgi region, while Gn possesses a significantly stronger self-association potential.
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Affiliation(s)
- Hannah Sabeth Sperber
- Institute for Biology, IRI Life Science, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115, Berlin, Germany.,Vitalant Research Institute, 270 Masonic Ave, San Francisco, CA, 94118, USA
| | - Robert-William Welke
- Institute for Biology, IRI Life Science, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115, Berlin, Germany
| | - Roberto Arturo Petazzi
- University of Potsdam, Institute of Biochemistry and Biology, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Ronny Bergmann
- Institute for Biology, IRI Life Science, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115, Berlin, Germany
| | - Matthias Schade
- Institute for Biology, IRI Life Science, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115, Berlin, Germany
| | - Yechiel Shai
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Salvatore Chiantia
- University of Potsdam, Institute of Biochemistry and Biology, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Andreas Herrmann
- Institute for Biology, IRI Life Science, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115, Berlin, Germany.
| | - Roland Schwarzer
- Institute for Biology, IRI Life Science, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115, Berlin, Germany. .,Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel. .,Gladstone Institute of Virology and Immunology, 1650 Owens Street, San Francisco, CA, 95158, USA.
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22
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Sun Y, Li J, Gao GF, Tien P, Liu W. Bunyavirales ribonucleoproteins: the viral replication and transcription machinery. Crit Rev Microbiol 2018. [PMID: 29516765 DOI: 10.1080/1040841x.2018.1446901] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The Bunyavirales order is one of the largest groups of segmented negative-sense single-stranded RNA viruses, which includes many pathogenic strains that cause severe human diseases. The RNA segments of the bunyavirus genome are separately encapsidated by multiple copies of nucleoprotein (N), and both termini of each N-encapsidated genomic RNA segment bind to one copy of the viral L polymerase protein. The viral genomic RNA, N and L protein together form the ribonucleoprotein (RNP) complex that constitutes the molecular machinery for viral genome replication and transcription. Recently, breakthroughs have been achieved in understanding the architecture of bunyavirus RNPs with the determination of the atomic structures of the N and L proteins from various members of this order. In this review, we discuss the structures and functions of these bunyavirus RNP components, as well as viral genome replication and transcription mechanisms.
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Affiliation(s)
- Yeping Sun
- a CAS Key Laboratory of Pathogenic Microbiology and Immunology , Institute of Microbiology, Chinese Academy of Sciences , Beijing , China
| | - Jing Li
- a CAS Key Laboratory of Pathogenic Microbiology and Immunology , Institute of Microbiology, Chinese Academy of Sciences , Beijing , China
| | - George F Gao
- a CAS Key Laboratory of Pathogenic Microbiology and Immunology , Institute of Microbiology, Chinese Academy of Sciences , Beijing , China.,b National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention , Beijing , China
| | - Po Tien
- a CAS Key Laboratory of Pathogenic Microbiology and Immunology , Institute of Microbiology, Chinese Academy of Sciences , Beijing , China
| | - Wenjun Liu
- a CAS Key Laboratory of Pathogenic Microbiology and Immunology , Institute of Microbiology, Chinese Academy of Sciences , Beijing , China
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Halldorsson S, Li S, Li M, Harlos K, Bowden TA, Huiskonen JT. Shielding and activation of a viral membrane fusion protein. Nat Commun 2018; 9:349. [PMID: 29367607 PMCID: PMC5783950 DOI: 10.1038/s41467-017-02789-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/28/2017] [Indexed: 11/23/2022] Open
Abstract
Entry of enveloped viruses relies on insertion of hydrophobic residues of the viral fusion protein into the host cell membrane. However, the intermediate conformations during fusion remain unknown. Here, we address the fusion mechanism of Rift Valley fever virus. We determine the crystal structure of the Gn glycoprotein and fit it with the Gc fusion protein into cryo-electron microscopy reconstructions of the virion. Our analysis reveals how the Gn shields the hydrophobic fusion loops of the Gc, preventing premature fusion. Electron cryotomography of virions interacting with membranes under acidic conditions reveals how the fusogenic Gc is activated upon removal of the Gn shield. Repositioning of the Gn allows extension of Gc and insertion of fusion loops in the outer leaflet of the target membrane. These data show early structural transitions that enveloped viruses undergo during host cell entry and indicate that analogous shielding mechanisms are utilized across diverse virus families. Viral fusion proteins undergo extensive conformational changes during entry but intermediate conformations often remain unknown. Here, the authors show how Gn of Rift Valley fever virus fusion protein shields hydrophobic fusion loops of Gc and how these loops embed in the target membrane at acidic conditions.
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Affiliation(s)
- Steinar Halldorsson
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Sai Li
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Mengqiu Li
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Karl Harlos
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Thomas A Bowden
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK.
| | - Juha T Huiskonen
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK. .,Helsinki Institute of Life Science and Faculty of Environmental and Biological Sciences, University of Helsinki, Viikinkaari 1, Helsinki, 00014, Finland.
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The Postfusion Structure of the Heartland Virus Gc Glycoprotein Supports Taxonomic Separation of the Bunyaviral Families Phenuiviridae and Hantaviridae. J Virol 2017; 92:JVI.01558-17. [PMID: 29070692 DOI: 10.1128/jvi.01558-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 10/17/2017] [Indexed: 11/20/2022] Open
Abstract
Heartland virus (HRTV) is an emerging human pathogen that belongs to the newly defined family Phenuiviridae, order Bunyavirales Gn and Gc are two viral surface glycoproteins encoded by the M segment and are required for early events during infection. HRTV delivers its genome into the cytoplasm by fusion of the viral envelope and endosomal membranes under low-pH conditions. Here, we describe the crystal structure of HRTV Gc in its postfusion conformation. The structure shows that Gc displays a typical class II fusion protein conformation, and the overall structure is identical to severe fever with thrombocytopenia syndrome virus (SFTSV) Gc, which also belongs to the Phenuiviridae family. However, our structural analysis indicates that the hantavirus Gc presents distinct features in the aspects of subdomain orientation, N-linked glycosylation, the interaction pattern between protomers, and the fusion loop conformation. This suggests their family-specific subunit arrangement during the fusogenic process and supports the recent taxonomic revision of bunyaviruses. Our results provide insights into the comprehensive comparison of class II membrane fusion proteins in two bunyavirus families, yielding valuable information for treatments against these human pathogens.IMPORTANCE HRTV is an insect-borne virus found in America that can infect humans. It belongs to the newly defined family Phenuiviridae, order Bunyavirales HRTV contains three single-stranded RNA segments (L, M, and S). The M segment of the virus encodes a polyprotein precursor that is cleaved into two glycoproteins, Gn and Gc. Gc is a fusion protein facilitating virus entry into host cells. Here, we report the crystal structure of the HRTV Gc protein. The structure displays a typical class II fusion protein conformation. Comparison of HRTV Gc with a recently solved structure of another bunyavirus Gc revealed that these Gc structures display a newly defined family specificity, supporting the recent International Committee on Taxonomy of Viruses reclassification of the bunyaviruses. Our results expand the knowledge of bunyavirus fusion proteins and help us to understand bunyavirus characterizations. This study provides useful information to improve protection against and therapies for bunyavirus infections.
