1
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Madsen JJ, Rossman JS. Cholesterol and M2 Rendezvous in Budding and Scission of Influenza A Virus. Subcell Biochem 2023; 106:441-459. [PMID: 38159237 DOI: 10.1007/978-3-031-40086-5_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: 01/03/2024]
Abstract
The cholesterol of the host cell plasma membrane and viral M2 protein plays a crucial role in multiple stages of infection and replication of the influenza A virus. Cholesterol is required for the formation of heterogeneous membrane microdomains (or rafts) in the budozone of the host cell that serves as assembly sites for the viral components. The raft microstructures act as scaffolds for several proteins. Cholesterol may further contribute to the mechanical forces necessary for membrane scission in the last stage of budding and help to maintain the stability of the virus envelope. The M2 protein has been shown to cause membrane scission in model systems by promoting the formation of curved lipid bilayer structures that, in turn, can lead to membrane vesicles budding off or scission intermediates. Membrane remodeling by M2 is intimately linked with cholesterol as it affects local lipid composition, fluidity, and stability of the membrane. Thus, both cholesterol and M2 protein contribute to the efficient and proper release of newly formed influenza viruses from the virus-infected cells.
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Affiliation(s)
- Jesper J Madsen
- Global and Planetary Health, Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, FL, USA.
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.
| | - Jeremy S Rossman
- School of Biosciences, University of Kent, Canterbury, Kent, UK
- Research-Aid Networks, Chicago, IL, USA
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2
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Ftouh M, Kalboussi N, Abid N, Sfar S, Mignet N, Bahloul B. Contribution of Nanotechnologies to Vaccine Development and Drug Delivery against Respiratory Viruses. PPAR Res 2021; 2021:6741290. [PMID: 34721558 PMCID: PMC8550859 DOI: 10.1155/2021/6741290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/08/2021] [Indexed: 12/12/2022] Open
Abstract
According to the Center for Disease Control and Prevention (CDC), the coronavirus disease 2019, a respiratory viral illness linked to significant morbidity, mortality, production loss, and severe economic depression, was the third-largest cause of death in 2020. Respiratory viruses such as influenza, respiratory syncytial virus, SARS-CoV-2, and adenovirus, are among the most common causes of respiratory illness in humans, spreading as pandemics or epidemics throughout all continents. Nanotechnologies are particles in the nanometer range made from various compositions. They can be lipid-based, polymer-based, protein-based, or inorganic in nature, but they are all bioinspired and virus-like. In this review, we aimed to present a short review of the different nanoparticles currently studied, in particular those which led to publications in the field of respiratory viruses. We evaluated those which could be beneficial for respiratory disease-based viruses; those which already have contributed, such as lipid nanoparticles in the context of COVID-19; and those which will contribute in the future either as vaccines or antiviral drug delivery systems. We present a short assessment based on a critical selection of evidence indicating nanotechnology's promise in the prevention and treatment of respiratory infections.
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Affiliation(s)
- Mahdi Ftouh
- Drug Development Laboratory LR12ES09, Faculty of Pharmacy, University of Monastir, Tunisia
| | - Nesrine Kalboussi
- Drug Development Laboratory LR12ES09, Faculty of Pharmacy, University of Monastir, Tunisia
- Sahloul University Hospital, Pharmacy Department, Sousse, Tunisia
| | - Nabil Abid
- Department of Biotechnology, High Institute of Biotechnology of Sidi Thabet, University of Manouba, BP-66, 2020 Ariana, Tunis, Tunisia
- Laboratory of Transmissible Diseases and Biological Active Substances LR99ES27, Faculty of Pharmacy, University of Monastir, Rue Ibn Sina, 5000 Monastir, Tunisia
| | - Souad Sfar
- Drug Development Laboratory LR12ES09, Faculty of Pharmacy, University of Monastir, Tunisia
| | - Nathalie Mignet
- University of Paris, INSERM, CNRS, UTCBS, Faculté de Pharmacie, 4 avenue de l'Observatoire, 75006 Paris, France
| | - Badr Bahloul
- Drug Development Laboratory LR12ES09, Faculty of Pharmacy, University of Monastir, Tunisia
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3
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Selzer L, Su Z, Pintilie GD, Chiu W, Kirkegaard K. Full-length three-dimensional structure of the influenza A virus M1 protein and its organization into a matrix layer. PLoS Biol 2020; 18:e3000827. [PMID: 32997652 PMCID: PMC7549809 DOI: 10.1371/journal.pbio.3000827] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 10/12/2020] [Accepted: 09/08/2020] [Indexed: 02/06/2023] Open
Abstract
Matrix proteins are encoded by many enveloped viruses, including influenza viruses, herpes viruses, and coronaviruses. Underneath the viral envelope of influenza virus, matrix protein 1 (M1) forms an oligomeric layer critical for particle stability and pH-dependent RNA genome release. However, high-resolution structures of full-length monomeric M1 and the matrix layer have not been available, impeding antiviral targeting and understanding of the pH-dependent transitions involved in cell entry. Here, purification and extensive mutagenesis revealed protein–protein interfaces required for the formation of multilayered helical M1 oligomers similar to those observed in virions exposed to the low pH of cell entry. However, single-layered helical oligomers with biochemical and ultrastructural similarity to those found in infectious virions before cell entry were observed upon mutation of a single amino acid. The highly ordered structure of the single-layered oligomers and their likeness to the matrix layer of intact virions prompted structural analysis by cryo-electron microscopy (cryo-EM). The resulting 3.4-Å–resolution structure revealed the molecular details of M1 folding and its organization within the single-shelled matrix. The solution of the full-length M1 structure, the identification of critical assembly interfaces, and the development of M1 assembly assays with purified proteins are crucial advances for antiviral targeting of influenza viruses. Multi-subunit shells of matrix proteins line the interior of infectious influenza virus particles. In this study, biochemical purification of wild-type and mutant influenza M1 proteins allows the structural determination of an oligomer whose shape corresponds to that of infectious virions and suggests mechanisms for its formation and dismantling during infection.
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Affiliation(s)
- Lisa Selzer
- Departments of Genetics Stanford University School of Medicine, Stanford, California, United States of America
| | - Zhaoming Su
- The State Key Laboratory of Biotherapy and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Sichuan, China
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, California, United States of America
| | - Grigore D. Pintilie
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, California, United States of America
| | - Wah Chiu
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, California, United States of America
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail: (KK); (WC)
| | - Karla Kirkegaard
- Departments of Genetics Stanford University School of Medicine, Stanford, California, United States of America
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail: (KK); (WC)
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4
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Shafiuddin M, Boon ACM. RNA Sequence Features Are at the Core of Influenza A Virus Genome Packaging. J Mol Biol 2019; 431:4217-4228. [PMID: 30914291 PMCID: PMC6756997 DOI: 10.1016/j.jmb.2019.03.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 02/18/2019] [Accepted: 03/11/2019] [Indexed: 11/23/2022]
Abstract
The influenza A virus (IAV), a respiratory pathogen for humans, poses serious medical and economic challenges to global healthcare systems. The IAV genome, consisting of eight single-stranded viral RNA segments, is incorporated into virions by a complex process known as genome packaging. Specific RNA sequences within the viral RNA segments serve as signals that are necessary for genome packaging. Although efficient packaging is a prerequisite for viral infectivity, many of the mechanistic details about this process are still missing. In this review, we discuss the recent advances toward the understanding of IAV genome packaging and focus on the RNA features that play a role in this process.
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Affiliation(s)
- Md Shafiuddin
- Department of Internal Medicine, Washington University in Saint Louis School of Medicine, St. Louis, MO 63110, USA
| | - Adrianus C M Boon
- Department of Internal Medicine, Washington University in Saint Louis School of Medicine, St. Louis, MO 63110, USA; Department of Molecular Microbiology and Microbial Pathogenesis, Washington University in Saint Louis School of Medicine, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University in Saint Louis School of Medicine, St. Louis, MO 63110, USA.
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5
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Vahey MD, Fletcher DA. Low-Fidelity Assembly of Influenza A Virus Promotes Escape from Host Cells. Cell 2018; 176:281-294.e19. [PMID: 30503209 DOI: 10.1016/j.cell.2018.10.056] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 09/05/2018] [Accepted: 10/26/2018] [Indexed: 12/11/2022]
Abstract
Influenza viruses inhabit a wide range of host environments using a limited repertoire of protein components. Unlike viruses with stereotyped shapes, influenza produces virions with significant morphological variability even within clonal populations. Whether this tendency to form pleiomorphic virions is coupled to compositional heterogeneity and whether it affects replicative fitness remains unclear. Here, we address these questions by developing a strain of influenza A virus amenable to rapid compositional characterization through quantitative, site-specific labeling of viral proteins. Using this strain, we find that influenza A produces virions with broad variations in size and composition from even single infected cells. This phenotypic variability contributes to virus survival during environmental challenges, including exposure to antivirals. Complementing genetic adaptations that act over larger populations and longer times, this "low-fidelity" assembly of influenza A virus allows small populations to survive environments that fluctuate over individual replication cycles.
