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Sutto-Ortiz P, Eléouët JF, Ferron F, Decroly E. Biochemistry of the Respiratory Syncytial Virus L Protein Embedding RNA Polymerase and Capping Activities. Viruses 2023; 15:v15020341. [PMID: 36851554 PMCID: PMC9960070 DOI: 10.3390/v15020341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/12/2023] [Accepted: 01/21/2023] [Indexed: 01/27/2023] Open
Abstract
The human respiratory syncytial virus (RSV) is a negative-sense, single-stranded RNA virus. It is the major cause of severe acute lower respiratory tract infection in infants, the elderly population, and immunocompromised individuals. There is still no approved vaccine or antiviral treatment against RSV disease, but new monoclonal prophylactic antibodies are yet to be commercialized, and clinical trials are in progress. Hence, urgent efforts are needed to develop efficient therapeutic treatments. RSV RNA synthesis comprises viral transcription and replication that are catalyzed by the large protein (L) in coordination with the phosphoprotein polymerase cofactor (P), the nucleoprotein (N), and the M2-1 transcription factor. The replication/transcription is orchestrated by the L protein, which contains three conserved enzymatic domains: the RNA-dependent RNA polymerase (RdRp), the polyribonucleotidyl transferase (PRNTase or capping), and the methyltransferase (MTase) domain. These activities are essential for the RSV replicative cycle and are thus considered as attractive targets for the development of therapeutic agents. In this review, we summarize recent findings about RSV L domains structure that highlight how the enzymatic activities of RSV L domains are interconnected, discuss the most relevant and recent antivirals developments that target the replication/transcription complex, and conclude with a perspective on identified knowledge gaps that enable new research directions.
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Affiliation(s)
| | - Jean-François Eléouët
- Unité de Virologie et Immunologie Moléculaires, INRAE, Université Paris Saclay, F78350 Jouy en Josas, France
| | - François Ferron
- Aix Marseille Université, CNRS, AFMB, UMR, 7257 Marseille, France
- European Virus Bioinformatics Center, Leutragraben 1, 07743 Jena, Germany
| | - Etienne Decroly
- Aix Marseille Université, CNRS, AFMB, UMR, 7257 Marseille, France
- Correspondence:
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Donovan-Banfield I, Milligan R, Hall S, Gao T, Murphy E, Li J, Shawli GT, Hiscox J, Zhuang X, McKeating JA, Fearns R, Matthews DA. Direct RNA sequencing of respiratory syncytial virus infected human cells generates a detailed overview of RSV polycistronic mRNA and transcript abundance. PLoS One 2022; 17:e0276697. [PMID: 36355791 PMCID: PMC9648745 DOI: 10.1371/journal.pone.0276697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 10/11/2022] [Indexed: 11/12/2022] Open
Abstract
To characterize species of viral mRNA transcripts generated during respiratory syncytial virus (RSV) infection, human fibroblast-like MRC-5 lung cells were infected with subgroup A RSV for 6, 16 and 24 hours. In addition, we characterised the viral transcriptome in infected Calu-3 lung epithelial cells at 48 hours post infection. Total RNA was harvested and polyadenylated mRNA was enriched and sequenced by direct RNA sequencing using an Oxford nanopore device. This platform yielded over 450,000 direct mRNA transcript reads which were mapped to the viral genome and analysed to determine the relative mRNA levels of viral genes using our in-house ORF-centric pipeline. We examined the frequency of polycistronic readthrough mRNAs were generated and assessed the length of the polyadenylated tails for each group of transcripts. We show a general but non-linear decline in gene transcript abundance across the viral genome, as predicted by the model of RSV gene transcription. However, the decline in transcript abundance is not uniform. The polyadenylate tails generated by the viral polymerase are similar in length to those generated by the host polyadenylation machinery and broadly declined in length for most transcripts as the infection progressed. Finally, we observed that the steady state abundance of transcripts with very short polyadenylate tails less than 20 nucleotides is less for N, SH and G transcripts in both cell lines compared to NS1, NS2, P, M, F and M2 which may reflect differences in mRNA stability and/or translation rates within and between the cell lines.
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Affiliation(s)
- I’ah Donovan-Banfield
- School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
- Department of Infection Biology and Microbiome, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Rachel Milligan
- School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Sophie Hall
- School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Tianyi Gao
- School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Eleanor Murphy
- School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Jack Li
- School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Ghada T. Shawli
- Department of Infection Biology and Microbiome, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Julian Hiscox
- Department of Infection Biology and Microbiome, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Xiaodong Zhuang
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Jane A. McKeating
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, United Kingdom
| | - Rachel Fearns
- Department of Microbiology, National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail: (DAM); (RF)
| | - David A. Matthews
- School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
- * E-mail: (DAM); (RF)
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Human Respiratory Syncytial Virus NS2 Protein Induces Autophagy by Modulating Beclin1 Protein Stabilization and ISGylation. mBio 2022; 13:e0352821. [PMID: 35038909 PMCID: PMC8764521 DOI: 10.1128/mbio.03528-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Paramyxoviruses such as respiratory syncytial virus (RSV) are the leading cause of pneumonia in infants, the elderly, and immunocompromised individuals. Understanding host-virus interactions is essential for the development of effective interventions. RSV induces autophagy to modulate the immune response. The viral factors and mechanisms underlying RSV-induced autophagy are unknown. Here, we identify the RSV nonstructural protein NS2 as the virus component mediating RSV-induced autophagy. We show that NS2 interacts and stabilizes the proautophagy mediator Beclin1 by preventing its degradation by the proteasome. NS2 further impairs interferon-stimulated gene 15 (ISG15)-mediated Beclin1 ISGylation and generates a pool of "hypo-ISGylated" active Beclin1 to engage in functional autophagy. Studies with NS2-deficient RSV revealed that NS2 contributes to RSV-mediated autophagy during infection. The present study is the first report to show direct activation of autophagy by a paramyxovirus nonstructural protein. We also report a new viral mechanism for autophagy induction wherein the viral protein NS2 promotes hypo-ISGylation of Beclin1 to ensure availability of active Beclin1 to engage in the autophagy process. IMPORTANCE Understanding host-virus interactions is essential for the development of effective interventions against respiratory syncytial virus (RSV), a paramyxovirus that is a leading cause of viral pneumonia in infants. RSV induces autophagy following infection, although the viral factors involved in this mechanism are unknown. Here, we identify the RSV nonstructural protein 2 (NS2) as the virus component involved in autophagy induction. NS2 promotes autophagy by interaction with and stabilization of the proautophagy mediator Beclin1 and by impairing its ISGylation to overcome autophagy inhibition. To the best of our knowledge, this is the first report of a viral protein regulating the autophagy pathway by modulating ISGylation of autophagy mediators. Our studies highlight a direct role of a paramyxovirus nonstructural protein in activating autophagy by interacting with the autophagy mediator Beclin1. NS2-mediated regulation of the autophagy and ISGylation processes is a novel function of viral nonstructural proteins to control the host response against RSV.
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Wei C, Chen YM, Chen Y, Qian W. The Missing Expression Level-Evolutionary Rate Anticorrelation in Viruses Does Not Support Protein Function as a Main Constraint on Sequence Evolution. Genome Biol Evol 2021; 13:evab049. [PMID: 33713114 PMCID: PMC7989579 DOI: 10.1093/gbe/evab049] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2021] [Indexed: 12/13/2022] Open
Abstract
One of the central goals in molecular evolutionary biology is to determine the sources of variation in the rate of sequence evolution among proteins. Gene expression level is widely accepted as the primary determinant of protein evolutionary rate, because it scales with the extent of selective constraints imposed on a protein, leading to the well-known negative correlation between expression level and protein evolutionary rate (the E-R anticorrelation). Selective constraints have been hypothesized to entail the maintenance of protein function, the avoidance of cytotoxicity caused by protein misfolding or nonspecific protein-protein interactions, or both. However, empirical tests evaluating the relative importance of these hypotheses remain scarce, likely due to the nontrivial difficulties in distinguishing the effect of a deleterious mutation on a protein's function versus its cytotoxicity. We realized that examining the sequence evolution of viral proteins could overcome this hurdle. It is because purifying selection against mutations in a viral protein that result in cytotoxicity per se is likely relaxed, whereas purifying selection against mutations that impair viral protein function persists. Multiple analyses of SARS-CoV-2 and nine other virus species revealed a complete absence of any E-R anticorrelation. As a control, the E-R anticorrelation does exist in human endogenous retroviruses where purifying selection against cytotoxicity is present. Taken together, these observations do not support the maintenance of protein function as the main constraint on protein sequence evolution in cellular organisms.
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Affiliation(s)
- Changshuo Wei
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yan-Ming Chen
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ying Chen
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Wenfeng Qian
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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Piedra FA, Qiu X, Teng MN, Avadhanula V, Machado AA, Kim DK, Hixson J, Bahl J, Piedra PA. Non-gradient and genotype-dependent patterns of RSV gene expression. PLoS One 2020; 15:e0227558. [PMID: 31923213 PMCID: PMC6953876 DOI: 10.1371/journal.pone.0227558] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/20/2019] [Indexed: 01/14/2023] Open
Abstract
Respiratory syncytial virus (RSV) is a nonsegmented negative-strand RNA virus (NSV) and a leading cause of severe lower respiratory tract illness in infants and the elderly. Transcription of the ten RSV genes proceeds sequentially from the 3’ promoter and requires conserved gene start (GS) and gene end (GE) signals. Previous studies using the prototypical GA1 genotype Long and A2 strains have indicated a gradient of gene transcription extending across the genome, with the highest level of mRNA coming from the most promoter-proximal gene, the first nonstructural (NS1) gene, and mRNA levels from subsequent genes dropping until reaching a minimum at the most promoter-distal gene, the polymerase (L) gene. However, recent reports show non-gradient levels of mRNA, with higher than expected levels from the attachment (G) gene. It is unknown to what extent different transcript stabilities might shape measured mRNA levels. It is also unclear whether patterns of RSV gene expression vary, or show strain- or genotype-dependence. To address this, mRNA abundances from five RSV genes were measured by quantitative real-time PCR (qPCR) in three cell lines and in cotton rats infected with RSV isolates belonging to four genotypes (GA1, ON, GB1, BA). Relative mRNA levels reached steady-state between four and 24 hours post-infection. Steady-state patterns were non-gradient and genotype-specific, where mRNA levels from the G gene exceeded those from the more promoter-proximal nucleocapsid (N) gene across isolates. Transcript stabilities could not account for the non-gradient patterns observed, indicating that relative mRNA levels more strongly reflect transcription than decay. Our results indicate that gene expression from a small but diverse set of RSV genotypes is non-gradient and genotype-dependent. We propose novel models of RSV transcription that can account for non-gradient transcription.
