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Jiang H, Nair V, Sun Y, Ding C. The diverse roles of peroxisomes in the interplay between viruses and mammalian cells. Antiviral Res 2024; 221:105780. [PMID: 38092324 DOI: 10.1016/j.antiviral.2023.105780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/26/2023]
Abstract
Peroxisomes are ubiquitous organelles found in eukaryotic cells that play a critical role in the oxidative metabolism of lipids and detoxification of reactive oxygen species (ROS). Recently, the role of peroxisomes in viral infections has been extensively studied. Although several studies have reported that peroxisomes exert antiviral activity, evidence indicates that viruses have also evolved diverse strategies to evade peroxisomal antiviral signals. In this review, we summarize the multiple roles of peroxisomes in the interplay between viruses and mammalian cells. Focus is given on the peroxisomal regulation of innate immune response, lipid metabolism, ROS production, and viral regulation of peroxisomal biosynthesis and degradation. Understanding the interactions between peroxisomes and viruses provides novel insights for the development of new antiviral strategies.
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Affiliation(s)
- Hui Jiang
- Department of Avian Infectious Diseases, Shanghai Veterinary Research Institute. Chinese Academy of Agricultural Science, Shanghai, China
| | - Venugopal Nair
- Avian Oncogenic Viruses Group, UK-China Centre of Excellence in Avian Disease Research, The Pirbright Institute, Pirbright, Guildford, Surrey, United Kingdom
| | - Yingjie Sun
- Department of Avian Infectious Diseases, Shanghai Veterinary Research Institute. Chinese Academy of Agricultural Science, Shanghai, China.
| | - Chan Ding
- Department of Avian Infectious Diseases, Shanghai Veterinary Research Institute. Chinese Academy of Agricultural Science, Shanghai, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China.
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2
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Ferreira V, Ferreira AR, Ribeiro D. Peroxisomes and Viruses: Overview on Current Knowledge and Experimental Approaches. Methods Mol Biol 2023; 2643:271-294. [PMID: 36952192 DOI: 10.1007/978-1-0716-3048-8_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2023]
Abstract
The general interest in the study of the interplay between peroxisomes and viruses has increased in recent years, with different reports demonstrating that distinct viruses modulate peroxisome-related mechanisms to either counteract the cellular antiviral response or support viral propagation. Nevertheless, mechanistical details are still scarce, and information is often incomplete. In this chapter, we present an overview of the current knowledge concerning the interplay between peroxisomes and different viruses. We furthermore present, compare, and discuss the most relevant experimental approaches and tools used in the different studies. Finally, we stress the importance of further, more detailed, and spatial-temporal analyses that encompass all the different phases of the viruses' infection cycles. These studies may lead to the discovery of novel peroxisome-related cellular mechanisms that can further be explored as targets for the development of novel antiviral therapies.
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Affiliation(s)
- Vanessa Ferreira
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal
| | - Ana Rita Ferreira
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal
| | - Daniela Ribeiro
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal.
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3
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Wanders RJA, Baes M, Ribeiro D, Ferdinandusse S, Waterham HR. The physiological functions of human peroxisomes. Physiol Rev 2023; 103:957-1024. [PMID: 35951481 DOI: 10.1152/physrev.00051.2021] [Citation(s) in RCA: 51] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Peroxisomes are subcellular organelles that play a central role in human physiology by catalyzing a range of unique metabolic functions. The importance of peroxisomes for human health is exemplified by the existence of a group of usually severe diseases caused by an impairment in one or more peroxisomal functions. Among others these include the Zellweger spectrum disorders, X-linked adrenoleukodystrophy, and Refsum disease. To fulfill their role in metabolism, peroxisomes require continued interaction with other subcellular organelles including lipid droplets, lysosomes, the endoplasmic reticulum, and mitochondria. In recent years it has become clear that the metabolic alliance between peroxisomes and other organelles requires the active participation of tethering proteins to bring the organelles physically closer together, thereby achieving efficient transfer of metabolites. This review intends to describe the current state of knowledge about the metabolic role of peroxisomes in humans, with particular emphasis on the metabolic partnership between peroxisomes and other organelles and the consequences of genetic defects in these processes. We also describe the biogenesis of peroxisomes and the consequences of the multiple genetic defects therein. In addition, we discuss the functional role of peroxisomes in different organs and tissues and include relevant information derived from model systems, notably peroxisomal mouse models. Finally, we pay particular attention to a hitherto underrated role of peroxisomes in viral infections.
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Affiliation(s)
- Ronald J A Wanders
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Pediatrics, Emma Children's Hospital, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,United for Metabolic Diseases, Amsterdam, The Netherlands
| | - Myriam Baes
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Daniela Ribeiro
- Institute of Biomedicine (iBiMED) and Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Sacha Ferdinandusse
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,United for Metabolic Diseases, Amsterdam, The Netherlands
| | - Hans R Waterham
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Pediatrics, Emma Children's Hospital, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,United for Metabolic Diseases, Amsterdam, The Netherlands
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4
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Ferreira AR, Marques M, Ramos B, Kagan JC, Ribeiro D. Emerging roles of peroxisomes in viral infections. Trends Cell Biol 2021; 32:124-139. [PMID: 34696946 DOI: 10.1016/j.tcb.2021.09.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 09/23/2021] [Accepted: 09/27/2021] [Indexed: 01/01/2023]
Abstract
Peroxisomes, essential subcellular organelles that fulfill important functions in lipid and reactive oxygen species metabolism, have recently emerged as key players during viral infections. Their importance for the establishment of the cellular antiviral response has been highlighted by numerous reports of specific evasion of peroxisome-dependent signaling by different viruses. Recent data demonstrate that peroxisomes also assume important proviral functions. Here, we review and discuss the recent advances in the study of the diverse roles of peroxisomes during viral infections, from animal to plant viruses, and from basic to translational perspectives. We further discuss the future development of this emerging area and propose that peroxisome-related mechanisms represent a promising target for the development of novel antiviral strategies.
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Affiliation(s)
- Ana Rita Ferreira
- Institute of Biomedicine (iBiMED) and Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Mariana Marques
- Institute of Biomedicine (iBiMED) and Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Bruno Ramos
- Institute of Biomedicine (iBiMED) and Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Jonathan C Kagan
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Daniela Ribeiro
- Institute of Biomedicine (iBiMED) and Department of Medical Sciences, University of Aveiro, Aveiro, Portugal.
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5
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Wong LH, Edgar JR, Martello A, Ferguson BJ, Eden ER. Exploiting Connections for Viral Replication. Front Cell Dev Biol 2021; 9:640456. [PMID: 33816489 PMCID: PMC8012536 DOI: 10.3389/fcell.2021.640456] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 02/01/2021] [Indexed: 12/16/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of the COVID-19 (coronavirus disease 2019) pandemic, is a positive strand RNA (+RNA) virus. Like other +RNA viruses, SARS-CoV-2 is dependent on host cell metabolic machinery to survive and replicate, remodeling cellular membranes to generate sites of viral replication. Viral RNA-containing double-membrane vesicles (DMVs) are a striking feature of +RNA viral replication and are abundant in SARS-CoV-2-infected cells. Their generation involves rewiring of host lipid metabolism, including lipid biosynthetic pathways. Viruses can also redirect lipids from host cell organelles; lipid exchange at membrane contact sites, where the membranes of adjacent organelles are in close apposition, has been implicated in the replication of several +RNA viruses. Here we review current understanding of DMV biogenesis. With a focus on the exploitation of contact site machinery by +RNA viruses to generate replication organelles, we discuss evidence that similar mechanisms support SARS-CoV-2 replication, protecting its RNA from the host cell immune response.
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Affiliation(s)
| | - James R. Edgar
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | | | - Brian J. Ferguson
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Emily R. Eden
- UCL Institute of Ophthalmology, London, United Kingdom
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6
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Chua SCJH, Tan HQ, Engelberg D, Lim LHK. Alternative Experimental Models for Studying Influenza Proteins, Host-Virus Interactions and Anti-Influenza Drugs. Pharmaceuticals (Basel) 2019; 12:E147. [PMID: 31575020 PMCID: PMC6958409 DOI: 10.3390/ph12040147] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 09/11/2019] [Accepted: 09/12/2019] [Indexed: 12/14/2022] Open
Abstract
Ninety years after the discovery of the virus causing the influenza disease, this malady remains one of the biggest public health threats to mankind. Currently available drugs and vaccines only partially reduce deaths and hospitalizations. Some of the reasons for this disturbing situation stem from the sophistication of the viral machinery, but another reason is the lack of a complete understanding of the molecular and physiological basis of viral infections and host-pathogen interactions. Even the functions of the influenza proteins, their mechanisms of action and interaction with host proteins have not been fully revealed. These questions have traditionally been studied in mammalian animal models, mainly ferrets and mice (as well as pigs and non-human primates) and in cell lines. Although obviously relevant as models to humans, these experimental systems are very complex and are not conveniently accessible to various genetic, molecular and biochemical approaches. The fact that influenza remains an unsolved problem, in combination with the limitations of the conventional experimental models, motivated increasing attempts to use the power of other models, such as low eukaryotes, including invertebrate, and primary cell cultures. In this review, we summarized the efforts to study influenza in yeast, Drosophila, zebrafish and primary human tissue cultures and the major contributions these studies have made toward a better understanding of the disease. We feel that these models are still under-utilized and we highlight the unique potential each model has for better comprehending virus-host interactions and viral protein function.
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Affiliation(s)
- Sonja C J H Chua
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore.
- NUS Immunology Program, Life Sciences Institute, National University of Singapore, Singapore 117456, Singapore.
- CREATE-NUS-HUJ Molecular Mechanisms of Inflammatory Diseases Programme, National University of Singapore, Singapore 138602, Singapore.
| | - Hui Qing Tan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore.