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Affiliation(s)
- Michael D Vahey
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA.
| | - Daniel A Fletcher
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA; University of California, Berkeley/University of California, San Francisco Graduate Group in Bioengineering, Berkeley, CA 94720, USA; Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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6
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Chaisri U, Chaicumpa W. Evolution of Therapeutic Antibodies, Influenza Virus Biology, Influenza, and Influenza Immunotherapy. BIOMED RESEARCH INTERNATIONAL 2018; 2018:9747549. [PMID: 29998138 PMCID: PMC5994580 DOI: 10.1155/2018/9747549] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 03/19/2018] [Accepted: 03/31/2018] [Indexed: 02/07/2023]
Abstract
This narrative review article summarizes past and current technologies for generating antibodies for passive immunization/immunotherapy. Contemporary DNA and protein technologies have facilitated the development of engineered therapeutic monoclonal antibodies in a variety of formats according to the required effector functions. Chimeric, humanized, and human monoclonal antibodies to antigenic/epitopic myriads with less immunogenicity than animal-derived antibodies in human recipients can be produced in vitro. Immunotherapy with ready-to-use antibodies has gained wide acceptance as a powerful treatment against both infectious and noninfectious diseases. Influenza, a highly contagious disease, precipitates annual epidemics and occasional pandemics, resulting in high health and economic burden worldwide. Currently available drugs are becoming less and less effective against this rapidly mutating virus. Alternative treatment strategies are needed, particularly for individuals at high risk for severe morbidity. In a setting where vaccines are not yet protective or available, human antibodies that are broadly effective against various influenza subtypes could be highly efficacious in lowering morbidity and mortality and controlling unprecedented epidemic/pandemic. Prototypes of human single-chain antibodies to several conserved proteins of influenza virus with no Fc portion (hence, no ADE effect in recipients) are available. These antibodies have high potential as a novel, safe, and effective anti-influenza agent.
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Affiliation(s)
- Urai Chaisri
- Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Wanpen Chaicumpa
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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7
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Gallagher JR, McCraw DM, Torian U, Gulati NM, Myers ML, Conlon MT, Harris AK. Characterization of Hemagglutinin Antigens on Influenza Virus and within Vaccines Using Electron Microscopy. Vaccines (Basel) 2018; 6:E31. [PMID: 29799445 PMCID: PMC6027289 DOI: 10.3390/vaccines6020031] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 05/11/2018] [Accepted: 05/21/2018] [Indexed: 01/08/2023] Open
Abstract
Influenza viruses affect millions of people worldwide on an annual basis. Although vaccines are available, influenza still causes significant human mortality and morbidity. Vaccines target the major influenza surface glycoprotein hemagglutinin (HA). However, circulating HA subtypes undergo continual variation in their dominant epitopes, requiring vaccines to be updated annually. A goal of next-generation influenza vaccine research is to produce broader protective immunity against the different types, subtypes, and strains of influenza viruses. One emerging strategy is to focus the immune response away from variable epitopes, and instead target the conserved stem region of HA. To increase the display and immunogenicity of the HA stem, nanoparticles are being developed to display epitopes in a controlled spatial arrangement to improve immunogenicity and elicit protective immune responses. Engineering of these nanoparticles requires structure-guided design to optimize the fidelity and valency of antigen presentation. Here, we review electron microscopy applied to study the 3D structures of influenza viruses and different vaccine antigens. Structure-guided information from electron microscopy should be integrated into pipelines for the development of both more efficacious seasonal and universal influenza vaccine antigens. The lessons learned from influenza vaccine electron microscopic research could aid in the development of novel vaccines for other pathogens.
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Affiliation(s)
- John R Gallagher
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA.
| | - Dustin M McCraw
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA.
| | - Udana Torian
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA.
| | - Neetu M Gulati
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA.
| | - Mallory L Myers
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA.
| | - Michael T Conlon
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA.
| | - Audray K Harris
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA.
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8
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Shibata T, Nerome K, Moriyama M, Hayakawa S, Kuroda K. Addition of an EGFP-tag to the N-terminal of influenza virus M1 protein impairs its ability to accumulate in ND10. J Virol Methods 2017; 252:75-79. [PMID: 29174083 DOI: 10.1016/j.jviromet.2017.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 11/10/2017] [Accepted: 11/19/2017] [Indexed: 02/07/2023]
Abstract
A previous report demonstrated that influenza virus infection induces accumulation of EGFP-tagged M1 protein (EGFP-M1) in the sub-nuclear domain ND10. Here, we show that the transfection of four viral protein (NP, PB2, PB1, PA) expression vectors and eight RNA segment expression vectors induced the formation of nuclear dots of EGFP-M1 as seen in virus infections. Omission of the segment 7 RNA expression vector, however, abolished the nuclear dots of EGFP-M1. This result suggests an essential role for authentic M1 protein and/or M2 protein, both of which are encoded in segment 7, in the formation of nuclear dots of EGFP-M1. Co-expression of M1 protein but not M2 protein with EGFP-M1 induced the formation of nuclear dots of EGFP-M1. The dots co-localized with PML protein, which is an indicator of ND10. When only M1 protein was expressed, immunostaining of M1 protein clearly revealed the nuclear dots and their colocalization with PML protein. These results demonstrate that the accumulation in ND10 is an intrinsic characteristic of M1 protein and EGFP addition abolishes this characteristic. The addition of EGFP to M1 protein induced a defect in M1 protein.
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Affiliation(s)
- Toshikatsu Shibata
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Ohyaguchikami-machi, Itabashi-ku, Tokyo 173-8610, Japan
| | - Kuniaki Nerome
- The Institute of Biological Resources, 893-2, Nakayama, Nago, Okinawa 905-0004, Japan
| | - Mitsuhiko Moriyama
- Division of Gastroenterology and Hepatology, Department of Medicine, Nihon University School of Medicine, 30-1 Ohyaguchikami-machi, Itabashi-ku, Tokyo 173-8610, Japan
| | - Satoshi Hayakawa
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Ohyaguchikami-machi, Itabashi-ku, Tokyo 173-8610, Japan
| | - Kazumichi Kuroda
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Ohyaguchikami-machi, Itabashi-ku, Tokyo 173-8610, Japan.
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9
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Gallagher JR, Torian U, McCraw DM, Harris AK. Structural studies of influenza virus RNPs by electron microscopy indicate molecular contortions within NP supra-structures. J Struct Biol 2016; 197:294-307. [PMID: 28007449 DOI: 10.1016/j.jsb.2016.12.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 11/19/2016] [Accepted: 12/16/2016] [Indexed: 12/29/2022]
Abstract
Ribonucleoprotein (RNP) complexes of influenza viruses are composed of multiple copies of the viral nucleoprotein (NP) that can form filamentous supra-structures. RNPs package distinct viral genomic RNA segments of different lengths into pleomorphic influenza virions. RNPs also function in viral RNA transcription and replication. Different RNP segments have varying lengths, but all must be incorporated into virions during assembly and then released during viral entry for productive infection cycles. RNP structures serve varied functions in the viral replication cycle, therefore understanding their molecular organization and flexibility is essential to understanding these functions. Here, we show using electron tomography and image analyses that isolated RNP filaments are not rigid helical structures, but instead display variations in lengths, curvatures, and even tolerated kinks and local unwinding. Additionally, we observed NP rings within RNP preparations, which were commonly composed of 5, 6, or 7 NP molecules and were of similar widths to filaments, suggesting plasticity in NP-NP interactions mediate RNP structural polymorphism. To demonstrate that NP alone could generate rings of variable oligomeric state, we performed 2D single particle image analysis on recombinant NP and found that rings of 4 and 5 protomers dominated, but rings of all compositions up to 7 were directly observed with variable frequency. This structural flexibility may be needed as RNPs carry out the interactions and conformational changes required for RNP assembly and genome packaging as well as virus uncoating.
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Affiliation(s)
- John R Gallagher
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA
| | - Udana Torian
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA
| | - Dustin M McCraw
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA
| | - Audray K Harris
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Room 6351, Bethesda, MD 20892, USA.
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10
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Stauffer S, Nebioglu F, Helenius A. In Vitro Disassembly of Influenza A Virus Capsids by Gradient Centrifugation. J Vis Exp 2016:e53909. [PMID: 27077390 DOI: 10.3791/53909] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Acid-triggered molecular processes closely control cell entry of many viruses that enter through the endocytic system. In the case of influenza A virus (IAV), virus fusion with the endosomal membrane as well as the subsequent disassembly of the viral capsid, called uncoating, is governed by the ionic conditions inside endocytic vesicles. The early steps in the virus life cycle are hard to study because endosomes cannot be directly accessed experimentally, creating the need for an in vitro approach. Here, we describe a method based on velocity gradient centrifugation of purified virions through a two-layer glycerol gradient, which enables analysis of the IAV core and its stability. The gradient contains a non-ionic detergent (NP-40) in its lower layer to remove the viral membrane by solubilization as the virus sediments toward the bottom. At neutral pH, viral cores are pelleted as stable structures. The major core components, matrix protein (M1) and the viral ribonucleoproteins (vRNPs), can be clearly identified in the pellet fraction by SDS-PAGE. Decreasing the pH to 6.0 or lower in the bottom layer selectively removes M1 from the pellet followed by release of vRNPs at more acidic conditions. Viral protein bands on Coomassie-stained gels can be subjected to densitometric quantification to monitor intermediate states of IAV disassembly. Besides pH, other factors that influence viral core stability can be assessed, such as salt concentration and putative viral uncoating factors, simply by modifying the detergent-containing glycerol layer accordingly. Taken together, the presented technique allows highly reproducible and quantitative analysis of viral uncoating in vitro. It can be applied to other enveloped viruses that undergo complex uncoating processes.
