1
|
Ciminski K, Flore V, Jakob C, Mues H, Smedegaard Frederiksen A, Schwemmle M, Bolte H, Giese S. Functionality of IAV packaging signals depends on site-specific charges within the viral nucleoprotein. J Virol 2024; 98:e0197223. [PMID: 38470155 PMCID: PMC11019843 DOI: 10.1128/jvi.01972-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 02/20/2024] [Indexed: 03/13/2024] Open
Abstract
The coordinated packaging of the segmented genome of the influenza A virus (IAV) into virions is an essential step of the viral life cycle. This process is controlled by the interaction of packaging signals present in all eight viral RNA (vRNA) segments and the viral nucleoprotein (NP), which binds vRNA via a positively charged binding groove. However, mechanistic models of how the packaging signals and NP work together to coordinate genome packaging are missing. Here, we studied genome packaging in influenza A/SC35M virus mutants that carry mutated packaging signals as well as specific amino acid substitutions at the highly conserved lysine (K) residues 184 and 229 in the RNA-binding groove of NP. Because these lysines are acetylated and thus neutrally charged in infected host cells, we replaced them with glutamine to mimic the acetylated, neutrally charged state or arginine to mimic the non-acetylated, positively charged state. Our analysis shows that the coordinated packaging of eight vRNAs is influenced by (i) the charge state of the replacing amino acid and (ii) its location within the RNA-binding groove. Accordingly, we propose that lysine acetylation induces different charge states within the RNA-binding groove of NP, thereby supporting the activity of specific packaging signals during coordinated genome packaging. IMPORTANCE Influenza A viruses (IAVs) have a segmented viral RNA (vRNA) genome encapsidated by multiple copies of the viral nucleoprotein (NP) and organized into eight distinct viral ribonucleoprotein complexes. Although genome segmentation contributes significantly to viral evolution and adaptation, it requires a highly sophisticated genome-packaging mechanism. How eight distinct genome complexes are incorporated into the virion is poorly understood, but previous research suggests an essential role for both vRNA packaging signals and highly conserved NP amino acids. By demonstrating that the packaging process is controlled by charge-dependent interactions of highly conserved lysine residues in NP and vRNA packaging signals, our study provides new insights into the sophisticated packaging mechanism of IAVs.
Collapse
Affiliation(s)
- Kevin Ciminski
- Institute of Virology, Freiburg University Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Viktoria Flore
- Institute of Virology, Freiburg University Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Celia Jakob
- Institute of Virology, Freiburg University Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Helen Mues
- Institute of Virology, Freiburg University Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anne Smedegaard Frederiksen
- Institute of Virology, Freiburg University Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Martin Schwemmle
- Institute of Virology, Freiburg University Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Hardin Bolte
- Institute of Virology, Freiburg University Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian Giese
- Institute of Virology, Freiburg University Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| |
Collapse
|
2
|
Yang R, Pan M, Guo J, Huang Y, Zhang QC, Deng T, Wang J. Mapping of the influenza A virus genome RNA structure and interactions reveals essential elements of viral replication. Cell Rep 2024; 43:113833. [PMID: 38416642 DOI: 10.1016/j.celrep.2024.113833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 12/04/2023] [Accepted: 02/02/2024] [Indexed: 03/01/2024] Open
Abstract
Influenza A virus (IAV) represents a constant public health threat. The single-stranded, segmented RNA genome of IAV is replicated in host cell nuclei as a series of 8 ribonucleoprotein complexes (vRNPs) with RNA structures known to exert essential function to support viral replication. Here, we investigate RNA secondary structures and RNA interactions networks of the IAV genome and construct an in vivo structure model for each of the 8 IAV genome segments. Our analyses reveal an overall in vivo and in virio resemblance of the IAV genome conformation but also wide disparities among long-range and intersegment interactions. Moreover, we identify a long-range RNA interaction that exerts an essential role in genome packaging. Disrupting this structure displays reduced infectivity, attenuating virus pathogenicity in mice. Our findings characterize the in vivo RNA structural landscape of the IAV genome and reveal viral RNA structures that can be targeted to develop antiviral interventions.
Collapse
Affiliation(s)
- Rui Yang
- The State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Minglei Pan
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China
| | - Jiamei Guo
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yong Huang
- The State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qiangfeng Cliff Zhang
- The State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Tao Deng
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China; CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Jianwei Wang
- NHC Key Laboratory of Systems Biology of Pathogens and Christophe Mérieux Laboratory, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China; Key Laboratory of Respiratory Disease Pathogenomics, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
| |
Collapse
|
3
|
Carter T, Iqbal M. The Influenza A Virus Replication Cycle: A Comprehensive Review. Viruses 2024; 16:316. [PMID: 38400091 PMCID: PMC10892522 DOI: 10.3390/v16020316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/15/2024] [Accepted: 02/17/2024] [Indexed: 02/25/2024] Open
Abstract
Influenza A virus (IAV) is the primary causative agent of influenza, colloquially called the flu. Each year, it infects up to a billion people, resulting in hundreds of thousands of human deaths, and causes devastating avian outbreaks with worldwide losses worth billions of dollars. Always present is the possibility that a highly pathogenic novel subtype capable of direct human-to-human transmission will spill over into humans, causing a pandemic as devastating if not more so than the 1918 influenza pandemic. While antiviral drugs for influenza do exist, they target very few aspects of IAV replication and risk becoming obsolete due to antiviral resistance. Antivirals targeting other areas of IAV replication are needed to overcome this resistance and combat the yearly epidemics, which exact a serious toll worldwide. This review aims to summarise the key steps in the IAV replication cycle, along with highlighting areas of research that need more focus.
