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Hohensee L, Scheibner D, Luttermann C, Shelton H, Dorhoi A, Abdelwhab EM, Blohm U. PB1-F2 of low pathogenicity H7N7 restricts apoptosis in avian cells. Virus Res 2024; 349:199444. [PMID: 39089370 DOI: 10.1016/j.virusres.2024.199444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 07/26/2024] [Accepted: 07/29/2024] [Indexed: 08/03/2024]
Abstract
Avian influenza viruses (AIV) pose a continuous challenge to global health and economy. While countermeasures exist to control outbreaks in poultry, the persistent circulation of AIV in wild aquatic and shorebirds presents a significant challenge to effective disease prevention efforts. PB1-F2 is a non-structural protein expressed from a second open reading frame (+1) of the polymerase basic 1 (PB1) segment. The sequence and length of the PB1-F2 protein can vary depending on the host of origin. While avian isolates typically carry full-length PB1-F2, isolates from mammals, often express truncated forms. The selective advantage of the full-length PB1-F2 in avian isolates is not fully understood. Most research on the role of PB1-F2 in influenza virus replication has been conducted in mammalian systems, where PB1-F2 interfered with the host immune response and induced apoptosis. Here, we used Low Pathogenicity (LP) AIV H7N7 expressing full-length PB1-F2 as well as a knockout mutant. We found that the full-length PB1-F2 of LPAIV prolonged survival of infected cells by limiting apoptotic cell death. Furthermore, PB1-F2 knockout LPAIV significantly decreased MHC-I expression on fibroblasts, delayed tissue healing and increased phagocytic uptake of infected cells, whereas LPAIV expressing PB1-F2 has limited effects. These findings indicate that full-length PB1-F2 enables AIV to cause prolonged infections without severely harming the avian host. Our observations may explain maintenance of AIV in the natural bird reservoir in absence of severe clinical signs.
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Affiliation(s)
- Luise Hohensee
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, Greifswald, Insel Riems 17493, Germany
| | - David Scheibner
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, Greifswald, Insel Riems 17493, Germany; Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, Greifswald, Insel Riems 17493, Germany
| | - Christine Luttermann
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, Greifswald, Insel Riems 17493, Germany
| | - Holly Shelton
- The Pirbright Institute, Pirbright, Ash Road, Surrey GU24 0NF, United Kingdom
| | - Anca Dorhoi
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, Greifswald, Insel Riems 17493, Germany
| | - Elsayed M Abdelwhab
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, Greifswald, Insel Riems 17493, Germany
| | - Ulrike Blohm
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, Greifswald, Insel Riems 17493, Germany.
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Tare DS, Keng SS, Walimbe AM, Pawar SD. Phylogeography and gene pool analysis of highly pathogenic avian influenza H5N1 viruses reported in India from 2006 to 2021. Arch Virol 2024; 169:111. [PMID: 38664271 DOI: 10.1007/s00705-024-06032-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 02/15/2024] [Indexed: 05/24/2024]
Abstract
India has reported highly pathogenic avian influenza (HPAI) H5N1 virus outbreaks since 2006, with the first human case reported in 2021. These included viruses belonging to the clades 2.2, 2.2.2, 2.2.2.1, 2.3.2.1a, and 2.3.2.1c. There are currently no data on the gene pool of HPAI H5N1 viruses in India. Molecular clock and phylogeography analysis of the HA and NA genes; and phylogenetic analysis of the internal genes of H5N1 viruses from India were carried out. Sequences reported from 2006 to 2015; and sequences from 2021 that were available in online databases were used in the analysis. Five separate introductions of H5N1 viruses into India were observed, via Indonesia or Korea (2002), Bangladesh (2009), Bhutan (2010), and China (2013, 2018) (clades 2.2, 2.2.2, 2.2.2.1, 2.3.2.1a, 2.3.2.1c, and 2.3.4.4b). Phylogenetic analysis revealed eight reassortant genotypes. The H5N1 virus isolated from the human case showed a unique reassortant genotype. Amino acid markers associated with adaptation to mammals were also present. This is the first report of the spatio-temporal origins and gene pool analysis of H5N1 viruses from India, highlighting the need for increased molecular surveillance.
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Affiliation(s)
- Deeksha S Tare
- ICMR-National Institute of Virology, 130/1, Sus Road, Pashan, Pune, 411021, India
| | - Sachin S Keng
- ICMR-National Institute of Virology, 130/1, Sus Road, Pashan, Pune, 411021, India
| | - Atul M Walimbe
- ICMR-National Institute of Virology, 130/1, Sus Road, Pashan, Pune, 411021, India
- ICMR-National Institute of Virology, 20-A, Dr. Ambedkar Road, Pune, 411001, India
| | - Shailesh D Pawar
- ICMR-National Institute of Virology, 130/1, Sus Road, Pashan, Pune, 411021, India.
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3
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Koch B, Shehata M, Müller-Ruttloff C, Gouda SA, Wetzstein N, Patyna S, Scholz A, Schmid T, Dietrich U, Münch C, Ziebuhr J, Geiger H, Martinez-Sobrido L, Baer PC, Mostafa A, Pleschka S. Influenza A virus replicates productively in primary human kidney cells and induces factors and mechanisms related to regulated cell death and renal pathology observed in virus-infected patients. Front Cell Infect Microbiol 2024; 14:1363407. [PMID: 38590437 PMCID: PMC10999593 DOI: 10.3389/fcimb.2024.1363407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Accepted: 02/29/2024] [Indexed: 04/10/2024] Open
Abstract
Introduction Influenza A virus (IAV) infection can cause the often-lethal acute respiratory distress syndrome (ARDS) of the lung. Concomitantly, acute kidney injury (AKI) is frequently noticed during IAV infection, correlating with an increased mortality. The aim of this study was to elucidate the interaction of IAV with human kidney cells and, thereby, to assess the mechanisms underlying IAV-mediated AKI. Methods To investigate IAV effects on nephron cells we performed infectivity assays with human IAV, as well as with human isolates of either low or highly pathogenic avian IAV. Also, transcriptome and proteome analysis of IAV-infected primary human distal tubular kidney cells (DTC) was performed. Furthermore, the DTC transcriptome was compared to existing transcriptomic data from IAV-infected lung and trachea cells. Results We demonstrate productive replication of all tested IAV strains on primary and immortalized nephron cells. Comparison of our transcriptome and proteome analysis of H1N1-type IAV-infected human primary distal tubular cells (DTC) with existing data from H1N1-type IAV-infected lung and primary trachea cells revealed enrichment of specific factors responsible for regulated cell death in primary DTC, which could be targeted by specific inhibitors. Discussion IAV not only infects, but also productively replicates on different human nephron cells. Importantly, multi-omics analysis revealed regulated cell death as potential contributing factor for the clinically observed kidney pathology in influenza.
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Affiliation(s)
- Benjamin Koch
- Department of Internal Medicine 4, Nephrology, University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Mahmoud Shehata
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), Cairo, Egypt
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany
| | - Christin Müller-Ruttloff
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany
- German Center for Infection Research (DZIF), Partner Site Giessen, Giessen, Germany
| | - Shady A. Gouda
- Institute for Biochemistry II, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Nils Wetzstein
- Department of Internal Medicine 2, Infectious Diseases, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Sammy Patyna
- Department of Internal Medicine 4, Nephrology, University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Anica Scholz
- Institute of Biochemistry I, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Tobias Schmid
- Institute of Biochemistry I, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Ursula Dietrich
- Institute for Tumor Biology and Experimental Therapy, Georg-Speyer-Haus, Frankfurt am Main, Germany
| | - Christian Münch
- Institute for Biochemistry II, Goethe University Frankfurt, Frankfurt am Main, Germany
- Frankfurt Cancer Institute (FCI), Frankfurt am Main, Germany
- Cardio-Pulmonary Institute, Frankfurt am Main, Germany
| | - John Ziebuhr
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany
- German Center for Infection Research (DZIF), Partner Site Giessen, Giessen, Germany
| | - Helmut Geiger
- Department of Internal Medicine 4, Nephrology, University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Luis Martinez-Sobrido
- Texas Biomedical Research Institute, Disease Intervention & Prevention (DIP) and Host Pathogen Interactions (HPI) Programs, San Antonio, TX, United States
| | - Patrick C. Baer
- Department of Internal Medicine 4, Nephrology, University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Ahmed Mostafa
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), Cairo, Egypt
- Texas Biomedical Research Institute, Disease Intervention & Prevention (DIP) and Host Pathogen Interactions (HPI) Programs, San Antonio, TX, United States
| | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany
- German Center for Infection Research (DZIF), Partner Site Giessen, Giessen, Germany
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4
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Blake ME, Kleinpeter AB, Jureka AS, Petit CM. Structural Investigations of Interactions between the Influenza a Virus NS1 and Host Cellular Proteins. Viruses 2023; 15:2063. [PMID: 37896840 PMCID: PMC10612106 DOI: 10.3390/v15102063] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 09/26/2023] [Accepted: 09/28/2023] [Indexed: 10/29/2023] Open
Abstract
The Influenza A virus is a continuous threat to public health that causes yearly epidemics with the ever-present threat of the virus becoming the next pandemic. Due to increasing levels of resistance, several of our previously used antivirals have been rendered useless. There is a strong need for new antivirals that are less likely to be susceptible to mutations. One strategy to achieve this goal is structure-based drug development. By understanding the minute details of protein structure, we can develop antivirals that target the most conserved, crucial regions to yield the highest chances of long-lasting success. One promising IAV target is the virulence protein non-structural protein 1 (NS1). NS1 contributes to pathogenicity through interactions with numerous host proteins, and many of the resulting complexes have been shown to be crucial for virulence. In this review, we cover the NS1-host protein complexes that have been structurally characterized to date. By bringing these structures together in one place, we aim to highlight the strength of this field for drug discovery along with the gaps that remain to be filled.
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Affiliation(s)
| | | | | | - Chad M. Petit
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (M.E.B.)
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5
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Guan L, Ping J, Lopes TJS, Fan S, Presler R, Neumann G, Kawaoka Y. Development of an Enhanced High-Yield Influenza Vaccine Backbone in Embryonated Chicken Eggs. Vaccines (Basel) 2023; 11:1364. [PMID: 37631932 PMCID: PMC10459923 DOI: 10.3390/vaccines11081364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/28/2023] Open
Abstract
Vaccination is an efficient approach to preventing influenza virus infections. Recently, we developed influenza A and B virus vaccine backbones that increased the yield of several vaccine viruses in Madin-Darby canine kidney (MDCK) and African green monkey kidney (Vero) cells. These vaccine backbones also increased viral replication in embryonated chicken eggs, which are the most frequently used platform for influenza vaccine manufacturing. In this study, to further increase the viral titers in embryonated chicken eggs, we introduced random mutations into the 'internal genes' (i.e., all influenza viral genes except those encoding the hemagglutinin and neuraminidase proteins) of the influenza A virus high-yield virus backbone we developed previously. The randomly mutated viruses were sequentially passaged in embryonated chicken eggs to select variants with increased replicative ability. We identified a candidate that conferred higher influenza virus growth than the high-yield parental virus backbone. Although the observed increases in virus growth may be considered small, they are highly relevant for vaccine manufacturers.
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Affiliation(s)
- Lizheng Guan
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Jihui Ping
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Tiago J. S. Lopes
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Shufang Fan
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Robert Presler
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Gabriele Neumann
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Yoshihiro Kawaoka
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
- Division of Virology, Department of Microbiology and Immunology, International Research Center for Infectious Diseases, The Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
- The Research Center for Global Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo 162-8655, Japan
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6
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Singh D, Thapa S, Mahawar H, Kumar D, Geat N, Singh SK. Prospecting potential of endophytes for modulation of biosynthesis of therapeutic bioactive secondary metabolites and plant growth promotion of medicinal and aromatic plants. Antonie van Leeuwenhoek 2022; 115:699-730. [PMID: 35460457 DOI: 10.1007/s10482-022-01736-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 03/26/2022] [Indexed: 01/13/2023]
Abstract
Medicinal and aromatic plants possess pharmacological properties (antidiabetes, anticancer, antihypertension, anticardiovascular, antileprosy, etc.) because of their potential to synthesize a wide range of therapeutic bioactive secondary metabolites. The concentration of bioactive secondry metabolites depends on plant species, local environment, soil type and internal microbiome. The internal microbiome of medicinal plants plays the crucial role in the production of bioactive secondary metabolites, namely alkaloids, steroids, terpenoids, peptides, polyketones, flavonoids, quinols and phenols. In this review, the host specific secondry metabolites produced by endophytes, their therapeutic properties and host-endophytes interaction in relation to production of bioactive secondry metaboloites and the role of endophytes in enhancing the production of bioactive secondry metabolites is discussed. How biological nitrogen fixation, phosphorus solubilization, micronutrient uptake, phytohormone production, disease suppression, etc. can play a vital role in enhacing the plant growth and development.The role of endophytes in enhancing the plant growth and content of bioactive secondary metabolites in medicinal and aromatic plants in a sustainable mode is highlighted.