- NUS Immunology Program, Life Sciences Institute, National University of Singapore, Singapore 117456, Singapore.
| | - David Engelberg
- CREATE-NUS-HUJ Molecular Mechanisms of Inflammatory Diseases Programme, National University of Singapore, Singapore 138602, Singapore.
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore.
- Department of Biological Chemistry, The Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
| | - Lina H K Lim
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore.
- NUS Immunology Program, Life Sciences Institute, National University of Singapore, Singapore 117456, Singapore.
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7
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Type III Interferon Restriction by Porcine Epidemic Diarrhea Virus and the Role of Viral Protein nsp1 in IRF1 Signaling. J Virol 2018; 92:JVI.01677-17. [PMID: 29187542 DOI: 10.1128/jvi.01677-17] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/21/2017] [Indexed: 01/16/2023] Open
Abstract
Type III interferons (IFNs) play a vital role in maintaining the antiviral state of the mucosal epithelial surface in the gut, and in turn, enteric viruses may have evolved to evade the type III IFN responses during infection. To study the possible immune evasion of the type III IFN response by porcine epidemic diarrhea virus (PEDV), a line of porcine intestinal epithelial cells was developed as a cell model for PEDV replication. IFN-λ1 and IFN-λ3 inhibited PEDV replication, indicating the anti-PEDV activity of type III IFNs. Of the 21 PEDV proteins, nsp1, nsp3, nsp5, nsp8, nsp14, nsp15, nsp16, open reading frame 3 (ORF3), E, M, and N were found to suppress type III IFN activities, and IRF1 (interferon regulatory factor 1) signaling mediated the suppression. PEDV specifically inhibited IRF1 nuclear translocation. The peroxisome is the innate antiviral signaling platform for the activation of IRF1-mediated IFN-λ production, and the numbers of peroxisomes were found to be decreased in PEDV-infected cells. PEDV nsp1 blocked the nuclear translocation of IRF1 and reduced the number of peroxisomes to suppress IRF1-mediated type III IFNs. Mutational studies showed that the conserved residues of nsp1 were crucial for IRF1-mediated IFN-λ suppression. Our study for the first time provides evidence that the porcine enteric virus PEDV downregulates and evades IRF1-mediated type III IFN responses by reducing the number of peroxisomes.IMPORTANCE Porcine epidemic diarrhea virus (PEDV) is a highly contagious enteric coronavirus that emerged in swine in the United States and has caused severe economic losses. PEDV targets intestinal epithelial cells in the gut, and intestinal epithelial cells selectively induce and respond to the production of type III interferons (IFNs). However, little is known about the modulation of the type III IFN response by PEDV in intestinal epithelial cells. In this study, we established a porcine intestinal epithelial cell model for PEDV replication. We found that PEDV inhibited IRF1-mediated type III IFN production by decreasing the number of peroxisomes in porcine intestinal epithelial cells. We also demonstrated that the conserved residues in the PEDV nsp1 protein were crucial for IFN suppression. This study for the first time shows PEDV evasion of the type III IFN response in intestinal epithelial cells, and it provides valuable information on host cell-virus interactions not only for PEDV but also for other enteric viral infections in swine.
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Influenza A Virus Virulence Depends on Two Amino Acids in the N-Terminal Domain of Its NS1 Protein To Facilitate Inhibition of the RNA-Dependent Protein Kinase PKR. J Virol 2017; 91:JVI.00198-17. [PMID: 28250123 DOI: 10.1128/jvi.00198-17] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 02/20/2017] [Indexed: 12/22/2022] Open
Abstract
The RNA-dependent protein kinase (PKR) has broad antiviral activity inducing translational shutdown of viral and cellular genes and is therefore targeted by various viral proteins to facilitate pathogen propagation. The pleiotropic NS1 protein of influenza A virus acts as silencer of PKR activation and ensures high-level viral replication and virulence. However, the exact manner of this inhibition remains controversial. To elucidate the structural requirements within the NS1 protein for PKR inhibition, we generated a set of mutant viruses, identifying highly conserved arginine residues 35 and 46 within the NS1 N terminus as being most critical not only for binding to and blocking activation of PKR but also for efficient virus propagation. Biochemical and Förster resonance energy transfer (FRET)-based interaction studies showed that mutation of R35 or R46 allowed formation of NS1 dimers but eliminated any detectable binding to PKR as well as to double-stranded RNA (dsRNA). Using in vitro and in vivo approaches to phenotypic restoration, we demonstrated the essential role of the NS1 N terminus for blocking PKR. The strong attenuation conferred by NS1 mutation R35A or R46A was substantially alleviated by stable knockdown of PKR in human cells. Intriguingly, both NS1 mutant viruses did not trigger any signs of disease in PKR+/+ mice, but replicated to high titers in lungs of PKR-/- mice and caused lethal infections. These data not only establish the NS1 N terminus as highly critical for neutralization of PKR's antiviral activity but also identify this blockade as an indispensable contribution of NS1 to the viral life cycle.IMPORTANCE Influenza A virus inhibits activation of the RNA-dependent protein kinase (PKR) by means of its nonstructural NS1 protein, but the underlying mode of inhibition is debated. Using mutational analysis, we identified arginine residues 35 and 46 within the N-terminal NS1 domain as highly critical for binding to and functional silencing of PKR. In addition, our data show that this is a main activity of amino acids 35 and 46, as the strong attenuation of corresponding mutant viruses in human cells was rescued to a large extent by lowering of PKR expression levels. Significantly, this corresponded with restoration of viral virulence for NS1 R35A and R46A mutant viruses in PKR-/- mice. Therefore, our data establish a model in which the NS1 N-terminal domain engages in a binding interaction to inhibit activation of PKR and ensure efficient viral propagation and virulence.
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9
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Flavivirus Infection Impairs Peroxisome Biogenesis and Early Antiviral Signaling. J Virol 2015; 89:12349-61. [PMID: 26423946 DOI: 10.1128/jvi.01365-15] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 09/23/2015] [Indexed: 12/16/2022] Open
Abstract
UNLABELLED Flaviviruses are significant human pathogens that have an enormous impact on the global health burden. Currently, there are very few vaccines against or therapeutic treatments for flaviviruses, and our understanding of how these viruses cause disease is limited. Evidence suggests that the capsid proteins of flaviviruses play critical nonstructural roles during infection, and therefore, elucidating how these viral proteins affect cellular signaling pathways could lead to novel targets for antiviral therapy. We used affinity purification to identify host cell proteins that interact with the capsid proteins of West Nile and dengue viruses. One of the cellular proteins that formed a stable complex with flavivirus capsid proteins is the peroxisome biogenesis factor Pex19. Intriguingly, flavivirus infection resulted in a significant loss of peroxisomes, an effect that may be due in part to capsid expression. We posited that capsid protein-mediated sequestration and/or degradation of Pex19 results in loss of peroxisomes, a situation that could result in reduced early antiviral signaling. In support of this hypothesis, we observed that induction of the lambda interferon mRNA in response to a viral RNA mimic was reduced by more than 80%. Together, our findings indicate that inhibition of peroxisome biogenesis may be a novel mechanism by which flaviviruses evade the innate immune system during early stages of infection. IMPORTANCE RNA viruses infect hundreds of millions of people each year, causing significant morbidity and mortality. Chief among these pathogens are the flaviviruses, which include dengue virus and West Nile virus. Despite their medical importance, there are very few prophylactic or therapeutic treatments for these viruses. Moreover, the manner in which they subvert the innate immune response in order to establish infection in mammalian cells is not well understood. Recently, peroxisomes were reported to function in early antiviral signaling, but very little is known regarding if or how pathogenic viruses affect these organelles. We report for the first time that flavivirus infection results in significant loss of peroxisomes in mammalian cells, which may indicate that targeting of peroxisomes is a key strategy used by viruses to subvert early antiviral defenses.
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Schrader M, Costello J, Godinho LF, Islinger M. Peroxisome-mitochondria interplay and disease. J Inherit Metab Dis 2015; 38:681-702. [PMID: 25687155 DOI: 10.1007/s10545-015-9819-7] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/21/2015] [Accepted: 01/26/2015] [Indexed: 12/16/2022]
Abstract
Peroxisomes and mitochondria are ubiquitous, highly dynamic organelles with an oxidative type of metabolism in eukaryotic cells. Over the years, substantial evidence has been provided that peroxisomes and mitochondria exhibit a close functional interplay which impacts on human health and development. The so-called "peroxisome-mitochondria connection" includes metabolic cooperation in the degradation of fatty acids, a redox-sensitive relationship, an overlap in key components of the membrane fission machineries and cooperation in anti-viral signalling and defence. Furthermore, combined peroxisome-mitochondria disorders with defects in organelle division have been revealed. In this review, we present the latest progress in the emerging field of peroxisomal and mitochondrial interplay in mammals with a particular emphasis on cooperative fatty acid β-oxidation, redox interplay, organelle dynamics, cooperation in anti-viral signalling and the resulting implications for disease.