Collapse
Affiliation(s)
- Toby Carter
- The Pirbright Institute, Ash Road, Pirbright, Woking GU24 0NF, UK;
| | | |
Collapse
|
4
|
Girard J, Jakob C, Toews LK, Fuchs J, Pohlmann A, Franzke K, Kolesnikova L, Jeney C, Beer M, Bron P, Schwemmle M, Bolte H. Disruption of influenza virus packaging signals results in various misassembled genome complexes. J Virol 2023; 97:e0107623. [PMID: 37811996 PMCID: PMC10617545 DOI: 10.1128/jvi.01076-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 08/25/2023] [Indexed: 10/10/2023] Open
Abstract
IMPORTANCE The influenza A virus genome consists of eight distinct viral RNAs (vRNAs) that are typically packaged into a single virion as an octameric complex. How this genome complex is assembled and incorporated into the virion is poorly understood, but previous research suggests a coordinative role for packaging signals present in all vRNAs. Here, we show that disruption of two packaging signals in a model H7N7 influenza A virus results in a mixture of virions with unusual vRNA content, including empty virions, virions with one to four vRNAs, and virions with octameric complexes composed of vRNA duplicates. Our results suggest that (i) the assembly of error-free octameric complexes proceeds through a series of defined vRNA sub-complexes and (ii) virions can bud without incorporating complete octameric complexes.
Collapse
Affiliation(s)
- Justine Girard
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Celia Jakob
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Lina Kathrin Toews
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jonas Fuchs
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anne Pohlmann
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Greifswald, Germany
| | - Kati Franzke
- Institute of Infectology, Friedrich-Loeffler-Institut, Greifswald, Germany
| | | | | | - Martin Beer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Greifswald, Germany
| | - Patrick Bron
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Martin Schwemmle
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Hardin Bolte
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| |
Collapse
|
5
|
Jakob C, Lovate GL, Desirò D, Gießler L, Smyth R, Marquet R, Lamkiewicz K, Marz M, Schwemmle M, Bolte H. Sequential disruption of SPLASH-identified vRNA-vRNA interactions challenges their role in influenza A virus genome packaging. Nucleic Acids Res 2023; 51:6479-6494. [PMID: 37224537 PMCID: PMC10325904 DOI: 10.1093/nar/gkad442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/02/2023] [Accepted: 05/10/2023] [Indexed: 05/26/2023] Open
Abstract
A fundamental step in the influenza A virus (IAV) replication cycle is the coordinated packaging of eight distinct genomic RNA segments (i.e. vRNAs) into a viral particle. Although this process is thought to be controlled by specific vRNA-vRNA interactions between the genome segments, few functional interactions have been validated. Recently, a large number of potentially functional vRNA-vRNA interactions have been detected in purified virions using the RNA interactome capture method SPLASH. However, their functional significance in coordinated genome packaging remains largely unclear. Here, we show by systematic mutational analysis that mutant A/SC35M (H7N7) viruses lacking several prominent SPLASH-identified vRNA-vRNA interactions involving the HA segment package the eight genome segments as efficiently as the wild-type virus. We therefore propose that the vRNA-vRNA interactions identified by SPLASH in IAV particles are not necessarily critical for the genome packaging process, leaving the underlying molecular mechanism elusive.
Collapse
Affiliation(s)
- Celia Jakob
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Gabriel L Lovate
- RNA Bioinformatics and High-Throughput Analysis, Faculty of Mathematics and Computer Science, Friedrich Schiller University Jena, Germany
| | - Daniel Desirò
- Department of Biochemistry, University of Cambridge, CambridgeCB2 1QW, UK
| | - Lara Gießler
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
| | - Redmond P Smyth
- Helmholtz Institute for RNA-based Infection Research, Helmholtz Centre for Infection Research, Würzburg, Germany
- Julius-Maximilians-Universität Würzburg, Faculty of Medicine, Würzburg, Germany
| | - Roland Marquet
- Architecture et Réactivité de l’ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Kevin Lamkiewicz
- RNA Bioinformatics and High-Throughput Analysis, Faculty of Mathematics and Computer Science, Friedrich Schiller University Jena, Germany
- German Center for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig, Germany
- European Virus Bioinformatics Center (EVBC), Jena, Germany
| | - Manja Marz
- RNA Bioinformatics and High-Throughput Analysis, Faculty of Mathematics and Computer Science, Friedrich Schiller University Jena, Germany
- German Center for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig, Germany
- European Virus Bioinformatics Center (EVBC), Jena, Germany
- FLI Leibniz Institute for Age Research, Jena, Germany
| | - Martin Schwemmle
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Hardin Bolte
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| |
Collapse
|
6
|
Yang L, Zhang Y, Yi W, Dong X, Niu M, Song Y, Han Y, Li H, Sun Y. A rapid and efficient platform for antiviral crRNA screening using CRISPR-Cas13a-based nucleic acid detection. Front Immunol 2023; 14:1116230. [PMID: 37228594 PMCID: PMC10203571 DOI: 10.3389/fimmu.2023.1116230] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 04/24/2023] [Indexed: 05/27/2023] Open
Abstract
Introduction Rapid and high-throughput screening of antiviral clustered regularly interspaced short palindromic repeat (CRISPR) RNAs (crRNAs) is urgently required for the CRISPR-Cas13a antiviral system. Based on the same principle, we established an efficient screening platform for antiviral crRNA through CRISPR-Cas13a nucleic acid detection. Method In this study, crRNAs targeting PA, PB1, NP, and PB2 of the influenza A virus (H1N1) were screened using CRISPR-Cas13a nucleic acid detection, and their antiviral effects were confirmed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The RNA secondary structures were predicted by bioinformatics methods. Results The results showed that crRNAs screened by CRISPR-Cas13a nucleic acid detection could effectively inhibit viral RNA in mammalian cells. Besides, we found that this platform for antiviral crRNA screening was more accurate than RNA secondary structure prediction. In addition, we validated the feasibility of the platform by screening crRNAs targeting NS of the influenza A virus (H1N1). Discussion This study provides a new approach for screening antiviral crRNAs and contributes to the rapid advancement of the CRISPR-Cas13a antiviral system.