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Affiliation(s)
- Felipe-Andrés Piedra
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX, United States of America
- * E-mail:
| | - Xueting Qiu
- Center for the Ecology of Infectious Diseases, Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Michael N. Teng
- Division of Allergy and Immunology, Department of Internal Medicine, University of South Florida Morsani College of Medicine, Tampa, FL, United States of America
| | - Vasanthi Avadhanula
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX, United States of America
| | - Annette A. Machado
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX, United States of America
| | - Do-Kyun Kim
- Human Genetics Center, School of Public Health, University of Texas Health Science Center, Houston, TX, United States of America
| | - James Hixson
- Human Genetics Center, School of Public Health, University of Texas Health Science Center, Houston, TX, United States of America
| | - Justin Bahl
- Center for the Ecology of Infectious Diseases, Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore
| | - Pedro A. Piedra
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States of America
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López D, Barriga A, Lorente E, Mir C. Immunoproteomic Lessons for Human Respiratory Syncytial Virus Vaccine Design. J Clin Med 2019; 8:E486. [PMID: 30974886 PMCID: PMC6518116 DOI: 10.3390/jcm8040486] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/01/2019] [Accepted: 04/09/2019] [Indexed: 11/25/2022] Open
Abstract
Accurate antiviral humoral and cellular immune responses require prior recognition of antigenic peptides presented by human leukocyte antigen (HLA) class I and II molecules on the surface of antigen-presenting cells. Both the helper and the cytotoxic immune responses are critical for the control and the clearance of human respiratory syncytial virus (HRSV) infection, which is a significant cause of morbidity and mortality in infected pediatric, immunocompromised and elderly populations. In this article we review the immunoproteomics studies which have defined the general antigen processing and presentation rules that determine both the immunoprevalence and the immunodominance of the cellular immune response to HRSV. Mass spectrometry and functional analyses have shown that the HLA class I and II cellular immune responses against HRSV are mainly focused on three viral proteins: fusion, matrix, and nucleoprotein. Thus, these studies have important implications for vaccine development against this virus, since a vaccine construct including these three relevant HRSV proteins could efficiently stimulate the major components of the adaptive immune system: humoral, helper, and cytotoxic effector immune responses.
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Affiliation(s)
- Daniel López
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain.
| | - Alejandro Barriga
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain.
| | - Elena Lorente
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain.
| | - Carmen Mir
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain.
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To assemble or not to assemble: The changing rules of pneumovirus transmission. Virus Res 2019; 265:68-73. [PMID: 30844414 DOI: 10.1016/j.virusres.2019.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/01/2019] [Indexed: 01/07/2023]
Abstract
Pneumoviruses represent a major public health burden across the world. Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV), two of the most recognizable pediatric infectious agents, belong to this family. These viruses are enveloped with a non-segmented negative-sense RNA genome, and their replication occurs in specialized cytosolic organelles named inclusion bodies (IB). The critical role of IBs in replication of pneumoviruses has begun to be elucidated, and our current understanding suggests they are highly dynamic structures. From IBs, newly synthesized nucleocapsids are transported to assembly sites, potentially via the actin cytoskeleton, to be incorporated into nascent virions. Released virions, which generally contain one genome, can then diffuse in the extracellular environment to target new cells and reinitiate the process of infection. This is a challenging business for virions, which must face several risks including the extracellular immune responses. In addition, several recent studies suggest that successful infection may be achieved more rapidly by multiple, rather than single, genomic copies being deposited into a target cell. Interestingly, recent data indicate that pneumoviruses have several mechanisms that permit their transmission en bloc, i.e. transmission of multiple genomes at the same time. These mechanisms include the well-studied syncytia formation as well as the newly described formation of long actin-based intercellular extensions. These not only permit en bloc viral transmission, but also bypass assembly of complete virions. In this review we describe several aspects of en bloc viral transmission and how these mechanisms are reshaping our understanding of pneumovirus replication, assembly and spread.
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Noton SL, Tremaglio CZ, Fearns R. Killing two birds with one stone: How the respiratory syncytial virus polymerase initiates transcription and replication. PLoS Pathog 2019; 15:e1007548. [PMID: 30817806 PMCID: PMC6394897 DOI: 10.1371/journal.ppat.1007548] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Sarah L. Noton
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Chadene Z. Tremaglio
- Department of Biology, University of Saint Joseph, West Hartford, Connecticut, United States of America
| | - Rachel Fearns
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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Richard CA, Rincheval V, Lassoued S, Fix J, Cardone C, Esneau C, Nekhai S, Galloux M, Rameix-Welti MA, Sizun C, Eléouët JF. RSV hijacks cellular protein phosphatase 1 to regulate M2-1 phosphorylation and viral transcription. PLoS Pathog 2018; 14:e1006920. [PMID: 29489893 PMCID: PMC5847313 DOI: 10.1371/journal.ppat.1006920] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 03/12/2018] [Accepted: 02/04/2018] [Indexed: 12/31/2022] Open
Abstract
Respiratory syncytial virus (RSV) RNA synthesis occurs in cytoplasmic inclusion bodies (IBs) in which all the components of the viral RNA polymerase are concentrated. In this work, we show that RSV P protein recruits the essential RSV transcription factor M2-1 to IBs independently of the phosphorylation state of M2-1. We also show that M2-1 dephosphorylation is achieved by a complex formed between P and the cellular phosphatase PP1. We identified the PP1 binding site of P, which is an RVxF-like motif located nearby and upstream of the M2-1 binding region. NMR confirmed both P-M2-1 and P-PP1 interaction regions in P. When the P-PP1 interaction was disrupted, M2-1 remained phosphorylated and viral transcription was impaired, showing that M2-1 dephosphorylation is required, in a cyclic manner, for efficient viral transcription. IBs contain substructures called inclusion bodies associated granules (IBAGs), where M2-1 and neo-synthesized viral mRNAs concentrate. Disruption of the P-PP1 interaction was correlated with M2-1 exclusion from IBAGs, indicating that only dephosphorylated M2-1 is competent for viral mRNA binding and hence for a previously proposed post-transcriptional function.
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Affiliation(s)
- Charles-Adrien Richard
- Unité de Virologie et Immunologie Moléculaires (UR892), INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Vincent Rincheval
- UMR1173, INSERM, Université de Versailles St. Quentin, Montigny le Bretonneux, France
| | - Safa Lassoued
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris-Saclay, Avenue de la Terrasse, Gif-sur-Yvette, France
| | - Jenna Fix
- Unité de Virologie et Immunologie Moléculaires (UR892), INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Christophe Cardone
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris-Saclay, Avenue de la Terrasse, Gif-sur-Yvette, France
| | - Camille Esneau
- Unité de Virologie et Immunologie Moléculaires (UR892), INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sergei Nekhai
- Center for Sickle Cell Disease and Department of Medicine, Howard University, Washington, D. C., United States of America
| | - Marie Galloux
- Unité de Virologie et Immunologie Moléculaires (UR892), INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Marie-Anne Rameix-Welti
- UMR1173, INSERM, Université de Versailles St. Quentin, Montigny le Bretonneux, France
- AP-HP, Laboratoire de Microbiologie, Hôpital Ambroise Paré, Boulogne-Billancourt, France
| | - Christina Sizun
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris-Saclay, Avenue de la Terrasse, Gif-sur-Yvette, France
| | - Jean-François Eléouët
- Unité de Virologie et Immunologie Moléculaires (UR892), INRA, Université Paris-Saclay, Jouy-en-Josas, France
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Fearns R, Deval J. New antiviral approaches for respiratory syncytial virus and other mononegaviruses: Inhibiting the RNA polymerase. Antiviral Res 2016; 134:63-76. [PMID: 27575793 DOI: 10.1016/j.antiviral.2016.08.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 07/27/2016] [Accepted: 08/07/2016] [Indexed: 11/16/2022]
Abstract
Worldwide, respiratory syncytial virus (RSV) causes severe disease in infants, the elderly, and immunocompromised people. No vaccine or effective antiviral treatment is available. RSV is a member of the non-segmented, negative-strand (NNS) group of RNA viruses and relies on its RNA-dependent RNA polymerase to transcribe and replicate its genome. Because of its essential nature and unique properties, the RSV polymerase has proven to be a good target for antiviral drugs, with one compound, ALS-8176, having already achieved clinical proof-of-concept efficacy in a human challenge study. In this article, we first provide an overview of the role of the RSV polymerase in viral mRNA transcription and genome replication. We then review past and current approaches to inhibiting the RSV polymerase, including use of nucleoside analogs and non-nucleoside inhibitors. Finally, we consider polymerase inhibitors that hold promise for treating infections with other NNS RNA viruses, including measles and Ebola.
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Affiliation(s)
- Rachel Fearns
- Department of Microbiology, Boston University School of Medicine, Boston, MA, USA.
| | - Jerome Deval
- Alios BioPharma, Inc., Part of the Janssen Pharmaceutical Companies, South San Francisco, CA, USA.
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Barik S. What Really Rigs Up RIG-I? J Innate Immun 2016; 8:429-36. [PMID: 27438016 PMCID: PMC6738806 DOI: 10.1159/000447947] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 06/23/2016] [Accepted: 06/23/2016] [Indexed: 12/24/2022] Open
Abstract
RIG-I (retinoic acid-inducible gene 1) is an archetypal member of the cytoplasmic DEAD-box dsRNA helicase family (RIG-I-like receptors or RLRs), the members of which play essential roles in the innate immune response of the metazoan cell. RIG-I functions as a pattern recognition receptor that detects nonself RNA as a pathogen-associated molecular pattern (PAMP). However, the exact molecular nature of the viral RNAs that act as a RIG-I ligand has remained a mystery and a matter of debate. In this article, we offer a critical review of the actual viral RNAs that act as PAMPs to activate RIG-I, as seen from the perspective of a virologist, including a recent report that the viral Leader-read-through transcript is a novel and effective RIG-I ligand.
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Affiliation(s)
- Sailen Barik
- Department of Biological, Geological and Environmental Sciences, and Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, Ohio, USA
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12
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Investigating the Influence of Ribavirin on Human Respiratory Syncytial Virus RNA Synthesis by Using a High-Resolution Transcriptome Sequencing Approach. J Virol 2016; 90:4876-4888. [PMID: 26656699 PMCID: PMC4859727 DOI: 10.1128/jvi.02349-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 11/18/2015] [Indexed: 11/20/2022] Open
Abstract
Human respiratory syncytial virus (HRSV) is a major cause of serious respiratory tract infection. Treatment options include administration of ribavirin, a purine analog, although the mechanism of its anti-HRSV activity is unknown. We used transcriptome sequencing (RNA-seq) to investigate the genome mutation frequency and viral mRNA accumulation in HRSV-infected cells that were left untreated or treated with ribavirin. In the absence of ribavirin, HRSV-specific transcripts accounted for up to one-third of total RNA reads from the infected-cell RNA population. Ribavirin treatment resulted in a >90% reduction in abundance of viral mRNA reads, while at the same time no such reduction was detected for the abundance of cellular transcripts. The presented data reveal that ribavirin significantly increases the frequency of HRSV-specific RNA mutations, suggesting a direct influence on the fidelity of the HRSV polymerase. The presented data show that transitions and transversions occur during HRSV replication and that these changes occur in hot spots along the HRSV genome. Examination of nucleotide substitution rates in the viral genome indicated an increase in the frequency of transition but not transversion mutations in the presence of ribavirin. In addition, our data indicate that in the continuous cell types used and at the time points analyzed, the abundances of some HRSV mRNAs do not reflect the order in which the mRNAs are transcribed. IMPORTANCE Human respiratory syncytial virus (HRSV) is a major pediatric pathogen. Ribavirin can be used in children who are extremely ill to reduce the amount of virus and to lower the burden of disease. Ribavirin is used as an experimental therapy with other viruses. The mechanism of action of ribavirin against HRSV is not well understood, although it is thought to increase the mutation rate of the viral polymerase during replication. To investigate this hypothesis, we used a high-resolution approach that allowed us to determine the genetic sequence of the virus to a great depth of coverage. We found that ribavirin did not cause a detectable change in the relative amounts of viral mRNA transcripts. However, we found that ribavirin treatment did indeed cause an increase in the number of mutations, which was associated with a decrease in virus production.