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25
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Structures of phlebovirus glycoprotein Gn and identification of a neutralizing antibody epitope. Proc Natl Acad Sci U S A 2017; 114:E7564-E7573. [PMID: 28827346 DOI: 10.1073/pnas.1705176114] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) and Rift Valley fever virus (RVFV) are two arthropod-borne phleboviruses in the Bunyaviridae family, which cause severe illness in humans and animals. Glycoprotein N (Gn) is one of the envelope proteins on the virus surface and is a major antigenic component. Despite its importance for virus entry and fusion, the molecular features of the phleboviruse Gn were unknown. Here, we present the crystal structures of the Gn head domain from both SFTSV and RVFV, which display a similar compact triangular shape overall, while the three subdomains (domains I, II, and III) making up the Gn head display different arrangements. Ten cysteines in the Gn stem region are conserved among phleboviruses, four of which are responsible for Gn dimerization, as revealed in this study, and they are highly conserved for all members in Bunyaviridae Therefore, we propose an anchoring mode on the viral surface. The complex structure of the SFTSV Gn head and human neutralizing antibody MAb 4-5 reveals that helices α6 in subdomain III is the key component for neutralization. Importantly, the structure indicates that domain III is an ideal region recognized by specific neutralizing antibodies, while domain II is probably recognized by broadly neutralizing antibodies. Collectively, Gn is a desirable vaccine target, and our data provide a molecular basis for the rational design of vaccines against the diseases caused by phleboviruses and a model for bunyavirus Gn embedding on the viral surface.
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26
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Amroun A, Priet S, de Lamballerie X, Quérat G. Bunyaviridae RdRps: structure, motifs, and RNA synthesis machinery. Crit Rev Microbiol 2017; 43:753-778. [PMID: 28418734 DOI: 10.1080/1040841x.2017.1307805] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Bunyaviridae family is the largest and most diverse family of RNA viruses. It has more than 350 members divided into five genera: Orthobunyavirus, Phlebovirus, Nairovirus, Hantavirus, and Tospovirus. They are present in the five continents, causing recurrent epidemics, epizootics, and considerable agricultural loss. The genome of bunyaviruses is divided into three segments of negative single-stranded RNA according to their relative size: L (Large), M (Medium) and S (Small) segment. Bunyaviridae RNA-dependent RNA polymerase (RdRp) is encoded by the L segment, and is in charge of the replication and transcription of the viral RNA in the cytoplasm of the infected cell. Viral RdRps share a characteristic right hand-like structure with three subdomains: finger, palm, and thumb subdomains that define the formation of the catalytic cavity. In addition to the N-terminal endonuclease domain, eight conserved motifs (A-H) have been identified in the RdRp of Bunyaviridae. In this review, we have summarized the recent insights from the structural and functional studies of RdRp to understand the roles of different motifs shared by RdRps, the mechanism of viral RNA replication, genome segment packaging by the nucleoprotein, cap-snatching, mRNA transcription, and other RNA mechanisms of bunyaviruses.
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Affiliation(s)
- Abdennour Amroun
- a Faculté de Médecine , UMR "Emergence des Pathologies Virales" (Aix-Marseille University - IRD 190 - Inserm 1207 - EHESP), Fondation IHU Méditerranée Infection, APHM Public Hospitals of Marseille , Marseille , France
| | - Stéphane Priet
- a Faculté de Médecine , UMR "Emergence des Pathologies Virales" (Aix-Marseille University - IRD 190 - Inserm 1207 - EHESP), Fondation IHU Méditerranée Infection, APHM Public Hospitals of Marseille , Marseille , France
| | - Xavier de Lamballerie
- a Faculté de Médecine , UMR "Emergence des Pathologies Virales" (Aix-Marseille University - IRD 190 - Inserm 1207 - EHESP), Fondation IHU Méditerranée Infection, APHM Public Hospitals of Marseille , Marseille , France
| | - Gilles Quérat
- a Faculté de Médecine , UMR "Emergence des Pathologies Virales" (Aix-Marseille University - IRD 190 - Inserm 1207 - EHESP), Fondation IHU Méditerranée Infection, APHM Public Hospitals of Marseille , Marseille , France
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27
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Abstract
The Bunyavirales Order encompasses nine families of enveloped viruses containing a single-stranded negative-sense RNA genome divided into three segments. The small (S) and large (L) segments encode proteins participating in genome replication in the infected cell cytoplasm. The middle (M) segment encodes the viral glycoproteins Gn and Gc, which are derived from a precursor polyprotein by host cell proteases. Entry studies are available only for a few viruses in the Order, and in each case they were shown to enter cells via receptor-mediated endocytosis. The acidic endosomal pH triggers the fusion of the viral envelope with the membrane of an endosome. Structural studies on two members of this Order, the phleboviruses and the hantaviruses, have shown that the membrane fusion protein Gc displays a class II fusion protein fold and is homologous to its counterparts in flaviviruses and alphaviruses, which are positive-sense, single-stranded RNA viruses. We analyze here recent data on the structure and function of the structure of the phlebovirus Gc and hantavirus Gn and Gc glycoproteins, and extrapolate common features identified in the amino acid sequences to understand also the structure and function of their counterparts in other families of the Bunyavirales Order. Our analysis also identified clear structural homology between the hantavirus Gn and alphavirus E2 glycoproteins, which make a heterodimer with the corresponding fusion proteins Gc and E1, respectively, revealing that not only the fusion protein has been conserved across viral families.