Collapse
Affiliation(s)
- Lan Yang
- State Key Laboratory of Pathogens and Biosafety, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Youcui Zhang
- State Key Laboratory of Pathogens and Biosafety, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fujian, China
| | - Wenyanbo Yi
- State Key Laboratory of Pathogens and Biosafety, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xue Dong
- State Key Laboratory of Pathogens and Biosafety, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Mengwei Niu
- State Key Laboratory of Pathogens and Biosafety, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yingjie Song
- State Key Laboratory of Pathogens and Biosafety, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yao Han
- State Key Laboratory of Pathogens and Biosafety, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Hao Li
- State Key Laboratory of Pathogens and Biosafety, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yansong Sun
- State Key Laboratory of Pathogens and Biosafety, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| |
Collapse
|
7
|
Mirska B, Woźniak T, Lorent D, Ruszkowska A, Peterson JM, Moss WN, Mathews DH, Kierzek R, Kierzek E. In vivo secondary structural analysis of Influenza A virus genomic RNA. Cell Mol Life Sci 2023; 80:136. [PMID: 37131079 PMCID: PMC10153785 DOI: 10.1007/s00018-023-04764-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 03/19/2023] [Accepted: 03/19/2023] [Indexed: 05/04/2023]
Abstract
Influenza A virus (IAV) is a respiratory virus that causes epidemics and pandemics. Knowledge of IAV RNA secondary structure in vivo is crucial for a better understanding of virus biology. Moreover, it is a fundament for the development of new RNA-targeting antivirals. Chemical RNA mapping using selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) coupled with Mutational Profiling (MaP) allows for the thorough examination of secondary structures in low-abundance RNAs in their biological context. So far, the method has been used for analyzing the RNA secondary structures of several viruses including SARS-CoV-2 in virio and in cellulo. Here, we used SHAPE-MaP and dimethyl sulfate mutational profiling with sequencing (DMS-MaPseq) for genome-wide secondary structure analysis of viral RNA (vRNA) of the pandemic influenza A/California/04/2009 (H1N1) strain in both in virio and in cellulo environments. Experimental data allowed the prediction of the secondary structures of all eight vRNA segments in virio and, for the first time, the structures of vRNA5, 7, and 8 in cellulo. We conducted a comprehensive structural analysis of the proposed vRNA structures to reveal the motifs predicted with the highest accuracy. We also performed a base-pairs conservation analysis of the predicted vRNA structures and revealed many highly conserved vRNA motifs among the IAVs. The structural motifs presented herein are potential candidates for new IAV antiviral strategies.
Collapse
Affiliation(s)
- Barbara Mirska
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Tomasz Woźniak
- Institute of Human Genetics, Polish Academy of Sciences, Strzeszynska 32, 60-479, Poznan, Poland
| | - Dagny Lorent
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Agnieszka Ruszkowska
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Jake M Peterson
- Roy J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Walter N Moss
- Roy J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - David H Mathews
- Department of Biochemistry & Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Avenue, Box 712, Rochester, NY, 14642, USA
| | - Ryszard Kierzek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Elzbieta Kierzek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland.
| |
Collapse
|
8
|
Du R, Cui Q, Chen Z, Zhao X, Lin X, Rong L. Revisiting influenza A virus life cycle from a perspective of genome balance. Virol Sin 2023; 38:1-8. [PMID: 36309307 PMCID: PMC10006207 DOI: 10.1016/j.virs.2022.10.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/18/2022] [Indexed: 11/06/2022] Open
Abstract
Influenza A virus (IAV) genome comprises eight negative-sense RNA segments, of which the replication is well orchestrated and the delicate balance of multiple segments are dynamically regulated throughout IAV life cycle. However, previous studies seldom discuss these balances except for functional hemagglutinin-neuraminidase balance that is pivotal for both virus entry and release. Therefore, we attempt to revisit IAV life cycle by highlighting the critical role of "genome balance". Moreover, we raise a "balance regression" model of IAV evolution that the virus evolves to rebalance its genome after reassortment or interspecies transmission, and direct a "balance compensation" strategy to rectify the "genome imbalance" as a result of artificial modifications during creation of recombinant IAVs. This review not only improves our understanding of IAV life cycle, but also facilitates both basic and applied research of IAV in future.