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Lorente E, Barriga A, Barnea E, Mir C, Gebe JA, Admon A, López D. Structural and Nonstructural Viral Proteins Are Targets of T-Helper Immune Response against Human Respiratory Syncytial Virus. Mol Cell Proteomics 2016; 15:2141-51. [PMID: 27090790 DOI: 10.1074/mcp.m115.057356] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Indexed: 11/06/2022] Open
Abstract
Proper antiviral humoral and cellular immune responses require previous recognition of viral antigenic peptides that are bound to HLA class II molecules, which are exposed on the surface of antigen-presenting cells. The helper immune response is critical for the control and the clearance of human respiratory syncytial virus (HRSV) infection, a virus with severe health risk in infected pediatric, immunocompromised, and elderly populations. In this study, using a mass spectrometry analysis of complex HLA class II-bound peptide pools that were isolated from large amounts of HRSV-infected cells, 19 naturally processed HLA-DR ligands, most of them included in a complex nested set of peptides, were identified. Both the immunoprevalence and the immunodominance of the HLA class II response to HRSV were focused on one nonstructural (NS1) and two structural (matrix and mainly fusion) proteins of the infective virus. These findings have clear implications for analysis of the helper immune response as well as for antiviral vaccine design.
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Affiliation(s)
- Elena Lorente
- From the ‡Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain
| | - Alejandro Barriga
- From the ‡Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain
| | - Eilon Barnea
- §Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Carmen Mir
- From the ‡Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain
| | - John A Gebe
- ¶Benaroya Research Institute, Seattle, WA 98101, USA
| | - Arie Admon
- §Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Daniel López
- From the ‡Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain,
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Regulation of Viral RNA Synthesis by the V Protein of Parainfluenza Virus 5. J Virol 2015; 89:11845-57. [PMID: 26378167 DOI: 10.1128/jvi.01832-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 09/06/2015] [Indexed: 02/08/2023] Open
Abstract
UNLABELLED Paramyxoviruses include many important animal and human pathogens. The genome of parainfluenza virus 5 (PIV5), a prototypical paramyxovirus, encodes a V protein that inhibits viral RNA synthesis. In this work, the mechanism of inhibition was investigated. Using mutational analysis and a minigenome system, we identified regions in the N and C termini of the V protein that inhibit viral RNA synthesis: one at the very N terminus of V and the second at the C terminus of V. Furthermore, we determined that residues L16 and I17 are critical for the inhibitory function of the N-terminal region of the V protein. Both regions interact with the nucleocapsid protein (NP), an essential component of the viral RNA genome complex (RNP). Mutations at L16 and I17 abolished the interaction between NP and the N-terminal domain of V. This suggests that the interaction between NP and the N-terminal domain plays a critical role in V inhibition of viral RNA synthesis by the N-terminal domain. Both the N- and C-terminal regions inhibited viral RNA replication. The C terminus inhibited viral RNA transcription, while the N-terminal domain enhanced viral RNA transcription, suggesting that the two domains affect viral RNA through different mechanisms. Interestingly, V also inhibited the synthesis of the RNA of other paramyxoviruses, such as Nipah virus (NiV), human parainfluenza virus 3 (HPIV3), measles virus (MeV), mumps virus (MuV), and respiratory syncytial virus (RSV). This suggests that a common host factor may be involved in the replication of these paramyxoviruses. IMPORTANCE We identified two regions of the V protein that interact with NP and determined that one of these regions enhances viral RNA transcription via its interaction with NP. Our data suggest that a common host factor may be involved in the regulation of paramyxovirus replication and could be a target for broad antiviral drug development. Understanding the regulation of paramyxovirus replication will enable the rational design of vaccines and potential antiviral drugs.
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15
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Johnstone C, Lorente E, Barriga A, Barnea E, Infantes S, Lemonnier FA, David CS, Admon A, López D. The viral transcription group determines the HLA class I cellular immune response against human respiratory syncytial virus. Mol Cell Proteomics 2015; 14:893-904. [PMID: 25635267 DOI: 10.1074/mcp.m114.045401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Indexed: 11/06/2022] Open
Abstract
The cytotoxic T-lymphocyte-mediated killing of virus-infected cells requires previous recognition of short viral antigenic peptides bound to human leukocyte antigen class I molecules that are exposed on the surface of infected cells. The cytotoxic T-lymphocyte response is critical for the clearance of human respiratory syncytial virus infection. In this study, naturally processed viral human leukocyte antigen class I ligands were identified with mass spectrometry analysis of complex human leukocyte antigen-bound peptide pools isolated from large amounts of human respiratory syncytial virus-infected cells. Acute antiviral T-cell response characterization showed that viral transcription determines both the immunoprevalence and immunodominance of the human leukocyte antigen class I response to human respiratory syncytial virus. These findings have clear implications for antiviral vaccine design.
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Affiliation(s)
- Carolina Johnstone
- From the ‡Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain
| | - Elena Lorente
- From the ‡Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain
| | - Alejandro Barriga
- From the ‡Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain
| | - Eilon Barnea
- §Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Susana Infantes
- From the ‡Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain
| | - François A Lemonnier
- ¶Unité d'Immunité Cellulaire Antivirale, Département d'Immunologie, Institut Pasteur, Paris Cedex 15, France
| | - Chella S David
- ‖Department of Immunology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Arie Admon
- §Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Daniel López
- From the ‡Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain;
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16
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Rameix-Welti MA, Le Goffic R, Hervé PL, Sourimant J, Rémot A, Riffault S, Yu Q, Galloux M, Gault E, Eléouët JF. Visualizing the replication of respiratory syncytial virus in cells and in living mice. Nat Commun 2014; 5:5104. [PMID: 25277263 PMCID: PMC7091779 DOI: 10.1038/ncomms6104] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 08/29/2014] [Indexed: 01/09/2023] Open
Abstract
Respiratory syncytial virus (RSV) is the most important cause of severe lower-respiratory tract disease in calves and young children, yet no human vaccine nor efficient curative treatments are available. Here we describe a recombinant human RSV reverse genetics system in which the red fluorescent protein (mCherry) or the firefly luciferase (Luc) genes are inserted into the RSV genome. Expression of mCherry and Luc are correlated with infection rate, allowing the monitoring of RSV multiplication in cell culture. Replication of the Luc-encoding virus in living mice can be visualized by bioluminescent imaging, bioluminescence being detected in the snout and lungs of infected mice after nasal inoculation. We propose that these recombinant viruses are convenient and valuable tools for screening of compounds active against RSV, and can be used as an extremely sensitive readout for studying effects of antiviral therapeutics in living mice.
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Affiliation(s)
- Marie-Anne Rameix-Welti
- Unité de Virologie et Immunologie Moleculaires (UR892), INRA, Jouy-en-Josas, F78352 France
- Physiopathologie et diagnostic des infections microbiennes, EA3647—EPIM, UFR des Sciences de la Santé Simone Veil—UVSQ, 2 avenue de la Source de la Bièvre, Montigny-Le-Bretonneux, 78180 France
- AP-HP, Hôpital Ambroise Paré, Laboratoire de Microbiologie, Boulogne-Billancourt, 92100 France
| | - Ronan Le Goffic
- Unité de Virologie et Immunologie Moleculaires (UR892), INRA, Jouy-en-Josas, F78352 France
| | - Pierre-Louis Hervé
- Unité de Virologie et Immunologie Moleculaires (UR892), INRA, Jouy-en-Josas, F78352 France
| | - Julien Sourimant
- Unité de Virologie et Immunologie Moleculaires (UR892), INRA, Jouy-en-Josas, F78352 France
- Physiopathologie et diagnostic des infections microbiennes, EA3647—EPIM, UFR des Sciences de la Santé Simone Veil—UVSQ, 2 avenue de la Source de la Bièvre, Montigny-Le-Bretonneux, 78180 France
| | - Aude Rémot
- Unité de Virologie et Immunologie Moleculaires (UR892), INRA, Jouy-en-Josas, F78352 France
| | - Sabine Riffault
- Unité de Virologie et Immunologie Moleculaires (UR892), INRA, Jouy-en-Josas, F78352 France
| | - Qin Yu
- Infection Innovative Medicines Unit, AstraZeneca R&D Boston, 35 Gatehouse Drive, Waltham, Massachusetts 02451, USA,
| | - Marie Galloux
- Unité de Virologie et Immunologie Moleculaires (UR892), INRA, Jouy-en-Josas, F78352 France
| | - Elyanne Gault
- Physiopathologie et diagnostic des infections microbiennes, EA3647—EPIM, UFR des Sciences de la Santé Simone Veil—UVSQ, 2 avenue de la Source de la Bièvre, Montigny-Le-Bretonneux, 78180 France
- AP-HP, Hôpital Ambroise Paré, Laboratoire de Microbiologie, Boulogne-Billancourt, 92100 France
| | - Jean-François Eléouët
- Unité de Virologie et Immunologie Moleculaires (UR892), INRA, Jouy-en-Josas, F78352 France
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Cecchinato M, Lupini C, Munoz Pogoreltseva OS, Listorti V, Mondin A, Drigo M, Catelli E. Development of a real-time RT-PCR assay for the simultaneous identification, quantitation and differentiation of avian metapneumovirus subtypes A and B. Avian Pathol 2013; 42:283-9. [PMID: 23650927 DOI: 10.1080/03079457.2013.788130] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In recent years, special attention has been paid to real-time polymerase chain reaction (PCR) for avian metapneumovirus (AMPV) diagnosis, due to its numerous advantages over classical PCR. A new multiplex quantitative real-time reverse transcription-PCR (qRT-PCR) with molecular beacon probe assay, designed to target the SH gene, was developed. The test was evaluated in terms of specificity, sensitivity and repeatability, and compared with conventional RT nested-PCR based on the G gene. All of the AMPV subtype A and B strains tested were amplified and specifically detected while no amplification occurred with other non-target bird respiratory pathogens. The detection limit of the assay was 10(-0.41) median infectious dose/ml and 10(1.15) median infectious dose/ml when the AMPV-B strain IT/Ty/B/Vr240/87 and the AMPV-A strain IT/Ty/A/259-01/03 were used, respectively, as templates. In all cases, the amplification efficiency was approximately 2 and the error values were <0.2. Standard curves, generated either using the serial dilution of an RNA suspension or RNA extracted from the serial dilution of titrated viral suspensions as templates, exhibited good linearity (R (2)>0.9375) between crossing point values and virus quantities, making the assay herein designed reliable for quantification. When the newly developed qRT-PCR was compared with a conventional RT nested-PCR, it showed greater sensitivity with RNA extracted from both positive controls and from experimentally infected birds. This assay can be effectively used for the detection, identification, differentiation and quantitation of AMPV subtype A or subtype B to assist in disease diagnosis and to carry out rapid surveillance with high levels of sensitivity and specificity.
