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Blanco-Lobo P, Nogales A, Rodríguez L, Martínez-Sobrido L. Novel Approaches for The Development of Live Attenuated Influenza Vaccines. Viruses 2019; 11:E190. [PMID: 30813325 PMCID: PMC6409754 DOI: 10.3390/v11020190] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 02/19/2019] [Accepted: 02/19/2019] [Indexed: 01/04/2023] Open
Abstract
Influenza virus still represents a considerable threat to global public health, despite the advances in the development and wide use of influenza vaccines. Vaccination with traditional inactivate influenza vaccines (IIV) or live-attenuated influenza vaccines (LAIV) remains the main strategy in the control of annual seasonal epidemics, but it does not offer protection against new influenza viruses with pandemic potential, those that have shifted. Moreover, the continual antigenic drift of seasonal circulating influenza viruses, causing an antigenic mismatch that requires yearly reformulation of seasonal influenza vaccines, seriously compromises vaccine efficacy. Therefore, the quick optimization of vaccine production for seasonal influenza and the development of new vaccine approaches for pandemic viruses is still a challenge for the prevention of influenza infections. Moreover, recent reports have questioned the effectiveness of the current LAIV because of limited protection, mainly against the influenza A virus (IAV) component of the vaccine. Although the reasons for the poor protection efficacy of the LAIV have not yet been elucidated, researchers are encouraged to develop new vaccination approaches that overcome the limitations that are associated with the current LAIV. The discovery and implementation of plasmid-based reverse genetics has been a key advance in the rapid generation of recombinant attenuated influenza viruses that can be used for the development of new and most effective LAIV. In this review, we provide an update regarding the progress that has been made during the last five years in the development of new LAIV and the innovative ways that are being explored as alternatives to the currently licensed LAIV. The safety, immunogenicity, and protection efficacy profile of these new LAIVs reveal their possible implementation in combating influenza infections. However, efforts by vaccine companies and government agencies will be needed for controlled testing and approving, respectively, these new vaccine methodologies for the control of influenza infections.
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Affiliation(s)
- Pilar Blanco-Lobo
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, NY 14642, USA.
| | - Aitor Nogales
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, NY 14642, USA.
| | - Laura Rodríguez
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, NY 14642, USA.
| | - Luis Martínez-Sobrido
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, NY 14642, USA.
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52
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Asha K, Kumar B. Emerging Influenza D Virus Threat: What We Know so Far! J Clin Med 2019; 8:jcm8020192. [PMID: 30764577 PMCID: PMC6406440 DOI: 10.3390/jcm8020192] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 01/20/2023] Open
Abstract
Influenza viruses, since time immemorial, have been the major respiratory pathogen known to infect a wide variety of animals, birds and reptiles with established lineages. They belong to the family Orthomyxoviridae and cause acute respiratory illness often during local outbreaks or seasonal epidemics and occasionally during pandemics. Recent studies have identified a new genus within the Orthomyxoviridae family. This newly identified pathogen, D/swine/Oklahoma/1334/2011 (D/OK), first identified in pigs with influenza-like illness was classified as the influenza D virus (IDV) which is distantly related to the previously characterized human influenza C virus. Several other back-to-back studies soon suggested cattle as the natural reservoir and possible involvement of IDV in the bovine respiratory disease complex was established. Not much is known about its likelihood to cause disease in humans, but it definitely poses a potential threat as an emerging pathogen in cattle-workers. Here, we review the evolution, epidemiology, virology and pathobiology of influenza D virus and the possibility of transmission among various hosts and potential to cause human disease.
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Affiliation(s)
- Kumari Asha
- Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA.
| | - Binod Kumar
- Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA.
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53
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Golovko AO, Koroleva ON, Tolstova AP, Kuz'mina NV, Dubrovin EV, Drutsa VL. Aggregation of Influenza A Virus Nuclear Export Protein. BIOCHEMISTRY (MOSCOW) 2018; 83:1411-1421. [PMID: 30482152 DOI: 10.1134/s0006297918110111] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Influenza A virus nuclear export protein (NEP) plays an important role in the viral life cycle. Recombinant NEP proteins containing (His)6-tag at either N- or C-terminus were obtained by heterologous expression in Escherichia coli cells and their high propensity for aggregation was demonstrated. Dynamic light scattering technique was used to study the kinetics and properties of NEP aggregation in solutions under different conditions (pH, ionic strength, presence of low-molecular-weight additives and organic solvents). Using atomic force microscopy, the predominance of spherical aggregates in all examined NEP preparations was shown, with some amyloid-like structures being observed in the case of NEP-C protein. A number of structure prediction programs were used to identify aggregation-prone regions in the NEP structure. All-atom molecular dynamics simulations indicate a high rate of NEP molecule aggregation and reveal the regions preferentially involved in the intermolecular contacts that are located at the edges of the rod-like protein molecule. Our results suggest that NEP aggregation is determined by different types of interactions and represents an intrinsic property of the protein that appears to be necessary for its functioning in vivo.
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Affiliation(s)
- A O Golovko
- Lomonosov Moscow State University, Department of Bioengineering and Bioinformatics, Moscow, 119991, Russia.
| | - O N Koroleva
- Lomonosov Moscow State University, Department of Chemistry, Moscow, 119991, Russia.
| | - A P Tolstova
- Lomonosov Moscow State University, Department of Physics, Moscow, 119991, Russia.
| | - N V Kuz'mina
- Lomonosov Moscow State University, Department of Biology, Moscow, 119991, Russia. .,Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, 119071, Russia
| | - E V Dubrovin
- Lomonosov Moscow State University, Department of Physics, Moscow, 119991, Russia.
| | - V L Drutsa
- Lomonosov Moscow State University, Belozersky Research Institute of Physico-Chemical Biology, Moscow, 119991, Russia.
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54
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Singh RK, Dhama K, Karthik K, Khandia R, Munjal A, Khurana SK, Chakraborty S, Malik YS, Virmani N, Singh R, Tripathi BN, Munir M, van der Kolk JH. A Comprehensive Review on Equine Influenza Virus: Etiology, Epidemiology, Pathobiology, Advances in Developing Diagnostics, Vaccines, and Control Strategies. Front Microbiol 2018; 9:1941. [PMID: 30237788 PMCID: PMC6135912 DOI: 10.3389/fmicb.2018.01941] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 07/31/2018] [Indexed: 01/23/2023] Open
Abstract
Among all the emerging and re-emerging animal diseases, influenza group is the prototype member associated with severe respiratory infections in wide host species. Wherein, Equine influenza (EI) is the main cause of respiratory illness in equines across globe and is caused by equine influenza A virus (EIV-A) which has impacted the equine industry internationally due to high morbidity and marginal morality. The virus transmits easily by direct contact and inhalation making its spread global and leaving only limited areas untouched. Hitherto reports confirm that this virus crosses the species barriers and found to affect canines and few other animal species (cat and camel). EIV is continuously evolving with changes at the amino acid level wreaking the control program a tedious task. Until now, no natural EI origin infections have been reported explicitly in humans. Recent advances in the diagnostics have led to efficient surveillance and rapid detection of EIV infections at the onset of outbreaks. Incessant surveillance programs will aid in opting a better control strategy for this virus by updating the circulating vaccine strains. Recurrent vaccination failures against this virus due to antigenic drift and shift have been disappointing, however better understanding of the virus pathogenesis would make it easier to design effective vaccines predominantly targeting the conserved epitopes (HA glycoprotein). Additionally, the cold adapted and canarypox vectored vaccines are proving effective in ceasing the severity of disease. Furthermore, better understanding of its genetics and molecular biology will help in estimating the rate of evolution and occurrence of pandemics in future. Here, we highlight the advances occurred in understanding the etiology, epidemiology and pathobiology of EIV and a special focus is on designing and developing effective diagnostics, vaccines and control strategies for mitigating the emerging menace by EIV.
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Affiliation(s)
- Raj K. Singh
- ICAR-Indian Veterinary Research Institute, Bareilly, India
| | - Kuldeep Dhama
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Bareilly, India
| | - Kumaragurubaran Karthik
- Central University Laboratory, Tamil Nadu Veterinary and Animal Sciences University, Chennai, India
| | - Rekha Khandia
- Department of Biochemistry and Genetics, Barkatullah University, Bhopal, India
| | - Ashok Munjal
- Department of Biochemistry and Genetics, Barkatullah University, Bhopal, India
| | | | - Sandip Chakraborty
- Department of Veterinary Microbiology, College of Veterinary Sciences and Animal Husbandry, West Tripura, India
| | - Yashpal S. Malik
- Division of Biological Standardization, ICAR-Indian Veterinary Research Institute, Bareilly, India
| | | | - Rajendra Singh
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Bareilly, India
| | | | - Muhammad Munir
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
| | - Johannes H. van der Kolk
- Division of Clinical Veterinary Medicine, Swiss Institute for Equine Medicine (ISME), Vetsuisse Faculty, University of Bern and Agroscope, Bern, Switzerland
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55
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Rajão DS, Pérez DR. Universal Vaccines and Vaccine Platforms to Protect against Influenza Viruses in Humans and Agriculture. Front Microbiol 2018; 9:123. [PMID: 29467737 PMCID: PMC5808216 DOI: 10.3389/fmicb.2018.00123] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/18/2018] [Indexed: 01/22/2023] Open
Abstract
Influenza virus infections pose a significant threat to public health due to annual seasonal epidemics and occasional pandemics. Influenza is also associated with significant economic losses in animal production. The most effective way to prevent influenza infections is through vaccination. Current vaccine programs rely heavily on the vaccine's ability to stimulate neutralizing antibody responses to the hemagglutinin (HA) protein. One of the biggest challenges to an effective vaccination program lies on the fact that influenza viruses are ever-changing, leading to antigenic drift that results in escape from earlier immune responses. Efforts toward overcoming these challenges aim at improving the strength and/or breadth of the immune response. Novel vaccine technologies, the so-called universal vaccines, focus on stimulating better cross-protection against many or all influenza strains. However, vaccine platforms or manufacturing technologies being tested to improve vaccine efficacy are heterogeneous between different species and/or either tailored for epidemic or pandemic influenza. Here, we discuss current vaccines to protect humans and animals against influenza, highlighting challenges faced to effective and uniform novel vaccination strategies and approaches.
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Affiliation(s)
- Daniela S. Rajão
- Department of Population Health, University of Georgia, Athens, GA, United States
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56
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Vasin AV, Petrova-Brodskaya AV, Plotnikova MA, Tsvetkov VB, Klotchenko SA. EVOLUTIONARY DYNAMICS OF STRUCTURAL AND FUNCTIONAL DOMAINS OF INFLUENZA A VIRUS NS1 PROTEIN. Vopr Virusol 2017; 62:246-258. [PMID: 36494956 DOI: 10.18821/0507-4088-2017-62-6-246-258] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Indexed: 12/13/2022]
Abstract
Influenza A virus (IAV) NS1 protein is one of the key viral factors responsible for virus-host interactions. NS1 counteracts host antiviral defense, participates in the processing and export of cellular mRNAs, regulates the activity of viral RNA polymerase and the expression of viral genes, and influences the cellular signaling systems. Multiple NS1 functions are carried out due to the interactions with cellular factors, the number of which exceeds one hundred. It is noteworthy that only two segments of IAV genome - NS and NP - did not undergo reassortment and evolved in the course of genetic drift, beginning with the pandemic of 1918 to the present. This fact may indicate the importance of NS1 and its numerous interactions with cellular factors in the interspecific adaptation of the virus. The review presents data on the evolution of the human IAV NS1 protein and analysis of the amino acid substitutions in the main structural and functional domains of NS1 protein during evolution.