Collapse
Affiliation(s)
- Ruikun Du
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250355, China; Qingdao Academy of Chinese Medicinal Sciences, Shandong University of Traditional Chinese Medicine, Qingdao, 266122, China.
| | - Qinghua Cui
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250355, China; Qingdao Academy of Chinese Medicinal Sciences, Shandong University of Traditional Chinese Medicine, Qingdao, 266122, China
| | - Zinuo Chen
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan, 250355, China
| | - Xiujuan Zhao
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250355, China
| | - Xiaojing Lin
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan, 250355, China
| | - Lijun Rong
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, 60612, USA.
| |
Collapse
|
9
|
Adaptive evolution of PB1 from influenza A(H1N1)pdm09 virus towards an enhanced fitness. Virology 2023; 578:1-6. [PMID: 36423573 DOI: 10.1016/j.virol.2022.11.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 11/18/2022]
Abstract
PB1 influenza virus retain traces of interspecies transmission and adaptation. Previous phylogenetic analyses highlighted mutations L298I, R386K and I517V in PB1 to have putatively ameliorated the A(H1N1)pdm09 adaptation to the human host. This study aimed to evaluate the reversal of these mutations and infer the role of these residues in the virus overall fitness and adaptation. We generate PB1-mutated viruses introducing I298L, K386R and V517I mutations in PB1 and evaluate their phenotypic impact on viral growth and on antigen yield. We observed a decrease in viral growth accompanied by a reduction in hemagglutination titer and neuraminidase activity, in comparison with wt. Our data indicate that the adaptive evolution occurred in the PB1 leads to an improved overall viral fitness; and such biologic advantaged has the potential to be applied to the optimization of influenza vaccine seed prototypes.
Collapse
|
10
|
Jakob C, Paul-Stansilaus R, Schwemmle M, Marquet R, Bolte H. The influenza A virus genome packaging network - complex, flexible and yet unsolved. Nucleic Acids Res 2022; 50:9023-9038. [PMID: 35993811 PMCID: PMC9458418 DOI: 10.1093/nar/gkac688] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/19/2022] [Accepted: 08/18/2022] [Indexed: 12/24/2022] Open
Abstract
The genome of influenza A virus (IAV) consists of eight unique viral RNA segments. This genome organization allows genetic reassortment between co-infecting IAV strains, whereby new IAVs with altered genome segment compositions emerge. While it is known that reassortment events can create pandemic IAVs, it remains impossible to anticipate reassortment outcomes with pandemic prospects. Recent research indicates that reassortment is promoted by a viral genome packaging mechanism that delivers the eight genome segments as a supramolecular complex into the virus particle. This finding holds promise of predicting pandemic IAVs by understanding the intermolecular interactions governing this genome packaging mechanism. Here, we critically review the prevailing mechanistic model postulating that IAV genome packaging is orchestrated by a network of intersegmental RNA-RNA interactions. Although we find supporting evidence, including segment-specific packaging signals and experimentally proposed RNA-RNA interaction networks, this mechanistic model remains debatable due to a current shortage of functionally validated intersegmental RNA-RNA interactions. We speculate that identifying such functional intersegmental RNA-RNA contacts might be hampered by limitations of the utilized probing techniques and the inherent complexity of the genome packaging mechanism. Nevertheless, we anticipate that improved probing strategies combined with a mutagenesis-based validation could facilitate their discovery.