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Affiliation(s)
- Sarah Stauffer
- Institute of Biochemistry, ETH Zurich; Department of Biochemistry, University of Zurich;
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11
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Choi HJ, Song JM, Bondy BJ, Compans RW, Kang SM, Prausnitz MR. Effect of Osmotic Pressure on the Stability of Whole Inactivated Influenza Vaccine for Coating on Microneedles. PLoS One 2015; 10:e0134431. [PMID: 26230936 PMCID: PMC4521748 DOI: 10.1371/journal.pone.0134431] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 07/10/2015] [Indexed: 11/18/2022] Open
Abstract
Enveloped virus vaccines can be damaged by high osmotic strength solutions, such as those used to protect the vaccine antigen during drying, which contain high concentrations of sugars. We therefore studied shrinkage and activity loss of whole inactivated influenza virus in hyperosmotic solutions and used those findings to improve vaccine coating of microneedle patches for influenza vaccination. Using stopped-flow light scattering analysis, we found that the virus underwent an initial shrinkage on the order of 10% by volume within 5 s upon exposure to a hyperosmotic stress difference of 217 milliosmolarity. During this shrinkage, the virus envelope had very low osmotic water permeability (1 - 6×10-4 cm s-1) and high Arrhenius activation energy (Ea = 15.0 kcal mol-1), indicating that the water molecules diffused through the viral lipid membranes. After a quasi-stable state of approximately 20 s to 2 min, depending on the species and hypertonic osmotic strength difference of disaccharides, there was a second phase of viral shrinkage. At the highest osmotic strengths, this led to an undulating light scattering profile that appeared to be related to perturbation of the viral envelope resulting in loss of virus activity, as determined by in vitro hemagglutination measurements and in vivo immunogenicity studies in mice. Addition of carboxymethyl cellulose effectively prevented vaccine activity loss in vitro and in vivo, believed to be due to increasing the viscosity of concentrated sugar solution and thereby reducing osmotic stress during coating of microneedles. These results suggest that hyperosmotic solutions can cause biphasic shrinkage of whole inactivated influenza virus which can damage vaccine activity at high osmotic strength and that addition of a viscosity enhancer to the vaccine coating solution can prevent osmotically driven damage and thereby enable preparation of stable microneedle coating formulations for vaccination.
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Affiliation(s)
- Hyo-Jick Choi
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Jae-Min Song
- Department of Global Medical Science, Sungshin Women's University, Seoul, Korea
| | - Brian J. Bondy
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Richard W. Compans
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Sang-Moo Kang
- Center for Inflammation, Immunity, & Infection and Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Mark R. Prausnitz
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- * E-mail:
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12
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Zhang K, Wang Z, Fan GZ, Wang J, Gao S, Li Y, Sun L, Yin CC, Liu WJ. Two polar residues within C-terminal domain of M1 are critical for the formation of influenza A Virions. Cell Microbiol 2015; 17:1583-93. [PMID: 25939747 PMCID: PMC4682459 DOI: 10.1111/cmi.12457] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 04/24/2015] [Accepted: 04/28/2015] [Indexed: 11/29/2022]
Abstract
The matrix protein 1 (M1) is the most abundant structural protein in influenza A virus particles. It oligomerizes to form the matrix layer under the lipid membrane, sustaining stabilization of the morphology of the virion. The present study indicates that M1 forms oligomers based on a fourfold symmetrical oligomerization pattern. Further analysis revealed that the oligomerization pattern of M1 was controlled by a highly conserved region within the C-terminal domain. Two polar residues of this region, serine-183 (S183) and threonine-185 (T185), were identified to be critical for the oligomerization pattern of M1. M1 point mutants suggest that single S183A or T185A substitution could result in the production of morphologically filamentous particles, while double substitutions, M1-S183A/T185A, totally disrupted the fourfold symmetry and resulted in the failure of virus production. These data indicate that the polar groups in these residues are essential to control the oligomerization pattern of M1. Thus, the present study will aid in determining the mechanisms of influenza A virus matrix layer formation during virus morphogenesis.
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Affiliation(s)
- Ke Zhang
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhao Wang
- Department of Biophysics, Health Science Center, Peking University, Beijing, 100191, China.,National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Gui-Zhen Fan
- Department of Biophysics, Health Science Center, Peking University, Beijing, 100191, China
| | - Juan Wang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Shengyan Gao
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yun Li
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Lei Sun
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Chang-Cheng Yin
- Department of Biophysics, Health Science Center, Peking University, Beijing, 100191, China
| | - Wen-Jun Liu
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,Center for Influenza Research and Early-warning, Chinese Academy of Sciences, Beijing, 100101, China
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13
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Hutchinson EC, Charles PD, Hester SS, Thomas B, Trudgian D, Martínez-Alonso M, Fodor E. Conserved and host-specific features of influenza virion architecture. Nat Commun 2014; 5:4816. [PMID: 25226414 PMCID: PMC4167602 DOI: 10.1038/ncomms5816] [Citation(s) in RCA: 193] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/28/2014] [Indexed: 01/11/2023] Open
Abstract
Viruses use virions to spread between hosts, and virion composition is therefore the primary determinant of viral transmissibility and immunogenicity. However, the virions of many viruses are complex and pleomorphic, making them difficult to analyse in detail. Here we address this by identifying and quantifying virion proteins with mass spectrometry, producing a complete and quantified model of the hundreds of viral and host-encoded proteins that make up the pleomorphic virions of influenza viruses. We show that a conserved influenza virion architecture is maintained across diverse combinations of virus and host. This ‘core’ architecture, which includes substantial quantities of host proteins as well as the viral protein NS1, is elaborated with abundant host-dependent features. As a result, influenza virions produced by mammalian and avian hosts have distinct protein compositions. Finally we note that influenza virions share an underlying protein composition with exosomes, suggesting that influenza virions form by subverting microvesicle production.
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Affiliation(s)
- Edward C Hutchinson
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Philip D Charles
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Svenja S Hester
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Benjamin Thomas
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - David Trudgian
- 1] Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK [2]
| | - Mónica Martínez-Alonso
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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14
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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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15
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Zhang K, Wang Z, Liu X, Yin C, Basit Z, Xia B, Liu W. Dissection of influenza A virus M1 protein: pH-dependent oligomerization of N-terminal domain and dimerization of C-terminal domain. PLoS One 2012; 7:e37786. [PMID: 22655068 PMCID: PMC3360003 DOI: 10.1371/journal.pone.0037786] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 04/26/2012] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND The matrix 1 (M1) protein of Influenza A virus plays many critical roles throughout the virus life cycle. The oligomerization of M1 is essential for the formation of the viral matrix layer during the assembly and budding process. METHODOLOGY/PRINCIPAL FINDINGS In the present study, we report that M1 can oligomerize in vitro, and that the oligomerization is pH-dependent. The N-terminal domain of M1 alone exists as multiple-order oligomers at pH 7.4, and the C-terminal domain alone forms an exclusively stable dimer. As a result, intact M1 can display different forms of oligomers and dimer is the smallest oligomerization state, at neutral pH. At pH 5.0, oligomers of the N-terminal domain completely dissociate into monomers, while the C-terminal domain remains in dimeric form. As a result, oligomers of intact M1 dissociate into a stable dimer at acidic pH. CONCLUSIONS/SIGNIFICANCE Oligomerization of M1 involves both the N- and C-terminal domains. The N-terminal domain determines the pH-dependent oligomerization characteristic, and C-terminal domain forms a stable dimer, which contributes to the dimerization of M1. The present study will help to unveil the mechanisms of influenza A virus assembly and uncoating process.
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Affiliation(s)
- Ke Zhang
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Zhao Wang
- Department of Biophysics, Health Science Center, Peking University, Beijing, China
| | - Xiaoling Liu
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Changcheng Yin
- Department of Biophysics, Health Science Center, Peking University, Beijing, China
| | - Zeshan Basit
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Bin Xia
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China
- * E-mail: (WL); (BX)
| | - Wenjun Liu
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Graduate University of Chinese Academy of Sciences, Beijing, China
- * E-mail: (WL); (BX)
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16
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Noda T, Sugita Y, Aoyama K, Hirase A, Kawakami E, Miyazawa A, Sagara H, Kawaoka Y. Three-dimensional analysis of ribonucleoprotein complexes in influenza A virus. Nat Commun 2012; 3:639. [PMID: 22273677 PMCID: PMC3272569 DOI: 10.1038/ncomms1647] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 12/08/2011] [Accepted: 12/15/2011] [Indexed: 02/01/2023] Open
Abstract
The influenza A virus genome consists of eight single-stranded negative-sense RNA (vRNA) segments. Although genome segmentation provides advantages such as genetic reassortment, which contributes to the emergence of novel strains with pandemic potential, it complicates the genome packaging of progeny virions. Here we elucidate, using electron tomography, the three-dimensional structure of ribonucleoprotein complexes (RNPs) within progeny virions. Each virion is packed with eight well-organized RNPs that possess rod-like structures of different lengths. Multiple interactions are found among the RNPs. The position of the eight RNPs is not consistent among virions, but a pattern suggests the existence of a specific mechanism for assembly of these RNPs. Analyses of budding progeny virions suggest two independent roles for the viral spike proteins: RNP association on the plasma membrane and the subsequent formation of the virion shell. Our data provide further insights into the mechanisms responsible for segmented-genome packaging into virions. The influenza A virus genome consists of eight RNA segments, which permits genetic reassortment and contributes to the emergence of novel strains with pandemic potential. Here, electron tomography is used to study the three-dimensional structure of ribonucleoprotein complexes within progeny virions.