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Affiliation(s)
- Pablo Guardado-Calvo
- Institut Pasteur, Unité de Virologie Structurale, Paris Cedex 15, France; CNRS UMR 3569 Virologie, Paris Cedex 15, France
| | - Félix A Rey
- Institut Pasteur, Unité de Virologie Structurale, Paris Cedex 15, France; CNRS UMR 3569 Virologie, Paris Cedex 15, France.
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28
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Drake MJ, Brennan B, Briley Jr K, Bart SM, Sherman E, Szemiel AM, Minutillo M, Bushman FD, Bates P. A role for glycolipid biosynthesis in severe fever with thrombocytopenia syndrome virus entry. PLoS Pathog 2017; 13:e1006316. [PMID: 28388693 PMCID: PMC5397019 DOI: 10.1371/journal.ppat.1006316] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 04/19/2017] [Accepted: 03/24/2017] [Indexed: 01/01/2023] Open
Abstract
A novel bunyavirus was recently found to cause severe febrile illness with high mortality in agricultural regions of China, Japan, and South Korea. This virus, named severe fever with thrombocytopenia syndrome virus (SFTSV), represents a new group within the Phlebovirus genus of the Bunyaviridae. Little is known about the viral entry requirements beyond showing dependence on dynamin and endosomal acidification. A haploid forward genetic screen was performed to identify host cell requirements for SFTSV entry. The screen identified dependence on glucosylceramide synthase (ugcg), the enzyme responsible for initiating de novo glycosphingolipid biosynthesis. Genetic and pharmacological approaches confirmed that UGCG expression and enzymatic activity were required for efficient SFTSV entry. Furthermore, inhibition of UGCG affected a post-internalization stage of SFTSV entry, leading to the accumulation of virus particles in enlarged cytoplasmic structures, suggesting impaired trafficking and/or fusion of viral and host membranes. These findings specify a role for glucosylceramide in SFTSV entry and provide a novel target for antiviral therapies.
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Affiliation(s)
- Mary Jane Drake
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Benjamin Brennan
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, United Kingdom
| | - Kenneth Briley Jr
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Stephen M. Bart
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Eric Sherman
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Agnieszka M. Szemiel
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, United Kingdom
| | - Madeleine Minutillo
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Frederic D. Bushman
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Paul Bates
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Ferron F, Weber F, de la Torre JC, Reguera J. Transcription and replication mechanisms of Bunyaviridae and Arenaviridae L proteins. Virus Res 2017; 234:118-134. [PMID: 28137457 PMCID: PMC7114536 DOI: 10.1016/j.virusres.2017.01.018] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/17/2017] [Accepted: 01/21/2017] [Indexed: 12/15/2022]
Abstract
Bunyavirus and arenavirus are important public health threats. Bunyavirus and arenavirus molecular biology, common and differential features. Implications of LACV L protein structure for understanding viral RNA synthesis. Current state and future perspectives on bunya- and arenavirus antivirals.
Bunyaviridae and Arenaviridae virus families include an important number of highly pathogenic viruses for humans. They are enveloped viruses with negative stranded RNA genomes divided into three (bunyaviruses) or two (arenaviruses) segments. Each genome segment is coated by the viral nucleoproteins (NPs) and the polymerase (L protein) to form a functional ribonucleoprotein (RNP) complex. The viral RNP provides the necessary context on which the L protein carries out the biosynthetic processes of RNA replication and gene transcription. Decades of research have provided a good understanding of the molecular processes underlying RNA synthesis, both RNA replication and gene transcription, for these two families of viruses. In this review we will provide a global view of the common features, as well as differences, of the molecular biology of Bunyaviridae and Arenaviridae. We will also describe structures of protein and protein-RNA complexes so far determined for these viral families, mainly focusing on the L protein, and discuss their implications for understanding the mechanisms of viral RNA replication and gene transcription within the architecture of viral RNPs, also taking into account the cellular context in which these processes occur. Finally, we will discuss the implications of these structural findings for the development of antiviral drugs to treat human diseases caused by members of the Bunyaviridae and Arenaviridae families.
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Affiliation(s)
- François Ferron
- Aix-Marseille Université, AFMB UMR 7257, 13288 Marseille, France; CNRS, AFMB UMR 7257, 13288 Marseille, France
| | - Friedemann Weber
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, D-35392 Giessen, Germany
| | | | - Juan Reguera
- Aix-Marseille Université, AFMB UMR 7257, 13288 Marseille, France; CNRS, AFMB UMR 7257, 13288 Marseille, France; INSERM, AFMB UMR 7257, 13288 Marseille, France.
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30
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Yuan F, Zheng A. Entry of severe fever with thrombocytopenia syndrome virus. Virol Sin 2016; 32:44-50. [PMID: 27995422 DOI: 10.1007/s12250-016-3858-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Accepted: 11/30/2016] [Indexed: 10/20/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a globe-shaped virus covered by a dense icosahedral array of glycoproteins Gn/Gc that mediate the attachment of the virus to host cells and the fusion of viral and cellular membranes. Several membrane factors are involved in virus entry, including C-type lectins and nonmuscle myosin heavy chain IIA. The post-fusion crystal structure of the Gc protein suggests that it is a class II membrane fusion protein, similar to the E/E1 protein of flaviviruses and alphaviruses. The virus particles are internalized into host cell endosomes through the clathrin-dependent pathway, where the low pH activates the fusion of the virus with the cell membrane. With information from studies on other bunyaviruses, herein we will review our knowledge of the entry process of SFTSV.