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Affiliation(s)
- Devendra Singh
- ICAR-Central Arid Zone Research Institute, Jodhpur, Rajasthan, 342003, India.
| | - Shobit Thapa
- ICAR-National Bureau of Agriculturally Important Microorganisms, Kushmaur, Mau Nath Bhanjan, Uttar Pradesh, 275103, India
| | - Himanshu Mahawar
- ICAR-Directorate of Weed Research (DWR), Maharajpur, Jabalpur, Madhya Pradesh, 482004, India
| | - Dharmendra Kumar
- ICAR- Central Potato Research Institute, Shimla, Himachal Pradesh, 171001, India
| | - Neelam Geat
- Agricultural Research Station, Agriculture University, Jodhpur, Rajasthan, 342304, India
| | - S K Singh
- ICAR-Central Arid Zone Research Institute, Jodhpur, Rajasthan, 342003, India
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7
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Evseev D, Magor KE. Molecular Evolution of the Influenza A Virus Non-structural Protein 1 in Interspecies Transmission and Adaptation. Front Microbiol 2021; 12:693204. [PMID: 34671321 PMCID: PMC8521145 DOI: 10.3389/fmicb.2021.693204] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 09/06/2021] [Indexed: 12/03/2022] Open
Abstract
The non-structural protein 1 (NS1) of influenza A viruses plays important roles in viral fitness and in the process of interspecies adaptation. It is one of the most polymorphic and mutation-tolerant proteins of the influenza A genome, but its evolutionary patterns in different host species and the selective pressures that underlie them are hard to define. In this review, we highlight some of the species-specific molecular signatures apparent in different NS1 proteins and discuss two functions of NS1 in the process of viral adaptation to new host species. First, we consider the ability of NS1 proteins to broadly suppress host protein expression through interaction with CPSF4. This NS1 function can be spontaneously lost and regained through mutation and must be balanced against the need for host co-factors to aid efficient viral replication. Evidence suggests that this function of NS1 may be selectively lost in the initial stages of viral adaptation to some new host species. Second, we explore the ability of NS1 proteins to inhibit antiviral interferon signaling, an essential function for viral replication without which the virus is severely attenuated in any host. Innate immune suppression by NS1 not only enables viral replication in tissues, but also dampens the adaptive immune response and immunological memory. NS1 proteins suppress interferon signaling and effector functions through a variety of protein-protein interactions that may differ from host to host but must achieve similar goals. The multifunctional influenza A virus NS1 protein is highly plastic, highly versatile, and demonstrates a diversity of context-dependent solutions to the problem of interspecies adaptation.
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Affiliation(s)
| | - Katharine E. Magor
- Department of Biological Sciences, Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB, Canada
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8
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Harrington WN, Kackos CM, Webby RJ. The evolution and future of influenza pandemic preparedness. Exp Mol Med 2021; 53:737-749. [PMID: 33953324 PMCID: PMC8099712 DOI: 10.1038/s12276-021-00603-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/29/2020] [Accepted: 12/31/2020] [Indexed: 12/17/2022] Open
Abstract
The influenza virus is a global threat to human health causing unpredictable yet recurring pandemics, the last four emerging over the course of a hundred years. As our knowledge of influenza virus evolution, distribution, and transmission has increased, paths to pandemic preparedness have become apparent. In the 1950s, the World Health Organization (WHO) established a global influenza surveillance network that is now composed of institutions in 122 member states. This and other surveillance networks monitor circulating influenza strains in humans and animal reservoirs and are primed to detect influenza strains with pandemic potential. Both the United States Centers for Disease Control and Prevention and the WHO have also developed pandemic risk assessment tools that evaluate specific aspects of emerging influenza strains to develop a systematic process of determining research and funding priorities according to the risk of emergence and potential impact. Here, we review the history of influenza pandemic preparedness and the current state of preparedness, and we propose additional measures for improvement. We also comment on the intersection between the influenza pandemic preparedness network and the current SARS-CoV-2 crisis. We must continually evaluate and revise our risk assessment and pandemic preparedness plans and incorporate new information gathered from research and global crises.
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Affiliation(s)
- Walter N Harrington
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Christina M Kackos
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, USA
- St. Jude Children's Research Hospital, Graduate School of Biomedical Sciences, Memphis, TN, USA
| | - Richard J Webby
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, USA.
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9
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Hamza H, Shehata MM, Mostafa A, Pleschka S, Planz O. Improved in vitro Efficacy of Baloxavir Marboxil Against Influenza A Virus Infection by Combination Treatment With the MEK Inhibitor ATR-002. Front Microbiol 2021; 12:611958. [PMID: 33679636 PMCID: PMC7928405 DOI: 10.3389/fmicb.2021.611958] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 01/22/2021] [Indexed: 01/21/2023] Open
Abstract
Currently, all available antiviral drugs against influenza virus (IV) that target the virus proteins directly, like Baloxavir acid (BXA), lead to viral resistance. Therefore, cellular mechanisms and factors essential for IV replication are promising antiviral targets. As IV strongly depends on the virus-induced Raf/MEK/ERK signal pathway for efficient generation of infectious progeny virions, this pathway represents an important target. We aimed to determine whether the MEK inhibitor ATR-002 (PD0184264) is able to impair replication of BXA-resistant influenza A virus (IAV) and whether a treatment combining BXA and ATR-002 improves the therapeutic efficiency in vitro. A549 cells infected with different IAV strains including BXA-resistant variants were treated with ATR-002 or BXA and the effect on virus titer reduction was determined. The synergistic effect of ATR-002 and BXA was also analyzed using different evaluation methods. The data demonstrated that ATR-002 has a significant and dose-dependent inhibitory effect on IAV replication across different strains and subtypes. IAV with the PA-I38T mutation shows resistance against BXA, but is still susceptible toward ATR-002. The combination of ATR-002 and BXA exhibited a synergistic potency reflected by low combination index values. In conclusion, we show that ATR-002 permits to counteract the limitations of BXA against BXA-resistant IAV. Moreover, the results support the use of ATR-002 (i) in a mono-therapy, as well as (ii) in a combined approach together with BXA. These findings might also apply to the treatment of infections with IAV, resistant against other direct-acting antiviral compounds.
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Affiliation(s)
- Hazem Hamza
- Department of Immunology, Institute for Cell Biology, Eberhard Karls University of Tübingen, Tübingen, Germany.,Virology Laboratory, Environmental Research Division, National Research Centre, Giza, Egypt
| | - Mahmoud M Shehata
- Virology Laboratory, Environmental Research Division, National Research Centre, Giza, Egypt.,Center of Scientific Excellence for Influenza Viruses, National Research Centre, Giza, Egypt
| | - Ahmed Mostafa
- Virology Laboratory, Environmental Research Division, National Research Centre, Giza, Egypt.,Center of Scientific Excellence for Influenza Viruses, National Research Centre, Giza, Egypt.,Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany
| | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany.,German Center for Infection Research (DZIF), Partner Site Giessen, Giessen, Germany
| | - Oliver Planz
- Department of Immunology, Institute for Cell Biology, Eberhard Karls University of Tübingen, Tübingen, Germany
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10
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Ibrahim M, Zakaria S, Bazid AHI, Kilany WH, Zain El-Abideen MA, Ali A. A single dose of inactivated oil-emulsion bivalent H5N8/H5N1 vaccine protects chickens against the lethal challenge of both highly pathogenic avian influenza viruses. Comp Immunol Microbiol Infect Dis 2020; 74:101601. [PMID: 33307456 DOI: 10.1016/j.cimid.2020.101601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 12/31/2022]
Abstract
In this study, two highly pathogenic avian influenza (HPAI) H5N8 viruses were isolated from chicken and geese in 2018 and 2019 (Chicken/ME-2018 and Geese/Egypt/MG4/2019). The hemagglutinin and neuraminidase gene analyses revealed their close relatedness to the clade-2.3.4.4b H5N8 viruses isolated from Egypt and Eurasian countries. A monovalent inactivated oil-emulsion vaccine containing a reassortant virus with HA gene of the Chicken/ME-2018/H5N8 strain and a bivalent vaccine containing same reassortant virus plus a previously generated reassortant H5N1 strain (CK/Eg/RG-173CAL/17). The safety of both vaccines was evaluated in specific-pathogen-free (SPF) chickens. To evaluate the efficacy of the prepared vaccines, 2-week-old SPF chickens were vaccinated with 0.5 mL of a vaccine formula containing 108/EID50 /dose from each strain via the subcutaneous route. Vaccinated birds were challenged with either wild-type HPAI-H5N8 or H5N1 viruses separately at 3 weeks post-vaccine. Results revealed that both vaccines induced protective hemagglutination-inhibiting (HI) antibody titers as early as 2 weeks PV (≥5.0 log2). Vaccinated birds were protected clinically against both subtypes (100 % protection). HPAI-H5N1 virus shedding was significantly reduced in birds that were vaccinated with the bivalent vaccine; meanwhile, HPAI-H5N8 virus shedding was completely neutralized in both tracheal and cloacal swabs after 3 days post-infection in birds that had been vaccinated with either vaccine. In conclusion, the developed bivalent vaccine proved to be efficient in protecting chickens clinically and reduced virus shedding via the respiratory and digestive tracts. The applicability of the multivalent avian influenza vaccines further supported their value to facilitate vaccination programs in endemic countries.
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Affiliation(s)
- Mahmoud Ibrahim
- Birds and Rabbit Medicine Department, Faculty of Veterinary Medicine, University of Sadat City, Sadat City, Minoufiya, 22857, Egypt
| | - Salah Zakaria
- Middle East for Vaccine Company (MEVAC™), Second Industrial Area, El-Salhyia El-Gededa, Sharkia, 44671, Egypt; Virology Department, Faculty of Veterinary Medicine, University of Sadat City Sadat City, Minoufiya, 22857, Egypt
| | - Abdel-Hamid I Bazid
- Virology Department, Faculty of Veterinary Medicine, University of Sadat City Sadat City, Minoufiya, 22857, Egypt
| | - Walid H Kilany
- Reference Laboratory for Veterinary Quality Control on Poultry Production (RLQP), AHRI, ARC, 12818 Giza, Egypt
| | - Mohamed A Zain El-Abideen
- Reference Laboratory for Veterinary Quality Control on Poultry Production (RLQP), AHRI, ARC, 12818 Giza, Egypt
| | - Ahmed Ali
- Poultry Diseases Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, 62511, Egypt.
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11
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Hartshorn KL. Innate Immunity and Influenza A Virus Pathogenesis: Lessons for COVID-19. Front Cell Infect Microbiol 2020; 10:563850. [PMID: 33194802 PMCID: PMC7642997 DOI: 10.3389/fcimb.2020.563850] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 09/11/2020] [Indexed: 12/15/2022] Open
Abstract
There is abundant evidence that the innate immune response to influenza A virus (IAV) is highly complex and plays a key role in protection against IAV induced infection and illness. Unfortunately it also clear that aspects of innate immunity can lead to severe morbidity or mortality from IAV, including inflammatory lung injury, bacterial superinfection, and exacerbation of reactive airways disease. We review broadly the virus and host factors that result in adverse outcomes from IAV and show evidence that inflammatory responses can become damaging even apart from changes in viral replication per se, with special focus on the positive and adverse effects of neutrophils and monocytes. We then evaluate in detail the role of soluble innate inhibitors including surfactant protein D and antimicrobial peptides that have a potential dual capacity for down-regulating viral replication and also inhibiting excessive inflammatory responses and how these innate host factors could possibly be harnessed to treat IAV infection. Where appropriate we draw comparisons and contrasts the SARS-CoV viruses and IAV in an effort to point out where the extensive knowledge existing regarding severe IAV infection could help guide research into severe COVID 19 illness or vice versa.