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Affiliation(s)
- Michael Schrader
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK,
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Fluorescence-Activated Cell Sorting-Based Analysis Reveals an Asymmetric Induction of Interferon-Stimulated Genes in Response to Seasonal Influenza A Virus. J Virol 2015; 89:6982-93. [PMID: 25903337 DOI: 10.1128/jvi.00857-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 04/18/2015] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED Influenza A virus (IAV) infection provokes an antiviral response involving the expression of type I and III interferons (IFN) and IFN-stimulated genes (ISGs) in infected cell cultures. However, the spatiotemporal dynamics of the IFN reaction are incompletely understood, as previous studies investigated mainly the population responses of virus-infected cultures, although substantial cell-to-cell variability has been documented. We devised a fluorescence-activated cell sorting-based assay to simultaneously quantify expression of viral antigens and ISGs, such as ISG15, MxA, and IFIT1, in IAV-infected cell cultures at the single-cell level. This approach revealed that seasonal IAV triggers an unexpected asymmetric response, as the major cell populations expressed either viral antigen or ISG, but rarely both. Further investigations identified a role of the viral NS1 protein in blocking ISG expression in infected cells, which surprisingly did not reduce paracrine IFN signaling to noninfected cells. Interestingly, viral ISG control was impaired in cultures infected with avian-origin IAV, including the H7N9 virus from eastern China. This phenotype was traced back to polymorphic NS1 amino acids known to be important for stable binding of the polyadenylation factor CPSF30 and concomitant suppression of host cell gene expression. Most significantly, mutation of two amino acids within the CPSF30 attachment site of NS1 from seasonal IAV diminished the strict control of ISG expression in infected cells and substantially attenuated virus replication. In conclusion, our approach revealed an asymmetric, NS1-dependent ISG induction in cultures infected with seasonal IAV, which appears to be essential for efficient virus propagation. IMPORTANCE Interferons are expressed by infected cells in response to IAV infection and play important roles in the antiviral immune response by inducing hundreds of interferon-stimulated genes (ISGs). Unlike many previous studies, we investigated the ISG response at the single-cell level, enabling novel insights into this virus-host interaction. Hence, cell cultures infected with seasonal IAV displayed an asymmetric ISG induction that was confined almost exclusively to noninfected cells. In comparison, ISG expression was observed in larger cell populations infected with avian-origin IAV, suggesting a more resolute antiviral response to these strains. Strict control of ISG expression by seasonal IAV was explained by the binding of the viral NS1 protein to the polyadenylation factor CPSF30, which reduces host cell gene expression. Mutational disruption of CPSF30 binding within NS1 concomitantly attenuated ISG control and replication of seasonal IAV, illustrating the importance of maintaining an asymmetric ISG response for efficient virus propagation.
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12
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Marc D. Influenza virus non-structural protein NS1: interferon antagonism and beyond. J Gen Virol 2014; 95:2594-2611. [PMID: 25182164 DOI: 10.1099/vir.0.069542-0] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Most viruses express one or several proteins that counter the antiviral defences of the host cell. This is the task of non-structural protein NS1 in influenza viruses. Absent in the viral particle, but highly expressed in the infected cell, NS1 dramatically inhibits cellular gene expression and prevents the activation of key players in the IFN system. In addition, NS1 selectively enhances the translation of viral mRNAs and may regulate the synthesis of viral RNAs. Our knowledge of the virus and of NS1 has increased dramatically during the last 15 years. The atomic structure of NS1 has been determined, many cellular partners have been identified and its multiple activities have been studied in depth. This review presents our current knowledge, and attempts to establish relationships between the RNA sequence, the structure of the protein, its ligands, its activities and the pathogenicity of the virus. A better understanding of NS1 could help in elaborating novel antiviral strategies, based on either live vaccines with altered NS1 or on small-compound inhibitors of NS1.
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Affiliation(s)
- Daniel Marc
- Université François Rabelais, UMR1282 Infectiologie et Santé Publique, 37000 Tours, France.,Pathologie et Immunologie Aviaire, INRA, UMR1282 Infectiologie et Santé Publique, 37380 Nouzilly, France
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13
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Tanner LB, Chng C, Guan XL, Lei Z, Rozen SG, Wenk MR. Lipidomics identifies a requirement for peroxisomal function during influenza virus replication. J Lipid Res 2014; 55:1357-65. [PMID: 24868094 DOI: 10.1194/jlr.m049148] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Indexed: 12/13/2022] Open
Abstract
Influenza virus acquires a host-derived lipid envelope during budding, yet a convergent view on the role of host lipid metabolism during infection is lacking. Using a mass spectrometry-based lipidomics approach, we provide a systems-scale perspective on membrane lipid dynamics of infected human lung epithelial cells and purified influenza virions. We reveal enrichment of the minor peroxisome-derived ether-linked phosphatidylcholines relative to bulk ester-linked phosphatidylcholines in virions as a unique pathogenicity-dependent signature for influenza not found in other enveloped viruses. Strikingly, pharmacological and genetic interference with peroxisomal and ether lipid metabolism impaired influenza virus production. Further integration of our lipidomics results with published genomics and proteomics data corroborated altered peroxisomal lipid metabolism as a hallmark of influenza virus infection in vitro and in vivo. Influenza virus may therefore tailor peroxisomal and particularly ether lipid metabolism for efficient replication.
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Affiliation(s)
- Lukas Bahati Tanner
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456 NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore 117456
| | - Charmaine Chng
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456
| | - Xue Li Guan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456 Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, 4002 Basel, Switzerland
| | - Zhengdeng Lei
- Centre for Computational Biology, Duke-NUS Graduate Medical School, Singapore 169857 Stem Cell Biology Program, Duke-NUS Graduate Medical School, Singapore 169857 Research Resources Center, University of Illinois at Chicago, Chicago, IL 60612
| | - Steven G Rozen
- Centre for Computational Biology, Duke-NUS Graduate Medical School, Singapore 169857 Stem Cell Biology Program, Duke-NUS Graduate Medical School, Singapore 169857
| | - Markus R Wenk
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456 NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore 117456 Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, 4002 Basel, Switzerland Department of Biological Sciences, National University of Singapore, Singapore 117597
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14
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Abstract
Virus replication requires lipid metabolism, but how lipids mediate virus infection remains obscure. In this issue, Amini-Bavil-Olyaee et al. (2013) reveal that IFITM proteins disturb cholesterol homeostasis to block virus entry. Previously, in Cell, Morita and colleagues (2013) showed the antiviral potency of the lipid mediator protectin D1.
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Affiliation(s)
- Lukas Bahati Tanner
- Department of Biochemistry, Yong Loo Lin School of Medicine and NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore 117456, Singapore
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15
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Jefferson M, Whelband M, Mohorianu I, Powell PP. The pestivirus N terminal protease N(pro) redistributes to mitochondria and peroxisomes suggesting new sites for regulation of IRF3 by N(pro.). PLoS One 2014; 9:e88838. [PMID: 24551175 PMCID: PMC3925175 DOI: 10.1371/journal.pone.0088838] [Citation(s) in RCA: 22] [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: 06/12/2013] [Accepted: 01/14/2014] [Indexed: 01/16/2023] Open
Abstract
The N-terminal protease of pestiviruses, N(pro) is a unique viral protein, both because it is a distinct autoprotease that cleaves itself from the following polyprotein chain, and also because it binds and inactivates IRF3, a central regulator of interferon production. An important question remains the role of N(pro) in the inhibition of apoptosis. In this study, apoptotic signals induced by staurosporine, interferon, double stranded RNA, sodium arsenate and hydrogen peroxide were inhibited by expression of wild type N(pro), but not by mutant protein N(pro) C112R, which we show is less efficient at promoting degradation of IRF3, and led to the conclusion that N(pro) inhibits the stress-induced intrinsic mitochondrial pathway through inhibition of IRF3-dependent Bax activation. Both expression of N(pro) and infection with Bovine Viral Diarrhea Virus (BVDV) prevented Bax redistribution and mitochondrial fragmentation. Given the role played by signaling platforms during IRF3 activation, we have studied the subcellular distribution of N(pro) and we show that, in common with many other viral proteins, N(pro) targets mitochondria to inhibit apoptosis in response to cell stress. N(pro) itself not only relocated to mitochondria but in addition, both N(pro) and IRF3 associated with peroxisomes, with over 85% of N(pro) puncta co-distributing with PMP70, a marker for peroxisomes. In addition, peroxisomes containing N(pro) and IRF3 associated with ubiquitin. IRF3 was degraded, whereas N(pro) accumulated in response to cell stress. These results implicate mitochondria and peroxisomes as new sites for IRF3 regulation by N(pro), and highlight the role of these organelles in the anti-viral pathway.
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Affiliation(s)
- Matthew Jefferson
- Biomedical Research Centre, Norwich Medical School and Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Matthew Whelband
- Biomedical Research Centre, Norwich Medical School and Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Irina Mohorianu
- Biomedical Research Centre, Norwich Medical School and Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Penny P. Powell
- Biomedical Research Centre, Norwich Medical School and Biological Sciences, University of East Anglia, Norwich, United Kingdom
- * E-mail:
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16
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Engel DA. The influenza virus NS1 protein as a therapeutic target. Antiviral Res 2013; 99:409-16. [PMID: 23796981 DOI: 10.1016/j.antiviral.2013.06.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 06/08/2013] [Accepted: 06/11/2013] [Indexed: 10/26/2022]
Abstract
Nonstructural protein 1 (NS1) of influenza A virus plays a central role in virus replication and blockade of the host innate immune response, and is therefore being considered as a potential therapeutic target. The primary function of NS1 is to dampen the host interferon (IFN) response through several distinct molecular mechanisms that are triggered by interactions with dsRNA or specific cellular proteins. Sequestration of dsRNA by NS1 results in inhibition of the 2'-5' oligoadenylate synthetase/RNase L antiviral pathway, and also inhibition of dsRNA-dependent signaling required for new IFN production. Binding of NS1 to the E3 ubiquitin ligase TRIM25 prevents activation of RIG-I signaling and subsequent IFN induction. Cellular RNA processing is also targeted by NS1, through recognition of cleavage and polyadenylation specificity factor 30 (CPSF30), leading to inhibition of IFN-β mRNA processing as well as that of other cellular mRNAs. In addition NS1 binds to and inhibits cellular protein kinase R (PKR), thus blocking an important arm of the IFN system. Many additional proteins have been reported to interact with NS1, either directly or indirectly, which may serve its anti-IFN and additional functions, including the regulation of viral and host gene expression, signaling pathways and viral pathogenesis. Many of these interactions are potential targets for small-molecule intervention. Structural, biochemical and functional studies have resulted in hypotheses for drug discovery approaches that are beginning to bear experimental fruit, such as targeting the dsRNA-NS1 interaction, which could lead to restoration of innate immune function and inhibition of virus replication. This review describes biochemical, cell-based and nucleic acid-based approaches to identifying NS1 antagonists.