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Affiliation(s)
- Fei Yuan
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Aihua Zheng
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
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31
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Mechanistic Insight into Bunyavirus-Induced Membrane Fusion from Structure-Function Analyses of the Hantavirus Envelope Glycoprotein Gc. PLoS Pathog 2016; 12:e1005813. [PMID: 27783711 PMCID: PMC5082683 DOI: 10.1371/journal.ppat.1005813] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 07/17/2016] [Indexed: 01/03/2023] Open
Abstract
Hantaviruses are zoonotic viruses transmitted to humans by persistently infected rodents, giving rise to serious outbreaks of hemorrhagic fever with renal syndrome (HFRS) or of hantavirus pulmonary syndrome (HPS), depending on the virus, which are associated with high case fatality rates. There is only limited knowledge about the organization of the viral particles and in particular, about the hantavirus membrane fusion glycoprotein Gc, the function of which is essential for virus entry. We describe here the X-ray structures of Gc from Hantaan virus, the type species hantavirus and responsible for HFRS, both in its neutral pH, monomeric pre-fusion conformation, and in its acidic pH, trimeric post-fusion form. The structures confirm the prediction that Gc is a class II fusion protein, containing the characteristic β-sheet rich domains termed I, II and III as initially identified in the fusion proteins of arboviruses such as alpha- and flaviviruses. The structures also show a number of features of Gc that are distinct from arbovirus class II proteins. In particular, hantavirus Gc inserts residues from three different loops into the target membrane to drive fusion, as confirmed functionally by structure-guided mutagenesis on the HPS-inducing Andes virus, instead of having a single "fusion loop". We further show that the membrane interacting region of Gc becomes structured only at acidic pH via a set of polar and electrostatic interactions. Furthermore, the structure reveals that hantavirus Gc has an additional N-terminal "tail" that is crucial in stabilizing the post-fusion trimer, accompanying the swapping of domain III in the quaternary arrangement of the trimer as compared to the standard class II fusion proteins. The mechanistic understandings derived from these data are likely to provide a unique handle for devising treatments against these human pathogens.
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32
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The Role of Phlebovirus Glycoproteins in Viral Entry, Assembly and Release. Viruses 2016; 8:v8070202. [PMID: 27455305 PMCID: PMC4974537 DOI: 10.3390/v8070202] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 07/13/2016] [Accepted: 07/14/2016] [Indexed: 01/08/2023] Open
Abstract
Bunyaviruses are enveloped viruses with a tripartite RNA genome that can pose a serious threat to animal and human health. Members of the Phlebovirus genus of the family Bunyaviridae are transmitted by mosquitos and ticks to humans and include highly pathogenic agents like Rift Valley fever virus (RVFV) and severe fever with thrombocytopenia syndrome virus (SFTSV) as well as viruses that do not cause disease in humans, like Uukuniemi virus (UUKV). Phleboviruses and other bunyaviruses use their envelope proteins, Gn and Gc, for entry into target cells and for assembly of progeny particles in infected cells. Thus, binding of Gn and Gc to cell surface factors promotes viral attachment and uptake into cells and exposure to endosomal low pH induces Gc-driven fusion of the viral and the vesicle membranes. Moreover, Gn and Gc facilitate virion incorporation of the viral genome via their intracellular domains and Gn and Gc interactions allow the formation of a highly ordered glycoprotein lattice on the virion surface. Studies conducted in the last decade provided important insights into the configuration of phlebovirus Gn and Gc proteins in the viral membrane, the cellular factors used by phleboviruses for entry and the mechanisms employed by phlebovirus Gc proteins for membrane fusion. Here, we will review our knowledge on the glycoprotein biogenesis and the role of Gn and Gc proteins in the phlebovirus replication cycle.
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RNA Encapsidation and Packaging in the Phleboviruses. Viruses 2016; 8:v8070194. [PMID: 27428993 PMCID: PMC4974529 DOI: 10.3390/v8070194] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 07/01/2016] [Accepted: 07/07/2016] [Indexed: 11/23/2022] Open
Abstract
The Bunyaviridae represents the largest family of segmented RNA viruses, which infect a staggering diversity of plants, animals, and insects. Within the family Bunyaviridae, the Phlebovirus genus includes several important human and animal pathogens, including Rift Valley fever virus (RVFV), severe fever with thrombocytopenia syndrome virus (SFTSV), Uukuniemi virus (UUKV), and the sandfly fever viruses. The phleboviruses have small tripartite RNA genomes that encode a repertoire of 5–7 proteins. These few proteins accomplish the daunting task of recognizing and specifically packaging a tri-segment complement of viral genomic RNA in the midst of an abundance of host components. The critical nucleation events that eventually lead to virion production begin early on in the host cytoplasm as the first strands of nascent viral RNA (vRNA) are synthesized. The interaction between the vRNA and the viral nucleocapsid (N) protein effectively protects and masks the RNA from the host, and also forms the ribonucleoprotein (RNP) architecture that mediates downstream interactions and drives virion formation. Although the mechanism by which all three genomic counterparts are selectively co-packaged is not completely understood, we are beginning to understand the hierarchy of interactions that begins with N-RNA packaging and culminates in RNP packaging into new virus particles. In this review we focus on recent progress that highlights the molecular basis of RNA genome packaging in the phleboviruses.
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Cryo-electron Microscopy Structure of the Native Prototype Foamy Virus Glycoprotein and Virus Architecture. PLoS Pathog 2016; 12:e1005721. [PMID: 27399201 PMCID: PMC4939959 DOI: 10.1371/journal.ppat.1005721] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 06/02/2016] [Indexed: 12/11/2022] Open
Abstract
Foamy viruses (FV) belong to the genus Spumavirus, which forms a distinct lineage in the Retroviridae family. Although the infection in natural hosts and zoonotic transmission to humans is asymptomatic, FVs can replicate well in human cells making it an attractive gene therapy vector candidate. Here we present cryo-electron microscopy and (cryo-)electron tomography ultrastructural data on purified prototype FV (PFV) and PFV infected cells. Mature PFV particles have a distinct morphology with a capsid of constant dimension as well as a less ordered shell of density between the capsid and the membrane likely formed by the Gag N-terminal domain and the cytoplasmic part of the Env leader peptide gp18LP. The viral membrane contains trimeric Env glycoproteins partly arranged in interlocked hexagonal assemblies. In situ 3D reconstruction by subtomogram averaging of wild type Env and of a Env gp48TM- gp80SU cleavage site mutant showed a similar spike architecture as well as stabilization of the hexagonal lattice by clear connections between lower densities of neighboring trimers. Cryo-EM was employed to obtain a 9 Å resolution map of the glycoprotein in its pre-fusion state, which revealed extensive trimer interactions by the receptor binding subunit gp80SU at the top of the spike and three central helices derived from the fusion protein subunit gp48TM. The lower part of Env, presumably composed of interlaced parts of gp48TM, gp80SU and gp18LP anchors the spike at the membrane. We propose that the gp48TM density continues into three central transmembrane helices, which interact with three outer transmembrane helices derived from gp18LP. Our ultrastructural data and 9 Å resolution glycoprotein structure provide important new insights into the molecular architecture of PFV and its distinct evolutionary relationship with other members of the Retroviridae. Foamy viruses (FVs), which belong to the retroviral genus Spumavirus, are endemic to non-human primates and can be transmitted to humans. They are considered as potential vectors for gene therapy due to their broad cell tropism and their apparent apathogenicity in natural hosts and humans. In order to gain more insight into the ultrastructure of the prototype FV (PFV) we performed (cryo-)electron tomography and microscopy of infected cells and of isolated virions. We find that PFV contains a nucleocapsid of constant dimensions at its center, an intermediate shell of protein positioned between the core capsid and the viral membrane and glycoprotein that arranges into regular hexagonal lattices on the virus membrane. Structural analysis of the glycoprotein was performed in situ to a resolution of 9Å, which shows regular helical features such as a trimeric coiled coil of the fusion protein subunit, a hallmark of class I fusion proteins, spacer arms between the glycoprotein trimers and the arrangement of six transmembrane helices, a characteristic feature of the PFV Env glycoprotein. We discuss our results in light of the evolutionary relationship of PFV with other retroviruses as well as the role of the unique glycoprotein architecture on the virus life cycle.