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Affiliation(s)
- A V Vasin
- Research Institute of Influenza.,Peter the Great St. Petersburg Polytechnic University
| | - A V Petrova-Brodskaya
- Research Institute of Influenza.,Peter the Great St. Petersburg Polytechnic University
| | | | - V B Tsvetkov
- Research Institute of Influenza.,A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences.,Federal Research and Clinical Center of Physical-Chemical Medicine
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57
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Shtykova EV, Bogacheva EN, Dadinova LA, Jeffries CM, Fedorova NV, Golovko AO, Baratova LA, Batishchev OV. Small-angle X-Ray analysis of macromolecular structure: the structure of protein NS2 (NEP) in solution. CRYSTALLOGR REP+ 2017. [DOI: 10.1134/s1063774517060220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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58
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Influenza virus genome reaches the plasma membrane via a modified endoplasmic reticulum and Rab11-dependent vesicles. Nat Commun 2017; 8:1396. [PMID: 29123131 PMCID: PMC5680169 DOI: 10.1038/s41467-017-01557-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 09/27/2017] [Indexed: 12/05/2022] Open
Abstract
Transport of neo-synthesized influenza A virus (IAV) viral ribonucleoproteins (vRNPs) from the nucleus to the plasma membrane involves Rab 11 but the precise mechanism remains poorly understood. We used metal-tagging and immunolabeling to visualize viral proteins and cellular endomembrane markers by electron microscopy of IAV-infected cells. Unexpectedly, we provide evidence that the vRNP components and the Rab11 protein are present at the membrane of a modified, tubulated endoplasmic reticulum (ER) that extends all throughout the cell, and on irregularly coated vesicles (ICVs). Some ICVs are found very close to the ER and to the plasma membrane. ICV formation is observed only in infected cells and requires an active Rab11 GTPase. Against the currently accepted model in which vRNPs are carried onto Rab11-positive recycling endosomes across the cytoplasm, our findings reveal that the endomembrane organelle that is primarily involved in the transport of vRNPs is the ER. Transport of neo-synthesized influenza A virus viral ribonucleoproteins (vRNPs) from the nucleus to the plasma membrane involves Rab 11 but the mechanism is unclear. Here the authors show that vRNPs are transported through a modified Rab11-positive endoplasmic reticulum and Rab11-dependent vesicles.
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59
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Lakdawala SS, Fodor E, Subbarao K. Moving On Out: Transport and Packaging of Influenza Viral RNA into Virions. Annu Rev Virol 2017; 3:411-427. [PMID: 27741407 DOI: 10.1146/annurev-virology-110615-042345] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Influenza A viruses bear an eight-segmented single-stranded negative-sense RNA genome that is replicated in the nucleus. Newly synthesized viral RNA (vRNA) segments are exported from the nucleus and transported to the plasma membrane for packaging into progeny virions. Influenza viruses exploit many host proteins during these events, and this is the portion of the viral life cycle when genetic reassortment among influenza viruses occurs. Reassortment among influenza A viruses allows viruses to expand their host range, virulence, and pandemic potential. This review covers recent studies on the export of vRNAs from the nucleus and their transport through the cytoplasm, progressive assembly, and packaging into progeny virus particles. Understanding these events and the constraints on genetic reassortment has implications for assessment of the pandemic potential of newly emerged influenza viruses, for vaccine production, for determination of viral fitness, and for identification of novel therapeutic targets.
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Affiliation(s)
- Seema S Lakdawala
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15219
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Kanta Subbarao
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892;
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60
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Su S, Fu X, Li G, Kerlin F, Veit M. Novel Influenza D virus: Epidemiology, pathology, evolution and biological characteristics. Virulence 2017; 8:1580-1591. [PMID: 28812422 DOI: 10.1080/21505594.2017.1365216] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
In 2011, a new virus was isolated from pigs with influenza-like symptoms and subsequently also from cattle, which are the main reservoir of the virus. It is similar to Influenza C virus (ICV), a (predominantly) human pathogen, causing respiratory disease in children. Since the virus is unable to reassort with ICV (and based on several other criteria as discussed in the text) it is now officially named as Influenzavirus D (IDV), a new genus of the Orthomyxoviridae. We summarize the epidemiology, pathology and evolution of IDV and its biological characteristics with emphasis on the only glycoprotein HEF. Based on the limited data available we finally consider whether IDV represent a public health threat.
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Affiliation(s)
- Shuo Su
- a Jiangsu Engineering Laboratory of Animal Immunology , Institute of Immunology and College of Veterinary Medicine, Nanjing Agricultural University , Nanjing , China
| | - Xinliang Fu
- b Key Laboratory of Zoonosis Prevention and Control of Guangdong Province and College of Veterinary Medicine , South China Agricultural University , Guangzhou , China
| | - Gairu Li
- a Jiangsu Engineering Laboratory of Animal Immunology , Institute of Immunology and College of Veterinary Medicine, Nanjing Agricultural University , Nanjing , China
| | - Fiona Kerlin
- c Institute for Virology, Center for Infection Medicine, Veterinary Faculty , Free University Berlin , Berlin , Germany
| | - Michael Veit
- c Institute for Virology, Center for Infection Medicine, Veterinary Faculty , Free University Berlin , Berlin , Germany
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61
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Functional Evolution of Influenza Virus NS1 Protein in Currently Circulating Human 2009 Pandemic H1N1 Viruses. J Virol 2017. [PMID: 28637754 DOI: 10.1128/jvi.00721-17] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In 2009, a novel H1N1 influenza virus emerged in humans, causing a global pandemic. It was previously shown that the NS1 protein from this human 2009 pandemic H1N1 (pH1N1) virus was an effective interferon (IFN) antagonist but could not inhibit general host gene expression, unlike other NS1 proteins from seasonal human H1N1 and H3N2 viruses. Here we show that the NS1 protein from currently circulating pH1N1 viruses has evolved to encode 6 amino acid changes (E55K, L90I, I123V, E125D, K131E, and N205S) with respect to the original protein. Notably, these 6 residue changes restore the ability of pH1N1 NS1 to inhibit general host gene expression, mainly by their ability to restore binding to the cellular factor CPSF30. This is the first report describing the ability of the pH1N1 NS1 protein to naturally acquire mutations that restore this function. Importantly, a recombinant pH1N1 virus containing these 6 amino acid changes in the NS1 protein (pH1N1/NSs-6mut) inhibited host IFN and proinflammatory responses to a greater extent than that with the parental virus (pH1N1/NS1-wt), yet virus titers were not significantly increased in cell cultures or in mouse lungs, and the disease was partially attenuated. The pH1N1/NSs-6mut virus grew similarly to pH1N1/NSs-wt in mouse lungs, but infection with pH1N1/NSs-6mut induced lower levels of proinflammatory cytokines, likely due to a general inhibition of gene expression mediated by the mutated NS1 protein. This lower level of inflammation induced by the pH1N1/NSs-6mut virus likely accounts for the attenuated disease phenotype and may represent a host-virus adaptation affecting influenza virus pathogenesis.IMPORTANCE Seasonal influenza A viruses (IAVs) are among the most common causes of respiratory infections in humans. In addition, occasional pandemics are caused when IAVs circulating in other species emerge in the human population. In 2009, a swine-origin H1N1 IAV (pH1N1) was transmitted to humans, infecting people then and up to the present. It was previously shown that the NS1 protein from the 2009 pandemic H1N1 (pH1N1) virus is not able to inhibit general gene expression. However, currently circulating pH1N1 viruses have evolved to encode 6 amino acid changes (E55K, L90I, I123V, E125D, K131E, and N205S) that allow the NS1 protein of contemporary pH1N1 strains to inhibit host gene expression, which correlates with its ability to interact with CPSF30. Infection with a recombinant pH1N1 virus encoding these 6 amino acid changes (pH1N1/NSs-6mut) induced lower levels of proinflammatory cytokines, resulting in viral attenuation in vivo This might represent an adaptation of pH1N1 virus to humans.
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62
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Zhao M, Wang L, Li S. Influenza A Virus-Host Protein Interactions Control Viral Pathogenesis. Int J Mol Sci 2017; 18:ijms18081673. [PMID: 28763020 PMCID: PMC5578063 DOI: 10.3390/ijms18081673] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 07/27/2017] [Accepted: 07/28/2017] [Indexed: 12/20/2022] Open
Abstract
The influenza A virus (IAV), a member of the Orthomyxoviridae family, is a highly transmissible respiratory pathogen and represents a continued threat to global health with considerable economic and social impact. IAV is a zoonotic virus that comprises a plethora of strains with different pathogenic profiles. The different outcomes of viral pathogenesis are dependent on the engagement between the virus and the host cellular protein interaction network. The interactions may facilitate virus hijacking of host molecular machinery to fulfill the viral life cycle or trigger host immune defense to eliminate the virus. In recent years, much effort has been made to discover the virus–host protein interactions and understand the underlying mechanisms. In this paper, we review the recent advances in our understanding of IAV–host interactions and how these interactions contribute to host defense and viral pathogenesis.
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Affiliation(s)
- Mengmeng Zhao
- 156 McElroy Hall, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
| | - Lingyan Wang
- 156 McElroy Hall, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
| | - Shitao Li
- 156 McElroy Hall, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
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63
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Mathew C, Ghildyal R. CRM1 Inhibitors for Antiviral Therapy. Front Microbiol 2017; 8:1171. [PMID: 28702009 PMCID: PMC5487384 DOI: 10.3389/fmicb.2017.01171] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 06/08/2017] [Indexed: 12/22/2022] Open
Abstract
Infectious diseases are a major global concern and despite major advancements in medical research, still cause significant morbidity and mortality. Progress in antiviral therapy is particularly hindered by appearance of mutants capable of overcoming the effects of drugs targeting viral components. Alternatively, development of drugs targeting host proteins essential for completion of viral lifecycle holds potential as a viable strategy for antiviral therapy. Nucleocytoplasmic trafficking pathways in particular are involved in several pathological conditions including cancer and viral infections, where hijacking or alteration of function of key transporter proteins, such as Chromosome Region Maintenance1 (CRM1) is observed. Overexpression of CRM1-mediated nuclear export is evident in several solid and hematological malignancies. Interestingly, CRM1-mediated nuclear export of viral components is crucial in various stages of the viral lifecycle and assembly. This review summarizes the role of CRM1 in cancer and selected viruses. Leptomycin B (LMB) is the prototypical inhibitor of CRM1 potent against various cancer cell lines overexpressing CRM1 and in limiting viral infections at nanomolar concentrations in vitro. However, the irreversible shutdown of nuclear export results in high cytotoxicity and limited efficacy in vivo. This has prompted search for synthetic and natural CRM1 inhibitors that can potentially be developed as broadly active antivirals, some of which are summarized in this review.