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Affiliation(s)
- Daniel A Engel
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, United States.
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17
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Zhu C, Zheng F, Sun T, Duan Y, Cao J, Feng H, Shang L, Zhu Y, Liu H. Interaction of avian influenza virus NS1 protein and nucleolar and coiled-body phosphoprotein 1. Virus Genes 2012. [PMID: 23188192 PMCID: PMC3610028 DOI: 10.1007/s11262-012-0849-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Nonstructural protein 1 (NS1) is a non-structural protein of avian influenza virus. It can interact with a variety of proteins of the host cells, enhancing the expression of viral proteins and changing the growth and metabolism of the host cells, thereby enhancing the virus’ pathogenicity and virulence. To investigate whether there are more host proteins that can interact with NS1 during viral infection, T7-phage display system was used to screen human lung cell cDNA library for proteins that could interact with NS1. One positive and specific clone was obtained and identified as nucleolar and coiled-body phosphoprotein 1(NOLC1). The interaction between these two proteins was further demonstrated by His-pull-down and co-immunoprecipitation experiments. Co-expression of both proteins in HeLa cell showed that NS1 and NOLC1 were co-localized in the cell’s nucleus. Gene truncation experiments revealed that the effector domain of NS1 was sufficient to interact with NOLC1. The results demonstrated a positive interaction between a viral NS1 and NOLC1 of the host cells, and provided a new target for drug screening.
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Affiliation(s)
- Chunyu Zhu
- Key Laboratory of Animal Resource and Epidemic Disease Prevention, Life Science School of Liaoning University, Shenyang 110036, China
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18
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Han X, Li Z, Chen H, Wang H, Mei L, Wu S, Zhang T, Liu B, Lin X. Influenza virus A/Beijing/501/2009(H1N1) NS1 interacts with β-tubulin and induces disruption of the microtubule network and apoptosis on A549 cells. PLoS One 2012; 7:e48340. [PMID: 23139776 PMCID: PMC3491056 DOI: 10.1371/journal.pone.0048340] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 09/24/2012] [Indexed: 11/18/2022] Open
Abstract
NS1 of influenza A virus is a key multifunctional protein that plays various roles in regulating viral replication mechanisms, host innate/adaptive immune responses, and cellular signalling pathways. These functions rely on its ability to participate in a multitude of protein-protein and protein-RNA interactions. To gain further insight into the role of NS1, a tandem affinity purification (TAP) method was utilized to find unknown interaction partner of NS1. The protein complexes of NS1 and its interacting partner were purified from A549 cell using TAP-tagged NS1 as bait, and co-purified cellular factors were identified by mass spectrometry (MS). We identified cellular β-tubulin as a novel interaction partner of NS1. The RNA-binding domain of NS1 interacts with β-tubulin through its RNA-binding domain, as judged by a glutathione S-transferase (GST) pull-down assay with the GST-fused functional domains of NS1. Immunofluorescence analysis further revealed that NS1 with β-tubulin co-localized in the nucleus. In addition, the disruption of the microtubule network and apoptosis were also observed on NS1-transfected A549 cells. Our findings suggest that influenza A virus may utilize its NS1 protein to interact with cellular β-tubulin to further disrupt normal cell division and induce apoptosis. Future work will illustrate whether this interaction is uniquely specific to the 2009 pandemic H1N1 virus.
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Affiliation(s)
- Xueqing Han
- Chinese Academy of Inspection and Quarantine, Beijing, China
| | - Zhihui Li
- Chinese Academy of Inspection and Quarantine, Beijing, China
| | - Hongjun Chen
- Chinese Academy of Inspection and Quarantine, Beijing, China
| | - Huiyu Wang
- Chinese Academy of Inspection and Quarantine, Beijing, China
| | - Lin Mei
- Chinese Academy of Inspection and Quarantine, Beijing, China
| | - Shaoqiang Wu
- Chinese Academy of Inspection and Quarantine, Beijing, China
| | - Tianyi Zhang
- College of Veterinary Medicine, China Agricultural University, Bejing, China
| | - Bohua Liu
- State Key Laboratory of Pathogens and Bio-security, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (XL); (BL)
| | - Xiangmei Lin
- Chinese Academy of Inspection and Quarantine, Beijing, China
- * E-mail: (XL); (BL)
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19
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Molecular basis of peroxisomal biogenesis disorders caused by defects in peroxisomal matrix protein import. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1326-36. [PMID: 22617146 DOI: 10.1016/j.bbadis.2012.05.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 03/26/2012] [Accepted: 05/09/2012] [Indexed: 12/28/2022]
Abstract
Peroxisomal biogenesis disorders (PBDs) represent a spectrum of autosomal recessive metabolic disorders that are collectively characterized by abnormal peroxisome assembly and impaired peroxisomal function. The importance of this ubiquitous organelle for human health is highlighted by the fact that PBDs are multisystemic disorders that often cause death in early infancy. Peroxisomes contribute to central metabolic pathways. Most enzymes in the peroxisomal matrix are linked to lipid metabolism and detoxification of reactive oxygen species. Proper assembly of peroxisomes and thus also import of their enzymes relies on specific peroxisomal biogenesis factors, so called peroxins with PEX being the gene acronym. To date, 13 PEX genes are known to cause PBDs when mutated. Studies of the cellular and molecular defects in cells derived from PBD patients have significantly contributed to the understanding of the functional role of the corresponding peroxins in peroxisome assembly. In this review, we discuss recent data derived from both human cell culture as well as model organisms like yeasts and present an overview on the molecular mechanism underlying peroxisomal biogenesis disorders with emphasis on disorders caused by defects in the peroxisomal matrix protein import machinery.
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20
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Lazarow PB. Viruses exploiting peroxisomes. Curr Opin Microbiol 2011; 14:458-69. [PMID: 21824805 DOI: 10.1016/j.mib.2011.07.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 07/05/2011] [Indexed: 11/29/2022]
Abstract
Viruses that are of great importance for global public health, including HIV, influenza and rotavirus, appear to exploit a remarkable organelle, the peroxisome, during intracellular replication in human cells. Peroxisomes are sites of lipid biosynthesis and catabolism, reactive oxygen metabolism, and other metabolic pathways. Viral proteins are targeted to peroxisomes (the spike protein of rotavirus) or interact with peroxisomal proteins (HIV's Nef and influenza's NS1) or use the peroxisomal membrane for RNA replication. The Nef interaction correlates strongly with the crucial Nef function of CD4 downregulation. Viral exploitation of peroxisomal lipid metabolism appears likely. Mostly, functional significance and mechanisms remain to be elucidated. Recently, peroxisomes were discovered to play a crucial role in the innate immune response by signaling the presence of intracellular virus, leading to the first rapid antiviral response. This review unearths, interprets and connects old data, in the hopes of stimulating new and promising research.
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Affiliation(s)
- Paul B Lazarow
- Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
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21
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Zhao L, Xu L, Zhou X, Zhu Q, Yang Z, Zhang C, Zhu X, Yu M, Zhang Y, Zhao X, Huang P. Interaction of influenza virus NS1 protein with growth arrest-specific protein 8. Virol J 2009; 6:218. [PMID: 19995461 PMCID: PMC2797798 DOI: 10.1186/1743-422x-6-218] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 12/09/2009] [Indexed: 11/10/2022] Open
Abstract
NS1 protein is the only non-structural protein encoded by the influenza A virus, and it contributes significantly to disease pathogenesis by modulating many virus and host cell processes. A two-hybrid screen for proteins that interact with NS1 from influenza A yielded growth arrest-specific protein 8. Gas8 associated with NS1 in vitro and in vivo. Deletion analysis revealed that the N-terminal 260 amino acids of Gas8 were able to interact with NS1, and neither the RNA-binding domain nor the effector domain of NS1 was sufficient for the NS1 interaction. We also found that actin, myosin, and drebrin interact with Gas8. NS1 and beta-actin proteins could be co-immunoprecipitated from extracts of transfected cells. Furthermore, actin and Gas8 co-localized at the plasma membrane. These results are discussed in relation to the possible functions of Gas8 protein and their relevance in influenza virus release.
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Affiliation(s)
- Lixia Zhao
- Laboratory of protein engineering, Beijing Institute of Biotechnology, Beijing 100071, PR China.
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22
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LI W, WANG G, ZENG J, ZHANG D, ZHANG H, CHEN X, CHEN Y, LI K. Differential transcription-activating capability of NS1 proteins from different influenza virus subtypes expressed in yeast. SCIENCE IN CHINA. SERIES C, LIFE SCIENCES 2009; 52:545-50. [PMID: 19557332 DOI: 10.1007/s11427-009-0072-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2009] [Accepted: 03/14/2009] [Indexed: 02/05/2023]
Abstract
Influenza A virus NS1 protein is an important regulatory factor with multiple functions and contributes greatly to viral pathogenesis. In the present study, transcription-activating potential of NS1 from different influenza A virus subtypes was examined in yeast two-hybrid system. The bait vectors containing different NS1 genes, along with an empty prey vector, were transformed into yeast AH109(for growth assay on QDO plate and alpha-galactosidase assay), and Y187(for beta-galactosidase assay). AH109 transformants with NS1 gene from H1N1, H5N1, and H9N2 viruses grew vigorously on the QDO plate and secreted high level of alpha-galactosidase. Also, Y187 bearing the above NS1 genes exhibited enhanced beta-galactosidase activity. Nevertheless, H3N2-NS1-transformed AH109 and Y187 yeasts did not grow on QDO plate and secrete beta-galactosidase, respectively. These findings denote the remarkable variation in NS1 proteins from different influenza A virus subtypes on the transcription-stimulating capability in yeast.