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Affiliation(s)
- Kevan L Hartshorn
- Section of Hematology Oncology, Boston University School of Medicine, Boston, MA, United States
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12
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Mostafa A, Blaurock C, Scheibner D, Müller C, Blohm U, Schäfer A, Gischke M, Salaheldin AH, Nooh HZ, Ali MA, Breithaupt A, Mettenleiter TC, Pleschka S, Abdelwhab EM. Genetic incompatibilities and reduced transmission in chickens may limit the evolution of reassortants between H9N2 and panzootic H5N8 clade 2.3.4.4 avian influenza virus showing high virulence for mammals. Virus Evol 2020; 6:veaa077. [PMID: 33343923 PMCID: PMC7733613 DOI: 10.1093/ve/veaa077] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The unprecedented spread of H5N8- and H9N2-subtype avian influenza virus (AIV) in birds across Asia, Europe, Africa, and North America poses a serious public health threat with a permanent risk of reassortment and the possible emergence of novel virus variants with high virulence in mammals. To gain information on this risk, we studied the potential for reassortment between two contemporary H9N2 and H5N8 viruses. While the replacement of the PB2, PA, and NS genes of highly pathogenic H5N8 by homologous segments from H9N2 produced infectious H5N8 progeny, PB1 and NP of H9N2 were not able to replace the respective segments from H5N8 due to residues outside the packaging region. Furthermore, exchange of the PB2, PA, and NS segments of H5N8 by those of H9N2 increased replication, polymerase activity and interferon antagonism of the H5N8 reassortants in human cells. Notably, H5N8 reassortants carrying the H9N2-subtype PB2 segment and to lesser extent the PA or NS segments showed remarkably increased virulence in mice as indicated by rapid onset of mortality, reduced mean time to death and increased body weight loss. Simultaneously, we observed that in chickens the H5N8 reassortants, particularly with the H9N2 NS segment, demonstrated significantly reduced transmission to co-housed chickens. Together, while the limited capacity for reassortment between co-circulating H9N2 and H5N8 viruses and the reduced bird-to-bird transmission of possible H5N8 reassortants in chickens may limit the evolution of such reassortant viruses, they show a higher replication potential in human cells and increased virulence in mammals.
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Affiliation(s)
| | | | | | - Christin Müller
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
| | - Ulrike Blohm
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany
| | - Alexander Schäfer
- Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany
| | | | | | - Hanaa Z Nooh
- Department of Anatomy and Histology, College of Medicine, Jouf University, Sakaka 72442, Aljouf Province, Saudi Arabia
| | - Mohamed A Ali
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), Dokki, 12622, Giza, Egypt
| | - Angele Breithaupt
- Department of Experimental Animal Facilities and Biorisk Management, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany
| | | | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
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13
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Mostafa A, Mahmoud SH, Shehata M, Müller C, Kandeil A, El-Shesheny R, Nooh HZ, Kayali G, Ali MA, Pleschka S. PA from a Recent H9N2 (G1-Like) Avian Influenza a Virus (AIV) Strain Carrying Lysine 367 Confers Altered Replication Efficiency and Pathogenicity to Contemporaneous H5N1 in Mammalian Systems. Viruses 2020; 12:v12091046. [PMID: 32962203 PMCID: PMC7551781 DOI: 10.3390/v12091046] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/15/2020] [Accepted: 09/18/2020] [Indexed: 12/03/2022] Open
Abstract
Egypt is a hotspot for H5- and H9-subtype avian influenza A virus (AIV) infections and co-infections in poultry by both subtypes have been frequently reported. However, natural genetic reassortment of these subtypes has not been reported yet. Here, we evaluated the genetic compatibility and replication efficiency of reassortants between recent isolates of an Egyptian H5N1 and a H9N2 AIV (H5N1EGY and H9N2EGY). All internal viral proteins-encoding segments of the contemporaneous G1-like H9N2EGY, expressed individually and in combination in the genetic background of H5N1EGY, were genetically compatible with the other H5N1EGY segments. At 37 °C the replication efficiencies of H5N1EGY reassortants expressing the H9N2EGY polymerase subunits PB2 and PA (H5N1PB2-H9N2EGY, H5N1PA-H9N2EGY) were higher than the wild-type H5N1EGY in Madin-Darby canine kidney (MDCK-II) cells. This could not be correlated to viral polymerase activity as this was found to be improved for H5N1PB2-H9N2EGY, but reduced for H5N1PA-H9N2EGY. At 33 °C and 39 °C, H5N1PB2-H9N2EGY and H5N1PA-H9N2EGY replicated to higher levels than the wild-type H5N1EGY in human Calu-3 and A549 cell lines. Nevertheless, in BALB/c mice both reassortants caused reduced mortality compared to the wild-type H5N1EGY. Genetic analysis of the polymerase-encoding segments revealed that the PAH9N2EGY and PB2H9N2EGY encode for a distinct uncharacterized mammalian-like variation (367K) and a well-known mammalian signature (591K), respectively. Introducing the single substitution 367K into the PA of H5N1EGY enabled the mutant virus H5N1PA-R367K to replicate more efficiently at 37 °C in primary human bronchial epithelial (NHBE) cells and also in A549 and Calu-3 cells at 33 °C and 39 °C. Furthermore, H5N1PA-R367K caused higher mortality in BALB/c mice. These findings demonstrate that H5N1 (Clade 2.2.1.2) reassortants carrying internal proteins-encoding segments of G1-like H9N2 viruses can emerge and may gain improved replication fitness. Thereby such H5N1/H9N2 reassortants could augment the zoonotic potential of H5N1 viruses, especially by acquiring unique mammalian-like aa signatures.
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Affiliation(s)
- Ahmed Mostafa
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), 12622 Giza, Egypt; (S.H.M.); (M.S.); (A.K.); (R.E.-S.)
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35390 Giessen, Germany;
- Correspondence: (A.M); (M.A.A.); (S.P.)
| | - Sara H. Mahmoud
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), 12622 Giza, Egypt; (S.H.M.); (M.S.); (A.K.); (R.E.-S.)
| | - Mahmoud Shehata
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), 12622 Giza, Egypt; (S.H.M.); (M.S.); (A.K.); (R.E.-S.)
| | - Christin Müller
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35390 Giessen, Germany;
| | - Ahmed Kandeil
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), 12622 Giza, Egypt; (S.H.M.); (M.S.); (A.K.); (R.E.-S.)
| | - Rabeh El-Shesheny
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), 12622 Giza, Egypt; (S.H.M.); (M.S.); (A.K.); (R.E.-S.)
- St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Hanaa Z. Nooh
- Anatomy and Embryology Department, Faculty of Medicine, Jouf University, Sakaka 2014, Saudi Arabia;
| | - Ghazi Kayali
- Department of Epidemiology, Human Genetics, and Environmental Sciences, University of Texas, Houston, TX 77030, USA;
- Human Link, Baabda 1109, Lebanon
| | - Mohamed A. Ali
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), 12622 Giza, Egypt; (S.H.M.); (M.S.); (A.K.); (R.E.-S.)
- Correspondence: (A.M); (M.A.A.); (S.P.)
| | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35390 Giessen, Germany;
- Correspondence: (A.M); (M.A.A.); (S.P.)
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14
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Campbell LK, Magor KE. Pattern Recognition Receptor Signaling and Innate Responses to Influenza A Viruses in the Mallard Duck, Compared to Humans and Chickens. Front Cell Infect Microbiol 2020; 10:209. [PMID: 32477965 PMCID: PMC7236763 DOI: 10.3389/fcimb.2020.00209] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/16/2020] [Indexed: 12/25/2022] Open
Abstract
Mallard ducks are a natural host and reservoir of avian Influenza A viruses. While most influenza strains can replicate in mallards, the virus typically does not cause substantial disease in this host. Mallards are often resistant to disease caused by highly pathogenic avian influenza viruses, while the same strains can cause severe infection in humans, chickens, and even other species of ducks, resulting in systemic spread of the virus and even death. The differences in influenza detection and antiviral effectors responsible for limiting damage in the mallards are largely unknown. Domestic mallards have an early and robust innate response to infection that seems to limit replication and clear highly pathogenic strains. The regulation and timing of the response to influenza also seems to circumvent damage done by a prolonged or dysregulated immune response. Rapid initiation of innate immune responses depends on viral recognition by pattern recognition receptors (PRRs) expressed in tissues where the virus replicates. RIG-like receptors (RLRs), Toll-like receptors (TLRs), and Nod-like receptors (NLRs) are all important influenza sensors in mammals during infection. Ducks utilize many of the same PRRs to detect influenza, namely RIG-I, TLR7, and TLR3 and their downstream adaptors. Ducks also express many of the same signal transduction proteins including TBK1, TRIF, and TRAF3. Some antiviral effectors expressed downstream of these signaling pathways inhibit influenza replication in ducks. In this review, we summarize the recent advances in our understanding of influenza recognition and response through duck PRRs and their adaptors. We compare basal tissue expression and regulation of these signaling components in birds, to better understand what contributes to influenza resistance in the duck.
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Affiliation(s)
- Lee K Campbell
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB, Canada
| | - Katharine E Magor
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB, Canada
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15
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Wang WC, Kuan CY, Tseng YJ, Chang CH, Liu YC, Chang YC, Hsu YC, Hsieh MK, Ou SC, Hsu WL. The Impacts of Reassortant Avian Influenza H5N2 Virus NS1 Proteins on Viral Compatibility and Regulation of Immune Responses. Front Microbiol 2020; 11:280. [PMID: 32226416 PMCID: PMC7080822 DOI: 10.3389/fmicb.2020.00280] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/06/2020] [Indexed: 11/25/2022] Open
Abstract
Avian influenza virus (AIV) can cause severe diseases in poultry worldwide. H6N1 AIV was the dominant enzootic subtype in 1985 in the chicken farms of Taiwan until the initial outbreak of a low pathogenic avian influenza (LPAI) H5N2 virus in 2003; thereafter, this and other LPAIs have been sporadically detected. In 2015, the outbreak of three novel H5Nx viruses of highly pathogenic avian influenza (HPAI) emerged and devastated Taiwanese chicken and waterfowl industries. The mechanism of variation in pathogenicity among these viruses is unclear; but, in light of the many biological functions of viral non-structural protein 1 (NS1), including interferon (IFN) antagonist and host range determinant, we hypothesized that NS genetic diversity contributes to AIV pathogenesis. To determine the impact of NS1 variants on viral infection dynamics, we established a reverse genetics system with the genetic backbone of the enzootic Taiwanese H6N1 for generation of reassortant AIVs carrying exogenous NS segments of three different Taiwanese H5N2 strains. We observed distinct cellular distributions of NS1 among the reassortant viruses. Moreover, exchange of the NS segment significantly influenced growth kinetics and induction of cytokines [IFN-α, IFN-β, and tumor necrosis factor alpha (TNF-α)] in an NS1- and host-specific manner. The impact of NS1 variants on viral replication appears related to their synergic effects on viral RNA-dependent RNA polymerase activity and IFN response. With these approaches, we revealed that NS1 is a key factor responsible for the diverse characteristics of AIVs in Taiwan.