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Affiliation(s)
- Takeshi Noda
- Department of Special Pathogens, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
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17
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Abstract
Influenza A virus is an enveloped virus with a segmented, single-strand, negative-sense RNA genome. Its virions show spherical or filamentous shapes of about 100 nm in diameter and occasionally irregular morphology, which exemplifies the pleomorphic nature of these virions. Each viral RNA segment forms a ribonucleoprotein complex (RNP), along with an RNA-dependent RNA polymerase complex and multiple copies of nucleoproteins; the RNPs reside in the enveloped virions. Here, we focus on electron microscopic analyses of influenza virions and RNPs. Based on the morphological and structural observations obtained by using electron microscopic techniques, we present a model of the native morphology of the influenza virion.
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Affiliation(s)
- Takeshi Noda
- Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo Tokyo, Japan
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18
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Noda T, Kawaoka Y. Structure of influenza virus ribonucleoprotein complexes and their packaging into virions. Rev Med Virol 2011; 20:380-91. [PMID: 20853340 DOI: 10.1002/rmv.666] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The influenza A virus genome consists of eight segmented, single-stranded, negative-sense RNAs. Each viral RNA (vRNA) segment forms a ribonucleoprotein (RNP) complex together with NPs and a polymerase complex, which is a fundamental unit for transcription and replication of the viral genome. Although the exact structure of the intact RNP remains poorly understood, recent electron microscopic studies have revealed certain structural characteristics of the RNP. This review focuses on the findings of these various electron microscopic analyses of RNPs extracted from virions and RNPs inside virions. Based on the morphological and structural observations, we present the architecture of RNPs within a virion and discuss the genome packaging mechanism by which the vRNA segments are incorporated into virions.
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Affiliation(s)
- Takeshi Noda
- Department of Special Pathogens, International Research Center for Infectious Diseases, University of Tokyo, Tokyo, Japan.
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19
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Nagabayashi T, Wolf K. Characterization of EV-2, a Virus Isolated from European Eels (Anguilla anguilla) with Stomatopapilloma. J Virol 2010; 30:358-64. [PMID: 16789177 PMCID: PMC353329 DOI: 10.1128/jvi.30.1.358-364.1979] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A virus designated EV-2 has been isolated from external tumor tissue and internal organs of European eels (Anguilla anguilla) with stomatopapilloma. It contains RNA and is ether, acid, and temperature labile above 4 degrees C, and concentrated preparations agglutinate chicken and sheep erythrocytes. The addition of actinomycin D during the first 2.75 h of infection inhibits viral replication. As determined in sucrose gradients, the buoyant density of the virus is 1.19 g/cm(3). EV-2 has a moderately pleomorphic spherical morphology; its diameter ranges from 80 to 140 nm. The virion has narrow, regularly spaced surface projections about 10 nm long. Replication in FHM cells at 15 degrees C shows new infectivity appearing at 10 h postinfection and reaching a plateau at 20 h. Cytopathic effects consist of cell fusion, syncytia, and irregularly rounded cell masses. Viral antigen was detected in the cytoplasm of infected cells by specific immunofluorescence.
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Affiliation(s)
- T Nagabayashi
- U.S. Fish and Wildlife Service, National Fish Health Research Laboratory, National Fisheries Center-Leetown, Kearneysville, West Virginia 25430
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20
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21
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Khan AU, Shakil S, Lal SK. Efficacy of neuraminidase (NA) inhibitors against H1N1 strains of different geographical regions: an in silico approach. Indian J Microbiol 2009; 49:370-6. [PMID: 23100800 PMCID: PMC3450193 DOI: 10.1007/s12088-009-0065-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 11/04/2009] [Indexed: 10/20/2022] Open
Abstract
This report described the efficacy of NA inhibitors against newly evolved strains of H1N1 viruses. This in silico study was designed to understand the mode of interactions of NA inhibitors with NA. Hence, ligand, oseltamivir, zanamivir and peramivir were docked with modeled NA, ACD65204 (USA/2007), BAA06717 (Japan/1992), ACE77988 (S. Korea/2005) and ACD65204 (USA/2007). This study is based on interaction energies. Ramachandran Z-scores for these modeled structures were found to be -0.998, -1.121, -0.870 and -1.023, respectively, which confirms the accuracy of the modeled structures. These interactions revealed that some of these interacting residues have remained conserved throughout all the pandemics. These amino acid residues were found to be R118, R152, R225, E277, E278, R293 and Y402. Moreover, our study concludes that peramivir is the most efficient inhibitor against NA of H1N1.
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Affiliation(s)
- Asad U. Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202002 India
| | - Shazi Shakil
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202002 India
| | - Sunil K. Lal
- International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067 India
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22
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Knyazev DG, Radyukhin VA, Sokolov VS. Intermolecular interactions of influenza M1 proteins on the model lipid membrane surface: A study using the inner field compensation method. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2009. [DOI: 10.1134/s1990747809010115] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Eierhoff T, Ludwig S, Ehrhardt C. The influenza A virus matrix protein as a marker to monitor initial virus internalisation. Biol Chem 2009; 390:509-15. [DOI: 10.1515/bc.2009.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractThe uptake of influenza A viruses (IAV) into cells represents an attractive antiviral drug target, e.g., by interfering with essential cellular or viral entry factors. So far, this process could only be studied by time-consuming microscopical methods. Thus, there is a lack of rapid and easy assay systems to monitor viral entry. Here, we describe a rapid procedure to analyse internalisation of IAV via Western blot detection of virion-associated matrix protein (M1), the most abundant protein within the viral particle. The assay is broadly applicable and detects different virus strains of various subtypes. As a proof of principle, treatment of cells with various known or presumed entry inhibitors resulted in reduced M1 levels. Removal of sialic acids, the receptors for IAV, led to a complete loss of the M1 signal, indicating that virus internalisation can be monitored already at the stage of attachment. Prevention of endosomal acidification resulted in a delayed degradation of M1 indicative of IAV particles trapped in endosomes. Thus, early detection of the virus-associated M1 protein is a rapid method to monitor different steps of influenza virus internalisation and has potential for application as a screening method for drugs that interfere with the uptake of IAV.
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Affiliation(s)
- Thorsten Eierhoff
- Institute of Molecular Virology, Westfälische Wilhelms University, Von Esmarch-Str. 56, D-48149 Münster, Germany
| | - Stephan Ludwig
- Institute of Molecular Virology, Westfälische Wilhelms University, Von Esmarch-Str. 56, D-48149 Münster, Germany
| | - Christina Ehrhardt
- Institute of Molecular Virology, Westfälische Wilhelms University, Von Esmarch-Str. 56, D-48149 Münster, Germany
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24
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Shibata T, Tanaka T, Shimizu K, Hayakawa S, Kuroda K. Immunofluorescence imaging of the influenza virus M1 protein is dependent on the fixation method. J Virol Methods 2008; 156:162-5. [PMID: 19027795 DOI: 10.1016/j.jviromet.2008.10.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 10/21/2008] [Accepted: 10/23/2008] [Indexed: 11/19/2022]
Abstract
The distribution of the matrix (M1) protein of influenza virus in infected cells was examined using immunostaining. The fixation method influenced strongly the immunofluorescence pattern of the M1 protein. The M1 protein was distributed uniformly in both the cytoplasm and in nuclei when cells that had been infected with virus were fixed with paraformaldehyde. In cells that had been fixed with methanol, however, nuclear dots of the M1 protein were clearly visible. The dots were evident at 8h post-inoculation. Up to 6h post-inoculation, only a diffuse distribution of the M1 protein was observed. The dots were co-localized with promyelocytic leukemia (PML) protein, a major component of nuclear domain 10 (ND10), also called PML oncogenic domains (PODs) or PML-nuclear bodies (NBs). These results indicate that the nuclear dots of the M1 protein in cells that had been fixed with methanol are not artifacts of the fixation method. Furthermore, methanol fixation is preferred for localization of the influenza M1 protein in nuclei using immunostaining.
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Affiliation(s)
- Toshikatsu Shibata
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Oyaguchi-kami-cho, Itabashi-ku, Tokyo, 173-8610, Japan
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25
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Studies of an influenza A virus temperature-sensitive mutant identify a late role for NP in the formation of infectious virions. J Virol 2008; 83:562-71. [PMID: 18987140 DOI: 10.1128/jvi.01424-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influenza A virus nucleoprotein (NP) is a single-stranded RNA-binding protein that encapsidates the virus genome and has essential functions in viral-RNA synthesis. Here, we report the characterization of a temperature-sensitive (ts) NP mutant (US3) originally generated in fowl plague virus (A/chicken/Rostock/34). Sequence analysis revealed a single mutation, M239L, in NP, consistent with earlier mapping studies assigning the ts lesion to segment 5. Introduction of this mutation into A/PR/8/34 virus by reverse genetics produced a ts phenotype, confirming the identity of the lesion. Despite an approximately 100-fold drop in the viral titer at the nonpermissive temperature, the mutant US3 polypeptide supported wild-type (WT) levels of genome transcription, replication, and protein synthesis, indicating a late-stage defect in function of the NP polypeptide. Nucleocytoplasmic trafficking of the US3 NP was also normal, and the virus actually assembled and released around sixfold more virus particles than the WT virus, with normal viral-RNA content. However, the particle/PFU ratio of these virions was 50-fold higher than that of WT virus, and many particles exhibited an abnormal morphology. Reverse-genetics studies in which A/PR/8/34 segment 7 was swapped with sequences from other strains of virus revealed a profound incompatibility between the M239L mutation and the A/Udorn/72 M1 gene, suggesting that the ts mutation affects M1-NP interactions. Thus, we have identified a late-acting defect in NP that, separate from its function in RNA synthesis, indicates a role for the polypeptide in virion assembly, most likely involving M1 as a partner.