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Affiliation(s)
| | - Reena Ghildyal
- Respiratory Virology Group, Centre for Research in Therapeutic Solutions, Health Research Institute, University of CanberraCanberra, ACT, Australia
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64
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Kesavardhana S, Kuriakose T, Guy CS, Samir P, Malireddi RKS, Mishra A, Kanneganti TD. ZBP1/DAI ubiquitination and sensing of influenza vRNPs activate programmed cell death. J Exp Med 2017. [PMID: 28634194 PMCID: PMC5551577 DOI: 10.1084/jem.20170550] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The activation mechanism of ZBP1/DAI to regulate virus-induced programmed cell death is not known. Kesavardhana et al. show that ZBP1 senses viral ribonucleoproteins to induce cell death upon influenza A virus infection. Apical activation of RIG-I–IFNAR signaling to upregulate ZBP1 and influenza-induced ZBP1 ubiquitination are critical events for ZBP1 activation. Innate sensing of influenza virus infection induces activation of programmed cell death pathways. We have recently identified Z-DNA–binding protein 1 (ZBP1) as an innate sensor of influenza A virus (IAV). ZBP1-mediated IAV sensing is critical for triggering programmed cell death in the infected lungs. Surprisingly, little is known about the mechanisms regulating ZBP1 activation to induce programmed cell death. Here, we report that the sensing of IAV RNA by retinoic acid inducible gene I (RIG-I) initiates ZBP1-mediated cell death via the RIG-I–MAVS–IFN-β signaling axis. IAV infection induces ubiquitination of ZBP1, suggesting potential regulation of ZBP1 function through posttranslational modifications. We further demonstrate that ZBP1 senses viral ribonucleoprotein (vRNP) complexes of IAV to trigger cell death. These findings collectively indicate that ZBP1 activation requires RIG-I signaling, ubiquitination, and vRNP sensing to trigger activation of programmed cell death pathways during IAV infection. The mechanism of ZBP1 activation described here may have broader implications in the context of virus-induced cell death.
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Affiliation(s)
| | - Teneema Kuriakose
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN
| | - Clifford S Guy
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN
| | - Parimal Samir
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN
| | | | - Ashutosh Mishra
- Proteomics and Mass Spectrometry Core, St. Jude Children's Research Hospital, Memphis, TN
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65
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Myaing MZ, Jumat MR, Huong TN, Tan BH, Sugrue RJ. Truncated forms of the PA protein containing only the C-terminal domains are associated with the ribonucleoprotein complex within H1N1 influenza virus particles. J Gen Virol 2017; 98:906-921. [PMID: 28141511 DOI: 10.1099/jgv.0.000721] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We have examined the expression profile of the influenza virus PA protein in pH1N1/2009 virus-infected cells. Immunoblotting analysis of virus-infected MDCK cells revealed the presence of full-length PA protein from 8 h post-infection, together with the simultaneous appearance of PA protein species of approximately 50, 35/39 and 20/25 kDa (collectively referred to as PA*). PA* was also detected in H1N1/WSN-virus-infected cells, indicating that its presence was not virus-specific, and it was also observed in virus-infected A549 and chick embryo fibroblast (CEF) cells, indicating that its presence was not cell-type-specific. PA* was detected in cells expressing the recombinant PA protein, indicating that the PA* formation occurred in the absence of virus infection. These data collectively indicated that PA* formation is an intrinsic property of PA gene expression. The association of PA* with purified influenza virus particles was demonstrated by immunoblotting, and a protease protection assay provided evidence that PA* was packaged into virus particles. The ribonucleoprotein (RNP) complex was isolated from purified influenza virus particles using glycerol gradient centrifugation, which demonstrated that PA* was associated with the RNP complex. To the best of our knowledge, this is the first report to demonstrate that PA protein species containing only segments of the C-terminal domain form during influenza virus infection. Furthermore, these truncated PA protein species are subsequently packaged into virus particles as part of the functional RNP complex.
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Affiliation(s)
- Myint Zu Myaing
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Muhammad Raihan Jumat
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Tra Nguyen Huong
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Boon Huan Tan
- Detection and Diagnostics Laboratory, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore
| | - Richard J Sugrue
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
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66
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Wu X, Wu X, Sun Q, Zhang C, Yang S, Li L, Jia Z. Progress of small molecular inhibitors in the development of anti-influenza virus agents. Am J Cancer Res 2017; 7:826-845. [PMID: 28382157 PMCID: PMC5381247 DOI: 10.7150/thno.17071] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 11/18/2016] [Indexed: 02/05/2023] Open
Abstract
The influenza pandemic is a major threat to human health, and highly aggressive strains such as H1N1, H5N1 and H7N9 have emphasized the need for therapeutic strategies to combat these pathogens. Influenza anti-viral agents, especially active small molecular inhibitors play important roles in controlling pandemics while vaccines are developed. Currently, only a few drugs, which function as influenza neuraminidase (NA) inhibitors and M2 ion channel protein inhibitors, are approved in clinical. However, the acquired resistance against current anti-influenza drugs and the emerging mutations of influenza virus itself remain the major challenging unmet medical needs for influenza treatment. It is highly desirable to identify novel anti-influenza agents. This paper reviews the progress of small molecular inhibitors act as antiviral agents, which include hemagglutinin (HA) inhibitors, RNA-dependent RNA polymerase (RdRp) inhibitors, NA inhibitors and M2 ion channel protein inhibitors etc. Moreover, we also summarize new, recently reported potential targets and discuss strategies for the development of new anti-influenza virus drugs.
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67
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Molecular characterization of a novel orthomyxovirus from rainbow and steelhead trout (Oncorhynchus mykiss). Virus Res 2017; 230:38-49. [PMID: 28088362 PMCID: PMC7111338 DOI: 10.1016/j.virusres.2017.01.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 01/06/2017] [Accepted: 01/08/2017] [Indexed: 11/23/2022]
Abstract
A novel virus, rainbow trout orthomyxovirus (RbtOV), was isolated in 1997 and again in 2000 from commercially-reared rainbow trout (Oncorhynchus mykiss) in Idaho, USA. The virus grew optimally in the CHSE-214 cell line at 15°C producing a diffuse cytopathic effect; however, juvenile rainbow trout exposed to cell culture-grown virus showed no mortality or gross pathology. Electron microscopy of preparations from infected cell cultures revealed the presence of typical orthomyxovirus particles. The complete genome of RbtOV is comprised of eight linear segments of single-stranded, negative-sense RNA having highly conserved 5' and 3'-terminal nucleotide sequences. Another virus isolated in 2014 from steelhead trout (also O. mykiss) in Wisconsin, USA, and designated SttOV was found to have eight genome segments with high amino acid sequence identities (89-99%) to the corresponding genes of RbtOV, suggesting these new viruses are isolates of the same virus species and may be more widespread than currently realized. The new isolates had the same genome segment order and the closest pairwise amino acid sequence identities of 16-42% with Infectious salmon anemia virus (ISAV), the type species and currently only member of the genus Isavirus in the family Orthomyxoviridae. However, pairwise comparisons of the predicted amino acid sequences of the 10 RbtOV and SttOV proteins with orthologs from representatives of the established orthomyxoviral genera and a phylogenetic analysis using the PB1 protein showed that while RbtOV and SttOV clustered most closely with ISAV, they diverged sufficiently to merit consideration as representatives of a novel genus. A set of PCR primers was designed using conserved regions of the PB1 gene to produce amplicons that may be sequenced for identification of similar fish orthomyxoviruses in the future.
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68
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Nogales A, Martínez-Sobrido L. Reverse Genetics Approaches for the Development of Influenza Vaccines. Int J Mol Sci 2016; 18:E20. [PMID: 28025504 PMCID: PMC5297655 DOI: 10.3390/ijms18010020] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 12/15/2016] [Accepted: 12/19/2016] [Indexed: 12/20/2022] Open
Abstract
Influenza viruses cause annual seasonal epidemics and occasional pandemics of human respiratory disease. Influenza virus infections represent a serious public health and economic problem, which are most effectively prevented through vaccination. However, influenza viruses undergo continual antigenic variation, which requires either the annual reformulation of seasonal influenza vaccines or the rapid generation of vaccines against potential pandemic virus strains. The segmented nature of influenza virus allows for the reassortment between two or more viruses within a co-infected cell, and this characteristic has also been harnessed in the laboratory to generate reassortant viruses for their use as either inactivated or live-attenuated influenza vaccines. With the implementation of plasmid-based reverse genetics techniques, it is now possible to engineer recombinant influenza viruses entirely from full-length complementary DNA copies of the viral genome by transfection of susceptible cells. These reverse genetics systems have provided investigators with novel and powerful approaches to answer important questions about the biology of influenza viruses, including the function of viral proteins, their interaction with cellular host factors and the mechanisms of influenza virus transmission and pathogenesis. In addition, reverse genetics techniques have allowed the generation of recombinant influenza viruses, providing a powerful technology to develop both inactivated and live-attenuated influenza vaccines. In this review, we will summarize the current knowledge of state-of-the-art, plasmid-based, influenza reverse genetics approaches and their implementation to provide rapid, convenient, safe and more effective influenza inactivated or live-attenuated vaccines.
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Affiliation(s)
- Aitor Nogales
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642, USA.
| | - Luis Martínez-Sobrido
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642, USA.
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69
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Li J, Zheng W, Hou L, Chen C, Fan W, Qu H, Jiang J, Liu J, Gao GF, Zhou J, Sun L, Liu W. Differential nucleocytoplasmic shuttling of the nucleoprotein of influenza a viruses and association with host tropism. Cell Microbiol 2016; 19. [DOI: 10.1111/cmi.12692] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 10/13/2016] [Accepted: 11/02/2016] [Indexed: 01/01/2023]
Affiliation(s)
- Jing Li
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
| | - Weinan Zheng
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
| | - Lidan Hou
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
- China Institute of Veterinary Drug Control; Beijing China
| | - Can Chen
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
- University of Chinese Academy of Sciences; Beijing China
| | - Wenhui Fan
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
| | - Hongren Qu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
| | - Jingwen Jiang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
- School of Life Sciences; University of Science and Technology of China; Hefei China
| | - Jinhua Liu
- Key Laboratory of Zoonosis of Ministry of Agriculture, College of Veterinary Medicine; China Agricultural University; Beijing China
| | - George F. Gao
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
- University of Chinese Academy of Sciences; Beijing China
- Beijing Institutes of Life Science; Chinese Academy of Sciences; Beijing China
- Office of Director-General; Chinese Center for Disease Control and Prevention; Beijing China
| | - Jiyong Zhou
- College of Veterinary Medicine; Nanjing Agricultural University; Nanjing China
| | - Lei Sun
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
- University of Chinese Academy of Sciences; Beijing China
| | - Wenjun Liu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology; Institute of Microbiology, Chinese Academy of Sciences; Beijing China
- University of Chinese Academy of Sciences; Beijing China
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70
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Lipsitch M, Barclay W, Raman R, Russell CJ, Belser JA, Cobey S, Kasson PM, Lloyd-Smith JO, Maurer-Stroh S, Riley S, Beauchemin CA, Bedford T, Friedrich TC, Handel A, Herfst S, Murcia PR, Roche B, Wilke CO, Russell CA. Viral factors in influenza pandemic risk assessment. eLife 2016; 5. [PMID: 27834632 PMCID: PMC5156527 DOI: 10.7554/elife.18491] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/03/2016] [Indexed: 12/13/2022] Open
Abstract
The threat of an influenza A virus pandemic stems from continual virus spillovers from reservoir species, a tiny fraction of which spark sustained transmission in humans. To date, no pandemic emergence of a new influenza strain has been preceded by detection of a closely related precursor in an animal or human. Nonetheless, influenza surveillance efforts are expanding, prompting a need for tools to assess the pandemic risk posed by a detected virus. The goal would be to use genetic sequence and/or biological assays of viral traits to identify those non-human influenza viruses with the greatest risk of evolving into pandemic threats, and/or to understand drivers of such evolution, to prioritize pandemic prevention or response measures. We describe such efforts, identify progress and ongoing challenges, and discuss three specific traits of influenza viruses (hemagglutinin receptor binding specificity, hemagglutinin pH of activation, and polymerase complex efficiency) that contribute to pandemic risk.