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Affiliation(s)
- WeiZhong LI
- Department of Microbiology and Immunology, Shantou University Medical College, Shantou 515041, China
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23
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Wressnigg N, Shurygina AP, Wolff T, Redlberger-Fritz M, Popow-Kraupp T, Muster T, Egorov A, Kittel C. Influenza B mutant viruses with truncated NS1 proteins grow efficiently in Vero cells and are immunogenic in mice. J Gen Virol 2009; 90:366-374. [DOI: 10.1099/vir.0.006122-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Contemporary influenza B virus strains were generated encoding C-terminally truncated NS1 proteins. Viable viruses containing the N-terminal 14, 38, 57 or 80 aa of the NS1 protein were rescued in Vero cells. The influenza B virus NS1-truncated mutants were impaired in their ability to counteract interferon (IFN) production, induce antiviral pro-inflammatory cytokines early after infection and show attenuated or restricted growth in IFN-competent hosts. In Vero cells, all of the mutant viruses replicated to high titres comparable to the wild-type influenza B virus. Mice that received a single, intranasal immunization of the NS1-truncated mutants elicited an antibody response and protection against wild-type virus challenge. Therefore, these NS1-truncated mutants should prove useful as potential candidates for live-attenuated influenza virus vaccines.
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Affiliation(s)
- Nina Wressnigg
- University of Vienna, Institute of Microbiology and Genetics, Dr Bohrgasse 9, 1030 Vienna, Austria
- Avir Greenhills Biotechnology, Gersthoferstrasse 29–31, 1180 Vienna, Austria
| | - Anna Polina Shurygina
- Influenza Research Institute, Russian Academy of Medical Sciences, Prof. Popov Str. 15/17, St Petersburg 197376, Russia
- Avir Greenhills Biotechnology, Gersthoferstrasse 29–31, 1180 Vienna, Austria
| | - Thorsten Wolff
- Robert Koch Institute, P15, Nordufer 20, 13353 Berlin, Germany
| | - Monika Redlberger-Fritz
- Clinical Institute for Virology, Medical University of Vienna, Kinderspitalgasse 15, 1090 Vienna, Austria
| | - Therese Popow-Kraupp
- Department of Dermatology, Medical University of Vienna, Währinger Gurtel 18–20, 1090 Vienna, Austria
| | - Thomas Muster
- Department of Dermatology, Medical University of Vienna, Währinger Gurtel 18–20, 1090 Vienna, Austria
- Avir Greenhills Biotechnology, Gersthoferstrasse 29–31, 1180 Vienna, Austria
| | - Andrej Egorov
- Avir Greenhills Biotechnology, Gersthoferstrasse 29–31, 1180 Vienna, Austria
| | - Christian Kittel
- Avir Greenhills Biotechnology, Gersthoferstrasse 29–31, 1180 Vienna, Austria
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24
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Hale BG, Randall RE, Ortín J, Jackson D. The multifunctional NS1 protein of influenza A viruses. J Gen Virol 2008; 89:2359-2376. [PMID: 18796704 DOI: 10.1099/vir.0.2008/004606-0] [Citation(s) in RCA: 806] [Impact Index Per Article: 50.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The non-structural (NS1) protein of influenza A viruses is a non-essential virulence factor that has multiple accessory functions during viral infection. In recent years, the major role ascribed to NS1 has been its inhibition of host immune responses, especially the limitation of both interferon (IFN) production and the antiviral effects of IFN-induced proteins, such as dsRNA-dependent protein kinase R (PKR) and 2'5'-oligoadenylate synthetase (OAS)/RNase L. However, it is clear that NS1 also acts directly to modulate other important aspects of the virus replication cycle, including viral RNA replication, viral protein synthesis, and general host-cell physiology. Here, we review the current literature on this remarkably multifunctional viral protein. In the first part of this article, we summarize the basic biochemistry of NS1, in particular its synthesis, structure, and intracellular localization. We then discuss the various roles NS1 has in regulating viral replication mechanisms, host innate/adaptive immune responses, and cellular signalling pathways. We focus on the NS1-RNA and NS1-protein interactions that are fundamental to these processes, and highlight apparent strain-specific ways in which different NS1 proteins may act. In this regard, the contributions of certain NS1 functions to the pathogenicity of human and animal influenza A viruses are also discussed. Finally, we outline practical applications that future studies on NS1 may lead to, including the rational design and manufacture of influenza vaccines, the development of novel antiviral drugs, and the use of oncolytic influenza A viruses as potential anti-cancer agents.
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Affiliation(s)
- Benjamin G Hale
- Centre for Biomolecular Sciences, University of St Andrews, St Andrews, Fife KY16 9ST, UK
| | - Richard E Randall
- Centre for Biomolecular Sciences, University of St Andrews, St Andrews, Fife KY16 9ST, UK
| | - Juan Ortín
- Centro Nacional de Biotecnología (CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
| | - David Jackson
- Centre for Biomolecular Sciences, University of St Andrews, St Andrews, Fife KY16 9ST, UK
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25
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Nagata K, Kawaguchi A, Naito T. Host factors for replication and transcription of the influenza virus genome. Rev Med Virol 2008; 18:247-60. [PMID: 18383427 DOI: 10.1002/rmv.575] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
For replication and transcription of the influenza virus genome of eight-segmented and negative-stranded RNAs, not only viral factors but also host-derived cellular factors (host factors) are required. This paper focuses on the identification and characterisation of the host factors involved in replication and transcription of the influenza virus genome, reviewing recent progresses in the related molecular mechanisms. Functional assay systems for screening of host factors using cell-free reconstitution systems and an yeast-based influenza virus replicon system are highlighted. We have summarised the property of host factors comprehensively and provided a clue for the perspective in the determination mechanism of host range and virulence and the development of a new strategy to control the influenza virus.
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Affiliation(s)
- Kyosuke Nagata
- Department of Infection Biology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
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26
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Landolt GA, Olsen CW. Up to new tricks - a review of cross-species transmission of influenza A viruses. Anim Health Res Rev 2007; 8:1-21. [PMID: 17692139 DOI: 10.1017/s1466252307001272] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Influenza is a highly contagious disease that has burdened both humans and animals since ancient times. In humans, the most dramatic consequences of influenza are associated with periodically occurring pandemics. Pandemics require the emergence of an antigenically novel virus to which the majority of the population lacks protective immunity. Historically, influenza A viruses from animals have contributed to the generation of human pandemic viruses and they may do so again in the future. It is, therefore, critical to understand the epidemiological and molecular mechanisms that allow influenza A viruses to cross species barriers. This review summarizes the current knowledge of influenza ecology, and the viral factors that are thought to determine influenza A virus species specificity.
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Affiliation(s)
- Gabriele A Landolt
- Department of Clinical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523, USA.
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27
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Anwar T, Khan AU. Identification of a casein kinase II phosphorylation domain in NS1 protein of H5N1 influenza virus. Bioinformation 2007; 2:57-61. [PMID: 18188421 PMCID: PMC2174419 DOI: 10.6026/97320630002057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 09/05/2007] [Accepted: 09/13/2007] [Indexed: 11/26/2022] Open
Abstract
Influenza virus causes febrile respiratory illness. The infection results in significant mortality, morbidity and economic disruption. In this bioinformatics
study, we used the NS1 (the conserved nonstructural) protein of influenza A virus to demonstrate its role in infectivity. Our in silico study revealed a new
Casein kinase II (CKII) phosphorylation domain at position 151-154. This domain was formed due to the mutation at position 151 (T151I). Moreover, considerable
difference in the secondary structure of this protein due to mutation was also reported. It is also confirmed by contact residue analysis that the changes in
secondary structure are due to mutations.
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Affiliation(s)
- Tamanna Anwar
- Interdisciplinary Biotechnology Unit Aligarh Muslim University, Aligarh 202002 India
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28
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Sorrell EM, Ramirez-Nieto GC, Gomez-Osorio IG, Perez DR. Genesis of pandemic influenza. Cytogenet Genome Res 2007; 117:394-402. [PMID: 17675883 DOI: 10.1159/000103203] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Accepted: 09/20/2006] [Indexed: 12/22/2022] Open
Abstract
During the last decade the number of reported outbreaks caused by highly pathogenic avian influenza (HPAI) in domestic poultry has drastically increased. At the same time, low pathogenic avian influenza (LPAI) strains, such as H9N2 in many parts of the Middle East and Asia and H6N2 in live bird markets in California, have become endemic. Each AI outbreak brings the concomitant possibility of poultry-to-human transmission. Indeed, human illness and death have resulted from such occasional transmissions with highly pathogenic avian H7N7 and H5N1 viruses while avian H9N2 viruses have been isolated from individuals with mild influenza. The transmission of avian influenza directly from poultry to humans has brought a sense of urgency in terms of understanding the mechanisms that lead to interspecies transmission of influenza. Domestic poultry species have been previously overlooked as potential intermediate hosts in the generation of influenza viruses with the capacity to infect humans. In this review, we will discuss molecular and epidemiological aspects that have led to the recurrent emergence of avian influenza strains with pandemic potential, with a particular emphasis on the current Asian H5N1 viruses.