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26
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Abstract
The genomic viral RNA (vRNA) segments of influenza A virus contain specific packaging signals at their termini that overlap the coding regions. To further characterize cis-acting signals in segment 7, we introduced synonymous mutations into the terminal coding regions. Mutation of codons that are normally highly conserved reduced virus growth in embryonated eggs and MDCK cells between 10- and 1,000-fold compared to that of the wild-type virus, whereas similar alterations to nonconserved codons had little effect. In all cases, the growth-impaired viruses showed defects in virion assembly and genome packaging. In eggs, nearly normal numbers of virus particles that in aggregate contained apparently equimolar quantities of the eight segments were formed, but with about fourfold less overall vRNA content than wild-type virions, suggesting that, on average, fewer than eight segments per particle were packaged. Concomitantly, the particle/PFU and segment/PFU ratios of the mutant viruses showed relative increases of up to 300-fold, with the behavior of the most defective viruses approaching that predicted for random segment packaging. Fluorescent staining of infected cells for the nucleoprotein and specific vRNAs confirmed that most mutant virus particles did not contain a full genome complement. The specific infectivity of the mutant viruses produced by MDCK cells was also reduced, but in this system, the mutations also dramatically reduced virion production. Overall, we conclude that segment 7 plays a key role in the influenza A virus genome packaging process, since mutation of as few as 4 nucleotides can dramatically inhibit infectious virus production through disruption of vRNA packaging.
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27
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Harris A, Cardone G, Winkler DC, Heymann JB, Brecher M, White JM, Steven AC. Influenza virus pleiomorphy characterized by cryoelectron tomography. Proc Natl Acad Sci U S A 2006; 103:19123-7. [PMID: 17146053 PMCID: PMC1748186 DOI: 10.1073/pnas.0607614103] [Citation(s) in RCA: 365] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Indexed: 11/18/2022] Open
Abstract
Influenza virus remains a global health threat, with millions of infections annually and the impending threat that a strain of avian influenza may develop into a human pandemic. Despite its importance as a pathogen, little is known about the virus structure, in part because of its intrinsic structural variability (pleiomorphy): the primary distinction is between spherical and elongated particles, but both vary in size. Pleiomorphy has thwarted structural analysis by image reconstruction of electron micrographs based on averaging many identical particles. In this study, we used cryoelectron tomography to visualize the 3D structures of 110 individual virions of the X-31 (H3N2) strain of influenza A. The tomograms distinguish two kinds of glycoprotein spikes [hemagglutinin (HA) and neuraminidase (NA)] in the viral envelope, resolve the matrix protein layer lining the envelope, and depict internal configurations of ribonucleoprotein (RNP) complexes. They also reveal the stems that link the glycoprotein ectodomains to the membrane and interactions among the glycoproteins, the matrix, and the RNPs that presumably control the budding of nascent virions from host cells. Five classes of virions, four spherical and one elongated, are distinguished by features of their matrix layer and RNP organization. Some virions have substantial gaps in their matrix layer ("molecular fontanels"), and others appear to lack a matrix layer entirely, suggesting the existence of an alternative budding pathway in which matrix protein is minimally involved.
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Affiliation(s)
- Audray Harris
- *Laboratory of Structural Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892; and
| | - Giovanni Cardone
- *Laboratory of Structural Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892; and
| | - Dennis C. Winkler
- *Laboratory of Structural Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892; and
| | - J. Bernard Heymann
- *Laboratory of Structural Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892; and
| | - Matthew Brecher
- Department of Microbiology, University of Virginia, Charlottesville, VA 22908
| | - Judith M. White
- Department of Microbiology, University of Virginia, Charlottesville, VA 22908
| | - Alasdair C. Steven
- *Laboratory of Structural Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892; and
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28
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Anwar T, Lal SK, Khan AU. Matrix protein 1: A comparative in silico study on different strains of influenza A H5N1 Virus. Bioinformation 2006; 1:253-6. [PMID: 17597902 PMCID: PMC1891697 DOI: 10.6026/97320630001253] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Accepted: 11/21/2006] [Indexed: 11/24/2022] Open
Abstract
The importance of influenza viruses as worldwide infectious agents is well
recognized. Specific mutations and evolution in influenza viruses is difficult
to predict. We studied specific mutations in matrix protein 1 (M1) of H5N1
influenza A virus together with properties associated with it using prediction
tools developed in Bioinformatics. Changes in hydrophobicity, polarity and
secondary structure at the site of mutation were noticed and documented to gain
insight towards its infection.
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Affiliation(s)
| | - Sunil K Lal
- International Center for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Asad U Khan
- Distributed Information Sub-centre
- Interdisciplinary Biotechnology Unit Aligarh Muslim University, Aligarh 202002, India
- Asad U Khan
E-mail:
Phone: +91 571 2723088; Fax: +91 571 2721776; Corresponding author
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29
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30
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Bourmakina SV, García-Sastre A. The morphology and composition of influenza A virus particles are not affected by low levels of M1 and M2 proteins in infected cells. J Virol 2005; 79:7926-32. [PMID: 15919950 PMCID: PMC1143655 DOI: 10.1128/jvi.79.12.7926-7932.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We generated a recombinant influenza A virus (Mmut) that produced low levels of matrix (M1) and M2 proteins in infected cells. Mmut virus propagated to significantly lower titers than did wild-type virus in cells infected at low multiplicity. By contrast, virion morphology and incorporation of viral proteins and vRNAs into virus particles were similar to those of wild-type virus. We propose that a threshold amount of M1 protein is needed for the assembly of viral components into an infectious particle and that budding is delayed in Mmut virus-infected cells until sufficient levels of M1 protein accumulate at the plasma membrane.
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Affiliation(s)
- Svetlana V Bourmakina
- Department of Microbiology, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, Box 1124, New York, NY 10029, USA
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31
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Garcia-Robles I, Akarsu H, Müller CW, Ruigrok RWH, Baudin F. Interaction of influenza virus proteins with nucleosomes. Virology 2005; 332:329-36. [PMID: 15661164 DOI: 10.1016/j.virol.2004.09.036] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2004] [Revised: 08/23/2004] [Accepted: 09/28/2004] [Indexed: 11/19/2022]
Abstract
During influenza virus infection, transcription and replication of the viral RNA take place in the cell nucleus. Directly after entry in the nucleus the viral ribonucleoproteins (RNPs, the viral subunits containing vRNA, nucleoprotein and the viral polymerase) are tightly associated with the nuclear matrix. Here, we have analysed the binding of RNPs, M1 and NS2/NEP proteins to purified nucleosomes, reconstituted histone octamers and purified single histones. RNPs and M1 both bind to the chromatin components but at two different sites, RNP to the histone tails and M1 to the globular domain of the histone octamer. NS2/NEP did not bind to nucleosomes at all. The possible consequences of these findings for nuclear release of newly made RNPs and for other processes during the infection cycle are discussed.
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32
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Burleigh LM, Calder LJ, Skehel JJ, Steinhauer DA. Influenza a viruses with mutations in the m1 helix six domain display a wide variety of morphological phenotypes. J Virol 2005; 79:1262-70. [PMID: 15613353 PMCID: PMC538569 DOI: 10.1128/jvi.79.2.1262-1270.2005] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several functions required for the replication of influenza A viruses have been attributed to the viral matrix protein (M1), and a number of studies have focused on a region of the M1 protein designated "helix six." This region contains an exposed positively charged stretch of amino acids, including the motif 101-RKLKR-105, which has been identified as a nuclear localization signal, but several studies suggest that this domain is also involved in functions such as binding to the ribonucleoprotein genome segments (RNPs), membrane association, interaction with the viral nuclear export protein, and virus assembly. In order to define M1 functions in more detail, a series of mutants containing alanine substitutions in the helix six region were generated in A/WSN/33 virus. These were analyzed for RNP-binding function, their capacity to incorporate into infectious viruses by using reverse genetics, the replication properties of rescued viruses, and the morphological phenotypes of the mutant virus particles. The most notable effect that was identified concerned single amino acid substitution mutants that caused significant alterations to the morphology of budded viruses. Whereas A/WSN/33 virus generally forms particles that are predominantly spherical, observations made by negative stain electron microscopy showed that several of the mutant virions, such as K95A, K98A, R101A, and K102A, display a wide range of shapes and sizes that varied in a temperature-dependent manner. The K102A mutant is particularly interesting in that it can form extended filamentous particles. These results support the proposition that the helix six domain is involved in the process of virus assembly.