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Affiliation(s)
- Marc Lipsitch
- Center for Communicable Disease Dynamics, Harvard T. H Chan School of Public Health, Boston, United States.,Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, United States.,Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, United States
| | - Wendy Barclay
- Division of Infectious Disease, Faculty of Medicine, Imperial College, London, United Kingdom
| | - Rahul Raman
- Department of Biological Engineering, Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States
| | - Charles J Russell
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, United States
| | - Jessica A Belser
- Centers for Disease Control and Prevention, Atlanta, United States
| | - Sarah Cobey
- Department of Ecology and Evolutionary Biology, University of Chicago, Chicago, United States
| | - Peter M Kasson
- Department of Biomedical Engineering, University of Virginia, Charlottesville, United States.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, United States
| | - James O Lloyd-Smith
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, United States.,Fogarty International Center, National Institutes of Health, Bethesda, United States
| | - Sebastian Maurer-Stroh
- Bioinformatics Institute, Agency for Science Technology and Research, Singapore, Singapore.,National Public Health Laboratory, Communicable Diseases Division, Ministry of Health, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Steven Riley
- MRC Centre for Outbreak Analysis and Modelling, School of Public Health, Imperial College London, London, United Kingdom.,Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | | | - Trevor Bedford
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Thomas C Friedrich
- Department of Pathobiological Sciences, University of Wisconsin School of Veterinary Medicine, Madison, United States
| | - Andreas Handel
- Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens, United States
| | - Sander Herfst
- Department of Viroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Pablo R Murcia
- MRC-University of Glasgow Centre For Virus Research, Glasgow, United Kingdom
| | | | - Claus O Wilke
- Center for Computational Biology and Bioinformatics, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, United States.,Department of Integrative Biology, The University of Texas at Austin, Austin, United States
| | - Colin A Russell
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
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71
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Virologic Differences Do Not Fully Explain the Diversification of Swine Influenza Viruses in the United States. J Virol 2016; 90:10074-10082. [PMID: 27581984 DOI: 10.1128/jvi.01218-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 08/12/2016] [Indexed: 11/20/2022] Open
Abstract
Influenza A(H1N1) viruses entered the U.S. swine population following the 1918 pandemic and remained genetically stable for roughly 80 years. In 1998, there was an outbreak of influenza-like illness among swine that was caused by A(H3N2) viruses containing the triple reassortant internal gene (TRIG) cassette. Following the TRIG cassette emergence, numerous reassortant viruses were isolated in nature, suggesting that the TRIG virus had an enhanced ability to reassort compared to the classical swine virus. The present study was designed to quantify the relative reassortment capacities of classical and TRIG swine viruses. Reverse genetic viruses were generated from the classical H1N1 virus A/swine/MN/37866/1999 (MN/99), the TRIG virus A/swine/NC/18161/2002 (NC/02), and a seasonal human H3N2 virus, A/TX/6/1996 (TX/96), to measure in vitro reassortment and growth potentials. After coinfection with NC/02 or MN/99 plus TX/96, H1/H3 double-positive cells were identified. Delayed TX/96 infection was fully excluded by both swine viruses. We then analyzed reassortant H3 viruses. Seventy-seven of 81 (95.1%) TX/96-NC/02 reassortants contained at least one polymerase gene segment from NC/02, whereas only 34 of 61 (55.7%) MN/99-TX/96 reassortants contained at least one polymerase gene segment from MN/99. Additionally, 38 of 81 (46.9%) NC/02-TX/96 reassortants contained all NC/02 polymerase gene segments, while none of the MN/99-TX/96 reassortants contained all MN/99 polymerase genes. There were 21 H3 reassortants between MN/99 and TX/96, compared to only 17 H3 reassortants between NC/02 and TX/96. Overall, the results indicate that there are no distinct differences in the ability of the TRIG to reassort with a human virus compared to the classical swine virus. IMPORTANCE There appear to be no differences in the abilities of classical swine and TRIG swine viruses to exclude a second virus, suggesting that under the right circumstances both viruses have similar opportunities to reassort. The increased percentage of TRIG polymerase gene segments in reassortant H3 viruses indicates that these viruses may be more compatible with gene segments from other viruses; however, this needs to be investigated further. Nevertheless, the classical swine virus also showed the ability to reassort, suggesting that factors other than reassortment capacity alone are responsible for the different epidemiologies of TRIG and classical swine viruses. The post-TRIG diversity was likely driven by increased intensive farming practices rather than virologic properties. Our results indicate that host ecology can be a significant factor in viral evolution.
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72
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Role of the B Allele of Influenza A Virus Segment 8 in Setting Mammalian Host Range and Pathogenicity. J Virol 2016; 90:9263-84. [PMID: 27489273 PMCID: PMC5044859 DOI: 10.1128/jvi.01205-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/28/2016] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED Two alleles of segment 8 (NS) circulate in nonchiropteran influenza A viruses. The A allele is found in avian and mammalian viruses, but the B allele is viewed as being almost exclusively found in avian viruses. This might reflect the fact that one or both of its encoded proteins (NS1 and NEP) are maladapted for replication in mammalian hosts. To test this, a number of clade A and B avian virus-derived NS segments were introduced into human H1N1 and H3N2 viruses. In no case was the peak virus titer substantially reduced following infection of various mammalian cell types. Exemplar reassortant viruses also replicated to similar titers in mice, although mice infected with viruses with the avian virus-derived segment 8s had reduced weight loss compared to that achieved in mice infected with the A/Puerto Rico/8/1934 (H1N1) parent. In vitro, the viruses coped similarly with type I interferons. Temporal proteomics analysis of cellular responses to infection showed that the avian virus-derived NS segments provoked lower levels of expression of interferon-stimulated genes in cells than wild type-derived NS segments. Thus, neither the A nor the B allele of avian virus-derived NS segments necessarily attenuates virus replication in a mammalian host, although the alleles can attenuate disease. Phylogenetic analyses identified 32 independent incursions of an avian virus-derived A allele into mammals, whereas 6 introductions of a B allele were identified. However, A-allele isolates from birds outnumbered B-allele isolates, and the relative rates of Aves-to-Mammalia transmission were not significantly different. We conclude that while the introduction of an avian virus segment 8 into mammals is a relatively rare event, the dogma of the B allele being especially restricted is misleading, with implications in the assessment of the pandemic potential of avian influenza viruses. IMPORTANCE Influenza A virus (IAV) can adapt to poultry and mammalian species, inflicting a great socioeconomic burden on farming and health care sectors. Host adaptation likely involves multiple viral factors. Here, we investigated the role of IAV segment 8. Segment 8 has evolved into two distinct clades: the A and B alleles. The B-allele genes have previously been suggested to be restricted to avian virus species. We introduced a selection of avian virus A- and B-allele segment 8s into human H1N1 and H3N2 virus backgrounds and found that these reassortant viruses were fully competent in mammalian host systems. We also analyzed the currently available public data on the segment 8 gene distribution and found surprisingly little evidence for specific avian host restriction of the B-clade segment. We conclude that B-allele segment 8 genes are, in fact, capable of supporting infection in mammals and that they should be considered during the assessment of the pandemic risk of zoonotic influenza A viruses.
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73
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Zhao X, Tefsen B, Li Y, Qi J, Lu G, Shi Y, Yan J, Xiao H, Gao GF. The NS1 gene from bat-derived influenza-like virus H17N10 can be rescued in influenza A PR8 backbone. J Gen Virol 2016; 97:1797-1806. [DOI: 10.1099/jgv.0.000509] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Affiliation(s)
- Xuejin Zhao
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
- Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Boris Tefsen
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
- Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, P. R. China
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, No 111, Ren Ai Road, Dushu Lake Higher Education Town, Suzhou Industrial Park (SIP), Suzhou 215123, P. R. China
| | - Yan Li
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
- Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Jianxun Qi
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
- Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Guangwen Lu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
- Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Yi Shi
- Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, P. R. China
- Beijing Institute of Life Science, Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Jinghua Yan
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Haixia Xiao
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
- Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - George F. Gao
- Beijing Institute of Life Science, Chinese Academy of Sciences, Beijing 100101, P. R. China
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
- Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, P. R. China
- Office of Director-General, Chinese Center for Disease Control and Prevention, Beijing 102206, P. R. China
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, P. R. China
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74
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Pohl MO, Lanz C, Stertz S. Late stages of the influenza A virus replication cycle-a tight interplay between virus and host. J Gen Virol 2016; 97:2058-2072. [PMID: 27449792 DOI: 10.1099/jgv.0.000562] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
After successful infection and replication of its genome in the nucleus of the host cell, influenza A virus faces several challenges before newly assembled viral particles can bud off from the plasma membrane, giving rise to a new infectious virus. The viral ribonucleoprotein (vRNP) complexes need to exit from the nucleus and be transported to the virus assembly sites at the plasma membrane. Moreover, they need to be bundled to ensure the incorporation of precisely one of each of the eight viral genome segments into newly formed viral particles. Similarly, viral envelope glycoproteins and other viral structural proteins need to be targeted to virus assembly sites for viral particles to form and bud off from the plasma membrane. During all these steps influenza A virus heavily relies on a tight interplay with its host, exploiting host-cell proteins for its own purposes. In this review, we summarize current knowledge on late stages of the influenza virus replication cycle, focusing on the role of host-cell proteins involved in this process.
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Affiliation(s)
- Marie O Pohl
- Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland
| | - Caroline Lanz
- Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland
| | - Silke Stertz
- Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland
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75
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Te Velthuis AJW, Fodor E. Influenza virus RNA polymerase: insights into the mechanisms of viral RNA synthesis. Nat Rev Microbiol 2016; 14:479-93. [PMID: 27396566 DOI: 10.1038/nrmicro.2016.87] [Citation(s) in RCA: 292] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The genomes of influenza viruses consist of multiple segments of single-stranded negative-sense RNA. Each of these segments is bound by the heterotrimeric viral RNA-dependent RNA polymerase and multiple copies of nucleoprotein, which form viral ribonucleoprotein (vRNP) complexes. It is in the context of these vRNPs that the viral RNA polymerase carries out transcription of viral genes and replication of the viral RNA genome. In this Review, we discuss our current knowledge of the structure of the influenza virus RNA polymerase, and insights that have been gained into the molecular mechanisms of viral transcription and replication, and their regulation by viral and host factors. Furthermore, we discuss how advances in our understanding of the structure and function of polymerases could help in identifying new antiviral targets.