Collapse
Affiliation(s)
| | | | - Martin Schwemmle
- To whom correspondence should be addressed. Tel: +49 761 203 6526; Fax: +49 761 203 6626;
| | - Roland Marquet
- Correspondence may also be addressed to Roland Marquet. Tel: +33 3 88 41 70 54; Fax: +33 3 88 60 22 18;
| | - Hardin Bolte
- Institute of Virology, Medical Center – University of Freiburg, 79104 Freiburg, Germany,Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
| |
Collapse
|
11
|
Diefenbacher M, Tan TJC, Bauer DLV, Stadtmueller BM, Wu NC, Brooke CB. Interactions between Influenza A Virus Nucleoprotein and Gene Segment Untranslated Regions Facilitate Selective Modulation of Viral Gene Expression. J Virol 2022; 96:e0020522. [PMID: 35467364 PMCID: PMC9131868 DOI: 10.1128/jvi.00205-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/29/2022] [Indexed: 11/20/2022] Open
Abstract
The influenza A virus (IAV) genome is divided into eight negative-sense, single-stranded RNA segments. Each segment exhibits a unique level and temporal pattern of expression; however, the exact mechanisms underlying the patterns of individual gene segment expression are poorly understood. We previously demonstrated that a single substitution in the viral nucleoprotein (NP:F346S) selectively modulates neuraminidase (NA) gene segment expression while leaving other segments largely unaffected. Given what is currently known about NP function, there is no obvious explanation for how changes in NP can selectively modulate the replication of individual gene segments. In this study, we found that the specificity of this effect for the NA segment is virus strain specific and depends on the untranslated region (UTR) sequences of the NA segment. While the NP:F346S substitution did not significantly alter the RNA binding or oligomerization activities of NP in vitro, it specifically decreased the ability of NP to promote NA segment viral RNA (vRNA) synthesis. In addition to NP residue F346, we identified two other adjacent aromatic residues in NP (Y385 and F479) capable of similarly regulating NA gene segment expression, suggesting a larger role for this domain in gene-segment specific regulation. Our findings reveal a novel role for NP in selective regulation of viral gene segment replication and provide a framework for understanding how the expression patterns of individual viral gene segments can be modulated during adaptation to new host environments. IMPORTANCE Influenza A virus (IAV) is a respiratory pathogen that remains a significant source of morbidity and mortality. Escape from host immunity or emergence into new host species often requires mutations that modulate the functional activities of the viral glycoproteins hemagglutinin (HA) and neuraminidase (NA), which are responsible for virus attachment to and release from host cells, respectively. Maintaining the functional balance between the activities of HA and NA is required for fitness across multiple host systems. Thus, selective modulation of viral gene expression patterns may be a key determinant of viral immune escape and cross-species transmission potential. We identified a novel mechanism by which the viral nucleoprotein (NP) gene can selectively modulate NA segment replication and gene expression through interactions with the segment UTRs. Our work highlights an unexpected role for NP in selective regulation of expression from the individual IAV gene segments.
Collapse
Affiliation(s)
- Meghan Diefenbacher
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Timothy J. C. Tan
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - David L. V. Bauer
- RNA Virus Replication Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Beth M. Stadtmueller
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Biomedical and Translational Sciences, Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Nicholas C. Wu
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Biomedical and Translational Sciences, Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Christopher B. Brooke
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| |
Collapse
|
12
|
Guillon A, Brea-Diakite D, Cezard A, Wacquiez A, Baranek T, Bourgeais J, Picou F, Vasseur V, Meyer L, Chevalier C, Auvet A, Carballido JM, Nadal Desbarats L, Dingli F, Turtoi A, Le Gouellec A, Fauvelle F, Donchet A, Crépin T, Hiemstra PS, Paget C, Loew D, Herault O, Naffakh N, Le Goffic R, Si-Tahar M. Host succinate inhibits influenza virus infection through succinylation and nuclear retention of the viral nucleoprotein. EMBO J 2022; 41:e108306. [PMID: 35506364 PMCID: PMC9194747 DOI: 10.15252/embj.2021108306] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/03/2022] [Accepted: 04/04/2022] [Indexed: 12/11/2022] Open
Abstract
Influenza virus infection causes considerable morbidity and mortality, but current therapies have limited efficacy. We hypothesized that investigating the metabolic signaling during infection may help to design innovative antiviral approaches. Using bronchoalveolar lavages of infected mice, we here demonstrate that influenza virus induces a major reprogramming of lung metabolism. We focused on mitochondria‐derived succinate that accumulated both in the respiratory fluids of virus‐challenged mice and of patients with influenza pneumonia. Notably, succinate displays a potent antiviral activity in vitro as it inhibits the multiplication of influenza A/H1N1 and A/H3N2 strains and strongly decreases virus‐triggered metabolic perturbations and inflammatory responses. Moreover, mice receiving succinate intranasally showed reduced viral loads in lungs and increased survival compared to control animals. The antiviral mechanism involves a succinate‐dependent posttranslational modification, that is, succinylation, of the viral nucleoprotein at the highly conserved K87 residue. Succinylation of viral nucleoprotein altered its electrostatic interactions with viral RNA and further impaired the trafficking of viral ribonucleoprotein complexes. The finding that succinate efficiently disrupts the influenza replication cycle opens up new avenues for improved treatment of influenza pneumonia.