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Affiliation(s)
- Laura M Burleigh
- Department of Microbiology and Immunology, Emory University School of Medicine, Rollins Research Center, 1510 Clifton Rd., Atlanta, GA 30322, USA
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Abstract
Influenza viruses are causative agents of an acute febrile respiratory disease called influenza (commonly known as "flu") and belong to the Orthomyxoviridae family. These viruses possess segmented, negative stranded RNA genomes (vRNA) and are enveloped, usually spherical and bud from the plasma membrane (more specifically, the apical plasma membrane of polarized epithelial cells). Complete virus particles, therefore, are not found inside infected cells. Virus particles consist of three major subviral components, namely the viral envelope, matrix protein (M1), and core (viral ribonucleocapsid [vRNP]). The viral envelope surrounding the vRNP consists of a lipid bilayer containing spikes composed of viral glycoproteins (HA, NA, and M2) on the outer side and M1 on the inner side. Viral lipids, derived from the host plasma membrane, are selectively enriched in cholesterol and glycosphingolipids. M1 forms the bridge between the viral envelope and the core. The viral core consists of helical vRNP containing vRNA (minus strand) and NP along with minor amounts of NEP and polymerase complex (PA, PB1, and PB2). For viral morphogenesis to occur, all three viral components, namely the viral envelope (containing lipids and transmembrane proteins), M1, and the vRNP must be brought to the assembly site, i.e. the apical plasma membrane in polarized epithelial cells. Finally, buds must be formed at the assembly site and virus particles released with the closure of buds. Transmembrane viral proteins are transported to the assembly site on the plasma membrane via the exocytic pathway. Both HA and NA possess apical sorting signals and use lipid rafts for cell surface transport and apical sorting. These lipid rafts are enriched in cholesterol, glycosphingolipids and are relatively resistant to neutral detergent extraction at low temperature. M1 is synthesized on free cytosolic polyribosomes. vRNPs are made inside the host nucleus and are exported into the cytoplasm through the nuclear pore with the help of M1 and NEP. How M1 and vRNPs are directed to the assembly site on the plasma membrane remains unclear. The likely possibilities are that they use a piggy-back mechanism on viral glycoproteins or cytoskeletal elements. Alternatively, they may possess apical determinants or diffuse to the assembly site, or a combination of these pathways. Interactions of M1 with M1, M1 with vRNP, and M1 with HA and NA facilitate concentration of viral components and exclusion of host proteins from the budding site. M1 interacts with the cytoplasmic tail (CT) and transmembrane domain (TMD) of glycoproteins, and thereby functions as a bridge between the viral envelope and vRNP. Lipid rafts function as microdomains for concentrating viral glycoproteins and may serve as a platform for virus budding. Virus bud formation requires membrane bending at the budding site. A combination of factors including concentration of and interaction among viral components, increased viscosity and asymmetry of the lipid bilayer of the lipid raft as well as pulling and pushing forces of viral and host components are likely to cause outward curvature of the plasma membrane at the assembly site leading to bud formation. Eventually, virus release requires completion of the bud due to fusion of the apposing membranes, leading to the closure of the bud, separation of the virus particle from the host plasma membrane and release of the virus particle into the extracellular environment. Among the viral components, M1 contains an L domain motif and plays a critical role in budding. Bud completion requires not only viral components but also host components. However, how host components facilitate bud completion remains unclear. In addition to bud completion, influenza virus requires NA to release virus particles from sialic acid residues on the cell surface and spread from cell to cell. Elucidation of both viral and host factors involved in viral morphogenesis and budding may lead to the development of drugs interfering with the steps of viral morphogenesis and in disease progression.
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Affiliation(s)
- Debi P Nayak
- Department of Microbiology, Immunology and Molecular Genetics, Jonsson Comprehensive Cancer Center, Molecular Biology Institute, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA.
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Liu T, Ye Z. Introduction of a temperature-sensitive phenotype into influenza A/WSN/33 virus by altering the basic amino acid domain of influenza virus matrix protein. J Virol 2004; 78:9585-91. [PMID: 15331690 PMCID: PMC514994 DOI: 10.1128/jvi.78.18.9585-9591.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Our previous studies with influenza A viruses indicated that the association of M1 with viral RNA and nucleoprotein (NP) is required for the efficient formation of helical ribonucleoprotein (RNP) and for the nuclear export of RNPs. RNA-binding domains of M1 map to the following two independent regions: a zinc finger motif at amino acid positions 148 to 162 and a series of basic amino acids (RKLKR) at amino acid positions 101 to 105. Altering the zinc finger motif of M1 reduces viral growth slightly. A substitution of Ser for Arg at either position 101 or position 105 of the RKLKR domain partially reduces the nuclear export of RNP and viral replication. To further understand the role of the zinc finger motif and the RKLKR domain in viral assembly and replication, we introduced multiple mutations by using reverse genetics to modify these regions of the M gene of influenza virus A/WSN/33. Of multiple mutants analyzed, a double mutant, R101S-R105S, of RKLKR resulted in a temperature-sensitive phenotype. The R101S-R105S double mutant had a greatly reduced ratio of M1 to NP in viral particles and a weaker binding of M1 to RNPs. These results suggest that mutations can be introduced into the RKLKR domain to control viral replication.
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Affiliation(s)
- Teresa Liu
- Laboratory of Pediatric and Respiratory Viral Diseases, Division of Viral Products, Office of Vaccine Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA
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35
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Hui EKW, Barman S, Yang TY, Nayak DP. Basic residues of the helix six domain of influenza virus M1 involved in nuclear translocation of M1 can be replaced by PTAP and YPDL late assembly domain motifs. J Virol 2003; 77:7078-92. [PMID: 12768027 PMCID: PMC156155 DOI: 10.1128/jvi.77.12.7078-7092.2003] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Influenza type A virus matrix (M1) protein possesses multiple functional motifs in the helix 6 (H6) domain (amino acids 91 to 105), including nuclear localization signal (NLS) (101-RKLKR-105) involved in translocating M1 from the cytoplasm into the nucleus. To determine the role of the NLS motif in the influenza virus life cycle, we mutated these and the neighboring sequences by site-directed mutagenesis, and influenza virus mutants were generated by reverse genetics. Our results show that infectious viruses were rescued by reverse genetics from all single alanine mutations of amino acids in the H6 domain and the neighboring region except in three positions (K104A and R105A within the NLS motif and E106A in loop 6 outside the NLS motif). Among the rescued mutant viruses, R101A and R105K exhibited reduced growth and small-plaque morphology, and all other mutant viruses showed the wild-type phenotype. On the other hand, three single mutations (K104A, K105A, and E106A) and three double mutations (R101A/K102A, K104A/K105A, and K102A/R105A) failed to generate infectious virus. Deletion (Delta YRKL) or mutation (4A) of YRKL also abolished generation of infectious virus. However, replacement of the YRKL motif with PTAP or YPDL as well as insertion of PTAP after 4A mutation yielded infectious viruses with the wild-type phenotype. Furthermore, mutant M1 proteins (R101A/K102A, Delta YRKL, 4A, PTAP, 4A+PTAP, and YPDL) when expressed alone from cloned cDNAs were only cytoplasmic, whereas the wild-type M1 expressed alone was both nuclear and cytoplasmic as expected. These results show that the nuclear translocation function provided by the positively charged residues within the NLS motif does not play a critical role in influenza virus replication. Furthermore, these sequences of H6 domain can be replaced by late (L) domain motifs and therefore may provide a function similar to that of the L domains of other negative-strand RNA and retroviruses.
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Affiliation(s)
- Eric Ka-Wai Hui
- Department of Microbiology, Immunology and Molecular Genetics, Jonsson Comprehensive Cancer Center, Molecular Biology Institute, UCLA School of Medicine, Los Angeles, California 90095-1747, USA
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Sato Y, Yoshioka K, Suzuki C, Awashima S, Hosaka Y, Yewdell J, Kuroda K. Localization of influenza virus proteins to nuclear dot 10 structures in influenza virus-infected cells. Virology 2003; 310:29-40. [PMID: 12788628 DOI: 10.1016/s0042-6822(03)00104-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We studied influenza virus M1 protein by generating HeLa and MDCK cell lines that express M1 genetically fused to green fluorescent protein (GFP). GFP-M1 was incorporated into virions produced by influenza virus infected MDCK cells expressing the fusion protein indicating that the fusion protein is at least partially functional. Following infection of either HeLa or MDCK cells with influenza A virus (but not influenza B virus), GFP-M1 redistributes from its cytosolic/nuclear location and accumulates in nuclear dots. Immunofluorescence revealed that the nuclear dots represent nuclear dot 10 (ND10) structures. The colocalization of authentic M1, as well as NS1 and NS2 protein, with ND10 was confirmed by immunofluorescence following in situ isolation of ND10. These findings demonstrate a previously unappreciated involvement of influenza virus with ND10, a structure involved in cellular responses to immune cytokines as well as the replication of a rapidly increasing list of viruses.