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Affiliation(s)
- Aartjan J W Te Velthuis
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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76
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Terrier O, Carron C, De Chassey B, Dubois J, Traversier A, Julien T, Cartet G, Proust A, Hacot S, Ressnikoff D, Lotteau V, Lina B, Diaz JJ, Moules V, Rosa-Calatrava M. Nucleolin interacts with influenza A nucleoprotein and contributes to viral ribonucleoprotein complexes nuclear trafficking and efficient influenza viral replication. Sci Rep 2016; 6:29006. [PMID: 27373907 PMCID: PMC4931502 DOI: 10.1038/srep29006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 06/09/2016] [Indexed: 01/18/2023] Open
Abstract
Influenza viruses replicate their single-stranded RNA genomes in the nucleus of infected cells and these replicated genomes (vRNPs) are then exported from the nucleus to the cytoplasm and plasma membrane before budding. To achieve this export, influenza viruses hijack the host cell export machinery. However, the complete mechanisms underlying this hijacking remain not fully understood. We have previously shown that influenza viruses induce a marked alteration of the nucleus during the time-course of infection and notably in the nucleolar compartment. In this study, we discovered that a major nucleolar component, called nucleolin, is required for an efficient export of vRNPs and viral replication. We have notably shown that nucleolin interacts with the viral nucleoprotein (NP) that mainly constitutes vRNPs. Our results suggest that this interaction could allow vRNPs to "catch" the host cell export machinery, a necessary step for viral replication.
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Affiliation(s)
- Olivier Terrier
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Coralie Carron
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Benoît De Chassey
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Julia Dubois
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Aurélien Traversier
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Thomas Julien
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
- VirNext, Faculté de Médecine RTH Laennec, Université Lyon 1, Lyon, France
| | - Gaëlle Cartet
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Anaïs Proust
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
- VirNext, Faculté de Médecine RTH Laennec, Université Lyon 1, Lyon, France
| | - Sabine Hacot
- Centre de Recherche en Cancérologie de Lyon, UMR Inserm 1052 CNRS 5286, Centre Léon Bérard, Lyon, France and Université de Lyon, Lyon, France
| | - Denis Ressnikoff
- CIQLE, Centre d’imagerie quantitative Lyon-Est, Université Claude Bernard Lyon 1, Lyon, France
| | - Vincent Lotteau
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Bruno Lina
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
- Hospices Civils de Lyon, Laboratory of Virology, Lyon, France
| | - Jean-Jacques Diaz
- Centre de Recherche en Cancérologie de Lyon, UMR Inserm 1052 CNRS 5286, Centre Léon Bérard, Lyon, France and Université de Lyon, Lyon, France
| | - Vincent Moules
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
- VirNext, Faculté de Médecine RTH Laennec, Université Lyon 1, Lyon, France
| | - Manuel Rosa-Calatrava
- Virologie et Pathologie Humaine - Team VirPath - Université Claude Bernard Lyon 1 - Hospices Civils de Lyon, Lyon, France
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Lyon, France
- VirNext, Faculté de Médecine RTH Laennec, Université Lyon 1, Lyon, France
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Rearrangement of Influenza Virus Spliced Segments for the Development of Live-Attenuated Vaccines. J Virol 2016; 90:6291-6302. [PMID: 27122587 DOI: 10.1128/jvi.00410-16] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 04/24/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Influenza viral infections represent a serious public health problem, with influenza virus causing a contagious respiratory disease which is most effectively prevented through vaccination. Segments 7 (M) and 8 (NS) of the influenza virus genome encode mRNA transcripts that are alternatively spliced to express two different viral proteins. This study describes the generation, using reverse genetics, of three different recombinant influenza A/Puerto Rico/8/1934 (PR8) H1N1 viruses containing M or NS viral segments individually or modified M or NS viral segments combined in which the overlapping open reading frames of matrix 1 (M1)/M2 for the modified M segment and the open reading frames of nonstructural protein 1 (NS1)/nuclear export protein (NEP) for the modified NS segment were split by using the porcine teschovirus 1 (PTV-1) 2A autoproteolytic cleavage site. Viruses with an M split segment were impaired in replication at nonpermissive high temperatures, whereas high viral titers could be obtained at permissive low temperatures (33°C). Furthermore, viruses containing the M split segment were highly attenuated in vivo, while they retained their immunogenicity and provided protection against a lethal challenge with wild-type PR8. These results indicate that influenza viruses can be effectively attenuated by the rearrangement of spliced segments and that such attenuated viruses represent an excellent option as safe, immunogenic, and protective live-attenuated vaccines. Moreover, this is the first time in which an influenza virus containing a restructured M segment has been described. Reorganization of the M segment to encode M1 and M2 from two separate, nonoverlapping, independent open reading frames represents a useful tool to independently study mutations in the M1 and M2 viral proteins without affecting the other viral M product. IMPORTANCE Vaccination represents our best therapeutic option against influenza viral infections. However, the efficacy of current influenza vaccines is suboptimal, and novel approaches are necessary for the prevention of disease caused by this important human respiratory pathogen. In this work, we describe a novel approach to generate safer and more efficient live-attenuated influenza virus vaccines (LAIVs) based on recombinant viruses whose genomes encode nonoverlapping and independent M1/M2 (split M segment [Ms]) or both M1/M2 and NS1/NEP (Ms and split NS segment [NSs]) open reading frames. Viruses containing a modified M segment were highly attenuated in mice but were able to confer, upon a single intranasal immunization, complete protection against a lethal homologous challenge with wild-type virus. Notably, the protection efficacy conferred by our viruses with split M segments was better than that conferred by the current temperature-sensitive LAIV. Altogether, these results open a new avenue for the development of safer and more protective LAIVs on the basis of the reorganization of spliced viral RNA segments in the genome.
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78
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Breen M, Nogales A, Baker SF, Martínez-Sobrido L. Replication-Competent Influenza A Viruses Expressing Reporter Genes. Viruses 2016; 8:v8070179. [PMID: 27347991 PMCID: PMC4974514 DOI: 10.3390/v8070179] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 06/16/2016] [Accepted: 06/19/2016] [Indexed: 12/12/2022] Open
Abstract
Influenza A viruses (IAV) cause annual seasonal human respiratory disease epidemics. In addition, IAV have been implicated in occasional pandemics with inordinate health and economic consequences. Studying IAV, in vitro or in vivo, requires the use of laborious secondary methodologies to identify virus-infected cells. To circumvent this requirement, replication-competent IAV expressing an easily traceable reporter protein can be used. Here we discuss the development and applications of recombinant replication-competent IAV harboring diverse fluorescent or bioluminescent reporter genes in different locations of the viral genome. These viruses have been employed for in vitro and in vivo studies, such as the screening of neutralizing antibodies or antiviral compounds, the identification of host factors involved in viral replication, cell tropism, the development of vaccines, or the assessment of viral infection dynamics. In summary, reporter-expressing, replicating-competent IAV represent a powerful tool for the study of IAV both in vitro and in vivo.
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Affiliation(s)
- Michael Breen
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
| | - Aitor Nogales
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
| | - Steven F Baker
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
| | - Luis Martínez-Sobrido
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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79
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Heaton NS, Moshkina N, Fenouil R, Gardner TJ, Aguirre S, Shah PS, Zhao N, Manganaro L, Hultquist JF, Noel J, Sachs D, Hamilton J, Leon PE, Chawdury A, Tripathi S, Melegari C, Campisi L, Hai R, Metreveli G, Gamarnik AV, García-Sastre A, Greenbaum B, Simon V, Fernandez-Sesma A, Krogan NJ, Mulder LCF, van Bakel H, Tortorella D, Taunton J, Palese P, Marazzi I. Targeting Viral Proteostasis Limits Influenza Virus, HIV, and Dengue Virus Infection. Immunity 2016; 44:46-58. [PMID: 26789921 DOI: 10.1016/j.immuni.2015.12.017] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/26/2015] [Accepted: 10/28/2015] [Indexed: 12/22/2022]
Abstract
Viruses are obligate parasites and thus require the machinery of the host cell to replicate. Inhibition of host factors co-opted during active infection is a strategy hosts use to suppress viral replication and a potential pan-antiviral therapy. To define the cellular proteins and processes required for a virus during infection is thus crucial to understanding the mechanisms of virally induced disease. In this report, we generated fully infectious tagged influenza viruses and used infection-based proteomics to identify pivotal arms of cellular signaling required for influenza virus growth and infectivity. Using mathematical modeling and genetic and pharmacologic approaches, we revealed that modulation of Sec61-mediated cotranslational translocation selectively impaired glycoprotein proteostasis of influenza as well as HIV and dengue viruses and led to inhibition of viral growth and infectivity. Thus, by studying virus-human protein-protein interactions in the context of active replication, we have identified targetable host factors for broad-spectrum antiviral therapies.
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Affiliation(s)
- Nicholas S Heaton
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Natasha Moshkina
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Romain Fenouil
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Thomas J Gardner
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Sebastian Aguirre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Priya S Shah
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158-2140, USA
| | - Nan Zhao
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Lara Manganaro
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Judd F Hultquist
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158-2140, USA
| | - Justine Noel
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - David Sachs
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Jennifer Hamilton
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Paul E Leon
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Amit Chawdury
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Division of Hematology and Oncology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Shashank Tripathi
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Camilla Melegari
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Laura Campisi
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Rong Hai
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Giorgi Metreveli
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Andrea V Gamarnik
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires 1405, Argentina
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Benjamin Greenbaum
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Division of Hematology and Oncology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Viviana Simon
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Ana Fernandez-Sesma
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158-2140, USA
| | - Lubbertus C F Mulder
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Harm van Bakel
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Domenico Tortorella
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158-2140, USA
| | - Peter Palese
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Ivan Marazzi
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA.
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80
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The host protein CLUH participates in the subnuclear transport of influenza virus ribonucleoprotein complexes. Nat Microbiol 2016; 1:16062. [DOI: 10.1038/nmicrobiol.2016.62] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 03/31/2016] [Indexed: 11/08/2022]
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81
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Influenza virus intracellular replication dynamics, release kinetics, and particle morphology during propagation in MDCK cells. Appl Microbiol Biotechnol 2016; 100:7181-92. [PMID: 27129532 PMCID: PMC4947482 DOI: 10.1007/s00253-016-7542-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/03/2016] [Accepted: 04/11/2016] [Indexed: 01/08/2023]
Abstract
Influenza viruses are respiratory pathogens and can cause severe disease. The best protection against influenza is provided by annual vaccination. These vaccines are produced in embryonated chicken eggs or using continuous animal cell lines. The latter processes are more flexible and scalable to meet the growing global demand. However, virus production in cell cultures is more expensive. Hence, further research is needed to make these processes more cost-effective and robust. We studied influenza virus replication dynamics to identify factors that limit the virus yield in adherent Madin-Darby canine kidney (MDCK) cells. The cell cycle stage of MDCK cells had no impact during early infection. Yet, our results showed that the influenza virus RNA synthesis levels out already 4 h post infection at a time when viral genome segments are exported from the nucleus. Nevertheless, virus release occurred at a constant rate in the following 16 h. Thereafter, the production of infectious viruses dramatically decreased, but cells continued to produce particles contributing to the hemagglutination (HA) titer. The majority of these particles from the late phase of infection were deformed or broken virus particles as well as large membranous structures decorated with viral surface proteins. These changes in particle characteristics and morphology need to be considered for the optimization of influenza virus production and vaccine purification steps. Moreover, our data suggest that in order to achieve higher cell-specific yields, a prolonged phase of viral RNA synthesis and/or a more efficient release of influenza virus particles is required.