Collapse
Affiliation(s)
- Antoine Guillon
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR 1100, Tours, France.,Université de Tours, Tours, France.,Service de Médecine Intensive Réanimation, CHRU de Tours, Tours, France
| | - Deborah Brea-Diakite
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR 1100, Tours, France.,Université de Tours, Tours, France
| | - Adeline Cezard
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR 1100, Tours, France.,Université de Tours, Tours, France
| | - Alan Wacquiez
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR 1100, Tours, France.,Université de Tours, Tours, France
| | - Thomas Baranek
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR 1100, Tours, France.,Université de Tours, Tours, France
| | - Jérôme Bourgeais
- Université de Tours, Tours, France.,CNRS ERL 7001 LNOx "Leukemic niche and redox metabolism", Tours, France.,Service d'Hématologie Biologique, CHRU de Tours, Tours, France
| | - Frédéric Picou
- Université de Tours, Tours, France.,CNRS ERL 7001 LNOx "Leukemic niche and redox metabolism", Tours, France.,Service d'Hématologie Biologique, CHRU de Tours, Tours, France
| | - Virginie Vasseur
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR 1100, Tours, France.,Université de Tours, Tours, France
| | - Léa Meyer
- Virologie et Immunologie Moléculaires, INRAe, Université Paris-Saclay, Jouy-en-Josas, France
| | - Christophe Chevalier
- Virologie et Immunologie Moléculaires, INRAe, Université Paris-Saclay, Jouy-en-Josas, France
| | - Adrien Auvet
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR 1100, Tours, France.,Université de Tours, Tours, France.,Service de Médecine Intensive Réanimation, CHRU de Tours, Tours, France
| | | | | | - Florent Dingli
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, Paris, France
| | - Andrei Turtoi
- Tumor Microenvironment Laboratory, Institut de Recherche en Cancérologie de Montpellier, INSERM U1194, Montpellier, France.,Institut du Cancer de Montpellier, Montpellier, France.,Université de Montpellier, Montpellier, France
| | - Audrey Le Gouellec
- CNRS, CHU Grenoble Alpes, Grenoble INP, TIMC-IMAG, University Grenoble Alpes, Grenoble, France
| | - Florence Fauvelle
- UGA/INSERM U1216, Grenoble Institute of Neurosciences, Grenoble, France.,UGA/INSERM US17, Grenoble MRI Facility IRMaGe, Grenoble, France
| | - Amélie Donchet
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes, Grenoble, France
| | - Thibaut Crépin
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes, Grenoble, France
| | - Pieter S Hiemstra
- Department of Pulmonology, Leiden University Medical Center, Leiden, Netherlands
| | - Christophe Paget
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR 1100, Tours, France.,Université de Tours, Tours, France
| | - Damarys Loew
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, Paris, France
| | - Olivier Herault
- Université de Tours, Tours, France.,CNRS ERL 7001 LNOx "Leukemic niche and redox metabolism", Tours, France.,Service d'Hématologie Biologique, CHRU de Tours, Tours, France
| | - Nadia Naffakh
- Institut Pasteur, Unité Biologie des ARN et Virus Influenza, CNRS UMR3569, Paris, France
| | - Ronan Le Goffic
- Virologie et Immunologie Moléculaires, INRAe, Université Paris-Saclay, Jouy-en-Josas, France
| | - Mustapha Si-Tahar
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR 1100, Tours, France.,Université de Tours, Tours, France
| |
Collapse
|
13
|
Chauhan RP, Gordon ML. An overview of influenza A virus genes, protein functions, and replication cycle highlighting important updates. Virus Genes 2022; 58:255-269. [PMID: 35471490 DOI: 10.1007/s11262-022-01904-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 04/04/2022] [Indexed: 10/18/2022]
Abstract
The recent research findings on influenza A virus (IAV) genome biology prompted us to present a comprehensive overview of IAV genes, protein functions, and replication cycle. The eight gene segments of the IAV genome encode 17 proteins, each having unique functions contributing to virus fitness in the host. The polymerase genes are essential determinants of IAV pathogenicity and virulence; however, other viral components also play crucial roles in the IAV replication, transmission, and adaptation. Specific adaptive mutations within polymerase (PB2, PB1, and PA) and glycoprotein-hemagglutinin (HA) and neuraminidase (NA) genes, may facilitate interspecies transmission and adaptation of IAV. The HA-NA interplay is essential for establishing the IAV infection; the low pH triggers the inactivation of HA-receptor binding, leading to significantly lower NA activities, indicating that the enzymatic function of NA is dependent on HA binding. While the HA and NA glycoproteins are required to initiate infection, M1, M2, NS1, and NEP proteins are essential for cytoplasmic trafficking of viral ribonucleoproteins (vRNPs) and the assembly of the IAV virions. The mechanisms that enable IAV to exploit the host cell resources to advance the infection are discussed. A comprehensive understanding of IAV genome biology is essential for developing antivirals to combat the IAV disease burden.
Collapse
Affiliation(s)
- Ravendra P Chauhan
- School of Laboratory Medicine and Medical Sciences, Nelson R. Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, 719 Umbilo Road, Durban, 4001, South Africa
| | - Michelle L Gordon
- School of Laboratory Medicine and Medical Sciences, Nelson R. Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, 719 Umbilo Road, Durban, 4001, South Africa.
| |
Collapse
|
14
|
Almeida F, Santos LA, Trigueiro-Louro JM, RebelodeAndrade H. Optimization of A(H1N1)pdm09 vaccine seed viruses: the source of PB1 and HA vRNA as a major determinant for antigen yield. Virus Res 2022; 315:198795. [DOI: 10.1016/j.virusres.2022.198795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 12/21/2022]
|
15
|
Li X, Qiao S, Zhao Y, Gu M, Gao R, Liu K, Ge Z, Ma J, Wang X, Hu J, Hu S, Liu X, Chen S, Peng D, Liu X. G1-like PB2 gene improves virus replication and competitive advantage of H9N2 virus. Virus Genes 2021; 57:521-528. [PMID: 34519961 DOI: 10.1007/s11262-021-01870-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 09/02/2021] [Indexed: 10/20/2022]
Abstract
H9N2 subtype avian influenza virus has dramatically evolved and undergone extensive reassortment since its emergence in early 1990s in China. The genotype S (G57), emerging in 2007 with the substitution of F98-like PB2 and M gene by G1-like ones, has become the overwhelming predominant genotype for the past 11 years since 2010. Here, we found that virus with G1-like PB2 were more efficient in protein expression and in infectious virus production than that with F98-like PB2 gene. By coinfected MDCK cells with the reassortant virus, more survival opportunity for viruses with G1-like PB2 than that of F/98-like was observed. Besides, in animal experiments, we found that the G1-like PB2 increases virus infectivity, replication, and virus shedding of H9N2 in chickens. Our results suggested that the substitution of G1-like PB2 play important role in promoting the fitness of genotype S H9N2 virus in China.