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Abstract
In the last decade, novel tick-borne pathogenic phleboviruses in the family Bunyaviridae, all closely related to Uukuniemi virus (UUKV), have emerged on different continents. To reproduce the tick-mammal switch in vitro, we first established a reverse genetics system to rescue UUKV with a genome close to that of the authentic virus isolated from the Ixodes ricinus tick reservoir. The IRE/CTVM19 and IRE/CTVM20 cell lines, both derived from I. ricinus, were susceptible to the virus rescued from plasmid DNAs and supported production of the virus over many weeks, indicating that infection was persistent. The glycoprotein GC was mainly highly mannosylated on tick cell-derived viral progeny. The second envelope viral protein, GN, carried mostly N-glycans not recognized by the classical glycosidases peptide-N-glycosidase F (PNGase F) and endoglycosidase H (Endo H). Treatment with β-mercaptoethanol did not impact the apparent molecular weight of GN. On viruses originating from mammalian BHK-21 cells, GN glycosylations were exclusively sensitive to PNGase F, and the electrophoretic mobility of the protein was substantially slower after the reduction of disulfide bonds. Furthermore, the amount of viral nucleoprotein per focus forming unit differed markedly whether viruses were produced in tick or BHK-21 cells, suggesting a higher infectivity for tick cell-derived viruses. Together, our results indicate that UUKV particles derived from vector tick cells have glycosylation and structural specificities that may influence the initial infection in mammalian hosts. This study also highlights the importance of working with viruses originating from arthropod vector cells in investigations of the cell biology of arbovirus transmission and entry into mammalian hosts. IMPORTANCE Tick-borne phleboviruses represent a growing threat to humans globally. Although ticks are important vectors of infectious emerging diseases, previous studies have mainly involved virus stocks produced in mammalian cells. This limitation tends to minimize the importance of host alternation in virus transmission to humans and initial infection at the molecular level. With this study, we have developed an in vitro tick cell-based model that allows production of the tick-borne Uukuniemi virus to high titers. Using this system, we found that virions derived from tick cells have specific structural properties and N-glycans that may enhance virus infectivity for mammalian cells. By shedding light on molecular aspects of tick-derived viral particles, our data illustrate the importance of considering the host switch in studying early virus-mammalian receptor/cell interactions. The information gained here lays the basis for future research on not only tick-borne phleboviruses but also all viruses and other pathogens transmitted by ticks.
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Perotti LE, Dharmavaram S, Klug WS, Marian J, Rudnick J, Bruinsma RF. Useful scars: Physics of the capsids of archaeal viruses. Phys Rev E 2016; 94:012404. [PMID: 27575161 DOI: 10.1103/physreve.94.012404] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Indexed: 11/07/2022]
Abstract
We propose a physical model for the capsids of tailed archaeal viruses as viscoelastic membranes under tension. The fluidity is generated by thermal motion of scarlike structures that are an intrinsic feature of the ground state of large particle arrays covering surfaces with nonzero Gauss curvature. The tension is generated by a combination of the osmotic pressure of the enclosed genome and an extension force generated by filamentous structure formation that drives the formation of the tails. In continuum theory, the capsid has the shape of a surface of constant mean curvature: an unduloid. Particle arrays covering unduloids are shown to exhibit pronounced subdiffusive and diffusive single-particle transport at temperatures that are well below the melting temperature of defect-free particle arrays on a surface with zero Gauss curvature.
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Affiliation(s)
- L E Perotti
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095, USA
| | - S Dharmavaram
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095, USA
| | - W S Klug
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095, USA
| | - J Marian
- Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA
| | - J Rudnick
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - R F Bruinsma
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
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Wuerth JD, Weber F. Phleboviruses and the Type I Interferon Response. Viruses 2016; 8:v8060174. [PMID: 27338447 PMCID: PMC4926194 DOI: 10.3390/v8060174] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 06/15/2016] [Accepted: 06/20/2016] [Indexed: 12/16/2022] Open
Abstract
The genus Phlebovirus of the family Bunyaviridae contains a number of emerging virus species which pose a threat to both human and animal health. Most prominent members include Rift Valley fever virus (RVFV), sandfly fever Naples virus (SFNV), sandfly fever Sicilian virus (SFSV), Toscana virus (TOSV), Punta Toro virus (PTV), and the two new members severe fever with thrombocytopenia syndrome virus (SFTSV) and Heartland virus (HRTV). The nonstructural protein NSs is well established as the main phleboviral virulence factor in the mammalian host. NSs acts as antagonist of the antiviral type I interferon (IFN) system. Recent progress in the elucidation of the molecular functions of a growing list of NSs proteins highlights the astonishing variety of strategies employed by phleboviruses to evade the IFN system.
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Affiliation(s)
- Jennifer Deborah Wuerth
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, Giessen 35392, Germany.
| | - Friedemann Weber
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, Giessen 35392, Germany.