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Affiliation(s)
- Wen-Chien Wang
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Chih-Ying Kuan
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Yu-Jing Tseng
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Chia-Hsuan Chang
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Yee-Chen Liu
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Yu-Chih Chang
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Yu-Chen Hsu
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Ming-Kun Hsieh
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Shan-Chia Ou
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Wei-Li Hsu
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
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16
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Krivitskaya VZ, Sorokin EV, Tsareva TR, Sergeeva MV, Kadyrova RA, Romanovskaya-Roman’ko EA, Shaldzhyan AA, Petrov SV, Petrova ER, Konovalova NI, Petrova PA. Generation and Characterization of the Monoclonal Antibody Panel Specific to the NS1 Protein of the Influenza A Virus. APPL BIOCHEM MICRO+ 2019. [DOI: 10.1134/s0003683818070049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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PR8 virus harbouring H5N1 NS gene contributed for THP-1 cell tropism. Virusdisease 2018; 29:548-552. [PMID: 30539061 DOI: 10.1007/s13337-018-0499-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 10/03/2018] [Indexed: 10/28/2022] Open
Abstract
Innate immune cells are key player in immune response to influenza virus infection. Influenza infected monocytes exacerbate the disease pathology. However, monocytes differ in susceptibilities to influenza virus infection. Herein, susceptibilities of U937 and THP-1 monocytic cells to PR8 virus infection, the associated cellular factor- sialic acid (SA) receptor distribution and viral factor were determined. Moreover, amino acid sequences in hemagglutinin (HA) receptor binding domain (RBD) of PR8 virus that determine SA preferences were analysed. PR8 infected U937 cells express significantly higher numbers of nucleoprotein positive cells suggesting U937 cells being more susceptible to influenza virus than THP-1 cells. Lectin staining suggested similar pattern of SA receptor distribution in both cells. Interestingly, sequence analysis of RBD suggested their preferences for alpha 2,3 SA receptors suggesting RBD sequences are not always determining for SA preferences. Furthermore, the resistance barrier on THP-1 cells was overcome by H5N1 NS gene. In conclusion, the study demonstrated that decreased susceptibility of THP-1 cells to PR8 virus could not be related to the SA receptor distribution, and H5N1 NS gene was sufficient to determine tropism for THP-1 cells. Hence, mechanistic basis of NS gene on cell tropism and contribution of other internal genes remained to be determined.
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18
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Mostafa A, Abdelwhab EM, Mettenleiter TC, Pleschka S. Zoonotic Potential of Influenza A Viruses: A Comprehensive Overview. Viruses 2018; 10:v10090497. [PMID: 30217093 PMCID: PMC6165440 DOI: 10.3390/v10090497] [Citation(s) in RCA: 154] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/24/2018] [Accepted: 09/13/2018] [Indexed: 02/06/2023] Open
Abstract
Influenza A viruses (IAVs) possess a great zoonotic potential as they are able to infect different avian and mammalian animal hosts, from which they can be transmitted to humans. This is based on the ability of IAV to gradually change their genome by mutation or even reassemble their genome segments during co-infection of the host cell with different IAV strains, resulting in a high genetic diversity. Variants of circulating or newly emerging IAVs continue to trigger global health threats annually for both humans and animals. Here, we provide an introduction on IAVs, highlighting the mechanisms of viral evolution, the host spectrum, and the animal/human interface. Pathogenicity determinants of IAVs in mammals, with special emphasis on newly emerging IAVs with pandemic potential, are discussed. Finally, an overview is provided on various approaches for the prevention of human IAV infections.
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Affiliation(s)
- Ahmed Mostafa
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany.
- Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), Giza 12622, Egypt.
| | - Elsayed M Abdelwhab
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany.
| | - Thomas C Mettenleiter
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany.
| | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany.
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19
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Petersen H, Mostafa A, Tantawy MA, Iqbal AA, Hoffmann D, Tallam A, Selvakumar B, Pessler F, Beer M, Rautenschlein S, Pleschka S. NS Segment of a 1918 Influenza A Virus-Descendent Enhances Replication of H1N1pdm09 and Virus-Induced Cellular Immune Response in Mammalian and Avian Systems. Front Microbiol 2018; 9:526. [PMID: 29623073 PMCID: PMC5874506 DOI: 10.3389/fmicb.2018.00526] [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: 01/30/2018] [Accepted: 03/08/2018] [Indexed: 12/14/2022] Open
Abstract
The 2009 pandemic influenza A virus (IAV) H1N1 strain (H1N1pdm09) has widely spread and is circulating in humans and swine together with other human and avian IAVs. This fact raises the concern that reassortment between H1N1pdm09 and co-circulating viruses might lead to an increase of H1N1pdm09 pathogenicity in different susceptible host species. Herein, we explored the potential of different NS segments to enhance the replication dynamics, pathogenicity and host range of H1N1pdm09 strain A/Giessen/06/09 (Gi-wt). The NS segments were derived from (i) human H1N1- and H3N2 IAVs, (ii) highly pathogenic- (H5- or H7-subtypes) or (iii) low pathogenic avian influenza viruses (H7- or H9-subtypes). A significant increase of growth kinetics in A549 (human lung epithelia) and NPTr (porcine tracheal epithelia) cells was only noticed in vitro for the reassortant Gi-NS-PR8 carrying the NS segment of the 1918-descendent A/Puerto Rico/8/34 (PR8-wt, H1N1), whereas all other reassortants showed either reduced or comparable replication efficiencies. Analysis using ex vivo tracheal organ cultures of turkeys (TOC-Tu), a species susceptible to IAV H1N1 infection, demonstrated increased replication of Gi-NS-PR8 compared to Gi-wt. Also, Gi-NS-PR8 induced a markedly higher expression of immunoregulatory and pro-inflammatory cytokines, chemokines and interferon-stimulated genes in A549 cells, THP-1-derived macrophages (dHTP) and TOC-Tu. In vivo, Gi-NS-PR8 induced an earlier onset of mortality than Gi-wt in mice, whereas, 6-week-old chickens were found to be resistant to both viruses. These data suggest that the specific characteristics of the PR8 NS segments can impact on replication, virus induced cellular immune responses and pathogenicity of the H1N1pdm09 in different avian and mammalian host species.
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Affiliation(s)
- Henning Petersen
- Clinic for Poultry, University of Veterinary Medicine Hannover, Hanover, Germany
| | - Ahmed Mostafa
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany.,Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), Cairo, Egypt
| | - Mohamed A Tantawy
- Institute for Experimental Infection Research, TWINCORE Centre for Experimental and Clinical Infection Research, Hanover, Germany.,Department of Hormones, Medical Research Division, National Research Centre, Cairo, Egypt
| | - Azeem A Iqbal
- Institute for Experimental Infection Research, TWINCORE Centre for Experimental and Clinical Infection Research, Hanover, Germany.,Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Donata Hoffmann
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Greifswald, Germany
| | - Aravind Tallam
- Institute for Experimental Infection Research, TWINCORE Centre for Experimental and Clinical Infection Research, Hanover, Germany
| | - Balachandar Selvakumar
- Max-Planck Laboratory for Heart and Lung Research, Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA) - CONICET-Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | - Frank Pessler
- Institute for Experimental Infection Research, TWINCORE Centre for Experimental and Clinical Infection Research, Hanover, Germany.,Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Martin Beer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Greifswald, Germany
| | - Silke Rautenschlein
- Clinic for Poultry, University of Veterinary Medicine Hannover, Hanover, Germany
| | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany
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20
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Abstract
Influenza A virus (IAV) is an RNA virus with a segmented genome. These viral properties allow for the rapid evolution of IAV under selective pressure, due to mutation occurring from error-prone replication and the exchange of gene segments within a co-infected cell, termed reassortment. Both mutation and reassortment give rise to genetic diversity, but constraints shape their impact on viral evolution: just as most mutations are deleterious, most reassortment events result in genetic incompatibilities. The phenomenon of segment mismatch encompasses both RNA- and protein-based incompatibilities between co-infecting viruses and results in the production of progeny viruses with fitness defects. Segment mismatch is an important determining factor of the outcomes of mixed IAV infections and has been addressed in multiple risk assessment studies undertaken to date. However, due to the complexity of genetic interactions among the eight viral gene segments, our understanding of segment mismatch and its underlying mechanisms remain incomplete. Here, we summarize current knowledge regarding segment mismatch and discuss the implications of this phenomenon for IAV reassortment and diversity.
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Affiliation(s)
- Maria C White
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
| | - Anice C Lowen
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
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21
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Pham NB, Ho TT, Nguyen GT, Le TT, Le NT, Chang HC, Pham MD, Conrad U, Chu HH. Nanodiamond enhances immune responses in mice against recombinant HA/H7N9 protein. J Nanobiotechnology 2017; 15:69. [PMID: 28982373 PMCID: PMC5629800 DOI: 10.1186/s12951-017-0305-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 09/23/2017] [Indexed: 12/31/2022] Open
Abstract
Background The continuing spread of the newly emerged H7N9 virus among poultry in China, as well as the possibility of human-to-human transmission, has attracted numerous efforts to develop an effective vaccine against H7N9. The use of nanoparticles in vaccinology is inspired by the fact that most pathogens have a dimension within the nano-size range and therefore can be processed efficiently by the immune system, which leads to a potent immune response. Herein, we report a facile approach to increase antigen size to achieve not only fast but also effective responses against the recombinant HA/H7N9 protein via a simple conjugation of the protein onto the surface of nanodiamond particles. Results In this study, trimeric Haemagglutinin (H7) that is transiently expressed in N. benthamiana was purified using affinity chromatography, and its trimeric state was revealed successfully by the cross-linking reaction. The trimeric H7 solution was subsequently mixed with a nanodiamond suspension in different ratios. The successful conjugation of the trimeric H7 onto the surface of nanodiamond particles was demonstrated by the changes in size and Zeta-potential of the particles before and after protein coating, Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and Western-blot analysis. Next, biofunction of the protein-nanodiamond conjugates was screened using a haemagglutination assay. A mixture containing 5 µg of trimeric H7 and 60 µg of nanodiamond corresponds to a ratio of 1:12 (w/w) of agglutinated chicken red blood cells at HA titer of 1024, which is 512-fold higher than the HA titer of free trimeric H7. After the 2nd and 3rd immunization in mice, ELISA and Western blot analyses demonstrated that the physical mixture of trimeric H7 protein and nanodiamond (1:12, w/w) elicited statistically significant stronger H7-specific-IgG response demonstrated by higher amounts of H7N9-specific IgG (over 15.4-fold with P < 0.05 after the second immunization). Conclusions These results indicated a potential effect inherent to nanodiamond towards modulating immune systems, which should be further evaluated and broadly applied in nanovaccine development.
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Affiliation(s)
- Ngoc Bich Pham
- Institute of Biotechnology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam.,Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam
| | - Thuong Thi Ho
- Institute of Biotechnology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam
| | - Giang Thu Nguyen
- Institute of Biotechnology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam
| | - Thuy Thi Le
- Institute of Biotechnology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam
| | - Ngoc Thu Le
- Institute of Biotechnology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam
| | - Huan-Cheng Chang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan, ROC
| | - Minh Dinh Pham
- Institute of Biotechnology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam.,Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan, ROC
| | - Udo Conrad
- Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - Ha Hoang Chu
- Institute of Biotechnology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam. .,Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Ha Noi, Vietnam.
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22
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Stoute S, Chin R, Crossley B, Gabriel Sentíes-Cué C, Bickford A, Pantin-Jackwood M, Breitmeyer R, Jones A, Carnaccini S, Shivaprasad HL. Highly Pathogenic Eurasian H5N8 Avian Influenza Outbreaks in Two Commercial Poultry Flocks in California. Avian Dis 2017; 60:688-93. [PMID: 27610732 DOI: 10.1637/11314-110615-case.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In January 2015, a highly pathogenic Eurasian lineage H5N8 avian influenza (AI) virus (AIV) was detected in a commercial meat turkey flock in Stanislaus County, CA. Approximately 3 wk later, a similar case was diagnosed in commercial brown layers from a different company located in Kings County, CA. Five 14-wk-old turkey hens were submitted to the California Animal Health and Food Safety Laboratory System (CAHFS), Turlock, and eleven 12-wk-old chickens were submitted to CAHFS, Tulare laboratory due to an acute increase in flock mortality. Gross lesions included enlarged and mottled pale spleens and pancreas in turkeys and chickens. Histologically, the major lesions observed in turkeys and chickens were splenitis, pancreatitis, encephalitis, and pneumonia. In both cases, diagnosis was based on real-time reverse transcriptase PCR (RRT-PCR), sequencing, and virus isolation from oropharyngeal and cloacal swabs. Confirmatory diagnosis and AIV characterization was done at the National Veterinary Services Laboratory, Ames, IA. The sequence of the AIV from both cases was 99% identical to an H5N8 AI virus (A/gyrfalcon/Washington/41088-6/2014) isolated from a captive gyrfalcon (Falco rusticolus) from Washington State in December 2014. Immunohistochemistry (IHC) performed on various tissues from both cases indicated a widespread AIV tissue distribution. Except for minor variations, the tissue distribution of the AI antigen was similar in the chickens and turkeys. There was positive IHC staining in the brain, spleen, pancreas, larynx, trachea, and lungs in both chickens and turkeys. Hearts, ovaries, and air sacs from the turkeys were also positive for the AI antigen. The liver sections from the chickens had occasional AI-positive staining in mononuclear cells, but the IHC on liver sections from the turkeys were negative. The bursa of Fabricius, small intestine, kidney, and skeletal muscle sections were negative for the AI antigen in both chickens and turkeys.