Collapse
Affiliation(s)
- Xiuli Li
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Shumiao Qiao
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Ying Zhao
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Min Gu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Ruyi Gao
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Kaituo Liu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Zhichuang Ge
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Jing Ma
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Xiaoquan Wang
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Jiao Hu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Shunlin Hu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Xiaowen Liu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Sujuan Chen
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Daxin Peng
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
| | - Xiufan Liu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China. .,Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu, China.
| |
Collapse
|
16
|
RNA Structures and Their Role in Selective Genome Packaging. Viruses 2021; 13:v13091788. [PMID: 34578369 PMCID: PMC8472981 DOI: 10.3390/v13091788] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/31/2021] [Accepted: 09/02/2021] [Indexed: 12/13/2022] Open
Abstract
To generate infectious viral particles, viruses must specifically select their genomic RNA from milieu that contains a complex mixture of cellular or non-genomic viral RNAs. In this review, we focus on the role of viral encoded RNA structures in genome packaging. We first discuss how packaging signals are constructed from local and long-range base pairings within viral genomes, as well as inter-molecular interactions between viral and host RNAs. Then, how genome packaging is regulated by the biophysical properties of RNA. Finally, we examine the impact of RNA packaging signals on viral evolution.
Collapse
|
17
|
Trifkovic S, Gilbertson B, Fairmaid E, Cobbin J, Rockman S, Brown LE. Gene Segment Interactions Can Drive the Emergence of Dominant Yet Suboptimal Gene Constellations During Influenza Virus Reassortment. Front Microbiol 2021; 12:683152. [PMID: 34335507 PMCID: PMC8317023 DOI: 10.3389/fmicb.2021.683152] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 06/23/2021] [Indexed: 11/13/2022] Open
Abstract
A segmented genome enables influenza virus to undergo reassortment when two viruses infect the same cell. Although reassortment is involved in the creation of pandemic influenza strains and is routinely used to produce influenza vaccines, our understanding of the factors that drive the emergence of dominant gene constellations during this process is incomplete. Recently, we defined a spectrum of interactions between the gene segments of the A/Udorn/307/72 (H3N2) (Udorn) strain that occur within virus particles, a major interaction being between the NA and PB1 gene segments. In addition, we showed that the Udorn PB1 is preferentially incorporated into reassortant viruses that express the Udorn NA. Here we use an influenza vaccine seed production model where eggs are coinfected with Udorn and the high yielding A/Puerto Rico/8/34 (H1N1) (PR8) virus and track viral genotypes through the reassortment process under antibody selective pressure to determine the impact of Udorn NA-PB1 co-selection. We discovered that 86% of the reassortants contained the PB1 from the Udorn parent after the initial co-infection and this bias towards Udorn PB1 was maintained after two further passages. Included in these were certain gene constellations containing Udorn HA, NA, and PB1 that confered low replicative fitness yet rapidly became dominant at the expense of more fit progeny, even when co-infection ratios of the two viruses favoured PR8. Fitness was not compromised, however, in the corresponding reassortants that also contained Udorn NP. Of particular note is the observation that relatively unfit reassortants could still fulfil the role of vaccine seed candidates as they provided high haemagglutinin (HA) antigen yields through co-production of non-infectious particles and/or by more HA molecules per virion. Our data illustrate the dynamics and complexity of reassortment and highlight how major gene segment interactions formed during packaging, in addition to antibody pressure, initially restrict the reassortant viruses that are formed.
Collapse
Affiliation(s)
- Sanja Trifkovic
- The Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Brad Gilbertson
- The Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Emily Fairmaid
- The Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Joanna Cobbin
- The Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Steven Rockman
- The Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.,Seqirus, Parkville, VIC, Australia
| | - Lorena E Brown
- The Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.,Global Station for Zoonosis Control, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan
| |
Collapse
|
18
|
Li X, Zhao Y, Qiao S, Gu M, Gao R, Ge Z, Xu X, Wang X, Ma J, Hu J, Hu S, Liu X, Chen S, Peng D, Jiao X, Liu X. The Packaging Regions of G1-Like PB2 Gene Contribute to Improving the Survival Advantage of Genotype S H9N2 Virus in China. Front Microbiol 2021; 12:655057. [PMID: 33967991 PMCID: PMC8096984 DOI: 10.3389/fmicb.2021.655057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 03/25/2021] [Indexed: 11/13/2022] Open
Abstract
The genotype S (G57) H9N2 virus, which first emerged in 2007 with the substitution of the G1-like PB2 gene for F98-like ones, has become the predominant genotype in the past 10 years. However, whether this substitution plays a role in the fitness of genotype S H9N2 viruses remains unknown. Comparison of the PB2 genes of F98-like and G1-like viruses revealed a close homology in amino acid sequences but great variations at nucleotide levels. We then determined if the packaging region, a unique sequence in each segment utilized for the assembly of the vRNA into virions, played a role in the fitness of the S genotype. The chimeric H9N2 virus with PB2 segments of the G1-like packaging regions significantly increased viral protein levels and polymerase activity. Substituting the packaging regions in the two terminals of F98-like PB2 with the sequence of G1-like further improved its competitive advantage. Substitution of the packaging regions of F98-like PB2 with those of G1-like sequences increased the infectivity of the chimeric virus in the lungs and brains of chicken at 3 days post infection (dpi) and extended the lengths of virus shedding time. Our study suggests that the packaging regions of the G1-like PB2 gene contribute to improve the survival advantage of the genotype S H9N2 virus in China.