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Structure of a phleboviral envelope glycoprotein reveals a consolidated model of membrane fusion. Proc Natl Acad Sci U S A 2016; 113:7154-9. [PMID: 27325770 DOI: 10.1073/pnas.1603827113] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
An emergent viral pathogen termed severe fever with thrombocytopenia syndrome virus (SFTSV) is responsible for thousands of clinical cases and associated fatalities in China, Japan, and South Korea. Akin to other phleboviruses, SFTSV relies on a viral glycoprotein, Gc, to catalyze the merger of endosomal host and viral membranes during cell entry. Here, we describe the postfusion structure of SFTSV Gc, revealing that the molecular transformations the phleboviral Gc undergoes upon host cell entry are conserved with otherwise unrelated alpha- and flaviviruses. By comparison of SFTSV Gc with that of the prefusion structure of the related Rift Valley fever virus, we show that these changes involve refolding of the protein into a trimeric state. Reverse genetics and rescue of site-directed histidine mutants enabled localization of histidines likely to be important for triggering this pH-dependent process. These data provide structural and functional evidence that the mechanism of phlebovirus-host cell fusion is conserved among genetically and patho-physiologically distinct viral pathogens.
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Albornoz A, Hoffmann AB, Lozach PY, Tischler ND. Early Bunyavirus-Host Cell Interactions. Viruses 2016; 8:v8050143. [PMID: 27213430 PMCID: PMC4885098 DOI: 10.3390/v8050143] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 05/15/2016] [Indexed: 12/12/2022] Open
Abstract
The Bunyaviridae is the largest family of RNA viruses, with over 350 members worldwide. Several of these viruses cause severe diseases in livestock and humans. With an increasing number and frequency of outbreaks, bunyaviruses represent a growing threat to public health and agricultural productivity globally. Yet, the receptors, cellular factors and endocytic pathways used by these emerging pathogens to infect cells remain largely uncharacterized. The focus of this review is on the early steps of bunyavirus infection, from virus binding to penetration from endosomes. We address current knowledge and advances for members from each genus in the Bunyaviridae family regarding virus receptors, uptake, intracellular trafficking and fusion.
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Affiliation(s)
- Amelina Albornoz
- Molecular Virology Laboratory, Fundación Ciencia & Vida, Av. Zañartu 1482, 7780272 Santiago, Chile.
| | - Anja B Hoffmann
- CellNetworks-Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
| | - Pierre-Yves Lozach
- CellNetworks-Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
| | - Nicole D Tischler
- Molecular Virology Laboratory, Fundación Ciencia & Vida, Av. Zañartu 1482, 7780272 Santiago, Chile.
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Abstract
Hantaviruses are emerging zoonotic pathogens that belong to the Bunyaviridae family. They have been classified as category A pathogens by CDC (centers for disease control and prevention). Hantaviruses pose a serious threat to human health because their infection causes two highly fatal diseases, hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS). These pathogens are transmitted to humans through aerosolized excreta of their infected rodent hosts. Hantaviruses have a tripartite-segmented negative-sense RNA genome. The three genomic RNA segments, S, M, and L, encode a nucleocapsid protein (N), a precursor glycoprotein that is processed into two envelope glycoproteins (Gn and Gc) and the viral RNA-dependent RNA polymerase (RdRp), respectively. N protein is the major structural component of the virus, its main function is to protect and encapsidate the three genomic RNAs forming three viral ribonucleocapsids. Recent studies have proposed that N in conjunction with RdRp plays important roles in the transcription and replication of viral genome. In addition, N preferentially facilitates the translation of viral mRNA in cells. Glycoproteins, Gn and Gc, play major roles in viral attachment and entry to the host cells, virulence, and assembly and packaging of new virions in infected cells. RdRp functions as RNA replicase and transcriptase to replicate and transcribe the viral RNA and is also thought to have endonuclease activity. Currently, no antiviral therapy or vaccine is available for the treatment of hantavirus-associated diseases. Understanding the molecular details of hantavirus life cycle will help in the identification of targets for antiviral therapeutics and in the design of potential antiviral drug for the treatment of HFRS and HCPS. Due to the alarming fatality of hantavirus diseases, development of an effective vaccine against hantaviruses is a necessity.
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Léger P, Tetard M, Youness B, Cordes N, Rouxel RN, Flamand M, Lozach PY. Differential Use of the C-Type Lectins L-SIGN and DC-SIGN for Phlebovirus Endocytosis. Traffic 2016; 17:639-56. [PMID: 26990254 DOI: 10.1111/tra.12393] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 12/21/2022]
Abstract
Bunyaviruses represent a growing threat to humans and livestock globally. The receptors, cellular factors and endocytic pathways used by these emerging pathogens to infect cells remain largely unidentified and poorly characterized. DC-SIGN is a C-type lectin highly expressed on dermal dendritic cells that has been found to act as an authentic entry receptor for many phleboviruses (Bunyaviridae), including Rift Valley fever virus (RVFV), Toscana virus (TOSV) and Uukuniemi virus (UUKV). We found that these phleboviruses can exploit another C-type lectin, L-SIGN, for infection. L-SIGN shares 77% sequence homology with DC-SIGN and is expressed on liver sinusoidal endothelial cells. L-SIGN is required for UUKV binding but not for virus internalization. An endocytosis-defective mutant of L-SIGN was still able to mediate virus uptake and infection, indicating that L-SIGN acts as an attachment receptor for phleboviruses rather than an endocytic receptor. Our results point out a fundamental difference in the use of the C-type lectins L-SIGN and DC-SIGN by UUKV to enter cells, although both proteins are closely related in terms of molecular structure and biological function. This study sheds new light on the molecular mechanisms by which phleboviruses target the liver and also highlights the added complexity in virus-receptor interactions beyond attachment.