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Affiliation(s)
- Simone Stoute
- A California Animal Health and Food Safety Laboratory System (CAHFS), University of California, Davis, Turlock Branch, 1550 N. Soderquist Road, Turlock, CA 95381
| | - Richard Chin
- B CAHFS, University of California, Davis, Tulare Branch, 18830 Road 112, Tulare, CA 93274
| | - Beate Crossley
- C CAHFS, University of California, Davis, Davis Branch, One Shields Avenue, Davis, CA 95616
| | - C Gabriel Sentíes-Cué
- A California Animal Health and Food Safety Laboratory System (CAHFS), University of California, Davis, Turlock Branch, 1550 N. Soderquist Road, Turlock, CA 95381
| | - Arthur Bickford
- A California Animal Health and Food Safety Laboratory System (CAHFS), University of California, Davis, Turlock Branch, 1550 N. Soderquist Road, Turlock, CA 95381
| | - Mary Pantin-Jackwood
- D Southeast Poultry Research Laboratory, United States National Poultry Research Center, United States Department of Agriculture, Agricultural Research Service, 934 College Station Road, Athens, GA 30605
| | - Richard Breitmeyer
- C CAHFS, University of California, Davis, Davis Branch, One Shields Avenue, Davis, CA 95616
| | - Annette Jones
- E California Department of Food and Agriculture, Animal Health and Food Safety Services, 2800 Gateway Oaks, Sacramento, CA 95814
| | - Silvia Carnaccini
- A California Animal Health and Food Safety Laboratory System (CAHFS), University of California, Davis, Turlock Branch, 1550 N. Soderquist Road, Turlock, CA 95381
| | - H L Shivaprasad
- B CAHFS, University of California, Davis, Tulare Branch, 18830 Road 112, Tulare, CA 93274
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23
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Liu S, Zhang L, Yao Z, Xing L, Liu K. In vitro and in vivo characterization of a novel H1N1/2009 influenza virus reassortant with an NS gene from a highly pathogenic H5N1 virus, isolated from a human. Arch Virol 2017; 162:2633-2642. [PMID: 28523521 DOI: 10.1007/s00705-017-3408-z] [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] [Received: 01/10/2017] [Accepted: 05/04/2017] [Indexed: 11/29/2022]
Abstract
The triple-reassortant H1N1/2009 influenza A virus, which caused the first influenza pandemic of the 21st century, is generally associated with mild disease and a relatively low mortality rate comparable to that of seasonal influenza virus outbreaks. There is a growing concern about the potential for reassortment between the low-mortality H1N1/2009 and other high-mortality influenza viruses. Here, we describe and characterize a novel reassortant H1N1/2009 influenza virus, isolated from a human sample, that contained an NS gene from a highly pathogenic H5N1 virus. We evaluated the effect of the acquired NS gene on viral virulence both in vitro and in vivo and found that the novel NS-reassorted influenza virus replicated well in different cell lines and several organs of BALB/c mice without prior adaption and induced a cytokine imbalance. Therefore, there is a continued risk for further reassortment of the H1N1/2009 virus, and therefore, systematic surveillance should be enhanced to prepare for the next possible pandemic.
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Affiliation(s)
- Shengbing Liu
- School of Medicine, Jiaxing University, Jiaxing, 314001, Zhejiang, China
| | - Liangyan Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No. 20 Dongda Street, Beijing, 100071, China
| | - Zhidong Yao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No. 20 Dongda Street, Beijing, 100071, China
| | - Li Xing
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No. 20 Dongda Street, Beijing, 100071, China
| | - Kun Liu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No. 20 Dongda Street, Beijing, 100071, China.
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24
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Influenza A Virus Virulence Depends on Two Amino Acids in the N-Terminal Domain of Its NS1 Protein To Facilitate Inhibition of the RNA-Dependent Protein Kinase PKR. J Virol 2017; 91:JVI.00198-17. [PMID: 28250123 DOI: 10.1128/jvi.00198-17] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 02/20/2017] [Indexed: 12/22/2022] Open
Abstract
The RNA-dependent protein kinase (PKR) has broad antiviral activity inducing translational shutdown of viral and cellular genes and is therefore targeted by various viral proteins to facilitate pathogen propagation. The pleiotropic NS1 protein of influenza A virus acts as silencer of PKR activation and ensures high-level viral replication and virulence. However, the exact manner of this inhibition remains controversial. To elucidate the structural requirements within the NS1 protein for PKR inhibition, we generated a set of mutant viruses, identifying highly conserved arginine residues 35 and 46 within the NS1 N terminus as being most critical not only for binding to and blocking activation of PKR but also for efficient virus propagation. Biochemical and Förster resonance energy transfer (FRET)-based interaction studies showed that mutation of R35 or R46 allowed formation of NS1 dimers but eliminated any detectable binding to PKR as well as to double-stranded RNA (dsRNA). Using in vitro and in vivo approaches to phenotypic restoration, we demonstrated the essential role of the NS1 N terminus for blocking PKR. The strong attenuation conferred by NS1 mutation R35A or R46A was substantially alleviated by stable knockdown of PKR in human cells. Intriguingly, both NS1 mutant viruses did not trigger any signs of disease in PKR+/+ mice, but replicated to high titers in lungs of PKR-/- mice and caused lethal infections. These data not only establish the NS1 N terminus as highly critical for neutralization of PKR's antiviral activity but also identify this blockade as an indispensable contribution of NS1 to the viral life cycle.IMPORTANCE Influenza A virus inhibits activation of the RNA-dependent protein kinase (PKR) by means of its nonstructural NS1 protein, but the underlying mode of inhibition is debated. Using mutational analysis, we identified arginine residues 35 and 46 within the N-terminal NS1 domain as highly critical for binding to and functional silencing of PKR. In addition, our data show that this is a main activity of amino acids 35 and 46, as the strong attenuation of corresponding mutant viruses in human cells was rescued to a large extent by lowering of PKR expression levels. Significantly, this corresponded with restoration of viral virulence for NS1 R35A and R46A mutant viruses in PKR-/- mice. Therefore, our data establish a model in which the NS1 N-terminal domain engages in a binding interaction to inhibit activation of PKR and ensure efficient viral propagation and virulence.
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25
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Kaiser A, Willer T, Sid H, Petersen H, Baumgärtner W, Steinberg P, Rautenschlein S. Susceptibility of primary chicken intestinal epithelial cells for low pathogenic avian influenza virus and velogenic viscerotropic Newcastle disease virus. Virus Res 2016; 225:50-63. [DOI: 10.1016/j.virusres.2016.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 07/01/2016] [Accepted: 09/02/2016] [Indexed: 11/25/2022]
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26
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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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27
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Kanrai P, Mostafa A, Madhugiri R, Lechner M, Wilk E, Schughart K, Ylösmäki L, Saksela K, Ziebuhr J, Pleschka S. Identification of specific residues in avian influenza A virus NS1 that enhance viral replication and pathogenicity in mammalian systems. J Gen Virol 2016; 97:2135-2148. [PMID: 27405649 DOI: 10.1099/jgv.0.000542] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Reassortment of their segmented genomes allows influenza A viruses (IAV) to gain new characteristics, which potentially enable them to cross the species barrier and infect new hosts. Improved replication was observed for reassortants of the strictly avian IAV A/FPV/Rostock/34 (FPV, H7N1) containing the NS segment from A/Goose/Guangdong/1/1996 (GD, H5N1), but not for reassortants containing the NS segment of A/Mallard/NL/12/2000 (MA, H7N3). The NS1 of GD and MA differ only in 8 aa positions. Here, we show that efficient replication of FPV-NSMA-derived mutants was linked to the presence of a single substitution (D74N) and more prominently to a triple substitution (P3S+R41K+D74N) in the NS1MA protein. The substitution(s) led to (i) increased virus titres, (ii) larger plaque sizes and (iii) increased levels and faster kinetics of viral mRNA and protein accumulation in mammalian cells. Interestingly, the NS1 substitutions did not affect viral growth characteristics in avian cells. Furthermore, we show that an FPV mutant with N74 in the NS1 (already possessing S3+K41) is able to replicate and cause disease in mice, demonstrating a key role of NS1 in the adaptation of avian IAV to mammalian hosts. Our data suggest that (i) adaptation to mammalian hosts does not necessarily compromise replication in the natural (avian) host and (ii) very few genetic changes may pave the way for zoonotic transmission. The study reinforces the need for close surveillance and characterization of circulating avian IAV to identify genetic signatures that indicate a potential risk for efficient transmission of avian strains to mammalian hosts.
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Affiliation(s)
- Pumaree Kanrai
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
| | - Ahmed Mostafa
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
- Center of Scientific Excellence for Influenza Viruses, National Research Center (NRC), 12311 Dokki, Giza, Egypt
| | - Ramakanth Madhugiri
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
| | - Marcus Lechner
- Department of Pharmaceutical Chemistry, Philipps University Marburg, Marbacher Weg 6, 35037 Marburg, Germany
| | - Esther Wilk
- Department of Infection Genetics, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Klaus Schughart
- Department of Infection Genetics, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Leena Ylösmäki
- Department of Virology, University of Helsinki, PO Box 21 (Haartmaninkatu 3) 00014, Finland
| | - Kalle Saksela
- Department of Virology, University of Helsinki, PO Box 21 (Haartmaninkatu 3) 00014, Finland
| | - John Ziebuhr
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
| | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
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28
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Lyoo KS, Na W, Yeom M, Jeong DG, Kim CU, Kim JK, Song D. Virulence of a novel reassortant canine H3N2 influenza virus in ferret, dog and mouse models. Arch Virol 2016; 161:1915-23. [PMID: 27138550 DOI: 10.1007/s00705-016-2868-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 04/15/2016] [Indexed: 10/21/2022]
Abstract
An outbreak of a canine influenza virus (CIV) H3N2 reassortant derived from pandemic (pdm) H1N1 and CIV H3N2 in companion animals has underscored the urgent need to monitor CIV infections for potential zoonotic transmission of influenza viruses to humans. In this study, we assessed the virulence of a novel CIV H3N2 reassortant, VC378, which was obtained from a dog that was coinfected with pdm H1N1 and CIV H3N2, in ferrets, dogs, and mice. Significantly enhanced virulence of VC378 was demonstrated in mice, although the transmissibility and pathogenicity of VC378 were similar to those of classical H3N2 in ferrets and dogs. This is notable because mice inoculated with an equivalent dose of classical CIV H3N2 showed no clinical signs and no lethality. We found that the PA and NS gene segments of VC378 were introduced from pdmH1N1, and these genes included the amino acid substitutions PA-P224S and NS-I123V, which were previously found to be associated with increased virulence in mice. Thus, we speculate that the natural reassortment between pdm H1N1 and CIV H3N2 can confer virulence and that continuous surveillance is needed to monitor the evolution of CIV in companion animals.
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Affiliation(s)
- Kwang-Soo Lyoo
- Korea Zoonosis Research Institute, Chonbuk National University, Iksan, Jeonbuk, 561-756, Republic of Korea
| | - Woonsung Na
- Korea Research Institute of Bioscience and Biotechnology, Taejon, 305-806, Republic of Korea.,Department of Pharmacy, College of Pharmacy, Korea University, Sejong, 339-700, Republic of Korea
| | - Minjoo Yeom
- Department of Pharmacy, College of Pharmacy, Korea University, Sejong, 339-700, Republic of Korea
| | - Dae-Gwin Jeong
- Korea Research Institute of Bioscience and Biotechnology, Taejon, 305-806, Republic of Korea
| | - Chang-Ung Kim
- Korea Research Institute of Bioscience and Biotechnology, Taejon, 305-806, Republic of Korea
| | - Jeong-Ki Kim
- Department of Pharmacy, College of Pharmacy, Korea University, Sejong, 339-700, Republic of Korea.
| | - Daesub Song
- Department of Pharmacy, College of Pharmacy, Korea University, Sejong, 339-700, Republic of Korea.