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Affiliation(s)
- Mattia Cecchinato
- Department of Animal Medicine, Production and Health, University of Padua, Legnaro, Padua, Italy.
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18
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Ogino T. In vitro capping and transcription of rhabdoviruses. Methods 2012; 59:188-98. [PMID: 22687619 DOI: 10.1016/j.ymeth.2012.05.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 05/12/2012] [Accepted: 05/31/2012] [Indexed: 11/26/2022] Open
Abstract
The RNA-dependent RNA polymerase L protein of vesicular stomatitis virus (VSV), a prototypic nonsegmented negative strand (NNS) RNA virus classified into the Rhabdoviridae family, has been used to investigate the fundamental molecular mechanisms of NNS RNA viral mRNA synthesis and processing. In vitro studies on mRNA cap formation with the VSV L protein eventually led to the discovery of the unconventional mRNA capping pathway catalyzed by the guanosine 5'-triphosphatase and RNA:GDP polyribonucleotidyltransferase (PRNTase) activities. The PRNTase activity is a novel enzymatic activity, which transfers 5'-monophosphorylated (p-) RNA from 5'-triphosphorylated (ppp-) RNA to GDP to form 5'-capped RNA (GpppRNA) in a viral mRNA-start sequence-dependent manner. This unconventional capping (pRNA transfer) reaction with PRNTase can be experimentally distinguished from the conventional capping (GMP transfer) reaction with eukaryotic GTP:RNA guanylyltransferase (GTase) on the basis of the following differences in their substrate specificity for the cap formation: PRNTase uses GDP and pppRNA, but not ppRNA, whereas GTase employs GTP, but not GDP, and ppRNA. The pRNA transfer reaction with PRNTase proceeds through a covalent enzyme-pRNA intermediate with a phosphoamide bond. Hence, to prove the PRNTase activity, it is necessary to demonstrate the following consecutive steps separately: (1) the enzyme forms a covalent enzyme-pRNA intermediate, and (2) the intermediate transfers pRNA to GDP. This article describes the methods for in vitro transcription and capping with the recombinant VSV L protein, which permit detailed characterization of its enzymatic reactions and mapping of active sites of its enzymatic domains. It is expected that these systems are adaptable to rhabdoviruses and, by extension, other NNS RNA viruses belonging to different families.
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Affiliation(s)
- Tomoaki Ogino
- Department of Molecular Genetics, Section of Virology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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19
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Characterization of a viral phosphoprotein binding site on the surface of the respiratory syncytial nucleoprotein. J Virol 2012; 86:8375-87. [PMID: 22623798 DOI: 10.1128/jvi.00058-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The human respiratory syncytial virus (HRSV) genome is composed of a negative-sense single-stranded RNA that is tightly associated with the nucleoprotein (N). This ribonucleoprotein (RNP) complex is the template for replication and transcription by the viral RNA-dependent RNA polymerase. RNP recognition by the viral polymerase involves a specific interaction between the C-terminal domain of the phosphoprotein (P) (P(CTD)) and N. However, the P binding region on N remains to be identified. In this study, glutathione S-transferase (GST) pulldown assays were used to identify the N-terminal core domain of HRSV N (N(NTD)) as a P binding domain. A biochemical characterization of the P(CTD) and molecular modeling of the N(NTD) allowed us to define four potential candidate pockets on N (pocket I [PI] to PIV) as hydrophobic sites surrounded by positively charged regions, which could constitute sites complementary to the P(CTD) interaction domain. The role of selected amino acids in the recognition of the N-RNA complex by P was first screened for by site-directed mutagenesis using a polymerase activity assay, based on an HRSV minigenome containing a luciferase reporter gene. When changed to Ala, most of the residues of PI were found to be critical for viral RNA synthesis, with the R132A mutant having the strongest effect. These mutations also reduced or abolished in vitro and in vivo P-N interactions, as determined by GST pulldown and immunoprecipitation experiments. The pocket formed by these residues is critical for P binding to the N-RNA complex, is specific for pneumovirus N proteins, and is clearly distinct from the P binding sites identified so far for other nonsegmented negative-strand viruses.
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20
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Multiple functional domains and complexes of the two nonstructural proteins of human respiratory syncytial virus contribute to interferon suppression and cellular location. J Virol 2011; 85:10090-100. [PMID: 21795342 DOI: 10.1128/jvi.00413-11] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Human respiratory syncytial virus (RSV), a major cause of severe respiratory diseases, efficiently suppresses cellular innate immunity, represented by type I interferon (IFN), using its two unique nonstructural proteins, NS1 and NS2. In a search for their mechanism, NS1 was previously shown to decrease levels of TRAF3 and IKKε, whereas NS2 interacted with RIG-I and decreased TRAF3 and STAT2. Here, we report on the interaction, cellular localization, and functional domains of these two proteins. We show that recombinant NS1 and NS2, expressed in lung epithelial A549 cells, can form homo- as well as heteromers. Interestingly, when expressed alone, substantial amounts of NS1 and NS2 localized to the nuclei and to the mitochondria, respectively. However, when coexpressed with NS2, as in RSV infection, NS1 could be detected in the mitochondria as well, suggesting that the NS1-NS2 heteromer localizes to the mitochondria. The C-terminal tetrapeptide sequence, DLNP, common to both NS1 and NS2, was required for some functions, but not all, whereas only the NS1 N-terminal region was important for IKKε reduction. Finally, NS1 and NS2 both interacted specifically with host microtubule-associated protein 1B (MAP1B). The contribution of MAP1B in NS1 function was not tested, but in NS2 it was essential for STAT2 destruction, suggesting a role of the novel DLNP motif in protein-protein interaction and IFN suppression.
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21
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Mutational analysis reveals a noncontractile but interactive role of actin and profilin in viral RNA-dependent RNA synthesis. J Virol 2009; 83:10869-76. [PMID: 19710142 DOI: 10.1128/jvi.01271-09] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
As obligatory parasites, viruses co-opt a variety of cellular functions for robust replication. The expression of the nonsegmented negative-strand RNA genome of respiratory syncytial virus (RSV), a significant pediatric pathogen, absolutely requires actin and is stimulated by the actin-regulatory protein profilin. As actin is a major contractile protein, it was important to determine whether the known functional domains of actin and profilin were important for their ability to activate RSV transcription. Analyses of recombinant mutants in a reconstituted RSV transcription system suggested that the divalent-cation-binding domain of actin is critically needed for binding to the RSV genome template and for the activation of viral RNA synthesis. In contrast, the nucleotide-binding domain and the N-terminal acidic domain were needed neither for template binding nor for transcription. Specific surface residues of actin, required for actin-actin contact during filamentation, were also nonessential for viral transcription. Unlike actin, profilin did not directly bind to the viral template but was recruited by actin. Mutation of the interactive residues of actin or profilin, resulting in the loss of actin-profilin binding, also abolished profilin's ability to stimulate viral transcription. Together, these results suggest that actin acts as a classical transcription factor for the virus by divalent-cation-dependent binding to the viral template and that profilin acts as a transcriptional cofactor, in part by associating with actin. This essential viral role of actin is independent of its contractile cellular role.
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22
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Bitko V, Musiyenko A, Bayfield MA, Maraia RJ, Barik S. Cellular La protein shields nonsegmented negative-strand RNA viral leader RNA from RIG-I and enhances virus growth by diverse mechanisms. J Virol 2008; 82:7977-87. [PMID: 18550659 PMCID: PMC2519562 DOI: 10.1128/jvi.02762-07] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Accepted: 05/29/2008] [Indexed: 12/25/2022] Open
Abstract
The La antigen (SS-B) associates with a wide variety of cellular and viral RNAs to affect gene expression in multiple systems. We show that La is the major cellular protein found to be associated with the abundant 44-nucleotide viral leader RNA (leRNA) early after infection with respiratory syncytial virus (RSV), a nonsegmented negative-strand RNA virus. Consistent with this, La redistributes from the nucleus to the cytoplasm in RSV-infected cells. Upon RNA interference knockdown of La, leRNA is redirected to associate with the RNA-binding protein RIG-I, a known activator of interferon (IFN) gene expression, and this is accompanied by the early induction of IFN mRNA. These results suggest that La shields leRNA from RIG-I, abrogating the early viral activation of type I IFN. We mapped the leRNA binding function to RNA recognition motif 1 of La and showed that while wild-type La greatly enhanced RSV growth, a La mutant defective in RSV leRNA binding also did not support RSV growth. Comparative studies of RSV and Sendai virus and the use of IFN-negative Vero cells indicated that La supports the growth of nonsegmented negative-strand RNA viruses by both IFN suppression and a potentially novel IFN-independent mechanism.
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Affiliation(s)
- Vira Bitko
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, AL 36688-0002, USA
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23
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Akt plays a critical role in replication of nonsegmented negative-stranded RNA viruses. J Virol 2007; 82:105-14. [PMID: 17959676 DOI: 10.1128/jvi.01520-07] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The order Mononegavirales (comprised of nonsegmented negative-stranded RNA viruses or NNSVs) contains many important pathogens. Parainfluenza virus 5 (PIV5), formerly known as simian virus 5, is a prototypical paramyxovirus and encodes a V protein, which has a cysteine-rich C terminus that is conserved among all paramyxoviruses. The V protein of PIV5, like that of many other paramyxoviruses, plays an important role in regulating viral RNA synthesis. In this work, we show that V interacts with Akt, a serine/threonine kinase, also known as protein kinase B. Both pharmacological inhibitors and small interfering RNA against Akt1 reduced PIV5 replication, indicating that Akt plays a critical role in PIV5 replication. Furthermore, treatment with Akt inhibitors also reduced the replication of several other paramyxoviruses, as well as vesicular stomatitis virus, the prototypical rhabdovirus, indicating that Akt may play a more universal role in NNSV replication. The phosphoproteins (P proteins) of NNSVs are essential cofactors for the viral RNA polymerase complex and require heavy phosphorylation for their activity. Inhibition of Akt activity reduced the level of P phosphorylation, suggesting that Akt is involved in regulating viral RNA synthesis. In addition, Akt1 phosphorylated a recombinant P protein of PIV5 purified from bacteria. The finding that Akt plays a critical role in replication of NNSV will lead to a better understanding of how these viruses replicate, as well as novel strategies to treat infectious diseases caused by NNSVs.