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82
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A high-throughput screening system targeting the nuclear export pathway via the third nuclear export signal of influenza A virus nucleoprotein. Virus Res 2016; 217:23-31. [PMID: 26948263 DOI: 10.1016/j.virusres.2016.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 02/07/2016] [Indexed: 11/22/2022]
Abstract
Two classes of antiviral drugs, M2 channel inhibitors and neuraminidase (NA) inhibitors, are currently approved for the treatment of influenza; however, the development of resistance against these agents limits their efficacy. Therefore, the identification of new targets and the development of new antiviral drugs against influenza are urgently needed. The third nuclear export signal (NES3) of nucleoprotein (NP) is the most important for viral replication among seven NESs encoded by four viral proteins, NP, M1, NS1, and NS2. NP-NES3 is critical for the nuclear export of NP, and targeting NP-NES3 is therefore a promising strategy that may lead to the development of antiviral drugs. However, a high-throughput screening (HTS) system to identify inhibitors of NP nuclear export has not been established. Here, we developed a novel HTS system to evaluate the inhibitory effects of compounds on the nuclear export pathway mediated by NP-NES3 using a MDCK cell line stably expressing NP-NES3 fused to a green fluorescent protein from aequorea coerulescens (AcGFP-NP-NES3) and a cell imaging analyzer. This HTS system was used to screen a 9600-compound library, leading to the identification of several hit compounds with inhibitory activity against the nuclear export of AcGFP-NP-NES3. The present HTS system provides a useful strategy for the identification of inhibitors targeting the nuclear export of NP via its NES3 sequence.
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83
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Eng CLP, Tong JC, Tan TW. Distinct Host Tropism Protein Signatures to Identify Possible Zoonotic Influenza A Viruses. PLoS One 2016; 11:e0150173. [PMID: 26915079 PMCID: PMC4767729 DOI: 10.1371/journal.pone.0150173] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 02/10/2016] [Indexed: 12/25/2022] Open
Abstract
Zoonotic influenza A viruses constantly pose a health threat to humans as novel strains occasionally emerge from the avian population to cause human infections. Many past epidemic as well as pandemic strains have originated from avian species. While most viruses are restricted to their primary hosts, zoonotic strains can sometimes arise from mutations or reassortment, leading them to acquire the capability to escape host species barrier and successfully infect a new host. Phylogenetic analyses and genetic markers are useful in tracing the origins of zoonotic infections, but there are still no effective means to identify high risk strains prior to an outbreak. Here we show that distinct host tropism protein signatures can be used to identify possible zoonotic strains in avian species which have the potential to cause human infections. We have discovered that influenza A viruses can now be classified into avian, human, or zoonotic strains based on their host tropism protein signatures. Analysis of all influenza A viruses with complete proteome using the host tropism prediction system, based on machine learning classifications of avian and human viral proteins has uncovered distinct signatures of zoonotic strains as mosaics of avian and human viral proteins. This is in contrast with typical avian or human strains where they show mostly avian or human viral proteins in their signatures respectively. Moreover, we have found that zoonotic strains from the same influenza outbreaks carry similar host tropism protein signatures characteristic of a common ancestry. Our results demonstrate that the distinct host tropism protein signature in zoonotic strains may prove useful in influenza surveillance to rapidly identify potential high risk strains circulating in avian species, which may grant us the foresight in anticipating an impending influenza outbreak.
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Affiliation(s)
- Christine L. P. Eng
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Joo Chuan Tong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Institute of High Performance Computing, Singapore, Singapore
| | - Tin Wee Tan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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84
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Hengrung N, El Omari K, Serna Martin I, Vreede FT, Cusack S, Rambo RP, Vonrhein C, Bricogne G, Stuart DI, Grimes JM, Fodor E. Crystal structure of the RNA-dependent RNA polymerase from influenza C virus. Nature 2015; 527:114-7. [PMID: 26503046 PMCID: PMC4783868 DOI: 10.1038/nature15525] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 08/25/2015] [Indexed: 12/17/2022]
Abstract
Negative-sense RNA viruses, such as influenza, encode large, multidomain RNA-dependent RNA polymerases that can both transcribe and replicate the viral RNA genome. In influenza virus, the polymerase (FluPol) is composed of three polypeptides: PB1, PB2 and PA/P3. PB1 houses the polymerase active site, whereas PB2 and PA/P3 contain, respectively, cap-binding and endonuclease domains required for transcription initiation by cap-snatching. Replication occurs through de novo initiation and involves a complementary RNA intermediate. Currently available structures of the influenza A and B virus polymerases include promoter RNA (the 5' and 3' termini of viral genome segments), showing FluPol in transcription pre-initiation states. Here we report the structure of apo-FluPol from an influenza C virus, solved by X-ray crystallography to 3.9 Å, revealing a new 'closed' conformation. The apo-FluPol forms a compact particle with PB1 at its centre, capped on one face by PB2 and clamped between the two globular domains of P3. Notably, this structure is radically different from those of promoter-bound FluPols. The endonuclease domain of P3 and the domains within the carboxy-terminal two-thirds of PB2 are completely rearranged. The cap-binding site is occluded by PB2, resulting in a conformation that is incompatible with transcription initiation. Thus, our structure captures FluPol in a closed, transcription pre-activation state. This reveals the conformation of newly made apo-FluPol in an infected cell, but may also apply to FluPol in the context of a non-transcribing ribonucleoprotein complex. Comparison of the apo-FluPol structure with those of promoter-bound FluPols allows us to propose a mechanism for FluPol activation. Our study demonstrates the remarkable flexibility of influenza virus RNA polymerase, and aids our understanding of the mechanisms controlling transcription and genome replication.
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Affiliation(s)
- Narin Hengrung
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Kamel El Omari
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Itziar Serna Martin
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Frank T Vreede
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Stephen Cusack
- European Molecular Biology Laboratory, Grenoble Outstation and University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Robert P Rambo
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot OX11 0DE, UK
| | - Clemens Vonrhein
- Global Phasing Ltd, Sheraton House, Castle Park, Cambridge CB3 0AX, UK
| | - Gérard Bricogne
- Global Phasing Ltd, Sheraton House, Castle Park, Cambridge CB3 0AX, UK
| | - David I Stuart
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot OX11 0DE, UK
| | - Jonathan M Grimes
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot OX11 0DE, UK
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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85
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Dahiru Rogo L, Rezaei F, Shafiei-Jandaghi NZ, Ghavami N, Fatemi-Nasab G, Mokhtari-Azad T. Analysis of amino acid changes in NS protein of influenza A/(H3N2) virus in Iranian isolates. Future Virol 2015. [DOI: 10.2217/fvl.15.90] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aim: Roles of NS gene of influenza A virus in virulence and replication are well established but extent of its variation in seasonal influenza A (H3N2) viruses in Iran is not well known. Materials & methods: NS gene of 37 (A/H3N2) virus isolates were sequenced and analyzed for information on genetic changes. Results: Data analysis of NS1 protein revealed two amino acid substitutions E26K and Q193R in almost all strains. Substitutions in T58P in 27.0%, A86S in 13.5% and each of V11G, M81I and P85T in 2.7% Iranian strains were also observed. Mutations in NS2/NEP protein were observed in K36E, Q101L and F107S. Conclusion: Many mutations were observed for the first time in Iranian strains. Their function remains to be determined.
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Affiliation(s)
- Lawal Dahiru Rogo
- Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, International Campus, Tehran, Iran
- Department of Medical Laboratory Science, Faculty of Allied Health Sciences, College of Health Sciences, Bayero University Kano, PMB 3011, Nigeria
| | - Farhad Rezaei
- Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, International Campus, Tehran, Iran
- National Influenza Center, Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Nazanin Z Shafiei-Jandaghi
- Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, International Campus, Tehran, Iran
- National Influenza Center, Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Nastaran Ghavami
- Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, International Campus, Tehran, Iran
- National Influenza Center, Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Ghazal Fatemi-Nasab
- Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, International Campus, Tehran, Iran
- National Influenza Center, Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Talat Mokhtari-Azad
- Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, International Campus, Tehran, Iran
- National Influenza Center, Department of Medical Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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86
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An A14U Substitution in the 3' Noncoding Region of the M Segment of Viral RNA Supports Replication of Influenza Virus with an NS1 Deletion by Modulating Alternative Splicing of M Segment mRNAs. J Virol 2015. [PMID: 26223635 PMCID: PMC4580205 DOI: 10.1128/jvi.00919-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The NS1 protein of influenza virus has multiple functions and is a determinant of virulence. Influenza viruses with NS1 deletions (DelNS1 influenza viruses) are a useful tool for studying virus replication and can serve as effective live attenuated vaccines, but deletion of NS1 severely diminishes virus replication, hampering functional studies and vaccine production. We found that WSN-DelNS1 viruses passaged in cells consistently adapted to gain an A14U substitution in the 3′ noncoding region of the M segment of viral RNA (vRNA) which restored replicative ability. DelNS1-M-A14U viruses cannot inhibit interferon expression in virus infected-cells, providing an essential model for studying virus replication in the absence of the NS1 protein. Characterization of DelNS1-M-A14U virus showed that the lack of NS1 has no apparent effect on expression of other viral proteins, with the exception of M mRNAs. Expression of the M transcripts, M1, M2, mRNA3, and mRNA4, is regulated by alternative splicing. The A14U substitution changes the splicing donor site consensus sequence of mRNA3, altering expression of M transcripts, with M2 expression significantly increased and mRNA3 markedly suppressed in DelNS1-M-A14U, but not DelNS1-M-WT, virus-infected cells. Further analysis revealed that the A14U substitution also affects promoter function during replication of the viral genome. The M-A14U mutation increases M vRNA synthesis in DelNS1 virus infection and enhances alternative splicing of M2 mRNA in the absence of other viral proteins. The findings demonstrate that NS1 is directly involved in influenza virus replication through modulation of alternative splicing of M transcripts and provide strategic information important to construction of vaccine strains with NS1 deletions. IMPORTANCE Nonstructural protein (NS1) of influenza virus has multiple functions. Besides its role in antagonizing host antiviral activity, NS1 is also believed to be involved in regulating virus replication, but mechanistic details are not clear. The NS1 protein is a virulence determinant which inhibits both innate and adaptive immunity and live attenuated viruses with NS1 deletions show promise as effective vaccines. However, deletion of NS1 causes severe attenuation of virus replication during infection, impeding functional studies and vaccine development. We characterized a replication-competent DelNS1 virus which carries an A14U substitution in the 3′ noncoding region of the vRNA M segment. We found that M-A14U mutation supports virus replication through modulation of alternative splicing of mRNAs transcribed from the M segment. Our findings give insight into the role of NS1 in influenza virus replication and provide an approach for constructing replication-competent strains with NS1 deletions for use in functional and vaccine studies.
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87
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Generation of a variety of stable Influenza A reporter viruses by genetic engineering of the NS gene segment. Sci Rep 2015; 5:11346. [PMID: 26068081 PMCID: PMC4464305 DOI: 10.1038/srep11346] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 05/21/2015] [Indexed: 11/08/2022] Open
Abstract
Influenza A viruses (IAV) pose a constant threat to the human population and therefore a better understanding of their fundamental biology and identification of novel therapeutics is of upmost importance. Various reporter-encoding IAV were generated to achieve these goals, however, one recurring difficulty was the genetic instability especially of larger reporter genes. We employed the viral NS segment coding for the non-structural protein 1 (NS1) and nuclear export protein (NEP) for stable expression of diverse reporter proteins. This was achieved by converting the NS segment into a single open reading frame (ORF) coding for NS1, the respective reporter and NEP. To allow expression of individual proteins, the reporter genes were flanked by two porcine Teschovirus-1 2A peptide (PTV-1 2A)-coding sequences. The resulting viruses encoding luciferases, fluorescent proteins or a Cre recombinase are characterized by a high genetic stability in vitro and in mice and can be readily employed for antiviral compound screenings, visualization of infected cells or cells that survived acute infection.