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Affiliation(s)
- Yoshiko Sato
- Department of Virology and Immunology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Liu T, Muller J, Ye Z. Association of influenza virus matrix protein with ribonucleoproteins may control viral growth and morphology. Virology 2002; 304:89-96. [PMID: 12490406 DOI: 10.1006/viro.2002.1669] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The matrix protein (M1) of influenza virus plays a central role in viral replication. In relation to viral growth and morphology, we studied the RNP-binding activity of M1s from high-growth strain A/Puerto Rico/8/34 (A/PR8/34) and the relatively low-growth wild-type strain A/Nanchang/933/95. The RNP-binding strength of M1 was studied by disruption of M1 from M1/RNP complexes with salt and acidic condition. Our results indicated that binding of M1 of high-growth A/PR8/34 was more difficult to break than the binding of M1 of low-growth A/Nanchang/933/95. Consistent with the presence of M1 in A/PR8/34, binding of M1 of Resvir-9, a reassortant containing P, M, and NS genes from A/PR8/34 and the rest of genes from A/Nanchang/933/95 and retaining relative high-growth characteristic, was relatively difficult to break than the binding of M1 of A/Nanchang/933/95. Physical properties of morphological features of these viruses were studied by velocity sucrose gradient centrifugation and transmission electron microscopy of purified viral particles, and by immunofluorescence staining of hemagglutinin expressed on the surface of infected cells. The results demonstrated that high-growth strains, A/PR8/34, and a relative high-growth reassortant, Resvir-9, had characteristics associated predominantly with spherical particles, while the low-growth strain, A/Nanchang/933/95, had characteristics of filamentous particles. These studies indicate that the binding between M1 and RNP complex might determine viral growth and morphology.
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Affiliation(s)
- Teresa Liu
- Laboratory of Pediatric and Respiratory Viral Diseases, Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics and Evaluation and Research, Food and Drug Administtration, Bethesda, Maryland 20892, USA
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38
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Abstract
The matrix protein (M1) of influenza virus plays an essential role in viral assembly and has a variety of functions, including association with influenza virus ribonucleoprotein (RNP). Our previous studies show that the association of M1 with viral RNA and nucleoprotein not only promotes formation of helical RNP but also is required for export of RNP from the nucleus during viral replication. The RNA-binding domains of M1 have been mapped to two independent regions: a zinc finger motif at amino acid positions 148 to 162 and a series of basic amino acids (RKLKR) at amino acid positions 101 to 105, which is also involved in RNP-binding activity. To further understand the role of the RNP-binding domain of M1 in viral assembly and replication, mutations in the coding sequences of RKLKR and the zinc finger motif of M1 were constructed using a PCR technique and introduced into wild-type influenza virus by reverse genetics. Altering the zinc finger motif of M1 only slightly affected viral growth. Substitution of Arg with Ser at position 101 or 105 of RKLKR did not have a major impact on nuclear export of RNP or viral replication. In contrast, deletion of RKLKR or substitution of Lys with Asn at position 102 or 104 of RKLKR resulted in a lethal mutation. These results indicate that the RKLKR domain of M1 protein plays an important role in viral replication.
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Affiliation(s)
- Teresa Liu
- Laboratory of Pediatric and Respiratory Viral Diseases, Division of Viral Products, Food and Drug Administration, Building 29A, 8800 Rockville Pike, Bethesda, MD 20892, USA
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39
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Ruigrok R, Baudin F, Petit I, Weissenhorn W. Role of influenza virus M1 protein in the viral budding process. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0531-5131(01)00637-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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40
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Huang X, Liu T, Muller J, Levandowski RA, Ye Z. Effect of influenza virus matrix protein and viral RNA on ribonucleoprotein formation and nuclear export. Virology 2001; 287:405-16. [PMID: 11531417 DOI: 10.1006/viro.2001.1067] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The formation of influenza virus ribonucleoprotein (RNP) is a necessary step in viral assembly and maturation in infected cells, but the mechanism remains incompletely understood. Influenza virus proteins such as matrix (M1) and cellular proteins have been implicated in assembly and transport of RNP. To study the assembly of RNP and the translocation of RNP complexes in cells, RNPs were reconstituted from nucleoprotein (NP), M1, and viral RNA (vRNA) synthesized in vitro. The syntheses were accomplished using specific plasmids in a system coupling transcription and translation under the control of the T7 promoter. The density of the resulting RNP complexes was analyzed by glycerol gradient centrifugation and the morphology was examined by transmission electron microscopy. Protomers of NP self-assembled into circular oligomers regardless of the presence of vRNA or M1. However, helical structures similar in conformation and density to RNPs purified directly from influenza virus were formed only when M1 and vRNA were also present. In the absence of vRNA, no helical structures were formed from NP and M1. The plasmids also contained the CMV promoter, which permitted expression of M1, NP, and vRNA in Madin-Darby canine kidney (MDCK). M1 and NP were both present in the cytoplasm of MDCK also expressing vRNA, but NP was retained in the nucleus of cells expressing M1 without vRNA. Our data demonstrate for the first time that vRNA and M1 together promote the self-assembly of influenza virus NP into the quaternary helical structure typical of the viral RNP. The results also indicate that the interaction of NP with vRNA and M1 in a system devoid of other viral proteins can lead to translocation of RNP from nucleus to cytoplasm.
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Affiliation(s)
- X Huang
- Laboratory of Pediatric and Respiratory Viral Diseases, Laboratory of Vector-Borne Viral Disease, Division of Viral Products, Office of Vaccines Research and Review, Food and Drug Administration, Maryland, Bethesda 20892, USA
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41
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Baudin F, Petit I, Weissenhorn W, Ruigrok RW. In vitro dissection of the membrane and RNP binding activities of influenza virus M1 protein. Virology 2001; 281:102-8. [PMID: 11222100 DOI: 10.1006/viro.2000.0804] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Spontaneous proteolysis of influenza virus M1 protein during crystallisation has defined an N-terminal domain of amino acids 1--164. Full-length M1, the N-terminal domain, and the C-terminal part of M1 (residues 165--252) were produced in Escherichia coli. In vitro tests showed that only full-length M1 and its N-terminal domain bind to negatively charged liposomes and that only full-length M1 and its C-terminal part bind to RNP. However, only full-length M1 had transcription inhibition activity. Several independent experimental approaches indicate that in vitro transcription inhibition occurs through polymerisation/aggregation of M1 onto RNP, or of M1 onto M1 already bound to RNP, rather than by binding to a specific active site on the nucleoprotein or the polymerase. The structure/function of influenza virus M1 will be compared with that of the Ebola virus matrix protein, VP40.
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Affiliation(s)
- F Baudin
- EMBL Grenoble Outstation, B.P. 156, 38042 Grenoble Cedex 9, France
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42
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Ruigrok RW, Barge A, Durrer P, Brunner J, Ma K, Whittaker GR. Membrane interaction of influenza virus M1 protein. Virology 2000; 267:289-98. [PMID: 10662624 DOI: 10.1006/viro.1999.0134] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The M1 protein of influenza virus is thought to make contact with the cytoplasmic tails of the glycoprotein spikes, lipid molecules in the viral membrane, and the internal ribonucleoprotein particles. Here we show electron micrographs of negatively stained virus particles in which M1 is visualized as a 60-A-long rod that touches the membrane but apparently is not membrane inserted. Photolabeling with a membrane restricted reagent resulted in labeling of the transmembrane region of haemagglutinin but not of M1, also suggesting that most of M1 is not embedded into the hydrophobic core of the viral membrane. Finally, in vitro reconstitution experiments using soluble M1 protein and synthetic liposomes or Madin-Darby canine kidney cell membranes suggest that M1 can bind to negatively charged liposomes and to the cellular membranes and that this binding can be prevented under high-salt conditions. Although none of these experiments prove that there does not exist a minor fraction of M1 that is membrane inserted, it appears that most of M1 in the virus is membrane associated through electrostatic interactions.
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Affiliation(s)
- R W Ruigrok
- EMBL Grenoble Outstation, Grenoble Cedex 9, 38042, France.
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43
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Zhirnov OP, Konakova TE, Garten W, Klenk H. Caspase-dependent N-terminal cleavage of influenza virus nucleocapsid protein in infected cells. J Virol 1999; 73:10158-63. [PMID: 10559331 PMCID: PMC113068 DOI: 10.1128/jvi.73.12.10158-10163.1999] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/1999] [Accepted: 08/26/1999] [Indexed: 12/23/2022] Open
Abstract
The nucleocapsid protein (NP) (56 kDa) of human influenza A viruses is cleaved in infected cells into a 53-kDa form. Likewise, influenza B virus NP (64 kDa) is cleaved into a 55-kDa protein with a 62-kDa intermediate (O. P. Zhirnov and A. G. Bukrinskaya, Virology 109:174-179, 1981). We show now that an antibody specific for the N terminus of influenza A virus NP reacted with the uncleaved 56-kDa form but not with the truncated NP53 form, indicating the removal of a 3-kDa peptide from the N terminus. Amino acid sequencing revealed the cleavage sites ETD16*G for A/Aichi/68 NP and sites DID7*G and EAD61*V for B/Hong Kong/72 NP. With D at position -1, acidic amino acids at position -3, and aliphatic ones at positions -2 and +1, the NP cleavage sites show a recognition motif typical for caspases, key enzymes of apoptosis. These caspase cleavage sites demonstrated evolutionary stability and were retained in NPs of all human influenza A and B viruses. NP of avian influenza viruses, which is not cleaved in infected cells, contains G instead of D at position 16. Oligopeptide DEVD derivatives, specific caspase inhibitors, were shown to prevent the intracellular cleavage of NP. All three events, the NP cleavage, the increase of caspase activity, and the development of apoptosis, coincide in cells infected with human influenza A and B viruses. The data suggest that intracellular cleavage of NP is exerted by host caspases and is associated with the development of apoptosis at the late stages of infection.
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Affiliation(s)
- O P Zhirnov
- D. I. Ivanovsky Institute of Virology, 123098 Moscow, Russia.