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Jeffree CE, Brown G, Aitken J, Su-Yin DY, Tan BH, Sugrue RJ. Ultrastructural analysis of the interaction between F-actin and respiratory syncytial virus during virus assembly. Virology 2007; 369:309-23. [PMID: 17825340 DOI: 10.1016/j.virol.2007.08.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2007] [Revised: 06/06/2007] [Accepted: 08/02/2007] [Indexed: 11/17/2022]
Abstract
During respiratory syncytial virus (RSV) infection there is a close physical interaction between the filamentous actin (F-actin) and the virus, involving both inclusion bodies and the virus filaments. This interaction appears to occur relatively early in the replication cycle, and can be detected from 8 h post-infection. Furthermore, during virus assembly we obtained evidence for the participation of an F-actin-associated signalling pathway involving phosphatidyl-3-kinase (PI3K). Treatment with the PI3K inhibitor LY294002 prevented the formation of virus filaments, although no effect was observed either on virus protein expression, or on trafficking of the virus glycoproteins to the cell surface. Inhibition of the activity of Rac GTPase, a down-stream effector of PI3K, by treatment with the Rac-specific inhibitor NSC23766 gave similar results. These data suggest that an intimate interaction occurs between actin and RSV, and that actin-associated signalling pathway, involving PI3K and Rac GTPase, may play an important role during virus assembly.
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Affiliation(s)
- Chris E Jeffree
- School of Biological Sciences, Daniel Rutherford Building, King's Buildings, Mayfield Road, University of Edinburgh Edinburgh, EH9 3JH, UK
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25
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Estrada B, Carter M, Barik S, Vidal R, Herbert D, Ramsey KM. Severe human metapneumovirus infection in hospitalized children. Clin Pediatr (Phila) 2007; 46:258-62. [PMID: 17416883 DOI: 10.1177/0009922806293896] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Human metapneumovirus is a recently discovered pathogen that causes upper and lower respiratory tract disease in children. This study describes the course of illness in hospitalized children with this infection. During a 6-month period, 11 children were diagnosed with human metapneumovirus infection by reverse transcription-polymerase chain reaction. Oxygen supplementation was required for 82% of patients. Severe disease developed in 45%, and mechanical ventilation was required. An apparent life-threatening event was the indication for hospitalization of 27% of patients infected with human metapneumovirus. Children with underlying asthma or neuromuscular disease had a prolonged hospitalization.
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Affiliation(s)
- Benjamin Estrada
- Division of Pediatric Infectious Diseases, University of South Alabama, Mobile, Alabama 36604, SUA. bestrada@ usouthal.edu
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26
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Barik S, Bitko V. Prospects of RNA interference therapy in respiratory viral diseases: update 2006. Expert Opin Biol Ther 2006; 6:1151-60. [PMID: 17049013 DOI: 10.1517/14712598.6.11.1151] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Respiratory viruses, such as influenza, parainfluenza and respiratory syncytial virus (RSV), claim millions of lives annually. At present, there is no completely effective vaccine or drug against these highly mutable RNA viruses. Passive antibody therapies for RSV, despite their limited application and staggering cost, enjoy a virtual monopoly in a multibillion-dollar global market. Recently, however, pioneering discoveries have launched RNA interference as a novel, nucleic acid-based therapy against viral pathogens. Specifically, small interfering RNAs (siRNAs) offered protection against respiratory syncytial virus, parainfluenza and influenza. siRNA against RSV has entered Phase I clinical trials in humans, and preliminary reports are promising. If appropriately formulated for improved specificity, delivery and pharmacokinetics, siRNAs may indeed become effective antivirals in the clinics of the future. This paper provides an overview of the prospects and hurdles facing the antiviral siRNA drugs, with special emphasis on RSV.
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Affiliation(s)
- Sailen Barik
- University of South Alabama College of Medicine, Department of Biochemistry and Molecular Biology, 307 University Blvd, Mobile, Alabama 36688-0002, USA.
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Cowton VM, McGivern DR, Fearns R. Unravelling the complexities of respiratory syncytial virus RNA synthesis. J Gen Virol 2006; 87:1805-1821. [PMID: 16760383 DOI: 10.1099/vir.0.81786-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Human respiratory syncytial virus (RSV) is the leading cause of paediatric respiratory disease and is the focus of antiviral- and vaccine-development programmes. These goals have been aided by an understanding of the virus genome architecture and the mechanisms by which it is expressed and replicated. RSV is a member of the order Mononegavirales and, as such, has a genome consisting of a single strand of negative-sense RNA. At first glance, transcription and genome replication appear straightforward, requiring self-contained promoter regions at the 3' ends of the genome and antigenome RNAs, short cis-acting elements flanking each of the genes and one polymerase. However, from these minimal elements, the virus is able to generate an array of capped, methylated and polyadenylated mRNAs and encapsidated antigenome and genome RNAs, all in the appropriate ratios to facilitate virus replication. The apparent simplicity of genome expression and replication is a consequence of considerable complexity in the polymerase structure and its cognate cis-acting sequences; here, our understanding of mechanisms by which the RSV polymerase proteins interact with signals in the RNA template to produce different RNA products is reviewed.
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MESH Headings
- Base Sequence
- DNA-Directed RNA Polymerases/metabolism
- Genome, Viral
- Humans
- Models, Biological
- Molecular Sequence Data
- Mononegavirales/genetics
- Mononegavirales/physiology
- Nucleocapsid/biosynthesis
- Nucleocapsid/genetics
- RNA, Antisense/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Viral/biosynthesis
- RNA, Viral/genetics
- Respiratory Syncytial Virus, Human/genetics
- Respiratory Syncytial Virus, Human/pathogenicity
- Respiratory Syncytial Virus, Human/physiology
- Transcription, Genetic
- Viral Proteins/metabolism
- Virus Replication
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Affiliation(s)
- Vanessa M Cowton
- Division of Pathology and Neuroscience, University of Dundee Medical School, Dundee DD1 9SY, UK
| | - David R McGivern
- Division of Pathology and Neuroscience, University of Dundee Medical School, Dundee DD1 9SY, UK
| | - Rachel Fearns
- Division of Pathology and Neuroscience, University of Dundee Medical School, Dundee DD1 9SY, UK
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Pham QN, Biacchesi S, Skiadopoulos MH, Murphy BR, Collins PL, Buchholz UJ. Chimeric recombinant human metapneumoviruses with the nucleoprotein or phosphoprotein open reading frame replaced by that of avian metapneumovirus exhibit improved growth in vitro and attenuation in vivo. J Virol 2006; 79:15114-22. [PMID: 16306583 PMCID: PMC1316028 DOI: 10.1128/jvi.79.24.15114-15122.2005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Chimeric versions of recombinant human metapneumovirus (HMPV) were generated by replacing the nucleoprotein (N) or phosphoprotein (P) open reading frame with its counterpart from the closely related avian metapneumovirus (AMPV) subgroup C. In Vero cells, AMPV replicated to an approximately 100-fold-higher titer than HMPV. Surprisingly, the N and P chimeric viruses replicated to a peak titer that was 11- and 25-fold higher, respectively, than that of parental HMPV. The basis for this effect is not known but was not due to obvious changes in the efficiency of gene expression. AMPV and the N and P chimeras were evaluated for replication, immunogenicity, and protective efficacy in hamsters. AMPV was attenuated compared to HMPV in this mammalian host on day 5 postinfection, but not on day 3, and only in the nasal turbinates. In contrast, the N and P chimeras were reduced approximately 100-fold in both the upper and lower respiratory tract on day 3 postinfection, although there was little difference by day 5. The N and P chimeras induced a high level of neutralizing serum antibodies and protective efficacy against HMPV; AMPV was only weakly immunogenic and protective against HMPV challenge, reflecting antigenic differences. In African green monkeys immunized intranasally and intratracheally, the mean peak titer of the P chimera was reduced 100- and 1,000-fold in the upper and lower respiratory tracts, whereas the N chimera was reduced only 10-fold in the lower respiratory tract. Both chimeras were comparable to wild-type HMPV in immunogenicity and protective efficacy. Thus, the P chimera is a promising live HMPV vaccine candidate that paradoxically combines improved growth in vitro with attenuation in vivo.
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Affiliation(s)
- Quynh N Pham
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892-8007, USA
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29
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Cheng X, Park H, Zhou H, Jin H. Overexpression of the M2-2 protein of respiratory syncytial virus inhibits viral replication. J Virol 2006; 79:13943-52. [PMID: 16254330 PMCID: PMC1280200 DOI: 10.1128/jvi.79.22.13943-13952.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The M2-2 protein of respiratory syncytial virus (RSV) is involved in regulation of viral RNA transcription and replication. Encoded by the next-to-last gene of RSV, the M2-2 open reading frame (ORF) overlaps with the upstream M2-1 ORF, suggesting that the production of the M2-2 protein might be tightly regulated during virus replication. To evaluate the effect of M2-2 overexpression on RSV replication, the M2-2 gene was separated from M2-1 by leaving it at the position prior to the M2-1 or moving it to the promoter proximal position as an independent transcriptional unit in the RSV A2 genome. Although recombinant viruses bearing the shuffled M2-2 gene were recovered and expressed higher levels of M2-2, most of these viruses grew poorly in HEp-2 cells. Sequence analysis revealed that various mutations (substitution, insertion, and deletion) occurred in the M2-2 gene, resulting in reduced M2-2 activity as measured by the RSV minigenome system. Further examination of the M2-2 sequence and its function showed that either one of the first two AUG codons located at the 5' end of M2-2 could be used to produce a functional M2-2 protein and that deletion of the first six amino acids from its N terminus or four amino acids from its C terminus greatly reduced its function. The effect of M2-2 protein on RSV replication was also studied by examining RSV replication in cells transiently expressing M2-2. The M2-2 protein expressed at a high level completely inhibited RSV replication. These results strongly suggested that the level of the M2-2 protein produced in the infected cells is critical to RSV replication.