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88
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Baker SF, Nogales A, Martínez-Sobrido L. Downregulating viral gene expression: codon usage bias manipulation for the generation of novel influenza A virus vaccines. Future Virol 2015. [PMID: 26213563 DOI: 10.2217/fvl.15.31] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Vaccination represents the best option to protect humans against influenza virus. However, improving the effectiveness of current vaccines could better stifle the health burden caused by viral infection. Protein synthesis from individual genes can be downregulated by synthetically deoptimizing a gene's codon usage. With more rapid and affordable nucleotide synthesis, generating viruses that contain genes with deoptimized codons is now feasible. Attenuated, vaccine-candidate viruses can thus be engineered with hitherto uncharacterized properties. With eight gene segments, influenza A viruses with variably recoded genomes can produce a spectrum of attenuation that is contingent on the gene segment targeted and the number of codon changes. This review summarizes different targets and approaches to deoptimize influenza A virus codons for novel vaccine generation.
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Affiliation(s)
- Steven F Baker
- Department of Microbiology & Immunology, University of Rochester, Rochester, NY, USA
| | - Aitor Nogales
- Department of Microbiology & Immunology, University of Rochester, Rochester, NY, USA
| | - Luis Martínez-Sobrido
- Department of Microbiology & Immunology, University of Rochester, Rochester, NY, USA
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89
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Tripathi S, Batra J, Lal SK. Interplay between influenza A virus and host factors: targets for antiviral intervention. Arch Virol 2015; 160:1877-91. [PMID: 26016443 DOI: 10.1007/s00705-015-2452-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 05/13/2015] [Indexed: 01/06/2023]
Abstract
Influenza A viruses (IAVs) pose a major public health threat worldwide. Recent experience with the 2013 H7N9 outbreak in China and the 2009 "swine flu" pandemic have shown that antiviral vaccines and drugs fall short of controlling the spread of disease in a timely and effective manner. Major problems include rapid emergence of drug-resistant influenza virus strains and the slow process of vaccine production. With the threat of a highly pathogenic H5N1 bird-flu pandemic looming large, it is crucial to develop novel ways of combating influenza A viruses. Targeting the host factors critical for influenza A virus replication has shown promise as a strategy to develop novel antiviral molecules with broad-spectrum protection. In this review, we summarize the role of currently identified host factors that play a critical role in the influenza A virus life cycle and discuss the most promising candidates for anti-influenza therapeutics.
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Affiliation(s)
- Shashank Tripathi
- Microbiology Department, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
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90
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Kamal RP, Katz JM, York IA. Molecular determinants of influenza virus pathogenesis in mice. Curr Top Microbiol Immunol 2015; 385:243-74. [PMID: 25038937 DOI: 10.1007/82_2014_388] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mice are widely used for studying influenza virus pathogenesis and immunology because of their low cost, the wide availability of mouse-specific reagents, and the large number of mouse strains available, including knockout and transgenic strains. However, mice do not fully recapitulate the signs of influenza infection of humans: transmission of influenza between mice is much less efficient than in humans, and influenza viruses often require adaptation before they are able to efficiently replicate in mice. In the process of mouse adaptation, influenza viruses acquire mutations that enhance their ability to attach to mouse cells, replicate within the cells, and suppress immunity, among other functions. Many such mouse-adaptive mutations have been identified, covering all 8 genomic segments of the virus. Identification and analysis of these mutations have provided insight into the molecular determinants of influenza virulence and pathogenesis, not only in mice but also in humans and other species. In particular, several mouse-adaptive mutations of avian influenza viruses have proved to be general mammalian-adaptive changes that are potential markers of pre-pandemic viruses. As well as evaluating influenza pathogenesis, mice have also been used as models for evaluation of novel vaccines and anti-viral therapies. Mice can be a useful animal model for studying influenza biology as long as differences between human and mice infections are taken into account.
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Affiliation(s)
- Ram P Kamal
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA,
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91
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Nogales A, Baker SF, Martínez-Sobrido L. Replication-competent influenza A viruses expressing a red fluorescent protein. Virology 2015; 476:206-216. [PMID: 25553516 PMCID: PMC4323957 DOI: 10.1016/j.virol.2014.12.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 11/25/2014] [Accepted: 12/02/2014] [Indexed: 11/16/2022]
Abstract
Like most animal viruses, studying influenza A in model systems requires secondary methodologies to identify infected cells. To circumvent this requirement, we describe the generation of replication-competent influenza A red fluorescent viruses. These influenza A viruses encode mCherry fused to the viral non-structural 1 (NS1) protein and display comparable growth kinetics to wild-type viruses in vitro. Infection of cells with influenza A mCherry viruses was neutralized with monoclonal antibodies and inhibited with antivirals to levels similar to wild-type virus. Influenza A mCherry viruses were also able to lethally infect mice, and strikingly, dose- and time-dependent kinetics of viral replication were monitored in whole excised mouse lungs using an in vivo imaging system (IVIS). By eliminating the need for secondary labeling of infected cells, influenza A mCherry viruses provide an ideal tool in the ongoing struggle to better characterize the virus and identify new therapeutics against influenza A viral infections.
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Affiliation(s)
- Aitor Nogales
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY, United States
| | - Steven F Baker
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY, United States
| | - Luis Martínez-Sobrido
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY, United States.
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92
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Chan JFW, To KKW, Chen H, Yuen KY. Cross-species transmission and emergence of novel viruses from birds. Curr Opin Virol 2015; 10:63-9. [PMID: 25644327 PMCID: PMC7102742 DOI: 10.1016/j.coviro.2015.01.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/29/2014] [Accepted: 01/09/2015] [Indexed: 12/29/2022]
Abstract
The role of birds in cross-species transmission and emergence of novel viruses such as avian influenza A viruses are discussed. The novel avian viruses identified between 2012 and 2014 are summarized. The concept of ‘pathogen augmentation’ is introduced.
Birds, the only living member of the Dinosauria clade, are flying warm-blooded vertebrates displaying high species biodiversity, roosting and migratory behavior, and a unique adaptive immune system. Birds provide the natural reservoir for numerous viral species and therefore gene source for evolution, emergence and dissemination of novel viruses. The intrusions of human into natural habitats of wild birds, the domestication of wild birds as pets or racing birds, and the increasing poultry consumption by human have facilitated avian viruses to cross species barriers to cause zoonosis. Recently, a novel adenovirus was exclusively found in birds causing an outbreak of Chlamydophila psittaci infection among birds and humans. Instead of being the primary cause of an outbreak by jumping directly from bird to human, a novel avian virus can be an augmenter of another zoonotic agent causing the outbreak. A comprehensive avian virome will improve our understanding of birds’ evolutionary dynamics.
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Affiliation(s)
- Jasper Fuk-Woo Chan
- State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, and Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region
| | - Kelvin Kai-Wang To
- State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, and Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region
| | - Honglin Chen
- State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, and Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region
| | - Kwok-Yung Yuen
- State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, and Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region.
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93
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Koçer ZA, Fan Y, Huether R, Obenauer J, Webby RJ, Zhang J, Webster RG, Wu G. Survival analysis of infected mice reveals pathogenic variations in the genome of avian H1N1 viruses. Sci Rep 2014; 4:7455. [PMID: 25503687 PMCID: PMC4264002 DOI: 10.1038/srep07455] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 11/24/2014] [Indexed: 11/09/2022] Open
Abstract
Most influenza pandemics have been caused by H1N1 viruses of purely or partially avian origin. Here, using Cox proportional hazard model, we attempt to identify the genetic variations in the whole genome of wild-type North American avian H1N1 influenza A viruses that are associated with their virulence in mice by residue variations, host origins of virus (Anseriformes-ducks or Charadriiformes-shorebirds), and host-residue interactions. In addition, through structural modeling, we predicted that several polymorphic sites associated with pathogenicity were located in structurally important sites, especially in the polymerase complex and NS genes. Our study introduces a new approach to identify pathogenic variations in wild-type viruses circulating in the natural reservoirs and ultimately to understand their infectious risks to humans as part of risk assessment efforts towards the emergence of future pandemic strains.
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Affiliation(s)
- Zeynep A Koçer
- Department of Infectious Diseases, Division of Virology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105, United States
| | - Yiping Fan
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105, United States
| | - Robert Huether
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105, United States
| | - John Obenauer
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105, United States
| | - Richard J Webby
- Department of Infectious Diseases, Division of Virology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105, United States
| | - Jinghui Zhang
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105, United States
| | - Robert G Webster
- Department of Infectious Diseases, Division of Virology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105, United States
| | - Gang Wu
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105, United States
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94
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Sung PY, Roy P. Sequential packaging of RNA genomic segments during the assembly of Bluetongue virus. Nucleic Acids Res 2014; 42:13824-38. [PMID: 25428366 PMCID: PMC4267631 DOI: 10.1093/nar/gku1171] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Bluetongue virus (BTV), a member of the Orbivirus genus within the Reoviridae family, has a genome of 10 double-stranded RNA segments, with three distinct size classes. Although the packaging of the viral genome is evidently highly specific such that every virus particle contains a set of 10 RNA segments, the order and mechanism of packaging are not understood. In this study we have combined the use of a cell-free in vitro assembly system with a novel RNA–RNA interaction assay to investigate the mechanism of single-stranded (ss) RNAs packaging during nascent capsid assembly. Exclusion of single or multiple ssRNA segments in the packaging reaction or their addition in different order significantly altered the outcome and suggested a particular role for the smallest segment, S10. Our data suggests that genome packaging probably initiates with the smallest segment which triggers RNA–RNA interaction with other smaller segments forming a complex network. Subsequently, the medium to larger size ssRNAs are recruited until the complete genome is packaging into the capsid. The untranslated regions of the smallest RNA segment, S10, is critical for the instigation of this process. We suggest that the selective packaging observed in BTV may also apply to other members of the Reoviridae family.