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29
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Mycoplasma gallisepticum modifies the pathogenesis of influenza A virus in the avian tracheal epithelium. Int J Med Microbiol 2016; 306:174-86. [PMID: 27079856 DOI: 10.1016/j.ijmm.2016.04.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/30/2016] [Accepted: 04/03/2016] [Indexed: 11/24/2022] Open
Abstract
Multiple respiratory infections have a significant impact on health and economy. Pathogenesis of co-infecting viruses and bacteria and their interaction with mucosal surfaces are poorly characterized. In this study we established a co-infection model based on pre-incubation of tracheal organ cultures (TOC) with Mycoplasma (M.) gallisepticum and a subsequent infection with avian influenza virus (AIV). Mycoplasma gallisepticum modified the pathogenesis of AIV as demonstrated in TOC of two different avian species (chickens and turkeys). Co-infection promoted bacterial growth in tracheal epithelium. Depending on the interaction time of M. gallisepticum with the host cells, AIV replication was either promoted or suppressed. M. gallisepticum inhibited the antiviral gene expression and affected AIV attachment to the host cell by desialylation of α-2,3 linked sialic acids. Ultrastructural analysis of co-infected TOC suggests that both pathogens may attach to and possibly infect the same epithelial cell. The obtained results contribute to better understanding of the interaction dynamics between M. gallisepticum and AIV. They highlight the importance of the time interval between infections as well as the biological properties of the involved pathogens as influencing factors in the outcome of respiratory infections.
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30
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Abdelwhab ESM, Veits J, Breithaupt A, Gohrbandt S, Ziller M, Teifke JP, Stech J, Mettenleiter TC. Prevalence of the C-terminal truncations of NS1 in avian influenza A viruses and effect on virulence and replication of a highly pathogenic H7N1 virus in chickens. Virulence 2016; 7:546-57. [PMID: 26981790 DOI: 10.1080/21505594.2016.1159367] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Highly pathogenic (HP) avian influenza viruses (AIV) evolve from low pathogenic (LP) precursors after circulation in poultry by reassortment and/or single mutations in different gene segments including that encoding NS1. The carboxyl terminal end (CTE) of NS1 exhibits deletions between amino acid 202 and 230 with still unknown impact on virulence of AIV in chickens. In this study, NS1 protein sequences of all AIV subtypes in birds from 1902 to 2015 were analyzed to study the prevalence and distribution of CTE truncation (ΔCTE). Thirteen different ΔCTE forms were observed in NS1 proteins from 11 HA and 8 NA subtypes with high prevalences in H9, H7, H6 and H10 and N9, N2, N6 and N1 subtypes particularly in chickens and minor poultry species. With 88% NS217 lacking amino acids 218-230 was the most common ΔCTE form followed by NS224 (3.6%). NS217 was found in 10 and 8 different HA and NA subtypes, respectively, whereas NS224 was detected exclusively in the Italian HPAIV H7N1 suggesting relevance for virulence. To test this assumption, 3 recombinant HPAIV H7N1 were constructed carrying wild-type HP NS1 (Hp-NS224), NS1 with extended CTE (Hp-NS230) or NS1 from LPAIV H7N1 (Hp-NSLp), and tested in-vitro and in-vivo. Extension of CTE in Hp NS1 significantly decreased virus replication in chicken embryo kidney cells. Truncation in the NS1 decreased the tropism of Hp-NS224 to the endothelium, central nervous system and respiratory tract epithelium without significant difference in virulence in chickens. This study described the variable forms of ΔCTE in NS1 and indicated that CTE is not an essential virulence determinant particularly for the Italian HPAIV H7N1 but may be a host-adaptation marker required for efficient virus replication.
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Affiliation(s)
- El-Sayed M Abdelwhab
- a Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health , Greifswald , Germany
| | - Jutta Veits
- a Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health , Greifswald , Germany
| | - Angele Breithaupt
- b Department of Experimental Animal Facilities and Biorisk Management , Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health , Greifswald , Germany
| | - Sandra Gohrbandt
- a Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health , Greifswald , Germany
| | - Mario Ziller
- c Biomathematics Working Group, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health , Greifswald , Germany
| | - Jens P Teifke
- b Department of Experimental Animal Facilities and Biorisk Management , Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health , Greifswald , Germany
| | - Jürgen Stech
- a Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health , Greifswald , Germany
| | - Thomas C Mettenleiter
- a Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health , Greifswald , Germany
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31
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Neumann G. H5N1 influenza virulence, pathogenicity and transmissibility: what do we know? Future Virol 2015; 10:971-980. [PMID: 26617665 DOI: 10.2217/fvl.15.62] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Highly pathogenic influenza viruses of the H5N1 subtype have infected more than 600 people since 1997, resulting in the deaths of approximately 60% of those infected. Multiple studies have established the viral hemagglutinin (HA) surface glycoprotein as the major determinant of H5N1 virulence. HA mediates host-specific virus binding to cells, and mutations that allow efficient binding to viral receptors on mammalian cells are critical (although not sufficient) for H5N1 transmissibility among mammals. The viral polymerase PB2 protein is also a critical virulence determinant, and adaptive mutations in this protein are crucial for efficient H5N1 virus replication in mammals. Additionally, viral proteins (such as NS1 and PB1-F2) with roles in innate immune responses also affect the virulence of highly pathogenic H5N1 viruses.
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Affiliation(s)
- Gabriele Neumann
- Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 575 Science Drive, Madison, WI 53711, USA; Tel.: +1 608 890 2907; ;
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32
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Schmier S, Mostafa A, Haarmann T, Bannert N, Ziebuhr J, Veljkovic V, Dietrich U, Pleschka S. In Silico Prediction and Experimental Confirmation of HA Residues Conferring Enhanced Human Receptor Specificity of H5N1 Influenza A Viruses. Sci Rep 2015; 5:11434. [PMID: 26091504 PMCID: PMC4473683 DOI: 10.1038/srep11434] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 05/27/2015] [Indexed: 12/01/2022] Open
Abstract
Newly emerging influenza A viruses (IAV) pose a major threat to human health by causing seasonal epidemics and/or pandemics, the latter often facilitated by the lack of pre-existing immunity in the general population. Early recognition of candidate pandemic influenza viruses (CPIV) is of crucial importance for restricting virus transmission and developing appropriate therapeutic and prophylactic strategies including effective vaccines. Often, the pandemic potential of newly emerging IAV is only fully recognized once the virus starts to spread efficiently causing serious disease in humans. Here, we used a novel phylogenetic algorithm based on the informational spectrum method (ISM) to identify potential CPIV by predicting mutations in the viral hemagglutinin (HA) gene that are likely to (differentially) affect critical interactions between the HA protein and target cells from bird and human origin, respectively. Predictions were subsequently validated by generating pseudotyped retrovirus particles and genetically engineered IAV containing these mutations and characterizing potential effects on virus entry and replication in cells expressing human and avian IAV receptors, respectively. Our data suggest that the ISM-based algorithm is suitable to identify CPIV among IAV strains that are circulating in animal hosts and thus may be a new tool for assessing pandemic risks associated with specific strains.
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Affiliation(s)
- Sonja Schmier
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Paul-Ehrlich-Str. 42-44, Frankfurt, Germany
| | - Ahmed Mostafa
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, Giessen, Germany.,Center of Scientific Excellence for Influenza Viruses, National Research Centre (NRC), Dokki, Giza, Egypt
| | - Thomas Haarmann
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Paul-Ehrlich-Str. 42-44, Frankfurt, Germany
| | - Norbert Bannert
- Robert-Koch-Institute, Division for HIV and other Retroviruses, Nordufer 20, Berlin, Germany
| | - John Ziebuhr
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, Giessen, Germany
| | - Veljko Veljkovic
- Centre for Multidisciplinary Research, Institute of Nuclear Sciences VINCA, Mihaila Petrovica 14, Belgrade, Serbia
| | - Ursula Dietrich
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Paul-Ehrlich-Str. 42-44, Frankfurt, Germany
| | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Schubertstrasse 81, Giessen, Germany
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33
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Influenza virus-induced caspase-dependent enlargement of nuclear pores promotes nuclear export of viral ribonucleoprotein complexes. J Virol 2015; 89:6009-21. [PMID: 25810542 DOI: 10.1128/jvi.03531-14] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 03/17/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Influenza A viruses (IAV) replicate their segmented RNA genome in the nucleus of infected cells and utilize caspase-dependent nucleocytoplasmic export mechanisms to transport newly formed ribonucleoprotein complexes (RNPs) to the site of infectious virion release at the plasma membrane. In this study, we obtained evidence that apoptotic caspase activation in IAV-infected cells is associated with the degradation of the nucleoporin Nup153, an integral subunit of the nuclear pore complex. Transmission electron microscopy studies revealed a distinct enlargement of nuclear pores in IAV-infected cells. Transient expression and subcellular accumulation studies of multimeric marker proteins in virus-infected cells provided additional evidence for increased nuclear pore diameters facilitating the translocation of large protein complexes across the nuclear membrane. Furthermore, caspase 3/7 inhibition data obtained in this study suggest that active, Crm1-dependent IAV RNP export mechanisms are increasingly complemented by passive, caspase-induced export mechanisms at later stages of infection. IMPORTANCE In contrast to the process seen with most other RNA viruses, influenza virus genome replication occurs in the nucleus (rather than the cytoplasm) of infected cells. Therefore, completion of the viral replication cycle critically depends on intracellular transport mechanisms that ensure the translocation of viral ribonucleoprotein (RNP) complexes across the nuclear membrane. Here, we demonstrate that virus-induced cellular caspase activities cause a widening of nuclear pores, thereby facilitating nucleocytoplasmic translocation processes and, possibly, promoting nuclear export of newly synthesized RNPs. These passive transport mechanisms are suggested to complement Crm1-dependent RNP export mechanisms known to occur at early stages of the replication cycle and may contribute to highly efficient production of infectious virus progeny at late stages of the viral replication cycle. The report provides an intriguing example of how influenza virus exploits cellular structures and regulatory pathways, including intracellular transport mechanisms, to complete its replication cycle and maximize the production of infectious virus progeny.
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Mao H, Guo B, Wang F, Sun Y, Lou X, Chen Y, Zhang L, Wang X, Li Z, Liu S, Qin S, Wei J, Pang Z, Chen Z, Zhang Y. A study of family clustering in two young girls with novel avian influenza A (H7N9) in Dongyang, Zhejiang Province, in 2014. J Clin Virol 2015; 63:18-24. [DOI: 10.1016/j.jcv.2014.11.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Revised: 11/18/2014] [Accepted: 11/27/2014] [Indexed: 01/25/2023]
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Mostafa A, Kanrai P, Petersen H, Ibrahim S, Rautenschlein S, Pleschka S. Efficient generation of recombinant influenza A viruses employing a new approach to overcome the genetic instability of HA segments. PLoS One 2015; 10:e0116917. [PMID: 25615576 PMCID: PMC4304806 DOI: 10.1371/journal.pone.0116917] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 12/16/2014] [Indexed: 12/14/2022] Open
Abstract
Influenza A viruses (IAVs) are the most relevant and continual source of severe infectious respiratory complications in humans and different animal species, especially poultry. Therefore, an efficient vaccination that elicits protective and neutralizing antibodies against the viral hemagglutinin (HA) and neuraminidase (NA) is an important strategy to counter annual epidemics or occasional pandemics. With the help of plasmid-based reverse genetics technology, it is possible that IAV vaccine strains (IVVS) are rapidly generated. However, the genetic instability of some cloned HA-cDNAs after transformation into competent bacteria represents a major obstacle. Herein, we report efficient cloning strategies of different genetically volatile HA segments (H5- and H9-subtypes) employing either a newly constructed vector for reverse genetics (pMKPccdB) or by the use of the Escherichia coli strain HB101. Both approaches represent improved and generalizable strategies to establish functional reverse genetics systems preventing genetic changes to the cloned (HA) segments of IAV facilitating more efficient rescue of recombinant IAV for basic research and vaccine development.