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Affiliation(s)
- Xing Cheng
- MedImmune Vaccines Inc., 297 N. Bernardo Ave., Mountain View, CA 94043, USA
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30
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Melero JA. Molecular Biology of Human Respiratory Syncytial Virus. RESPIRATORY SYNCYTIAL VIRUS 2006. [DOI: 10.1016/s0168-7069(06)14001-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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31
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Liuzzi M, Mason SW, Cartier M, Lawetz C, McCollum RS, Dansereau N, Bolger G, Lapeyre N, Gaudette Y, Lagacé L, Massariol MJ, Dô F, Whitehead P, Lamarre L, Scouten E, Bordeleau J, Landry S, Rancourt J, Fazal G, Simoneau B. Inhibitors of respiratory syncytial virus replication target cotranscriptional mRNA guanylylation by viral RNA-dependent RNA polymerase. J Virol 2005; 79:13105-15. [PMID: 16189012 PMCID: PMC1235819 DOI: 10.1128/jvi.79.20.13105-13115.2005] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Respiratory syncytial virus (RSV) is a major cause of respiratory illness in infants, immunocompromised patients, and the elderly. New antiviral agents would be important tools in the treatment of acute RSV disease. RSV encodes its own RNA-dependent RNA polymerase that is responsible for the synthesis of both genomic RNA and subgenomic mRNAs. The viral polymerase also cotranscriptionally caps and polyadenylates the RSV mRNAs at their 5' and 3' ends, respectively. We have previously reported the discovery of the first nonnucleoside transcriptase inhibitor of RSV polymerase through high-throughput screening. Here we report the design of inhibitors that have improved potency both in vitro and in antiviral assays and that also exhibit activity in a mouse model of RSV infection. We have isolated virus with reduced susceptibility to this class of inhibitors. The mutations conferring resistance mapped to a novel motif within the RSV L gene, which encodes the catalytic subunit of RSV polymerase. This motif is distinct from the catalytic region of the L protein and bears some similarity to the nucleotide binding domain within nucleoside diphosphate kinases. These findings lead to the hypothesis that this class of inhibitors may block synthesis of RSV mRNAs by inhibiting guanylylation of viral transcripts. We show that short transcripts produced in the presence of inhibitor in vitro do not contain a 5' cap but, instead, are triphosphorylated, confirming this hypothesis. These inhibitors constitute useful tools for elucidating the molecular mechanism of RSV capping and represent valid leads for the development of novel anti-RSV therapeutics.
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Affiliation(s)
- Michel Liuzzi
- Department of Biological Sciences, Boehringer Ingelheim (Canada) Ltd., Laval, Quebec.
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32
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Brown G, Rixon HWM, Steel J, McDonald TP, Pitt AR, Graham S, Sugrue RJ. Evidence for an association between heat shock protein 70 and the respiratory syncytial virus polymerase complex within lipid-raft membranes during virus infection. Virology 2005; 338:69-80. [PMID: 15936795 DOI: 10.1016/j.virol.2005.05.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Revised: 03/15/2005] [Accepted: 05/03/2005] [Indexed: 11/24/2022]
Abstract
In this report, the interaction between respiratory syncytial virus (RSV) and heat shock protein 70 (HSP70) was examined. Although no significant increase in total HSP70 protein levels was observed during virus infection, analysis of the HSP70 content in lipid-raft membranes from mock- and virus-infected cells revealed an increase in the levels of raft-associated HSP70 during virus infection. Fluorescence microscopy demonstrated that this transport of HSP70 into lipid-raft membranes correlated with the appearance of HSP70 within virus-induced inclusion bodies. Furthermore, co-localisation of HSP70 with the virus N protein and the raft lipid GM1 was observed within these structures. Immunoprecipitation experiments demonstrated the ability of HSP70 to interact with the virus polymerase complex in lipid-rafts in an ATP-dependent manner. Collectively, these data suggest that RSV may induce cellular changes which allow the recruitment of specific host-cell factors, via lipid-raft membranes, to the polymerase complex.
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Affiliation(s)
- Gaie Brown
- MRC Virology Unit, Institute of Virology, University of Glasgow, Church Street, Glasgow G11 5JR, UK
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33
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McDonald TP, Pitt AR, Brown G, Rixon HWM, Sugrue RJ. Evidence that the respiratory syncytial virus polymerase complex associates with lipid rafts in virus-infected cells: a proteomic analysis. Virology 2005; 330:147-57. [PMID: 15527841 DOI: 10.1016/j.virol.2004.09.034] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Revised: 08/31/2004] [Accepted: 09/28/2004] [Indexed: 10/26/2022]
Abstract
The interaction between the respiratory syncytial virus (RSV) polymerase complex and lipid rafts was examined in HEp2 cells. Lipid-raft membranes were prepared from virus-infected cells and their protein content was analysed by Western blotting and mass spectrometry. This analysis revealed the presence of the N, P, L, M2-1 and M proteins. However, these proteins appeared to differ from one another in their association with these structures, with the M2-1 protein showing a greater partitioning into raft membranes compared to that of the N, P or M proteins. Determination of the polymerase activity profile of the gradient fractions revealed that 95% of the detectable viral enzyme activity was associated with lipid-raft membranes. Furthermore, analysis of virus-infected cells by confocal microscopy suggested an association between these proteins and the raft-lipid, GM1. Together, these results provide evidence that the RSV polymerase complex is able to associate with lipid rafts in virus-infected cells.
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34
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Munir S, Sharma JM, Kapur V. Transcriptional response of avian cells to infection with Newcastle disease virus. Virus Res 2005; 107:103-8. [PMID: 15567039 DOI: 10.1016/j.virusres.2004.07.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2004] [Revised: 05/28/2004] [Accepted: 07/10/2004] [Indexed: 11/30/2022]
Abstract
Newcastle disease virus (NDV) causes widespread disease in poultry and wild-birds throughout the world. cDNA microarray analysis was used to examine the effect of NDV infection on host cell transcription. The results show that NDV infection causes an apparent suppression of the interferon response genes during the early stages of infection. In addition, the results reveal transcriptional silencing of cytoskeletal proteins such as the alpha, beta, and gamma types of actin, and a downregulation of the thioredoxin gene, a likely mediator of apoptosis with possible implications in NDV pathogenesis. Comparative analyses show that a majority of genes that were transcriptionally regulated during infection with another common respiratory pathogen of poultry, the avian pneumovirus, remained unaltered during NDV infection, suggesting that even phylogenetically related viruses elicit unique or "signature" patterns of host transcriptional profiles during infection of host cells.
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Affiliation(s)
- Shirin Munir
- Department of Microbiology, University of Minnesota, St. Paul, MN 55108, USA
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35
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Abstract
Our laboratory provided the first proof-of-concept that double-stranded short interfering RNA (ds-siRNA) can act as potent and specific antiviral agents. Designed against specific mRNAs of nonsegmented negative-stranded RNA (NNR) viruses, siRNAs abrogated expression of the corresponding viral proteins, and generated the predicted viral phenotypes. Knockdown was demonstrated across different genera: respiratory syncytial virus (RSV), a pneumovirus; vesicular stomatitis virus (VSV), a rhabdovirus; and human parainfluenza virus (HPIV), a paramyxovirus. The targeted genes could have a wide range of functions, thus documenting the versatility of the technique. Interestingly, antisense single-stranded siRNA (ss-siRNA) was also effective, albeit at a higher concentration. NNR viral genomic and antigenomic RNA, which are encapsidated by nucleocapsid protein and serve as templates for viral RNA-dependent RNA polymerase, were resistant to siRNA. Together, siRNAs offer complementary advantages over traditional mutational analyses that are difficult to perform in NNR viruses, and are also an important new tool to dissect host-virus interactive pathways.
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Affiliation(s)
- Sailen Barik
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, 307 University Blvd., Mobile, AL 36688, USA.
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36
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Mason SW, Lawetz C, Gaudette Y, Dô F, Scouten E, Lagacé L, Simoneau B, Liuzzi M. Polyadenylation-dependent screening assay for respiratory syncytial virus RNA transcriptase activity and identification of an inhibitor. Nucleic Acids Res 2004; 32:4758-67. [PMID: 15356293 PMCID: PMC519107 DOI: 10.1093/nar/gkh809] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
RNA-dependent RNA polymerase from respiratory syncytial virus (RSV) is a multi-subunit ribonucleoprotein (RNP) complex that, in addition to synthesizing the full 15 222 nt viral genomic RNA, is able to synthesize all 10 viral mRNAs. We have prepared crude RNP from RSV-infected HEp-2 cells, based on a method previously used for Newcastle disease virus, and established a novel polyadenylation-dependent capture [poly(A) capture] assay to screen for potential inhibitors of RSV transcriptase activity. In this homogeneous assay, radiolabeled full-length polyadenylated mRNAs produced by the viral RNP are detected through capture on immobilized biotinylated oligo(dT) in a 96-well streptavidin-coated FlashPlate. Possible inhibitors identified with this assay could interfere at any step required for the production of complete RSV mRNAs, including transcription, polyadenylation and, potentially, co-transcriptional guanylylation. A specific inhibitor of RSV transcriptase with antiviral activity was identified through screening of this assay.
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Affiliation(s)
- Stephen W Mason
- Department of Biological Sciences, Boehringer Ingelheim (Canada) Ltd, Laval, Québec H7S 2G5, Canada.
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37
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Rodríguez L, Cuesta I, Asenjo A, Villanueva N. Human respiratory syncytial virus matrix protein is an RNA-binding protein: binding properties, location and identity of the RNA contact residues. J Gen Virol 2004; 85:709-719. [PMID: 14993657 DOI: 10.1099/vir.0.19707-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The human respiratory syncytial virus (HRSV) matrix (M) protein is a structural internal membrane protein. Here we have shown that, like its orthomyxovirus and rhabdovirus counterparts, it has RNA-binding capacity, as determined by retardation of (32)P-labelled riboprobes in gel electrophoresis, cross-linking with UV light and Northern-Western assays. Its binding to RNA was neither sequence-specific nor showed a length requirement, although it had cooperative kinetics with a K(d) of 25 nM and probably two different types of RNA-binding sites. After preparative cross-linking of (32)P-labelled riboprobes with purified, renatured HRSV Long strain M protein (256 residues), the residues in contact with RNA were located between amino acids 120 and 170, in the central part of the molecule. Lysine (positions 121, 130, 156 and 157) and arginine (position 170) residues located within this region and conserved among pneumovirus M proteins of different origins were found to be essential for RNA contact. M protein expression did not affect the replication and transcription of HRSV RNA analogues in vivo (except when expressed in large amounts), in contrast to the in vitro transcription inhibition described previously. In addition, M protein was found to aggregate into high-molecular-mass oligomers, both in the presence and absence of its RNA-binding activity. The formation of these structures has been related in other viruses to either viral or host-cell RNA metabolism.
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Affiliation(s)
- Lorena Rodríguez
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2, Majadahonda, Madrid 28220, Spain
| | - Isabel Cuesta
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2, Majadahonda, Madrid 28220, Spain
| | - Ana Asenjo
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2, Majadahonda, Madrid 28220, Spain
| | - Nieves Villanueva
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2, Majadahonda, Madrid 28220, Spain
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Abstract
Complementary DNA clones of measles virus N, N (S228Q; L229D), Ncore (N1-400), Ntail (N401-525), P, PNT (P1-230), PCT (P231-507), L, MEL (L800-2183) and EL (L1300-2183) were fused in frame downstream of the Gal4 binding domain (BD) or activating domain (AD). All but BD-L, BD-MEL and BD-EL, were detected by western blot, with additional C- and/or N-terminal truncated products in the case of BD-N, and BD-P. BD-P and BD-PNT directly activated the reporter genes, indicating that the PNT domain displays transactivating properties. In yeast two-hybrid assays, PNT and PCT domains bind to Ncore and Ntail domains, respectively, indicating that N and P interact in a head to tail orientation via two independent binding sites. BD-N (S228Q; L229D) and AD-N displayed no or poor interaction with P proteins possibly because they may not be properly folded. L binding site on P lies within the PCT domain, and two PCT binding sites lie within the L1-799 and L800-1300 regions. Thus, N to P and P to L protein interactions in measles virus shared many features with other related Paramyxoviridae. From a human cDNA library, several candidate partners of N protein were identified which all reacted with BD-Ncore, and RNA was found to bridge the N protein with one partner.