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Affiliation(s)
- Psylvia Léger
- CellNetworks - Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Marilou Tetard
- INRS-Institut Armand-Frappier, Laval, Canada.,Current address: Inserm UMR_S1134, Paris, France
| | - Berthe Youness
- CellNetworks - Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany.,INRS-Institut Armand-Frappier, Laval, Canada.,Reproduction Genetics Unit, Department of Gynecological Endocrinology and Reproductive Medicine, University Hospital, Heidelberg, Germany
| | - Nicole Cordes
- CellNetworks - Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Ronan N Rouxel
- INRS-Institut Armand-Frappier, Laval, Canada.,UR_0892 Unité de Virologie et Immunologie Moléculaire, INRA, CRJ, Jouy-en-Josas, France
| | - Marie Flamand
- Structural Virology, Institut Pasteur, Paris, France
| | - Pierre-Yves Lozach
- CellNetworks - Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany.,INRS-Institut Armand-Frappier, Laval, Canada
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Bitto D, Halldorsson S, Caputo A, Huiskonen JT. Low pH and Anionic Lipid-dependent Fusion of Uukuniemi Phlebovirus to Liposomes. J Biol Chem 2016; 291:6412-22. [PMID: 26811337 PMCID: PMC4813561 DOI: 10.1074/jbc.m115.691113] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Indexed: 12/14/2022] Open
Abstract
Many phleboviruses (family Bunyaviridae) are emerging as medically important viruses. These viruses enter target cells by endocytosis and low pH-dependent membrane fusion in late endosomes. However, the necessary and sufficient factors for fusion have not been fully characterized. We have studied the minimal fusion requirements of a prototypic phlebovirus, Uukuniemi virus, in an in vitro virus-liposome assay. We show that efficient lipid mixing between viral and liposome membranes requires close to physiological temperatures and phospholipids with negatively charged headgroups, such as the late endosomal phospholipid bis(monoacylglycero)phosphate. We further demonstrate that bis(monoacylglycero)phosphate increases Uukuniemi virus fusion beyond the lipid mixing stage. By using electron cryotomography of viral particles in the presence or absence of liposomes, we observed that the conformation of phlebovirus glycoprotein capsomers changes from the native conformation toward a more elongated conformation at a fusion permissive pH. Our results suggest a rationale for phlebovirus entry in late endosomes.
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Affiliation(s)
- David Bitto
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford OX3 7BN, United Kingdom
| | - Steinar Halldorsson
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford OX3 7BN, United Kingdom
| | - Alessandro Caputo
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford OX3 7BN, United Kingdom
| | - Juha T Huiskonen
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford OX3 7BN, United Kingdom
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Léger P, Lozach PY. Bunyaviruses: from transmission by arthropods to virus entry into the mammalian host first-target cells. Future Virol 2015. [DOI: 10.2217/fvl.15.52] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The Bunyaviridae constitute a large family of animal RNA viruses distributed worldwide, most members of which are transmitted to vertebrate hosts by arthropods and can cause severe pathologies in humans and livestock. With an increasing number of outbreaks, arthropod-borne bunyaviruses (arbo-bunyaviruses) present a global threat to public health and agricultural productivity. Yet transmission, tropism, receptors and cell entry remain poorly characterized. The focus of this review is on the initial infection of mammalian hosts by arbo-bunyaviruses from cellular and molecular perspectives, with particular attention to the human host. We address current knowledge and advances regarding the identity of the first-target cells and the subsequent processes of entry and penetration into the cytosol. Aspects of the vector-to-host switch that influence the early steps of cell infection in mammalian skin, where incoming particles are introduced by infected arthropods, are also highlighted and discussed.
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Affiliation(s)
- Psylvia Léger
- CellNetworks – Cluster of Excellence & Department of Infectious Diseases, Virology, University Hospital Heidelberg, D-69120 Heidelberg, Germany
| | - Pierre-Yves Lozach
- CellNetworks – Cluster of Excellence & Department of Infectious Diseases, Virology, University Hospital Heidelberg, D-69120 Heidelberg, Germany
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Generation of mutant Uukuniemi viruses lacking the nonstructural protein NSs by reverse genetics indicates that NSs is a weak interferon antagonist. J Virol 2015; 89:4849-56. [PMID: 25673721 DOI: 10.1128/jvi.03511-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 02/04/2015] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED Uukuniemi virus (UUKV) is a tick-borne member of the Phlebovirus genus (family Bunyaviridae) and has been widely used as a safe laboratory model to study aspects of bunyavirus replication. Recently, a number of new tick-borne phleboviruses have been discovered, some of which, like severe fever with thrombocytopenia syndrome virus and Heartland virus, are highly pathogenic in humans. UUKV could now serve as a useful comparator to understand the molecular basis for the different pathogenicities of these related viruses. We established a reverse-genetics system to recover UUKV entirely from cDNA clones. We generated two recombinant viruses, one in which the nonstructural protein NSs open reading frame was deleted from the S segment and one in which the NSs gene was replaced with green fluorescent protein (GFP), allowing convenient visualization of viral infection. We show that the UUKV NSs protein acts as a weak interferon antagonist in human cells but that it is unable to completely counteract the interferon response, which could serve as an explanation for its inability to cause disease in humans. IMPORTANCE Uukuniemi virus (UUKV) is a tick-borne phlebovirus that is apathogenic for humans and has been used as a convenient model to investigate aspects of phlebovirus replication. Recently, new tick-borne phleboviruses have emerged, such as severe fever with thrombocytopenia syndrome virus in China and Heartland virus in the United States, that are highly pathogenic, and UUKV will now serve as a comparator to aid in the understanding of the molecular basis for the virulence of these new viruses. To help such investigations, we have developed a reverse-genetics system for UUKV that permits manipulation of the viral genome. We generated viruses lacking the nonstructural protein NSs and show that UUKV NSs is a weak interferon antagonist. In addition, we created a virus that expresses GFP and thus allows convenient monitoring of virus replication. These new tools represent a significant advance in the study of tick-borne phleboviruses.
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Lei XY, Liu MM, Yu XJ. Severe fever with thrombocytopenia syndrome and its pathogen SFTSV. Microbes Infect 2015; 17:149-54. [DOI: 10.1016/j.micinf.2014.12.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/01/2014] [Accepted: 12/02/2014] [Indexed: 12/20/2022]
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Abstract
Uukuniemi virus (UUKV) is a model system for investigating the genus Phlebovirus of the Bunyaviridae. We report the UUKV glycome, revealing differential processing of the Gn and Gc virion glycoproteins. Both glycoproteins display poly-N-acetyllactosamines, consistent with virion assembly in the medial Golgi apparatus, whereas oligomannose-type glycans required for DC-SIGN-dependent cellular attachment are predominant on Gc. Local virion structure and the route of viral egress from the cell leave a functional imprint on the phleboviral glycome.