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44
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Ye Z, Liu T, Offringa DP, McInnis J, Levandowski RA. Association of influenza virus matrix protein with ribonucleoproteins. J Virol 1999; 73:7467-73. [PMID: 10438836 PMCID: PMC104273 DOI: 10.1128/jvi.73.9.7467-7473.1999] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To characterize the sites and nature of binding of influenza A virus matrix protein (M1) to ribonucleoprotein (RNP), M1 of A/WSN/33 was altered by deletion or site-directed mutagenesis, expressed in vitro, and allowed to attach to RNP under a variety of conditions. Approximately 70% of the wild-type (Wt) M1 bound to RNP at pH 7.0, but less than 5% of M1 associated with RNP at pH 5.0. Increasing the concentration of NaCl reduced M1 binding, but even at a high salt concentration (0.6 M NaCl), approximately 20% of the input M1 was capable of binding to RNP. Mutations altering potential M1 RNA-binding regions (basic amino acids 101RKLKR105 and the zinc finger motif at amino acids 148 to 162) had varied effect: mutations of amino acids 101 to 105 reduced RNP binding compared to the Wt M1, but mutations of zinc finger motif did not. Treatment of RNP with RNase reduced M1 binding by approximately half, but even M1 mutants lacking RNA-binding regions had residual binding to RNase-treated RNP provided that the N-terminal 76 amino acids of M1 (containing two hydrophobic domains) were intact. Addition of detergent to the reaction mixture further reduced binding related to the N-terminal 76 amino acids and showed the greatest effect for mutations affecting the RNA-binding regions of basic amino acids. The data suggest that M1 interacts with both the RNA and protein components of RNP in assembly and disassembly of influenza A viruses.
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Affiliation(s)
- Z Ye
- Laboratory of Pediatric and Respiratory Viral Diseases, Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA.
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45
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Abstract
Matrix protein M1 purified from influenza A and B viruses has been analyzed for its ability to specifically interact with cellular proteins by immune coprecipitation and by an in vitro binding assay on nitrocellulose on PVDF membranes. When M1 was mixed with lysates of uninfected cells there was selective binding of histones H2A, H2B, H3, and H4. Week binding of H1 was also observed. The binding specificity of M1 was confirmed by using purified histones. The M1-histone complexes were dependent on pH and ionic strength, indicating electrostatic interactions. Chemical cleavage of M1 by formic acid into an N-terminal 9-kDa fragment and a C-terminal 18-kDa fragment did not abolish interaction with histones. However, after treatment with 1 M sodium chloride cleaved M1 no longer bound to histones, whereas uncleaved M1 showed an increased binding activity after salt treatment. These findings suggest that both N- and C-terminal domains of M1 are involved in histone binding and that conformation of M is an important factor in this interaction. The data support the notion that there is specific interaction of M1 with nucleosomes during the nuclear phase of influenza virus replication.
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Affiliation(s)
- O P Zhirnov
- D. I. Ivanovsky Institute of Virology, Moscow, Russia
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46
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Mena I, Vivo A, Pérez E, Portela A. Rescue of a synthetic chloramphenicol acetyltransferase RNA into influenza virus-like particles obtained from recombinant plasmids. J Virol 1996; 70:5016-24. [PMID: 8764008 PMCID: PMC190455 DOI: 10.1128/jvi.70.8.5016-5024.1996] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We have shown previously that COS-1 cells infected with a vaccinia virus recombinant (vTF7-3) which expresses the T7 RNA polymerase gene and then transfected with four pGEM-derived plasmids encoding the influenza A virus core proteins (nucleoprotein, PB1, PB2, and PA polypeptides) can express a synthetic influenza virus-like chloramphenicol [correction of chloramphenical] acetyltransferase (CAT) RNA (I. Mena, S. de la Luna, C. Albo, J. Martín, A. Nieto, J. Ortín, and A. Portela, J. Gen. Virol. 75:2109-2114, 1994). Here we demonstrate that by supplying the vTF7-3-infected cells with plasmids containing cDNAs of all 10 influenza virus-encoded proteins, the transfected CAT RNA can be expressed and rescued into particles that are budded into the supernatant fluids. The released particles can transfer the enclosed CAT RNA to MDCK cultures and resemble true influenza virions in that they require trypsin treatment to deliver the RNA to fresh cells and are neutralized by a monoclonal antibody specific for the influenza A virus hemagglutinin. Moreover, analysis by electron microscopy showed that the culture medium harvested from the transfected cells contained vesicles that could be labeled with an anti-HA monoclonal antibody and that were similar in size and morphology to authentic influenza virus particles. It is also shown that detection of recombinant particles capable of transmitting the CAT RNA does not require expression of the influenza virus nonstructural protein NS1. All of these data indicate that influenza virus-like particles enclosing a synthetic virus-like RNA can be assembled in cells expressing all viral structural components from recombinant plasmids.
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Affiliation(s)
- I Mena
- Centro Nacional de Biología Celular y Retrovirus, Instituto de Salud Carlos III, Madrid, Spain
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47
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Abstract
This chapter focuses on the contributions that studies with viruses have made to current concepts in cell biology. Among the important advantages that viruses provide in such studies is their structural and genetic simplicity. The chapter describes the methods for growth, assay, and purification of viruses and infection of cells by several viruses that have been widely utilized for studies of cellular processes. Most investigations of virus replication at the cellular level are carried out using animal cells in culture. For the events in individual cells to occur with a high level of synchrony, single cycle growth conditions are used. Cells are infected using a high multiplicity of infectious virus particles in a low volume of medium to enhance the efficiency of virus adsorption to cell surfaces. After the adsorption period, the residual inoculum is removed and replaced with an appropriate culture medium. During further incubation, each individual cell in the culture is at a similar temporal stage in the viral replication process. Therefore, experimental procedures carried out on the entire culture reflect the replicative events occurring within an individual cell. The length of a single cycle of virus growth can range from a few hours to several days, depending on the virus type.
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Affiliation(s)
- R W Compans
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322
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48
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Zhirnov OP. Isolation of matrix protein M1 from influenza viruses by acid-dependent extraction with nonionic detergent. Virology 1992; 186:324-30. [PMID: 1727609 DOI: 10.1016/0042-6822(92)90090-c] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Influenza viruses were disrupted layer by layer with the nonionic detergent NP-40 at fixed pH. Treatment of the virions with NP-40 at neutral or mildly alkaline pH (6.8-8.0) yielded viral core structures containing M1 protein. The matrix M1 protein was selectively extracted from cores at acidic pH 3.0-4.5 with citrate, acetate, and phosphate buffers or with morpholinoethanesulfonic acid. The resulting M1 protein sedimented in a glycerol gradient with a coefficient of 2.8 S and most likely existed as a monomeric form of the 27,000-Da polypeptide. An antigenic map of the monomeric protein M1 tested with a panel of monoclonal anti-M1 antibodies was found to be similar to those of the assembled M1 protein in whole virions. The isolated M1 protein retained biological properties and inhibited the RNA polymerase activity of viral RNP. This transcription-inhibition function of M1 monomers was specifically restricted by one of the monoclonal antibodies studied.
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Affiliation(s)
- O P Zhirnov
- D.I. Ivanovsky Virology Institute, Moscow, USSR
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Zhirnov OP. Solubilization of matrix protein M1/M from virions occurs at different pH for orthomyxo- and paramyxoviruses. Virology 1990; 176:274-9. [PMID: 2158693 DOI: 10.1016/0042-6822(90)90253-n] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Enveloped viruses, of which the orthomyxo- and paramyxoviruses are members, are known to be uncoated by nonionic detergents in a salt concentration-dependent manner. In this study we have shown that detergent uncoating of myxoviruses depends not only on salt concentration but also on pH. Treatment of orthomyxoviruses with Nonidet-P40 or Triton N-101 at low salt concentrations results in solubilization of surface virion glycopolypeptides in alkaline and neutral pH (9.0-6.5), but in acidic pH (6.0-5.0) the viral matrix protein M1 is also removed, and the viral ribonucleoprotein complex is released. Conversely, the paramyxovirus matrix protein M is more completely solubilized in alkaline pH (pH 9.0) than in neutral and acidic pH 7.4-5.0. The described pH-dependent differences are discussed in terms of orthomyxo- and paramyxovirus uncoating in target cells.
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Affiliation(s)
- O P Zhirnov
- D.I. Ivanovsky Institute of Virology, Moscow, USSR
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50
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Gregoriades A, Guzman GG, Paoletti E. The phosphorylation of the integral membrane (M1) protein of influenza virus. Virus Res 1990; 16:27-41. [PMID: 2349833 DOI: 10.1016/0168-1702(90)90041-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The phosphorylation of the internal and integral membrane (M1) protein of influenza virus was studied. Four points can be made based on the data: (1) The M1 contains at least two moles of phosphate per mole of M1. (2) Phosphorylation of M1 is conserved between influenza A, B and C viruses. Other characteristics of the M1 are also conserved, such as solubility in organic solvent, heterogeneity and ability to partition into lipid vesicles. (3) M1 is phosphorylated in cells infected with a vaccinia recombinant (vP273) containing only the gene of M1, either as a result of a vaccinia virus associated kinase or a cellular one. (4) The phosphate is located within or in close proximity to the major stretch of neutral and hydrophobic amino acids found in M1, as determined by analyzing cyanogen bromide fragments.
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Affiliation(s)
- A Gregoriades
- Department of Basic Sciences, New York College of Podiatric Medicine, NY 10035
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