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Affiliation(s)
- M Chen
- Immunité et Infections Virales, CNRS-UCBL UMR5537, IFR 62 Laennec, 69372 Cedex 08, Lyon, France
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Abstract
BACKGROUND Human respiratory syncytial virus (HRSV) is a leading cause of serious pediatric respiratory disease worldwide. Natural infection provides only partial protection as repeat infections occur throughout life. A brief review of the extent of antigenic and genetic variation observed in HRSV clinical isolates is presented. METHODS AND RESULTS Recent experimental research is reviewed, describing key factors that may explain the ability of HRSV to cause multiple infections in the same individual even in the presence of an existing immune response. It is well-appreciated that variability of the G protein, both between and within antigenic subgroups A and B, is partially responsible for repeat HRSV infections. A high level of nucleotide change resulting in amino acid change provides strong evidence for selective pressure for change in G sequences, thus new HRSV variants. Although little variation in gene-coding sequences is observed in the F protein (the second major protective antigen), new evidence of genetic variation has identified alteration of gene expression levels by selection of changes in the gene end termination signal that precedes the gene encoding the F protein. Due to obligatory sequential transcription, these changes affect downstream gene expression levels. These data suggest that modulation of F protein levels may provide a selective advantage in the presence of a preexisting immune response. CONCLUSIONS Experimental data in HRSV demonstrate that variation exists not only in gene-coding sequences but also in the signals that control gene expression. Thus alteration in the expression of key proteins provides a second type of antigenic "variation." A better understanding of these differences is critical to the development of an effective vaccine.
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Affiliation(s)
- Gail W Wertz
- Department of Microbiology, University of Alabama at Birmingham, USA.
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40
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Cartee TL, Megaw AG, Oomens AGP, Wertz GW. Identification of a single amino acid change in the human respiratory syncytial virus L protein that affects transcriptional termination. J Virol 2003; 77:7352-60. [PMID: 12805433 PMCID: PMC164798 DOI: 10.1128/jvi.77.13.7352-7360.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infectious Human respiratory syncytial virus (HRSV) with an aberrant RNA synthesis pattern was recovered from a cDNA clone. The virus displayed increased levels of polycistronic readthrough mRNAs resulting from failure of the polymerase to terminate transcription efficiently at the gene ends. An asparagine (N) to aspartic acid (D) change at amino acid 1049 in the large (L) polymerase protein was found to be responsible for the readthrough phenotype. Virus encoding N at position 1049 displayed an RNA synthesis pattern indistinguishable from the A2 strain of HRSV. We compared the transcriptional activities of polymerases that encoded an N or D at position 1049 (L(1049N) or L(1049D)) by using dicistronic subgenomic replicons and found that the alteration of amino acid 1049 specifically affected transcriptional termination but had no effect on genome replication. L(1049N) recognized and terminated transcription at each of the naturally occurring gene junctions with differing efficiencies but at significantly higher efficiency than L(1049D). The abilities of the polymerases to recognize the cis-acting gene end signals required for termination were compared by examining the effect of single nucleotide changes at positions 1 to 8 of the M gene end and were found to be similar. This work identifies a single amino acid position in the polymerase that specifically affects the ability of the polymerase to terminate transcription, but which does not affect genome replication or interaction with the M2-1 protein. This work shows the critical importance of the previously defined cis-acting signals for termination, confirms differential termination at the varied gene junctions, and shows that the polymerase responds to the cis-acting sequences similarly, whether it has N or D at position 1049.
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Affiliation(s)
- Tara L Cartee
- Department of Microbiology, University of Alabama School of Medicine, Birmingham, Alabama 35294, USA
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41
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Bitko V, Oldenburg A, Garmon NE, Barik S. Profilin is required for viral morphogenesis, syncytium formation, and cell-specific stress fiber induction by respiratory syncytial virus. BMC Microbiol 2003; 3:9. [PMID: 12740026 PMCID: PMC156654 DOI: 10.1186/1471-2180-3-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2003] [Accepted: 05/09/2003] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Actin is required for the gene expression and morphogenesis of respiratory syncytial virus (RSV), a clinically important Pneumovirus of the Paramyxoviridae family. In HEp-2 cells, RSV infection also induces actin stress fibers, which may be important in the immunopathology of the RSV disease. Profilin, a major regulator of actin polymerization, stimulates viral transcription in vitro. Thus, we tested the role of profilin in RSV growth and RSV-actin interactions in cultured cells (ex vivo). RESULTS We tested three cell lines: HEp-2 (human), A549 (human), and L2 (rat). In all three, RSV grew well and produced fused cells (syncytium), and two RSV proteins, namely, the phosphoprotein P and the nucleocapsid protein N, associated with profilin. In contrast, induction of actin stress fibers by RSV occurred in HEp-2 and L2 cells, but not in A549. Knockdown of profilin by RNA interference had a small effect on viral macromolecule synthesis but strongly inhibited maturation of progeny virions, cell fusion, and induction of stress fibers. CONCLUSIONS Profilin plays a cardinal role in RSV-mediated cell fusion and viral maturation. In contrast, interaction of profilin with the viral transcriptional proteins P and N may only nominally activate viral RNA-dependent RNA polymerase. Stress fiber formation is a cell-specific response to infection, requiring profilin and perhaps other signaling molecules that are absent in certain cell lines. Stress fibers per se play no role in RSV replication in cell culture. Clearly, the cellular architecture controls multiple steps of host-RSV interaction, some of which are regulated by profilin.
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Affiliation(s)
- Vira Bitko
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Anja Oldenburg
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Nicolle E Garmon
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Sailen Barik
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
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Zhou H, Cheng X, Jin H. Identification of amino acids that are critical to the processivity function of respiratory syncytial virus M2-1 protein. J Virol 2003; 77:5046-53. [PMID: 12692207 PMCID: PMC153968 DOI: 10.1128/jvi.77.9.5046-5053.2003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The M2-1 protein of respiratory syncytial virus (RSV) is a transcription processivity factor that is essential for virus replication. The function of RSV M2-1 protein can be examined by using an RSVlacZ minigenome assay in vitro since the expression of the lacZ gene is dependent on M2-1. The M2-1 protein of pneumonia virus of mice (PVM), also a member of the Pneumovirus genus, functions poorly in the RSVlacZ minigenome assay despite conservation of the Cys(3)-His(1) motif at its N terminus and an overall 40% amino acid identity with RSV M2-1. To identify the amino acids responsible for the differences between these two proteins, two chimeric proteins were constructed. The RSV/PVM (RP) M2-1 chimera that contains the N-terminal 30 amino acids from RSV and the remaining C-terminal 148 amino acids from PVM maintained a level of activity at an ca. 36% of RSV M2-1. However, the PVM/RSV (PR) M2-1 chimera with the N-terminal 29 amino acids from PVM and 164 amino acids from RSV had an activity of <5% of RSV M2-1, indicating that the functional determinants are mainly located in the N terminus of M2-1. Mutagenesis of the N terminus of PR M2-1 and RSV M2-1 identified that Leu-16 and Asn-17 of RSV M2-1 are critical to the M2-1 function. In addition, several charged residues in the N terminus of RSV M2-1 also contributed to the functional integrity of M2-1.
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Affiliation(s)
- Helen Zhou
- MedImmune Vaccines, Inc., Mountain View, California 94043, USA
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43
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Krempl C, Murphy BR, Collins PL. Recombinant respiratory syncytial virus with the G and F genes shifted to the promoter-proximal positions. J Virol 2002; 76:11931-42. [PMID: 12414935 PMCID: PMC136893 DOI: 10.1128/jvi.76.23.11931-11942.2002] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome of human respiratory syncytial virus (RSV) encodes 10 mRNAs and 11 proteins in the order 3'-NS1-NS2-N-P-M-SH-G-F-M2-1/M2-2-L-5'. The G and F glycoproteins are the major RSV neutralization and protective antigens. It seems likely that a high level of expression of G and F would be desirable for a live RSV vaccine. For mononegaviruses, the gene order is a major factor controlling the level of mRNA and protein expression due to the polar gradient of sequential transcription. In order to increase the expression of G and F, recombinant RSVs based on strain A2 were constructed in which the G or F gene was shifted from the sixth or seventh position (in a genome lacking the SH gene), respectively, to the first position (rRSV-G1/DeltaSH and rRSV-F1/DeltaSH, respectively). Another virus was made in which G and F were shifted together to the first and second positions, respectively (rRSV-G1F2/DeltaSH). Shifting one or two genes to the promoter-proximal position resulted in increased mRNA and protein expression of the shifted genes, with G and F expression increased up to 2.4-and 7.8-fold, respectively, at the mRNA level and approximately 2.5-fold at the protein level, compared to the parental virus. Interestingly, the transcription of downstream genes was not greatly affected even though shifting G or F, or G and F together, had the consequence of moving the block of genes NS1-NS2-N-P-M-(G) one or two positions further from the promoter. The efficiency of replication of the gene shift viruses in vitro was increased up to 10-fold. However, their efficiency of replication in the lower respiratory tracts of mice was statistically indistinguishable from that of the parental virus. In the upper respiratory tract, replication was slightly reduced on some days for viruses in which G was in the first position. The magnitude of the G-specific antibody response to the gene shift viruses was similar to that to the parental virus, whereas the F-specific response was increased up to fourfold, although this was not reflected in an increase of the neutralizing activity. Thus, shifting the G and F genes to the promoter-proximal position increased virus replication in vitro, had little effect on replication in the mouse, and increased the antigen-specific immunogenicity of the virus beyond that of parental RSV.