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Hantavirus Gn and Gc envelope glycoproteins: key structural units for virus cell entry and virus assembly. Viruses 2014; 6:1801-22. [PMID: 24755564 PMCID: PMC4014721 DOI: 10.3390/v6041801] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/20/2014] [Accepted: 03/31/2014] [Indexed: 01/24/2023] Open
Abstract
In recent years, ultrastructural studies of viral surface spikes from three different genera within the Bunyaviridae family have revealed a remarkable diversity in their spike organization. Despite this structural heterogeneity, in every case the spikes seem to be composed of heterodimers formed by Gn and Gc envelope glycoproteins. In this review, current knowledge of the Gn and Gc structures and their functions in virus cell entry and exit is summarized. During virus cell entry, the role of Gn and Gc in receptor binding has not yet been determined. Nevertheless, biochemical studies suggest that the subsequent virus-membrane fusion activity is accomplished by Gc. Further, a class II fusion protein conformation has been predicted for Gc of hantaviruses, and novel crystallographic data confirmed such a fold for the Rift Valley fever virus (RVFV) Gc protein. During virus cell exit, the assembly of different viral components seems to be established by interaction of Gn and Gc cytoplasmic tails (CT) with internal viral ribonucleocapsids. Moreover, recent findings show that hantavirus glycoproteins accomplish important roles during virus budding since they self-assemble into virus-like particles. Collectively, these novel insights provide essential information for gaining a more detailed understanding of Gn and Gc functions in the early and late steps of the hantavirus infection cycle.
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Olal D, Dick A, Woods VL, Liu T, Li S, Devignot S, Weber F, Saphire EO, Daumke O. Structural insights into RNA encapsidation and helical assembly of the Toscana virus nucleoprotein. Nucleic Acids Res 2014; 42:6025-37. [PMID: 24688060 PMCID: PMC4027202 DOI: 10.1093/nar/gku229] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Toscana virus is an emerging bunyavirus in Mediterranean Europe where it accounts for 80% of pediatric meningitis cases during the summer. The negative-strand ribonucleic acid (RNA) genome of the virus is wrapped around the virally encoded nucleoprotein N to form the ribonucleoprotein complex (RNP). We determined crystal structures of hexameric N alone (apo) and in complex with a nonameric single-stranded RNA. RNA is sequestered in a sequence-independent fashion in a deep groove inside the hexamer. At the junction between two adjacent copies of Ns, RNA binding induced an inter-subunit rotation, which opened the RNA-binding tunnel and created a new assembly interface at the outside of the hexamer. Based on these findings, we suggest a structural model for how binding of RNA to N promotes the formation of helical RNPs, which are a characteristic hallmark of many negative-strand RNA viruses.
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Affiliation(s)
- Daniel Olal
- Max Delbrück Center for Molecular Medicine, Crystallography, Robert-Rössle-Strasse 10, 13125 Berlin, Germany Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Alexej Dick
- Max Delbrück Center for Molecular Medicine, Crystallography, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Virgil L Woods
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Tong Liu
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Sheng Li
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Stephanie Devignot
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Erica Ollmann Saphire
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Oliver Daumke
- Max Delbrück Center for Molecular Medicine, Crystallography, Robert-Rössle-Strasse 10, 13125 Berlin, Germany Freie Universität Berlin, Biochemistry, Takustrasse 6, 14195 Berlin, Germany
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Relating structure to evolution in class II viral membrane fusion proteins. Curr Opin Virol 2014; 5:34-41. [PMID: 24525225 PMCID: PMC4028412 DOI: 10.1016/j.coviro.2014.01.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 01/17/2014] [Indexed: 12/25/2022]
Abstract
Until 2013, class II proteins had only been found in flaviviruses and alphaviruses. A class II fusion protein was recently discovered in the unrelated phlebovirus genus. Within the same family as alphaviruses, rubella virus has a divergent class II fold. Pestiviruses, although they are Flaviviridae, have fusion proteins from a novel class. Viral class II proteins may originate from cellular class II fusion protein ancestors.
Enveloped viruses must fuse their lipid membrane to a cellular membrane to deliver the viral genome into the cytoplasm for replication. Viral envelope proteins catalyze this critical membrane fusion event. They fall into at least three distinct structural classes. Class II fusion proteins have a conserved three-domain architecture and are found in many important viral pathogens. Until 2013, class II proteins had only been found in flaviviruses and alphaviruses. However, in 2013 a class II fusion protein was discovered in the unrelated phlebovirus genus, and two unexpectedly divergent envelope proteins were identified in families that also contain prototypical class II proteins. The structural relationships of newly identified class II proteins, reviewed herein, shift the paradigm for how these proteins evolved.
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50
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Reguera J, Cusack S, Kolakofsky D. Segmented negative strand RNA virus nucleoprotein structure. Curr Opin Virol 2014; 5:7-15. [PMID: 24486721 DOI: 10.1016/j.coviro.2014.01.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 12/11/2013] [Accepted: 01/08/2014] [Indexed: 12/12/2022]
Abstract
Negative strand RNA virus (NSV) genomes are never free, but always found assembled with multiple copies of their nucleoprotein, as RNPs. A flurry of papers describing the X-ray crystal structures of several segmented NSV nucleoproteins have recently appeared. The most significant feature of these various structures is that the arms that are used to oligomerize the nucleoproteins on their genome RNAs are highly flexible, permitting these RNPs to assume virtually unlimited geometries. The structural flexibility of segmented NSV RNPs is undoubtedly important in all aspects of their biology, including genome replication and circularization, and the selection of one copy of each segment for packaging into virus particles.
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Affiliation(s)
- Juan Reguera
- European Molecular Biology Laboratory, Grenoble Outstation and UJF-EMBL-CNRS International Unit of Virus Host-Cell Interactions, 6 rue Jules Horowitz, BP181, Grenoble Cedex 9 38042, France
| | - Stephen Cusack
- European Molecular Biology Laboratory, Grenoble Outstation and UJF-EMBL-CNRS International Unit of Virus Host-Cell Interactions, 6 rue Jules Horowitz, BP181, Grenoble Cedex 9 38042, France
| | - Daniel Kolakofsky
- Department of Microbiology and Molecular Medicine, University of Geneva School of Medicine, CMU, 1 rue Michel-Servet, Geneva 1211, Switzerland.
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