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Affiliation(s)
- Ahmed Mostafa
- Center of Scientific Excellence for Influenza Viruses, National Research Center (NRC), Cairo, Egypt
| | - Pumaree Kanrai
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany
| | - Henning Petersen
- Clinic for Poultry, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Sherif Ibrahim
- Department of genetic engineering, Veterinary Serum and Vaccines Research Institute (VSVRI), Agricultural Research Center (ARC), Cairo, Egypt
| | - Silke Rautenschlein
- Clinic for Poultry, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany
- * E-mail:
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Westenius V, Mäkelä SM, Ziegler T, Julkunen I, Österlund P. Efficient replication and strong induction of innate immune responses by H9N2 avian influenza virus in human dendritic cells. Virology 2014; 471-473:38-48. [DOI: 10.1016/j.virol.2014.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 07/30/2014] [Accepted: 10/02/2014] [Indexed: 12/22/2022]
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Effects of different NS genes of avian influenza viruses and amino acid changes on pathogenicity of recombinant A/Puerto Rico/8/34 viruses. Vet Microbiol 2014; 175:17-25. [PMID: 25480165 DOI: 10.1016/j.vetmic.2014.11.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 11/04/2014] [Accepted: 11/07/2014] [Indexed: 11/21/2022]
Abstract
To examine the effects of the NS1 and NEP genes of avian influenza viruses (AIVs) on pathogenicity in mice, we generated recombinant PR8 viruses containing 3 different NS genes of AIVs. In contrast to the reverse genetics-generated PR8 (rPR8) strain and other recombinant viruses, the recombinant virus rPR8-NS(0028), which contained the NS gene of A/chicken/KBNP-0028/2000 (H9N2) (0028), was non-pathogenic to mice. The novel single mutations of 0028 NS1 to corresponding amino acid of PR8 NS1, G139D and S151T increased the pathogenicity of rPR8-NS(0028). The replacement of the PL motifs (EPEV or RSEV) of pathogenic recombinant viruses with that of 0028 (GSEV) did not reduce the pathogenicity of the viruses. However, a recombinant virus with an EPEV-grafted 0028 NS gene was more pathogenic than rPR8-NS(0028) but less than rPR8. The lower pathogenicity of rPR8-NS(0028) might be associated with the lower virus titer and IFN-β level in the lungs of infected mice, and be attributed to G139, S151 and GSEV-PL motif of NS1 gene of 0028. In conclusion we defined new amino acid residues of NS1 related to mice pathogenicity and the presence of pathogenic NS genes among low pathogenic AIVs may encourage continuous monitoring of their mammalian pathogenicity.
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Nacken W, Anhlan D, Hrincius ER, Mostafa A, Wolff T, Sadewasser A, Pleschka S, Ehrhardt C, Ludwig S. Activation of c-jun N-terminal kinase upon influenza A virus (IAV) infection is independent of pathogen-related receptors but dependent on amino acid sequence variations of IAV NS1. J Virol 2014; 88:8843-52. [PMID: 24872593 PMCID: PMC4136289 DOI: 10.1128/jvi.00424-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 05/20/2014] [Indexed: 12/28/2022] Open
Abstract
UNLABELLED A hallmark cell response to influenza A virus (IAV) infections is the phosphorylation and activation of c-jun N-terminal kinase (JNK). However, so far it is not fully clear which molecules are involved in the activation of JNK upon IAV infection. Here, we report that the transfection of influenza viral-RNA induces JNK in a retinoic acid-inducible gene I (RIG-I)-dependent manner. However, neither RIG-I-like receptors nor MyD88-dependent Toll-like receptors were found to be involved in the activation of JNK upon IAV infection. Viral JNK activation may be blocked by addition of cycloheximide and heat shock protein inhibitors during infection, suggesting that the expression of an IAV-encoded protein is responsible for JNK activation. Indeed, the overexpression of nonstructural protein 1 (NS1) of certain IAV subtypes activated JNK, whereas those of some other subtypes failed to activate JNK. Site-directed mutagenesis experiments using NS1 of the IAV H7N7, H5N1, and H3N2 subtypes identified the amino acid residue phenylalanine (F) at position 103 to be decisive for JNK activation. Cleavage- and polyadenylation-specific factor 30 (CPSF30), whose binding to NS1 is stabilized by the amino acids F103 and M106, is not involved in JNK activation. Conclusively, subtype-specific sequence variations in the IAV NS1 protein result in subtype-specific differences in JNK signaling upon IAV infection. IMPORTANCE Influenza A virus (IAV) infection leads to the activation or modulation of multiple signaling pathways. Here, we demonstrate for the first time that the c-jun N-terminal kinase (JNK), a long-known stress-activated mitogen-activated protein (MAP) kinase, is activated by RIG-I when cells are treated with IAV RNA. However, at the same time, nonstructural protein 1 (NS1) of IAV has an intrinsic JNK-activating property that is dependent on IAV subtype-specific amino acid variations around position 103. Our findings identify two different and independent pathways that result in the activation of JNK in the course of an IAV infection.
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Affiliation(s)
- Wolfgang Nacken
- Institute of Molecular Virology (IMV), Centre of Molecular Biology of Inflammation (ZMBE), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Darisuren Anhlan
- Institute of Molecular Virology (IMV), Centre of Molecular Biology of Inflammation (ZMBE), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Eike R Hrincius
- Institute of Molecular Virology (IMV), Centre of Molecular Biology of Inflammation (ZMBE), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Ahmed Mostafa
- Virology Laboratory, National Research Center, Cairo, Egypt
| | - Thorsten Wolff
- Division of Influenza and other Respiratory Viruses, Robert Koch Institute (RKI), Berlin, Germany
| | - Anne Sadewasser
- Division of Influenza and other Respiratory Viruses, Robert Koch Institute (RKI), Berlin, Germany
| | - Stephan Pleschka
- Institute of Medical Virology, Justus Liebig University Giessen, Giessen, Germany
| | - Christina Ehrhardt
- Institute of Molecular Virology (IMV), Centre of Molecular Biology of Inflammation (ZMBE), Westfälische Wilhelms-Universität Münster, Münster, Germany Cells in Motion Cluster of Excellence, University of Münster, Münster, Germany
| | - Stephan Ludwig
- Institute of Molecular Virology (IMV), Centre of Molecular Biology of Inflammation (ZMBE), Westfälische Wilhelms-Universität Münster, Münster, Germany Cells in Motion Cluster of Excellence, University of Münster, Münster, Germany
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Xu J, Zhong HA, Madrahimov A, Helikar T, Lu G. Molecular phylogeny and evolutionary dynamics of influenza A nonstructural (NS) gene. INFECTION GENETICS AND EVOLUTION 2014; 22:192-200. [DOI: 10.1016/j.meegid.2013.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 10/01/2013] [Accepted: 10/14/2013] [Indexed: 01/23/2023]
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Abstract
UNLABELLED NS1 of influenza A virus is a potent antagonist of host antiviral interferon responses. This multifunctional protein with two distinctive domains, an RNA-binding domain (RBD) and an effector domain (ED) separated by a linker region (LR), is implicated in replication, pathogenesis, and host range. Although the structures of individual domains of NS1 from different strains of influenza viruses have been reported, the only structure of full-length NS1 available to date is from an H5N1 strain (A/Vietnam/1203/2004). By carrying out crystallographic analyses of full-length H6N6-NS1 (A/blue-winged teal/MN/993/1980) and an LR deletion mutant, combined with mutational analysis, we show here that these full-length NS1 structures provide an exquisite structural sampling of various conformational states of NS1 that based on the orientation of the ED with respect to RBD can be summarized as "open," "semi-open," and "closed" conformations. Our studies show that preference for these states is clearly dictated by determinants such as linker length, residue composition at position 71, and a mechanical hinge, providing a structural basis for strain-dependent functional variations in NS1. Because of the flexibility inherent in the LR, any particular NS1 could sample the conformational space around these states to engage ED in different quaternary interactions so that it may participate in specific protein-protein or protein-RNA interactions to allow for the known multifunctionality of NS1. We propose that such conformational plasticity provides a mechanism for autoregulating NS1 functions, depending on its temporal distribution, posttranslational modifications, and nuclear or cellular localization, during the course of virus infection. IMPORTANCE NS1 of influenza A virus is a multifunctional protein associated with numerous strain-specific regulatory functions during viral infection, including conferring resistance to antiviral interferon induction, replication, pathogenesis, virulence, and host range. NS1 has two domains, an RNA-binding domain and an effector domain separated by a linker. To date, the only full-length NS1 structure available is that from an H5N1 strain (A/Vietnam/1203/2004). Here, we determined crystal structures of the wild type and a linker region mutant of the H6N6 NS1 (A/blue-winged teal/MN/993/1980), which together with the previously determined H5N1 NS1 structure show that NS1 exhibits significant strain-dependent structural polymorphism due to variations in linker length, residue composition at position 71, and a mechanical hinge. Such a structural polymorphism may be the basis for strain-specific functions associated with NS1.
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Vergara-Alert J, Busquets N, Ballester M, Chaves AJ, Rivas R, Dolz R, Wang Z, Pleschka S, Majó N, Rodríguez F, Darji A. The NS segment of H5N1 avian influenza viruses (AIV) enhances the virulence of an H7N1 AIV in chickens. Vet Res 2014; 45:7. [PMID: 24460592 PMCID: PMC3922795 DOI: 10.1186/1297-9716-45-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 01/17/2014] [Indexed: 12/25/2022] Open
Abstract
Some outbreaks involving highly pathogenic avian influenza viruses (HPAIV) of subtypes H5 and H7 were caused by avian-to-human transmissions. In nature, different influenza A viruses can reassort leading to new viruses with new characteristics. We decided to investigate the impact that the NS-segment of H5 HPAIV would have on viral pathogenicity of a classical avian H7 HPAIV in poultry, a natural host. We focussed this study based on our previous work that demonstrated that single reassortment of the NS-segment from an H5 HPAIV into an H7 HPAIV changes the ability of the virus to replicate in mammalian hosts. Our present data show that two different H7-viruses containing an NS-segment from H5–types (FPV NS GD or FPV NS VN) show an overall highly pathogenic phenotype compared with the wild type H7–virus (FPV), as characterized by higher viral shedding and earlier manifestation of clinical signs. Correlating with the latter, higher amounts of IFN-β mRNA were detected in the blood of NS-reassortant infected birds, 48 h post-infection (pi). Although lymphopenia was detected in chickens from all AIV-infected groups, also 48 h pi those animals challenged with NS-reassortant viruses showed an increase of peripheral monocyte/macrophage-like cells expressing high levels of IL-1β, as determined by flow cytometry. Taken together, these findings highlight the importance of the NS-segment in viral pathogenicity which is directly involved in triggering antiviral and pro-inflammatory cytokines found during HPAIV pathogenesis in chickens.
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Affiliation(s)
- Júlia Vergara-Alert
- Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès 08193, Spain.
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Abstract
Influenza has been recognized as a respiratory disease in swine since its first appearance concurrent with the 1918 "Spanish flu" human pandemic. All influenza viruses of significance in swine are type A, subtype H1N1, H1N2, or H3N2 viruses. Influenza viruses infect epithelial cells lining the surface of the respiratory tract, inducing prominent necrotizing bronchitis and bronchiolitis and variable interstitial pneumonia. Cell death is due to direct virus infection and to insult directed by leukocytes and cytokines of the innate immune system. The most virulent viruses consistently express the following characteristics of infection: (1) higher or more prolonged virus replication, (2) excessive cytokine induction, and (3) replication in the lower respiratory tract. Nearly all the viral proteins contribute to virulence. Pigs are susceptible to infection with both human and avian viruses, which often results in gene reassortment between these viruses and endemic swine viruses. The receptors on the epithelial cells lining the respiratory tract are major determinants of infection by influenza viruses from other hosts. The polymerases, especially PB2, also influence cross-species infection. Methods of diagnosis and characterization of influenza viruses that infect swine have improved over the years, driven both by the availability of new technologies and by the necessity of keeping up with changes in the virus. Testing of oral fluids from pigs for virus and antibody is a recent development that allows efficient sampling of large numbers of animals.