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MESH Headings
- Animals
- Antibodies, Viral/blood
- Base Sequence
- Cell Line
- DNA, Viral/genetics
- Gene Expression
- Genes, Viral
- Genome, Viral
- Humans
- Mice
- Mice, Inbred BALB C
- Molecular Sequence Data
- Promoter Regions, Genetic
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Recombination, Genetic
- Respiratory Syncytial Virus, Human/genetics
- Respiratory Syncytial Virus, Human/immunology
- Respiratory Syncytial Virus, Human/pathogenicity
- Respiratory Syncytial Virus, Human/physiology
- Viral Proteins/genetics
- Virus Replication/genetics
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Affiliation(s)
- Christine Krempl
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892-8007, USA
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44
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Harmon SB, Wertz GW. Transcriptional termination modulated by nucleotides outside the characterized gene end sequence of respiratory syncytial virus. Virology 2002; 300:304-15. [PMID: 12350361 DOI: 10.1006/viro.2002.1541] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The genes of respiratory syncytial (RS) virus are transcribed sequentially by the viral RNA polymerase from a single 3'-proximal promoter. Polyadenylation and termination are directed by a sequence at the end of each gene, after which the polymerase crosses an intergenic region and reinitiates at the start sequence of the next gene. The 10 viral genes have different gene end sequences and different termination efficiencies, which allow for regulation of gene expression, since termination of each gene is required for initiation of the downstream gene. RNA sequences within the previously characterized 13 nucleotide gene end, including a conserved sequence 3'-UCAAU-5' and a tract of U residues, are important for termination. In this study, two additional sequence elements outside of the 13 nucleotide gene end were found to modulate termination efficiency: the A residue upstream of the 3'-UCAAU-5' sequence, and the first nucleotide of the intergenic region when it follows a U(4) tract.
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Affiliation(s)
- Shawn B Harmon
- Department of Microbiology, University of Alabama School of Medicine, Birmingham, Alabama 35294, USA
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45
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Ghildyal R, Mills J, Murray M, Vardaxis N, Meanger J. Respiratory syncytial virus matrix protein associates with nucleocapsids in infected cells. J Gen Virol 2002; 83:753-757. [PMID: 11907323 DOI: 10.1099/0022-1317-83-4-753] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Little is known about the functions of the matrix (M) protein of respiratory syncytial virus (RSV). By analogy with other negative-strand RNA viruses, the M protein should inhibit the viral polymerase prior to packaging and facilitate virion assembly. In this study, localization of the RSV M protein in infected cells and its association with the RSV nucleocapsid complex was investigated. RSV-infected cells were shown to contain characteristic cytoplasmic inclusions. Further analysis showed that these inclusions were localization sites of the M protein as well as the N, P, L and M2-1 proteins described previously. The M protein co-purified with viral ribonucleoproteins (RNPs) from RSV-infected cells. The transcriptase activity of purified RNPs was enhanced by treatment with antibodies to the M protein in a dose-dependent manner. These data suggest that the M protein is associated with RSV nucleocapsids and, like the matrix proteins of other negative-strand RNA viruses, can inhibit virus transcription.
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Affiliation(s)
- R Ghildyal
- Children's Virology Research Unit, Macfarlane Burnet Institute for Medical Research and Public Health, PO Box 254, Yarra Bend Road, Fairfield, Victoria 3078, Australia1
| | - J Mills
- Children's Virology Research Unit, Macfarlane Burnet Institute for Medical Research and Public Health, PO Box 254, Yarra Bend Road, Fairfield, Victoria 3078, Australia1
| | - M Murray
- Children's Virology Research Unit, Macfarlane Burnet Institute for Medical Research and Public Health, PO Box 254, Yarra Bend Road, Fairfield, Victoria 3078, Australia1
| | - N Vardaxis
- Department of Medical Laboratory Science, School of Medical Sciences, RMIT University, Bundoora, Victoria 3083, Australia2
| | - J Meanger
- Children's Virology Research Unit, Macfarlane Burnet Institute for Medical Research and Public Health, PO Box 254, Yarra Bend Road, Fairfield, Victoria 3078, Australia1
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46
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Cartee TL, Wertz GW. Respiratory syncytial virus M2-1 protein requires phosphorylation for efficient function and binds viral RNA during infection. J Virol 2001; 75:12188-97. [PMID: 11711610 PMCID: PMC116116 DOI: 10.1128/jvi.75.24.12188-12197.2001] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The M2-1 protein of respiratory syncytial (RS) virus is a transcriptional processivity and antitermination factor. The M2-1 protein has a Cys3His1 zinc binding motif which is essential for function, is phosphorylated, and has been shown to interact with the RS virus nucleocapsid (N) protein. In the work reported here, we determined the sites at which the M2-1 protein was phosphorylated and investigated the importance of these phosphorylated residues for M2-1 function in transcription. By combining protease digestion, matrix-assisted laser desorption ionization-time of flight mass spectrometry, and site-directed mutagenesis, we identified the phosphorylated residues as serines 58 and 61, not threonine 56 and serine 58 as previously reported. Serines 58 and 61 and the surrounding amino acids are in a consensus sequence for phosphorylation by casein kinase I. Consistent with this, we showed that the unphosphorylated M2-1 protein synthesized in Escherichia coli could be phosphorylated in vitro by casein kinase I. The effect of eliminating phosphorylation by site-specific mutagenesis of serines 58 and 61 on the function of the M2-1 protein in transcription of RS virus subgenomic replicons was assayed. The activities of the M2-1 protein phosphorylation mutants in transcriptional antitermination were tested over a range of concentrations and were found to be substantially inhibited at all concentrations. The data show that phosphorylation is important for the M2-1 protein function in transcription. However, mutation of the M2-1 phosphorylation sites did not interfere with the ability of the M2-1 protein to interact with the N protein in transfected cells. The interaction of the M2-1 and N proteins in cotransfected cells was found to be sensitive to RNase A, indicating that the M2-1-N protein interaction was mediated via RNA. Furthermore, the M2-1 protein was shown to bind monocistronic and polycistronic RS virus mRNAs during infection.
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Affiliation(s)
- T L Cartee
- Department of Microbiology, University of Alabama School of Medicine, Birmingham, Alabama 35294, USA
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47
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Ogino T, Yamadera T, Nonaka T, Imajoh-Ohmi S, Mizumoto K. Enolase, a cellular glycolytic enzyme, is required for efficient transcription of Sendai virus genome. Biochem Biophys Res Commun 2001; 285:447-55. [PMID: 11444863 DOI: 10.1006/bbrc.2001.5160] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cellular proteins (host factors) may play key roles in transcription of Sendai virus (SeV) genome. We have previously shown that the host factor activity, which stimulates in vitro mRNA synthesis of SeV, from bovine brain comprises at least three complementary factors, and two of them were identified as tubulin and phosphoglycerate kinase (PGK). Here the third host factor activity was further resolved into two complementary factors, and one of them was purified to an almost single polypeptide chain with an apparent M(r) of 52,000 (p52) and was identified as a glycolytic enzyme, enolase. Recombinant human alpha-enolase, as did p52, acted synergistically with other three host factors to stimulate SeV mRNA synthesis. West-Western blot analysis demonstrated that tubulin specifically binds enolase as well as PGK, suggesting that these two glycolytic enzymes regulate SeV transcription through their interactions with tubulin.
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Affiliation(s)
- T Ogino
- Department of Biochemistry, School of Pharmaceutical Sciences, Kitasato University, Shirokane, Minato-ku, Tokyo 108-8641, Japan
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48
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Harmon SB, Megaw AG, Wertz GW. RNA sequences involved in transcriptional termination of respiratory syncytial virus. J Virol 2001; 75:36-44. [PMID: 11119571 PMCID: PMC113895 DOI: 10.1128/jvi.75.1.36-44.2001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
RNA signals at the ends of the genes of respiratory syncytial (RS) virus direct polyadenylation and termination of viral transcription. These gene ends contain two conserved regions, a pentanucleotide and a tract of uridylate (U) residues, separated by an A/U-rich central region that is less well conserved. The U tract is thought to be the template for polyadenylation of viral mRNAs by reiterative transcription. The cis-acting requirements for termination were investigated by mutagenesis of the matrix (M) gene end (3'-UCAAUUAUUUUUU-5') in a dicistronic RNA replicon. Termination efficiencies were quantitated by intracellular metabolic labeling of monocistronic mRNAs and the dicistronic readthrough RNAs that result when termination fails to occur. All three regions of the gene end were necessary for termination. Mutation of each of the first 8 nucleotides of the M gene end to all other nucleotides showed that nucleotides 2 to 6 were important for termination and intolerant of change, whereas nucleotides 1 and 7 were tolerant of change. At position 8, A or U allowed termination, but G or C did not. Both the length and the position of the U tract were important for termination. U residues at positions 9 to 12 were necessary, while additional U residues at position 8, and especially position 13, enhanced termination efficiency. Altering the length of the central region abolished termination, suggesting that the position of the U tract with respect to the 3'-UCAAU-5' sequence was critical. The termination efficiencies of each of the 10 genes of RS virus are different. Since transcription is obligatorily sequential and termination of each gene is required for transcription of the next gene downstream, these differences may contribute to gene regulation. In agreement with our data, the naturally occurring gene ends of RS virus that terminate inefficiently have short U tracts or other sequence features that correlated with decreased termination when similar mutations were analyzed in RNA replicons.
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Affiliation(s)
- S B Harmon
- Department of Microbiology, University of Alabama at Birmingham, 35294, USA
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49
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Abstract
Bovine respiratory syncytial virus (BRSV) infection is the major cause of respiratory disease in calves during the first year of life. The study of the virus has been difficult because of its lability and very poor growth in cell culture. However, during the last decade, the introduction of new immunological and biotechnological techniques has facilitated a more extensive study of BRSV as illustrated by the increasing number of papers published. Despite this growing focus, many aspects of the pathogenesis, epidemiology, immunology etc. remain obscure. The course and outcome of the infection is very complex and unpredictable which makes the diagnosis and subsequent therapy very difficult. BRSV is closely related to human respiratory syncytial virus (HRSV) which is an important cause of respiratory disease in young children. In contrast to BRSV, the recent knowledge of HRSV is regularly extensively reviewed in several books and journals. The present paper contains an updated review on BRSV covering most aspects of the structure, molecular biology, pathogenesis, pathology, clinical features, epidemiology, diagnosis and immunology based on approximately 140 references from international research journals.
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50
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Larsen LE. Bovine respiratory syncytial virus (BRSV): a review. Acta Vet Scand 2000; 41:1-24. [PMID: 10920473 PMCID: PMC7996406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/1999] [Accepted: 12/28/1999] [Indexed: 02/17/2023] Open
Abstract
Bovine respiratory syncytial virus (BRSV) infection is the major cause of respiratory disease in calves during the first year of life. The study of the virus has been difficult because of its lability and very poor growth in cell culture. However, during the last decade, the introduction of new immunological and biotechnological techniques has facilitated a more extensive study of BRSV as illustrated by the increasing number of papers published. Despite this growing focus, many aspects of the pathogenesis, epidemiology, immunology etc. remain obscure. The course and outcome of the infection is very complex and unpredictable which makes the diagnosis and subsequent therapy very difficult. BRSV is closely related to human respiratory syncytial virus (HRSV) which is an important cause of respiratory disease in young children. In contrast to BRSV, the recent knowledge of HRSV is regularly extensively reviewed in several books and journals. The present paper contains an updated review on BRSV covering most aspects of the structure, molecular biology, pathogenesis, pathology, clinical features, epidemiology, diagnosis and immunology based on approximately 140 references from international research journals.
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Affiliation(s)
- L E Larsen
- Danish Veterinary Laboratory, Copenhagen, Denmark.
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