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Affiliation(s)
- E M Sorrell
- University of Maryland, Virginia-Maryland College of Veterinary Medicine, Department of Veterinary Medicine, College Park, MD 20742, USA
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29
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Opitz B, Rejaibi A, Dauber B, Eckhard J, Vinzing M, Schmeck B, Hippenstiel S, Suttorp N, Wolff T. IFNbeta induction by influenza A virus is mediated by RIG-I which is regulated by the viral NS1 protein. Cell Microbiol 2007; 9:930-8. [PMID: 17140406 DOI: 10.1111/j.1462-5822.2006.00841.x] [Citation(s) in RCA: 225] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Influenza A virus causes epidemics of respiratory diseases in humans leading to thousands of death annually. One of its major virulence factors, the non-structural protein 1 (NS1), exhibits interferon-antagonistic properties. While epithelial cells of the respiratory tract are the primary targets of influenza virus, the virus-sensing mechanisms in these cells eventually leading to IFNbeta production are incompletely understood. Here we show that infection of epithelial cells with NS1-deficient influenza A virus upregulated expression of two molecules that have been previously implicated in sensing of RNA viruses, the retinoic acid-inducible gene I (RIG-I) and the melanoma differentiation-associated gene 5 (MDA5). Gene silencing and overexpression experiments demonstrated that RIG-I, its adapter interferon-beta promoter stimulator 1 (IPS-1) and interferon-regulated factor 3 (IRF3) were involved in influenza A virus-mediated production of the antiviral IFNbeta. In addition, we showed that the NS1 protein is capable to inhibit the RIG-I-induced signalling, a mechanism which corresponded to the observation that only NS1-deficient but not the wild-type virus induced high-level production of IFNbeta. In conclusion, we demonstrated a critical involvement of RIG-I, IPS-1 and IRF3 in influenza A virus infection of epithelial cells.
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Affiliation(s)
- Bastian Opitz
- Department of Internal Medicine/Infectious Diseases and Pulmonary Medicine, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
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30
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Kawaguchi A, Nagata K. [Molecular mechanism of replication and transcription of the influenza virus genome and host factors]. Uirusu 2006; 56:99-108. [PMID: 17038818 DOI: 10.2222/jsv.56.99] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The genome of influenza A virus is a set of eight segmented- and single-stranded RNAs. A basic transcription and replication unit is the genome complexed with viral RNA-dependent RNA polymerases and nucleoprotein (NP). For the efficient transcription and replication of the genome, not only viral factors but also host cell-derived factors are required. Although receptor and protease molecules play important roles in infection and pathogenicity, it is also possible that host factors involved in the virus genome function determine these. PB2, for instance, is reported to be a possible candidate for determination of the host range of avian influenza viruses. Here we summarize recent progresses in the molecular mechanism of the influenza virus genome transcription and replication and discuss the involvement of host factors in these processes.
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Affiliation(s)
- Atsushi Kawaguchi
- Department of Infection Biology, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Japan
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31
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Kretschmer U, Bonhagen K, Debes GF, Mittrücker HW, Erb KJ, Liesenfeld O, Zaiss D, Kamradt T, Syrbe U, Hamann A. Expression of selectin ligands on murine effector and IL-10-producing CD4+ T cells from non-infected and infected tissues. Eur J Immunol 2004; 34:3070-81. [PMID: 15384048 DOI: 10.1002/eji.200424972] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Endothelial selectins are crucial for the recruitment of leukocytes into sites of inflammation. On T cells, ligands for selectins become induced upon differentiation into the effector/memory stage. Initial in vitro studies suggested a correlation between the Th1 phenotype and ligand expression, but whether this also holds true in vivo remained uncertain. We here analyzed selectin ligands on CD4+ T cells producing IFN-gamma, IL-4 or IL-10, prototypic cytokines of the Th1, Th2 and Tr1 subset, respectively. We analyzed mice infected with influenza virus, the bacterium Listeria, and the parasites Toxoplasma (all Th1 models) or Nippostrongylus (Th2 model). A link between the Th1 phenotype and ligand expression was not found in vivo. Surprisingly, the potentially regulatory IL-10-producing T cells displayed the highest frequency of ligand-positive cells in general. Within the inflamed tissues, the frequencies of P-selectin-binding cells increased in the dominant subset, either Th1 or Th2. Up-regulation was also found for E-selectin ligands during influenza, but not Nippostrongylus infection. In conclusion, conditions driving T cell polarization into either Th1 or Th2 in vivo do not affect the expression of selectin ligands, but acquisition of P-selectin binding and hence migration into inflamed tissues is boosted by an inflammatory milieu.
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Affiliation(s)
- Ute Kretschmer
- Experimentelle Rheumatologie, Medizinische Klinik, Charité Universitätsmedizin Berlin, Berlin, Germany
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32
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Dauber B, Heins G, Wolff T. The influenza B virus nonstructural NS1 protein is essential for efficient viral growth and antagonizes beta interferon induction. J Virol 2004; 78:1865-72. [PMID: 14747551 PMCID: PMC369500 DOI: 10.1128/jvi.78.4.1865-1872.2004] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We analyzed the functions of the influenza B virus nonstructural NS1-B protein, both by utilizing a constructed mutant virus (Delta NS1-B) lacking the NS1 gene and by testing the activities of the protein when expressed in cells. The mutant virus replicated to intermediate levels in 6-day-old embryonated chicken eggs that contain an immature interferon (IFN) system, whereas older eggs did not support viral propagation to a significant extent. The Delta NS1-B virus was a substantially stronger inducer of beta IFN (IFN-beta) transcripts in human lung epithelial cells than the wild type, and furthermore, transiently expressed NS1-B protein efficiently inhibited virus-dependent activation of the IFN-beta promoter. Interestingly, replication of the Delta NS1-B knockout virus was attenuated by more than 4 orders of magnitude in tissue culture cells containing or lacking functional IFN-alpha/beta genes. These findings show that the NS1-B protein functions as a viral IFN antagonist and indicate a further requirement of this protein for efficient viral replication that is unrelated to blocking IFN effects.
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33
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Ludwig S, Wang X, Ehrhardt C, Zheng H, Donelan N, Planz O, Pleschka S, García-Sastre A, Heins G, Wolff T. The influenza A virus NS1 protein inhibits activation of Jun N-terminal kinase and AP-1 transcription factors. J Virol 2002; 76:11166-71. [PMID: 12368362 PMCID: PMC136597 DOI: 10.1128/jvi.76.21.11166-11171.2002] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2002] [Accepted: 07/23/2002] [Indexed: 12/29/2022] Open
Abstract
The influenza A virus nonstructural NS1 protein is known to modulate host cell gene expression and to inhibit double-stranded RNA (dsRNA)-mediated antiviral responses. Here we identify NS1 as the first viral protein that antagonizes virus- and dsRNA-induced activation of the stress response-signaling pathway mediated through Jun N-terminal kinase.
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Affiliation(s)
- Stephan Ludwig
- Institut für Molekulare Medizin, Heinrich Heine-Universität, 40225 Düsseldorf, Germany
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34
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Schultz-Cherry S, Dybdahl-Sissoko N, Neumann G, Kawaoka Y, Hinshaw VS. Influenza virus ns1 protein induces apoptosis in cultured cells. J Virol 2001; 75:7875-81. [PMID: 11483732 PMCID: PMC115031 DOI: 10.1128/jvi.75.17.7875-7881.2001] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The importance of influenza viruses as worldwide pathogens in humans, domestic animals, and poultry is well recognized. Discerning how influenza viruses interact with the host at a cellular level is crucial for a better understanding of viral pathogenesis. Influenza viruses induce apoptosis through mechanisms involving the interplay of cellular and viral factors that may depend on the cell type. However, it is unclear which viral genes induce apoptosis. In these studies, we show that the expression of the nonstructural (NS) gene of influenza A virus is sufficient to induce apoptosis in MDCK and HeLa cells. Further studies showed that the multimerization domain of the NS1 protein but not the effector domain is required for apoptosis. However, this mutation is not sufficient to inhibit apoptosis using whole virus.
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Affiliation(s)
- S Schultz-Cherry
- Southeast Poultry Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Athens, Georgia 30605, USA.
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35
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Paragas J, Talon J, O'Neill RE, Anderson DK, García-Sastre A, Palese P. Influenza B and C virus NEP (NS2) proteins possess nuclear export activities. J Virol 2001; 75:7375-83. [PMID: 11462009 PMCID: PMC114972 DOI: 10.1128/jvi.75.16.7375-7383.2001] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2001] [Accepted: 05/16/2001] [Indexed: 11/20/2022] Open
Abstract
Nucleocytoplasmic transport of viral ribonucleoproteins (vRNPs) is an essential aspect of the replication cycle for influenza A, B, and C viruses. These viruses replicate and transcribe their genomes in the nuclei of infected cells. During the late stages of infection, vRNPs must be exported from the nucleus to the cytoplasm prior to transport to viral assembly sites on the cellular plasma membrane. Previously, we demonstrated that the influenza A virus nuclear export protein (NEP, formerly referred to as the NS2 protein) mediates the export of vRNPs. In this report, we suggest that for influenza B and C viruses the nuclear export function is also performed by the orthologous NEP proteins (formerly referred to as the NS2 protein). The influenza virus B and C NEP proteins interact in the yeast two-hybrid assay with a subset of nucleoporins and with the Crm1 nuclear export factor and can functionally replace the effector domain from the human immunodeficiency virus type 1 Rev protein. We established a plasmid transfection system for the generation of virus-like particles (VLPs) in which a functional viral RNA-like chloramphenicol acetyltransferase (CAT) gene is delivered to a new cell. VLPs generated in the absence of the influenza B virus NEP protein were unable to transfer the viral RNA-like CAT gene to a new cell. From these data, we suggest that the nuclear export of the influenza B and C vRNPs are mediated through interaction between NEP proteins and the cellular nucleocytoplasmic export machinery.