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Affiliation(s)
- Po-Yu Sung
- Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, UK
| | - Polly Roy
- Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, UK
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95
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Cyclic avian mass mortality in the northeastern United States is associated with a novel orthomyxovirus. J Virol 2014; 89:1389-403. [PMID: 25392223 DOI: 10.1128/jvi.02019-14] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Since 1998, cyclic mortality events in common eiders (Somateria mollissima), numbering in the hundreds to thousands of dead birds, have been documented along the coast of Cape Cod, MA, USA. Although longitudinal disease investigations have uncovered potential contributing factors responsible for these outbreaks, detecting a primary etiological agent has proven enigmatic. Here, we identify a novel orthomyxovirus, tentatively named Wellfleet Bay virus (WFBV), as a potential causative agent of these outbreaks. Genomic analysis of WFBV revealed that it is most closely related to members of the Quaranjavirus genus within the family Orthomyxoviridae. Similar to other members of the genus, WFBV contains an alphabaculovirus gp64-like glycoprotein that was demonstrated to have fusion activity; this also tentatively suggests that ticks (and/or insects) may vector the virus in nature. However, in addition to the six RNA segments encoding the prototypical structural proteins identified in other quaranjaviruses, a previously unknown RNA segment (segment 7) encoding a novel protein designated VP7 was discovered in WFBV. Although WFBV shows low to moderate levels of sequence similarity to Quaranfil virus and Johnston Atoll virus, the original members of the Quaranjavirus genus, additional antigenic and genetic analyses demonstrated that it is closely related to the recently identified Cygnet River virus (CyRV) from South Australia, suggesting that WFBV and CyRV may be geographic variants of the same virus. Although the identification of WFBV in part may resolve the enigma of these mass mortality events, the details of the ecology and epidemiology of the virus remain to be determined. IMPORTANCE The emergence or reemergence of viral pathogens resulting in large-scale outbreaks of disease in humans and/or animals is one of the most important challenges facing biomedicine. For example, understanding how orthomyxoviruses such as novel influenza A virus reassortants and/or mutants emerge to cause epidemic or pandemic disease is at the forefront of current global health concerns. Here, we describe the emergence of a novel orthomyxovirus, Wellfleet Bay virus (WFBV), which has been associated with cyclic large-scale bird die-offs in the northeastern United States. This initial characterization study provides a foundation for further research into the evolution, epidemiology, and ecology of newly emerging orthomyxoviruses, such as WFBV, and their potential impacts on animal and/or human health.
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96
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Interaction of NS2 with AIMP2 facilitates the switch from ubiquitination to SUMOylation of M1 in influenza A virus-infected cells. J Virol 2014; 89:300-11. [PMID: 25320310 DOI: 10.1128/jvi.02170-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Influenza A viruses (IAVs) rely on host factors to support their life cycle, as viral proteins hijack or interact with cellular proteins to execute their functions. Identification and understanding of these factors would increase our knowledge of the molecular mechanisms manipulated by the viruses. In this study, we searched for novel binding partners of the influenza A virus NS2 protein, the nuclear export protein responsible for overcoming host range restriction, by a yeast two-hybrid screening assay and glutathione S-transferase-pulldown and coimmunoprecipitation assays and identified AIMP2, a potent tumor suppressor that usually functions to regulate protein stability, as one of the major NS2-binding candidates. We found that the presence of NS2 protected AIMP2 from ubiquitin-mediated degradation in NS2-transfected cells and AIMP2 functioned as a positive regulator of IAV replication. Interestingly, AIMP2 had no significant effect on NS2 but enhanced the stability of the matrix protein M1. Further, we provide evidence that AIMP2 recruitment switches the modification of M1 from ubiquitination to SUMOylation, which occurs on the same attachment site (K242) on M1 and thereby promotes M1-mediated viral ribonucleoprotein complex nuclear export to increase viral replication. Collectively, our results reveal a new mechanism of AIMP2 mediation of influenza virus replication. IMPORTANCE Although the ubiquitination of M1 during IAV infection has been observed, the precise modification site and the molecular consequences of this modification remain obscure. Here, we demonstrate for the first time that ubiquitin and SUMO compete for the same lysine (K242) on M1 and the interaction of NS2 with AIMP2 facilitates the switch of the M1 modification from ubiquitination to SUMOylation, thus increasing viral replication.
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97
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Appearance of L90I and N205S Mutations in Effector Domain of NS1 Gene of pdm (09) H1N1 Virus from India during 2009-2013. Adv Virol 2014; 2014:861709. [PMID: 25309598 PMCID: PMC4181907 DOI: 10.1155/2014/861709] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/10/2014] [Accepted: 08/12/2014] [Indexed: 11/18/2022] Open
Abstract
In the present study, full length sequencing of NS gene was done in 91 samples which were obtained from patients over the time period of five years from 2009 to 2013. The sequencing of NS gene was undertaken in order to determine the changes/mutations taking place in the NS gene of A H1N1 pdm (09) since its emergence in 2009. Analysis has shown that the majority of samples belong to New York (G1 type) strain with valine at position 123. Effector domain of NS1 protein displays the appearance of three mutations L90I, I123V, and N205S in almost all the samples from 2010 onwards. Phylogenetic analysis of available NS1 sequences from India has grouped all the sequences into four clusters with mean genetic distance ranging from 12% to 24% between the clusters. Variability in length of NS1 protein was seen in sequences from these clusters, 230-amino-acid-residue NS1 for all strains from year 2007 to 2008 and for 21 strains from year 2009 and 219-residue products for 37 strains from year 2009 and all strains from year 2010 to 2013. Mutations like K62R, K131Q, L147R, and A202P were observed for the first time in NS1 protein and their function remains to be determined.
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98
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Mutations to PB2 and NP proteins of an avian influenza virus combine to confer efficient growth in primary human respiratory cells. J Virol 2014; 88:13436-46. [PMID: 25210184 DOI: 10.1128/jvi.01093-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Influenza pandemics occur when influenza A viruses (IAV) adapted to other host species enter humans and spread through the population. Pandemics are relatively rare due to host restriction of IAV: strains adapted to nonhuman species do not readily infect, replicate in, or transmit among humans. IAV can overcome host restriction through reassortment or adaptive evolution, and these are mechanisms by which pandemic strains arise in nature. To identify mutations that facilitate growth of avian IAV in humans, we have adapted influenza A/duck/Alberta/35/1976 (H1N1) (dk/AB/76) virus to a high-growth phenotype in differentiated human tracheo-bronchial epithelial (HTBE) cells. Following 10 serial passages of three independent lineages, the bulk populations showed similar growth in HTBE cells to that of a human seasonal virus. The coding changes present in six clonal isolates were determined. The majority of changes were located in the polymerase complex and nucleoprotein (NP), and all isolates carried mutations in the PB2 627 domain and regions of NP thought to interact with PB2. Using reverse genetics, the impact on growth and polymerase activity of individual and paired mutations in PB2 and NP was evaluated. The results indicate that coupling of the mammalian-adaptive mutation PB2 E627K or Q591K to selected mutations in NP further augments the growth of the corresponding viruses. In addition, minimal combinations of three (PB2 Q236H, E627K, and NP N309K) or two (PB2 Q591K and NP S50G) mutations were sufficient to recapitulate the efficient growth in HTBE cells of dk/AB/76 viruses isolated after 10 passages in this substrate. IMPORTANCE Influenza A viruses adapted to birds do not typically grow well in humans. However, as has been seen recently with H5N1 and H7N9 subtype viruses, productive and virulent infection of humans with avian influenza viruses can occur. The ability of avian influenza viruses to adapt to new host species is a consequence of their high mutation rate that supports their zoonotic potential. Understanding of the adaptation of avian viruses to mammals strengthens public health efforts aimed at controlling influenza. In particular, it is critical to know how readily and through mutation to which functional components avian influenza viruses gain the ability to grow efficiently in humans. Our data show that as few as three mutations, in the PB2 and NP proteins, support robust growth of a low-pathogenic, H1N1 duck isolate in primary human respiratory cells.
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99
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Interactome analysis of the influenza A virus transcription/replication machinery identifies protein phosphatase 6 as a cellular factor required for efficient virus replication. J Virol 2014; 88:13284-99. [PMID: 25187537 DOI: 10.1128/jvi.01813-14] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The negative-sense RNA genome of influenza A virus is transcribed and replicated by the viral RNA-dependent RNA polymerase (RdRP). The viral RdRP is an important host range determinant, indicating that its function is affected by interactions with cellular factors. However, the identities and the roles of most of these factors remain unknown. Here, we employed affinity purification followed by mass spectrometry to identify cellular proteins that interact with the influenza A virus RdRP in infected human cells. We purified RdRPs using a recombinant influenza virus in which the PB2 subunit of the RdRP is fused to a Strep-tag. When this tagged subunit was purified from infected cells, copurifying proteins included the other RdRP subunits (PB1 and PA) and the viral nucleoprotein and neuraminidase, as well as 171 cellular proteins. Label-free quantitative mass spectrometry revealed that the most abundant of these host proteins were chaperones, cytoskeletal proteins, importins, proteins involved in ubiquitination, kinases and phosphatases, and mitochondrial and ribosomal proteins. Among the phosphatases, we identified three subunits of the cellular serine/threonine protein phosphatase 6 (PP6), including the catalytic subunit PPP6C and regulatory subunits PPP6R1 and PPP6R3. PP6 was found to interact directly with the PB1 and PB2 subunits of the viral RdRP, and small interfering RNA (siRNA)-mediated knockdown of the catalytic subunit of PP6 in infected cells resulted in the reduction of viral RNA accumulation and the attenuation of virus growth. These results suggest that PP6 interacts with and positively regulates the activity of the influenza virus RdRP. IMPORTANCE Influenza A viruses are serious clinical and veterinary pathogens, causing substantial health and economic impacts. In addition to annual seasonal epidemics, occasional global pandemics occur when viral strains adapt to humans from other species. To replicate efficiently and cause disease, influenza viruses must interact with a large number of host factors. The reliance of the viral RNA-dependent RNA polymerase (RdRP) on host factors makes it a major host range determinant. This study describes and quantifies host proteins that interact, directly or indirectly, with a subunit of the RdRP. It increases our understanding of the role of host proteins in viral replication and identifies a large number of potential barriers to pandemic emergence. Identifying host factors allows their importance for viral replication to be tested. Here, we demonstrate a role for the cellular phosphatase PP6 in promoting viral replication, contributing to our emerging knowledge of regulatory phosphorylation in influenza virus biology.
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100
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Svancarova P, Svetlikova D, Betakova T. Synergic and antagonistic effect of small hairpin RNAs targeting the NS gene of the influenza A virus in cells and mice. Virus Res 2014; 195:100-11. [PMID: 25192613 DOI: 10.1016/j.virusres.2014.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 07/24/2014] [Accepted: 08/11/2014] [Indexed: 02/06/2023]
Abstract
In the present study, we demonstrate the effect of individual and mixtures of shRNAs targeting the NS gene to treat an established infection of influenza A virus (IAV). We prepared 10 shRNAs targeting the NS gene of the IAV, and these shRNAs were tested individually or in mixtures 16h after infection. Our results revealed: (i) shRNA targeting the NS1 transcript decreased the virus titre up to 21% (P<0.01), (ii) shRNA targeting NEP transcript did not influence the replication of IAV in the infected cells; (iii) a mixture of shRNAs targeting the NS1 transcript was less effective than the individual shRNAs and decreased the virus titre up to 42% in vitro; (iv) a mixture of individually inactive shRNAs targeting the NEP transcript significantly inhibited the replication of IAV in vitro; (v) the activities of the individual shRNAs in vivo predominantly corresponded to their activities in vitro; (vi) a synergistic effect of the shRNAs was observed in vivo; and (vii) a shRNA targeting the region common to both the NS1 and NEP transcripts, shNS593, exhibited the strongest inhibition and reduced the virus titre up to 16.4% in vitro, prolonged the survival of the mice by three days and abolished the protective effect of other shRNAs in vivo. shRNAs inhibited influenza virus infection in a gene-specific manner. NS1 mRNA was significantly reduced in lungs treated with shRNAs and the levels of RIG-1, IFN-α, IFN-β and IFN-γ mRNAs shRNAs were not altered.
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Affiliation(s)
- Petra Svancarova
- Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovak Republic
| | - Darina Svetlikova
- Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovak Republic
| | - Tatiana Betakova
- Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovak Republic; Centre for Molecular Medicine, Vlarska 3-7, 831 01 Bratislava, Slovak Republic.
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