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Affiliation(s)
- B H Janke
- DVM, PhD, Veterinary Diagnostic Laboratory, Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
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43
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Tripathi S, White MR, Hartshorn KL. The amazing innate immune response to influenza A virus infection. Innate Immun 2013; 21:73-98. [PMID: 24217220 DOI: 10.1177/1753425913508992] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Influenza A viruses (IAVs) remain a major health threat and a prime example of the significance of innate immunity. Our understanding of innate immunity to IAV has grown dramatically, yielding new concepts that change the way we view innate immunity as a whole. Examples include the role of p53, autophagy, microRNA, innate lymphocytes, endothelial cells and gut commensal bacteria in pulmonary innate immunity. Although the innate response is largely beneficial, it also contributes to major complications of IAV, including lung injury, bacterial super-infection and exacerbation of reactive airways disease. Research is beginning to dissect out which components of the innate response are helpful or harmful. IAV uses its limited genetic complement to maximum effect. Several viral proteins are dedicated to combating innate responses, while other viral structural or replication proteins multitask as host immune modulators. Many host innate immune proteins also multitask, having roles in cell cycle, signaling or normal lung biology. We summarize the plethora of new findings and attempt to integrate them into the larger picture of how humans have adapted to the threat posed by this remarkable virus. We explore how our expanded knowledge suggests ways to modulate helpful and harmful inflammatory responses, and develop novel treatments.
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Affiliation(s)
- Shweta Tripathi
- Boston University School of Medicine, Department of Medicine, Boston, MA, USA
| | - Mitchell R White
- Boston University School of Medicine, Department of Medicine, Boston, MA, USA
| | - Kevan L Hartshorn
- Boston University School of Medicine, Department of Medicine, Boston, MA, USA
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Abdelwhab EM, Veits J, Mettenleiter TC. Avian influenza virus NS1: A small protein with diverse and versatile functions. Virulence 2013; 4:583-8. [PMID: 24051601 PMCID: PMC3906290 DOI: 10.4161/viru.26360] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Affiliation(s)
- E M Abdelwhab
- Friedrich-Loeffler-Institut; Federal Research Institute for Animal Health; Institute of Molecular Biology; Insel Riems, Germany
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45
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Yiu Lai K, Wing Yiu Ng G, Fai Wong K, Fan Ngai Hung I, Kam Fai Hong J, Fan Cheng F, Kwok Cheung Chan J. Human H7N9 avian influenza virus infection: a review and pandemic risk assessment. Emerg Microbes Infect 2013; 2:e48. [PMID: 26038484 PMCID: PMC3824111 DOI: 10.1038/emi.2013.48] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 06/12/2013] [Accepted: 06/18/2013] [Indexed: 12/20/2022]
Abstract
China is undergoing a recent outbreak of a novel H7N9 avian influenza virus (nH7N9) infection that has thus far involved 132 human patients, including 37 deaths. The nH7N9 virus is a reassortant virus originating from the H7N3, H7N9 and H9N2 avian influenza viruses. nH7N9 isolated from humans contains features related to adaptation to humans, including a Q226L mutation in the hemagglutinin cleavage site and E627K and D701N mutations in the PB2 protein. Live poultry markets provide an environment for the emergence, spread and maintenance of nH7N9 as well as for the selection of mutants that facilitate nH7N9 binding to and replication in the human upper respiratory tract. Innate immune suppression conferred by the internal genes of H9N2 may contribute to the virulence of nH7N9. The quail may serve as the intermediate host during the adaptation of avian influenza viruses from domestic waterfowl to gallinaceous poultry, such as chickens and related terrestrial-based species, due to the selection of viral mutants with a short neuraminidase stalk. Infections in chickens, common quails, red-legged partridges and turkeys may select for mutants with human receptor specificity. Infection in Ratitae species may lead to the selection of PB2-E627K and PB2-D701N mutants and the conversion of nH7N9 to a highly pathogenic avian influenza virus.
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Affiliation(s)
- Kang Yiu Lai
- Department of Intensive Care, Queen Elizabeth Hospital , Hong Kong, China
| | - George Wing Yiu Ng
- Department of Intensive Care, Queen Elizabeth Hospital , Hong Kong, China
| | - Kit Fai Wong
- Department of Pathology, Queen Elizabeth Hospital , Hong Kong, China
| | | | | | - Fanny Fan Cheng
- Department of Medicine, Queen Elizabeth Hospital , Hong Kong, China
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Mostafa A, Kanrai P, Ziebuhr J, Pleschka S. Improved dual promotor-driven reverse genetics system for influenza viruses. J Virol Methods 2013; 193:603-10. [PMID: 23886561 DOI: 10.1016/j.jviromet.2013.07.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 07/01/2013] [Accepted: 07/10/2013] [Indexed: 12/25/2022]
Abstract
Reverse genetic systems for influenza A virus (IAV) allow the generation of genetically manipulated infectious virus from a set of transfected plasmid DNAs encoding the eight genomic viral RNA segments (vRNA). For this purpose, cDNAs representing these eight vRNA segments are cloned into specific plasmid vectors that allow the generation of vRNA-like transcripts using polymerase I (Pol I). In addition, these plasmids support the transcription of viral mRNA by polymerase II (Pol II), leading to the expression of viral protein(s) encoded by the respective transcripts. In an effort to develop this system further, we constructed the bi-directional vector pMPccdB. It is based on pHW2000 (Hoffmann et al., 2000b) but contains additionally (i) the ccdB gene whose expression is lethal for most Escherichia coli strains and therefore used as a negative selection marker and (ii) more efficient AarI cloning sites that flank the ccdB gene on either side. Furthermore, we used a modified one-step restriction/ligation protocol to insert the desired cDNA into the respective pMPccdB vector DNA. Both the use of a negative selection marker and an improved cloning protocol were shown to facilitate the generation of genetically engineered IAV as illustrated in this study by the cloning and rescue of the 2009 pandemic isolate A/Giessen/6/2009 (Gi-H1N1).
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Affiliation(s)
- Ahmed Mostafa
- Institute of Medical Virology, Justus Liebig University Giessen, BFS, Schubertstrasse 81, 35392 Giessen, Germany; Virology Laboratory, Environmental Research Division, National Research Center, 12311 Dokki, Giza, Egypt.
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47
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Stech J, Mettenleiter TC. Virulence determinants of high-pathogenic avian influenza viruses in gallinaceous poultry. Future Virol 2013. [DOI: 10.2217/fvl.13.27] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
High-pathogenic avian influenza viruses (HPAIV) cause devastating outbreaks in domestic poultry worldwide. Moreover, they repeatedly lead to severe, even fatal disease in humans, raising concerns about their pandemic potential. HPAIV have evolved from circulating low-pathogenic precursors in several independent events by spontaneous acquisition of a polybasic cleavage site in the hemagglutinin (HA) envelope protein. Remarkably, in nature, HPAIV are confined to the HA serotypes H5 and H7 from the 16 HA serotypes known in birds. However, experimental introduction of a polybasic cleavage site into non-H5/H7 HA may result in a highly pathogenic phenotype, indicating that emergence of HPAIV with novel serotypes is conceivable, but requires further adaptation to the chicken host.
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Affiliation(s)
- Jürgen Stech
- Institute of Molecular Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, 17493 Greifswald-Insel Riems, Germany
| | - Thomas C Mettenleiter
- Institute of Molecular Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, 17493 Greifswald-Insel Riems, Germany
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Reassortment of NS segments modifies highly pathogenic avian influenza virus interaction with avian hosts and host cells. J Virol 2013; 87:5362-71. [PMID: 23468508 DOI: 10.1128/jvi.02969-12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Highly pathogenic avian influenza viruses (HPAIV) of subtypes H5 and H7 have caused numerous outbreaks in diverse poultry species and rising numbers of human infections. Both HPAIV subtypes support a growing concern of a pandemic outbreak, specifically via the avian-human link. Natural reassortment of both HPAIV subtypes is a possible event with unpredictable outcome for virulence and host specificity of the progeny virus for avian and mammalian species. NS reassortment of H5N1 HPAIV viruses in the background of A/FPV/Rostock/1934 (H7N1) HPAIV has been shown to change virus replication kinetics and host cell responses in mammalian cells. However, not much is known about the virus-host interaction of such viruses in avian species. In the present study, we show that the NS segment of A/Vietnam/1203/2004 (FPV NS VN, H5N1) HPAIV significantly altered the characteristics of the H7 prototype HPAIV in tracheal organ cultures (TOC) of chicken and turkey in vitro, with decreased replication efficiency accompanied by increased induction of type I interferon (IFN) and apoptosis. Furthermore, species-specific differences between chicken and turkey were demonstrated. Interestingly, NS-reassortant FPV NS VN showed an overall highly pathogenic phenotype, with increased virulence and replication potential compared to the wild-type virus after systemic infection of chicken and turkey embryos. Our data demonstrate that single reassortment of an H5-type NS into an H7-type HPAIV significantly changed virus replication abilities and influenced the avian host cell response without prior adaptation.
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49
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Exposure to a low pathogenic A/H7N2 virus in chickens protects against highly pathogenic A/H7N1 virus but not against subsequent infection with A/H5N1. PLoS One 2013; 8:e58692. [PMID: 23469288 PMCID: PMC3587606 DOI: 10.1371/journal.pone.0058692] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 02/05/2013] [Indexed: 11/22/2022] Open
Abstract
Recent evidences have demonstrated that the presence of low pathogenic avian influenza viruses (LPAIV) may play an important role in host ecology and transmission of avian influenza viruses (AIV). While some authors have clearly demonstrated that LPAIV can mutate to render highly pathogenic avian influenza viruses (HPAIV), others have shown that their presence could provide the host with enough immunological memory to resist re-infections with HPAIV. In order to experimentally study the role of pre-existing host immunity, chickens previously infected with H7N2 LPAIV were subsequently challenged with H7N1 HPAIV. Pre-infection of chickens with H7N2 LAPIV conferred protection against the lethal challenge with H7N1 HPAIV, dramatically reducing the viral shedding, the clinical signs and the pathological outcome. Correlating with the protection afforded, sera from chickens primed with H7N2 LPAIV reacted with the H7-AIV subtype in hemagglutination inhibition assay and specifically with the N2-neuraminidase antigen. Conversely, subsequent exposure to H5N1 HPAIV resulted in a two days-delay on the onset of disease but all chickens died by 7 days post-challenge. Lack of protection correlated with the absence of H5-hemagglutining inhibitory antibodies prior to H5N1 HPAIV challenge. Our data suggest that in naturally occurring outbreaks of HPAIV, birds with pre-existing immunity to LPAIV could survive lethal infections with HA-homologous HPAIV but not subsequent re-infections with HA-heterologous HPAIV. These results could be useful to better understand the dynamics of AIV in chickens and might help in future vaccine formulations.
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Zhu C, Zheng F, Sun T, Duan Y, Cao J, Feng H, Shang L, Zhu Y, Liu H. Interaction of avian influenza virus NS1 protein and nucleolar and coiled-body phosphoprotein 1. Virus Genes 2012. [PMID: 23188192 PMCID: PMC3610028 DOI: 10.1007/s11262-012-0849-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Nonstructural protein 1 (NS1) is a non-structural protein of avian influenza virus. It can interact with a variety of proteins of the host cells, enhancing the expression of viral proteins and changing the growth and metabolism of the host cells, thereby enhancing the virus’ pathogenicity and virulence. To investigate whether there are more host proteins that can interact with NS1 during viral infection, T7-phage display system was used to screen human lung cell cDNA library for proteins that could interact with NS1. One positive and specific clone was obtained and identified as nucleolar and coiled-body phosphoprotein 1(NOLC1). The interaction between these two proteins was further demonstrated by His-pull-down and co-immunoprecipitation experiments. Co-expression of both proteins in HeLa cell showed that NS1 and NOLC1 were co-localized in the cell’s nucleus. Gene truncation experiments revealed that the effector domain of NS1 was sufficient to interact with NOLC1. The results demonstrated a positive interaction between a viral NS1 and NOLC1 of the host cells, and provided a new target for drug screening.
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Affiliation(s)
- Chunyu Zhu
- Key Laboratory of Animal Resource and Epidemic Disease Prevention, Life Science School of Liaoning University, Shenyang 110036, China
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