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Affiliation(s)
- J Paragas
- Department of Microbiology, Mount Sinai School of Medicine, New York University, New York, New York 10029, USA
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36
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Basler CF, Reid AH, Dybing JK, Janczewski TA, Fanning TG, Zheng H, Salvatore M, Perdue ML, Swayne DE, García-Sastre A, Palese P, Taubenberger JK. Sequence of the 1918 pandemic influenza virus nonstructural gene (NS) segment and characterization of recombinant viruses bearing the 1918 NS genes. Proc Natl Acad Sci U S A 2001; 98:2746-51. [PMID: 11226311 PMCID: PMC30210 DOI: 10.1073/pnas.031575198] [Citation(s) in RCA: 222] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The influenza A virus pandemic of 1918-1919 resulted in an estimated 20-40 million deaths worldwide. The hemagglutinin and neuraminidase sequences of the 1918 virus were previously determined. We here report the sequence of the A/Brevig Mission/1/18 (H1N1) virus nonstructural (NS) segment encoding two proteins, NS1 and nuclear export protein. Phylogenetically, these genes appear to be close to the common ancestor of subsequent human and classical swine strain NS genes. Recently, the influenza A virus NS1 protein was shown to be a type I IFN antagonist that plays an important role in viral pathogenesis. By using the recently developed technique of generating influenza A viruses entirely from cloned cDNAs, the hypothesis that the 1918 virus NS1 gene played a role in virulence was tested in a mouse model. In a BSL3+ laboratory, viruses were generated that possessed either the 1918 NS1 gene alone or the entire 1918 NS segment in a background of influenza A/WSN/33 (H1N1), a mouse-adapted virus derived from a human influenza strain first isolated in 1933. These 1918 NS viruses replicated well in tissue culture but were attenuated in mice as compared with the isogenic control viruses. This attenuation in mice may be related to the human origin of the 1918 NS1 gene. These results suggest that interaction of the NS1 protein with host-cell factors plays a significant role in viral pathogenesis.
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Affiliation(s)
- C F Basler
- Department of Microbiology, Mount Sinai School of Medicine, New York, NY 10029, USA
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37
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Aragón T, de la Luna S, Novoa I, Carrasco L, Ortín J, Nieto A. Eukaryotic translation initiation factor 4GI is a cellular target for NS1 protein, a translational activator of influenza virus. Mol Cell Biol 2000; 20:6259-68. [PMID: 10938102 PMCID: PMC86100 DOI: 10.1128/mcb.20.17.6259-6268.2000] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Influenza virus NS1 protein is an RNA-binding protein whose expression alters several posttranscriptional regulatory processes, like polyadenylation, splicing, and nucleocytoplasmic transport of cellular mRNAs. In addition, NS1 protein enhances the translational rate of viral, but not cellular, mRNAs. To characterize this effect, we looked for targets of NS1 influenza virus protein among cellular translation factors. We found that NS1 coimmunoprecipitates with eukaryotic initiation factor 4GI (eIF4GI), the large subunit of the cap-binding complex eIF4F, either in influenza virus-infected cells or in cells transfected with NS1 cDNA. Affinity chromatography studies using a purified His-NS1 protein-containing matrix showed that the fusion protein pulls down endogenous eIF4GI from COS-1 cells and labeled eIF4GI translated in vitro, but not the eIF4E subunit of the eIF4F factor. Similar in vitro binding experiments with eIF4GI deletion mutants indicated that the NS1-binding domain of eIF4GI is located between residues 157 and 550, in a region where no other component of the translational machinery is known to interact. Moreover, using overlay assays and pull-down experiments, we showed that NS1 and eIF4GI proteins interact directly, in an RNA-independent manner. Mapping of the eIF4GI-binding domain in the NS1 protein indicated that the first 113 N-terminal amino acids of the protein, but not the first 81, are sufficient to bind eIF4GI. The first of these mutants has been previously shown to act as a translational enhancer, while the second is defective in this activity. Collectively, these and previously published data suggest a model where NS1 recruits eIF4GI specifically to the 5' untranslated region (5' UTR) of the viral mRNA, allowing for the preferential translation of the influenza virus messengers.
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Affiliation(s)
- T Aragón
- Centro Nacional de Biotecnología (CSIC), Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain
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38
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Reinhardt J, Wolff T. The influenza A virus M1 protein interacts with the cellular receptor of activated C kinase (RACK) 1 and can be phosphorylated by protein kinase C. Vet Microbiol 2000; 74:87-100. [PMID: 10799781 DOI: 10.1016/s0378-1135(00)00169-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The M1 protein of influenza A virus has multiple regulatory functions during the infectious cycle, which include mediation of nuclear export of viral ribonucleoproteins, inhibition of viral transcription and a crucial role in virus assembly and budding. The only known modification of the M1 protein is by phosphorylation through yet-to-be-identified kinases. We postulated that at least some of the M1 functions are exerted or regulated through interactions with cellular components. In a screen for such cellular mediators, the protein receptor of the activated C-kinase (RACK 1) was identified by its interaction with the viral M1 protein in the yeast two hybrid system. The physical M1-RACK 1 interaction was confirmed in glutathione-S-transferase-based coprecipitation assays for the diverged M1 proteins of avian, swine and human influenza A virus strains. This conservation suggests that the M1-RACK 1 interaction is of general importance during influenza A virus infections. RACK 1 has previously been identified to specifically bind the activated form of protein kinase C (PKC) and is assumed to anchor the kinase at membranes in the vicinity of its substrates. Since the M1 protein becomes phosphorylated during influenza virus infection, we examined if PKC could catalyze the phosphate transfer. We demonstrate that virion-derived and recombinant M1 protein can indeed be efficiently phosphorylated by purified PKC. Moreover, in cell extracts, we detected M1 phosphorylation activity that was strongly reduced in the presence of the PKC-specific inhibitor compound GF109203X. These data suggest that PKC is the main M1-phosphorylating activity in the cell. Since both, the M1 protein and PKC have been shown to interact with RACK 1, we suggest that the M1-RACK 1 interaction is involved in M1 phosphorylation.
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Affiliation(s)
- J Reinhardt
- Institut für Virologie, Philipps-Universität Marburg, Robert-Koch-Str. 17, 35037, Marburg, Germany
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39
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Abstract
Significant progress has been made in understanding the process of influenza A virus replication in cell culture; however, much less is known about the genetic control of virus-host interactions in disease. This review provides an overview of the genetic analysis of influenza virus biology. The functional map of the individual genes of influenza A virus is presented as well as the status of our current understanding of pathogenesis. Influenza has a segmented genome so it is possible to obtain reassortants that contain novel combinations of genome segments derived from different viruses. This is a very useful genetic tool and is also an important aspect of influenza evolution and biology. Human influenza viruses originate from avian strains of influenza virus so that influenza infection is at its basis a zoonosis. Influenza virus strains are host-restricted, however, and avian strains must be adapted to the human host. So questions of host-range and interaction with host factors are important determinants of the ability of influenza virus to cause disease in humans. Host-range is restricted primarily due to host-specific interactions of the ribonucleocapsid and the viral receptor. There are two classes of drugs for inhibiting influenza infection, amantadine HCl and neuraminidase inhibitors. The mode of action and basis for resistance to these drugs are presented. Prospective targets for antiviral therapy are also discussed.
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Affiliation(s)
- E G Brown
- Dept. of Biochemistry, Microbiology and Immunology, University of Ottawa, Ontario, Canada
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40
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Ludwig S, Pleschka S, Wolff T. A fatal relationship--influenza virus interactions with the host cell. Viral Immunol 1999; 12:175-96. [PMID: 10532647 DOI: 10.1089/vim.1999.12.175] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Influenza A viruses are important worldwide pathogens for humans and different animal species. The infectious agent is the prototype of the orthomyxoviridae which are characterized by a segmented negative strand RNA genome that is replicated in the nucleus of the infected cell. The genome has a combined coding capacity of about 13 kb and contains the genetic information for ten viral proteins. Despite this relatively small coding capacity--large DNA viruses like herpes or poxviruses express about 150-200 gene products--influenza A viruses are able to successfully infect and multiply in a wide range of mammalian and avian species. It is therefore not surprising that influenza A viruses extensively use and manipulate host cell functions. This includes multiple interactions of viral proteins with cellular proteins. In recent years an increasing amount of information about the identity of the cellular factors that are involved in viral transcription and replication, intracellular trafficking of viral components and assembly of the virus particle has accumulated. This article aims to review recent developments in this field with a focus on cellular factors and processes which are activated by the virus to either support viral replication or to counteract host-cell defense mechanisms.
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Affiliation(s)
- S Ludwig
- Institut für Medizinische Strahlenkunde und Zellforschung, Julius-Maximilians Universität, Würzburg, Germany.
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41
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Falcón AM, Fortes P, Marión RM, Beloso A, Ortín J. Interaction of influenza virus NS1 protein and the human homologue of Staufen in vivo and in vitro. Nucleic Acids Res 1999; 27:2241-7. [PMID: 10325410 PMCID: PMC148787 DOI: 10.1093/nar/27.11.2241] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A screening for human proteins capable of interacting with influenza virus NS1 has been carried out using the two-hybrid genetic trap in yeast. A cDNA corresponding to the human homologue of Drosophila melanogaster Staufen protein (hStaufen) was isolated that fulfilled all genetic controls of the two-hybrid protocol. Using a hStaufen cDNA isolated from a lambda human library, the interaction of hStaufen and NS1 proteins was characterised in vivo and in vitro. Co-transfection of NS1 cDNA and a partial cDNA of hStaufen led to the relocalisation of recombinant hStaufen protein from its normal accumulation site in the cytoplasm to the nuclear location of NS1 protein. NS1 and hStaufen proteins could be co-immunoprecipitated from extracts of co-transfected cells and from mixtures of extracts containing either protein, as well as from extracts of influenza virus-infected cells. Furthermore, both proteins co-localised in the ribosomal and polysomal fractions of influenza virus-infected cells. The interaction was also detected in pull-down experiments using a resin containing purified hStaufen and NS1 protein translated in vitro. Deletion mapping of the NS1 gene indicated that a mutant protein containing the N-terminal 81 amino acids is unable to interact with hStaufen, in spite of retaining full RNA-binding capacity. These results are discussed in relation to the possible mechanisms of action of hStaufen and its relevance for influenza virus infection.
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Affiliation(s)
- A M Falcón
- Centro Nacional de Biotecnología (CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
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42
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Palese P, Muster T, Zheng H, O'Neill R, Garcia-Sastre A. Learning from our foes: a novel vaccine concept for influenza virus. ARCHIVES OF VIROLOGY. SUPPLEMENTUM 1999; 15:131-8. [PMID: 10470274 DOI: 10.1007/978-3-7091-6425-9_9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
Concerted efforts to study the molecular biology of influenza viruses and the ability to genetically engineer them have dramatically advanced our understanding of the functions of influenza viral genes and gene products. The only nonstructural protein (NS1) coded for by the influenza virus was shown to possess interferon antagonist activity and thus to play an important role in countering the interferon (antiviral) response of the host following infection. Influenza A and B virus mutants with "weak" anti-interferon activity are highly attenuated because the host is able to mount an effective interferon response. It is suggested that these NS1-modified attenuated influenza viruses can induce a protective immune response and that they are ideal live virus vaccine candidates against influenza.
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Affiliation(s)
- P Palese
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, USA
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43
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García-Sastre A, Egorov A, Matassov D, Brandt S, Levy DE, Durbin JE, Palese P, Muster T. Influenza A virus lacking the NS1 gene replicates in interferon-deficient systems. Virology 1998; 252:324-30. [PMID: 9878611 DOI: 10.1006/viro.1998.9508] [Citation(s) in RCA: 785] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The NS1 protein is the only nonstructural protein encoded by influenza A virus. It has been proposed that the NS1 performs several regulatory functions during the viral replication cycle, including the regulation of synthesis, transport, splicing, and translation of mRNAs. Through the use of reverse genetics, a viable transfectant influenza A virus (delNS1) which lacks the NS1 gene has been generated. Our results indicate that the NS1 of influenza A virus is an auxiliary (virulence) factor which plays a crucial role in inhibiting interferon-mediated antiviral responses of the host.
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Affiliation(s)
- A García-Sastre
- Department of Microbiology, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, New York, 10029, USA
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44
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Wolff T, O'Neill RE, Palese P. NS1-Binding protein (NS1-BP): a novel human protein that interacts with the influenza A virus nonstructural NS1 protein is relocalized in the nuclei of infected cells. J Virol 1998; 72:7170-80. [PMID: 9696811 PMCID: PMC109939 DOI: 10.1128/jvi.72.9.7170-7180.1998] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We used the yeast interaction trap system to identify a novel human 70-kDa protein, termed NS1-binding protein (NS1-BP), which interacts with the nonstructural NS1 protein of the influenza A virus. The genetic interaction was confirmed by the specific coprecipitation of the NS1 protein from solution by a glutathione S-transferase-NS1-BP fusion protein and glutathione-Sepharose. NS1-BP contains an N-terminal BTB/POZ domain and five kelch-like tandem repeat elements of approximately 50 amino acids. In noninfected cells, affinity-purified antibodies localized NS1-BP in nuclear regions enriched with the spliceosome assembly factor SC35, suggesting an association of NS1-BP with the cellular splicing apparatus. In influenza A virus-infected cells, NS1-BP relocalized throughout the nucleoplasm and appeared distinct from the SC35 domains, which suggests that NS1-BP function may be disturbed or altered. The addition of a truncated NS1-BP mutant protein to a HeLa cell nuclear extract efficiently inhibited pre-mRNA splicing but not spliceosome assembly. This result could be explained by a possible dominant-negative effect of the NS1-BP mutant protein and suggests a role of the wild-type NS1-BP in promoting pre-mRNA splicing. These data suggest that the inhibition of splicing by the NS1 protein may be mediated by binding to NS1-BP.
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Affiliation(s)
- T Wolff
- Institut für Virologie, Philipps-Universität Marburg, 35037 Marburg, Germany.
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45
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Egorov A, Brandt S, Sereinig S, Romanova J, Ferko B, Katinger D, Grassauer A, Alexandrova G, Katinger H, Muster T. Transfectant influenza A viruses with long deletions in the NS1 protein grow efficiently in Vero cells. J Virol 1998; 72:6437-41. [PMID: 9658085 PMCID: PMC109801 DOI: 10.1128/jvi.72.8.6437-6441.1998] [Citation(s) in RCA: 165] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
We established a reverse genetics system for the nonstructural (NS) gene segment of influenza A virus. This system is based on the use of the temperature-sensitive (ts) reassortant virus 25A-1. The 25A-1 virus contains the NS gene from influenza A/Leningrad/134/57 virus and the remaining gene segments from A/Puerto Rico (PR)/8/34 virus. This particular gene constellation was found to be responsible for the ts phenotype. For reverse genetics of the NS gene, a plasmid-derived NS gene from influenza A/PR/8/34 virus was ribonucleoprotein transfected into cells that were previously infected with the 25A-1 virus. Two subsequent passages of the transfection supernatant at 40 degreesC selected viruses containing the transfected NS gene derived from A/PR/8/34 virus. The high efficiency of the selection process permitted the rescue of transfectant viruses with large deletions of the C-terminal part of the NS1 protein. Viable transfectant viruses containing the N-terminal 124, 80, or 38 amino acids of the NS1 protein were obtained. Whereas all deletion mutants grew to high titers in Vero cells, growth on Madin-Darby canine kidney (MDCK) cells and replication in mice decreased with increasing length of the deletions. In Vero cells expression levels of viral proteins of the deletion mutants were similar to those of the wild type. In contrast, in MDCK cells the level of the M1 protein was significantly reduced for the deletion mutants.
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Affiliation(s)
- A Egorov
- Institute of Applied Microbiology, University of Agriculture, A-1190 Vienna, Austria.
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46
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Multiple Levels of Posttranscriptional Regulation of Influenza Virus Gene Expression. ACTA ACUST UNITED AC 1998. [DOI: 10.1006/smvy.1997.0136] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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47
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O'Neill RE, Talon J, Palese P. The influenza virus NEP (NS2 protein) mediates the nuclear export of viral ribonucleoproteins. EMBO J 1998; 17:288-96. [PMID: 9427762 PMCID: PMC1170379 DOI: 10.1093/emboj/17.1.288] [Citation(s) in RCA: 318] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Nuclear import and export of viral nucleic acids is crucial for the replication cycle of many viruses, and elucidation of the mechanism of these steps may provide a paradigm for understanding general biological processes. Influenza virus replicates its RNA genome in the nucleus of infected cells. The influenza virus NS2 protein, which had no previously assigned function, was shown to mediate the nuclear export of virion RNAs by acting as an adaptor between viral ribonucleoprotein complexes and the nuclear export machinery of the cell. A functional domain on the NS2 with characteristics of a nuclear export signal was mapped: it interacts with cellular nucleoporins, can functionally replace the effector domain of the human immunodeficiency virus type 1 (HIV-1) Rev protein and mediates rapid nuclear export when cross-linked to a reporter protein. Microinjection of anti-NS2 antibodies into infected cells inhibited nuclear export of viral ribonucleoproteins, suggesting that the Rev-like NS2 mediates this process. Therefore, we have renamed this Rev-like factor the influenza virus nuclear export protein or NEP. We propose a model by which NEP acts as a protein adaptor molecule bridging viral ribonucleoproteins and the nuclear pore complex.
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Affiliation(s)
- R E O'Neill
- Department of Microbiology, Mount Sinai School of Medicine, 1 Gustave L.Levy Place, New York, NY 10029, USA
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48
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Momose F, Handa H, Nagata K. Identification of host factors that regulate the influenza virus RNA polymerase activity. Biochimie 1996; 78:1103-8. [PMID: 9150891 DOI: 10.1016/s0300-9084(97)86736-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Transcription and replication of the influenza virus RNA genome take place in the nuclei of infected cells. Ribonucleoprotein (RNP) complexes consisting of viral RNA, RNA polymerase, and nucleocapsid protein (NP) are proven to be the catalytic unit for RNA synthesis, while it has been indicated that the viral RNA polymerase activity is modulated by host-derived nuclear factors. Here we have identified such host factors present in nuclear extracts prepared from uninfected HeLa cells with biochemical complementation assays using the in vitro RNA synthesis system. The stimulatory activity was not absorbed to phosphocellulose but was tightly bound to Q-Sepharose. The eluate recovered from Q-Sepharose was able to stimulate the RNA synthesis catalyzed by both RNP complexes and purified RNA polymerase and NP. The stimulatory activity was further separated into two distinct fractions, designated RAF-1 (RNA polymerase activating factor-1) and RAF-2 fractions, through phenyl-Sepharose column chromatography. When these fractions were fractionated through a gel filtration column, RAF-1 and RAF-2 activities were recovered in fractions corresponding to the molecular mass of 350 kDa and 60 kDa, respectively. Furthermore, the RAF-2 fraction was shown to contain an inhibitory activity, tentatively designated RIF-1 (RNA polymerase inhibitory factor-1). RIF-1 sedimented as fast as bovine serum albumin in glycerol density gradient centrifugation. Roles of these host factors are discussed in the context of viral RNA transcription and replication.
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Affiliation(s)
- F Momose
- Department of Biomolecular Engineering, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
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