Collapse
Affiliation(s)
- Xiuli Li
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Ying Zhao
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Shumiao Qiao
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Min Gu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Ruyi Gao
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Zhichuang Ge
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Xiulong Xu
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, China.,Yangzhou University Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Institutes of Agricultural Science and Technology Development, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, China
| | - Xiaoquan Wang
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Jing Ma
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Jiao Hu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Shunlin Hu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Xiaowen Liu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Sujuan Chen
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Daxin Peng
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Xinan Jiao
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, China.,Yangzhou University Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Institutes of Agricultural Science and Technology Development, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China
| | - Xiufan Liu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China
| |
Collapse
|
19
|
Conserved Structural Motifs of Two Distant IAV Subtypes in Genomic Segment 5 RNA. Viruses 2021; 13:v13030525. [PMID: 33810157 PMCID: PMC8004953 DOI: 10.3390/v13030525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/18/2021] [Accepted: 03/19/2021] [Indexed: 12/14/2022] Open
Abstract
The functionality of RNA is fully dependent on its structure. For the influenza A virus (IAV), there are confirmed structural motifs mediating processes which are important for the viral replication cycle, including genome assembly and viral packaging. Although the RNA of strains originating from distant IAV subtypes might fold differently, some structural motifs are conserved, and thus, are functionally important. Nowadays, NGS-based structure modeling is a source of new in vivo data helping to understand RNA biology. However, for accurate modeling of in vivo RNA structures, these high-throughput methods should be supported with other analyses facilitating data interpretation. In vitro RNA structural models complement such approaches and offer RNA structures based on experimental data obtained in a simplified environment, which are needed for proper optimization and analysis. Herein, we present the secondary structure of the influenza A virus segment 5 vRNA of A/California/04/2009 (H1N1) strain, based on experimental data from DMS chemical mapping and SHAPE using NMIA, supported by base-pairing probability calculations and bioinformatic analyses. A comparison of the available vRNA5 structures among distant IAV strains revealed that a number of motifs present in the A/California/04/2009 (H1N1) vRNA5 model are highly conserved despite sequence differences, located within previously identified packaging signals, and the formation of which in in virio conditions has been confirmed. These results support functional roles of the RNA secondary structure motifs, which may serve as candidates for universal RNA-targeting inhibitory methods.
Collapse
|
20
|
Li X, Gu M, Zheng Q, Gao R, Liu X. Packaging signal of influenza A virus. Virol J 2021; 18:36. [PMID: 33596956 PMCID: PMC7890907 DOI: 10.1186/s12985-021-01504-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 02/02/2021] [Indexed: 12/15/2022] Open
Abstract
Influenza A virus (IAV) contains a genome with eight single-stranded, negative-sense RNA segments that encode 17 proteins. During its assembly, all eight separate viral RNA (vRNA) segments are incorporated into virions in a selective manner. Evidence suggested that the highly selective genome packaging mechanism relies on RNA-RNA or protein-RNA interactions. The specific structures of each vRNA that contribute to mediating the packaging of the vRNA into virions have been described and identified as packaging signals. Abundant research indicated that sequences required for genome incorporation are not series and are varied among virus genotypes. The packaging signals play important roles in determining the virus replication, genome incorporation and genetic reassortment of influenza A virus. In this review, we discuss recent studies on influenza A virus packaging signals to provide an overview of their characteristics and functions.
Collapse
Affiliation(s)
- Xiuli Li
- Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, 48 East Wenhui Road, Yangzhou, Jiangsu, China
| | - Min Gu
- Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, 48 East Wenhui Road, Yangzhou, Jiangsu, China
| | - Qinmei Zheng
- Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, 48 East Wenhui Road, Yangzhou, Jiangsu, China
| | - Ruyi Gao
- Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, 48 East Wenhui Road, Yangzhou, Jiangsu, China
| | - Xiufan Liu
- Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, 48 East Wenhui Road, Yangzhou, Jiangsu, China.
| |
Collapse
|
21
|
Piasecka J, Jarmolowicz A, Kierzek E. Organization of the Influenza A Virus Genomic RNA in the Viral Replication Cycle-Structure, Interactions, and Implications for the Emergence of New Strains. Pathogens 2020; 9:pathogens9110951. [PMID: 33203084 PMCID: PMC7696059 DOI: 10.3390/pathogens9110951] [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: 10/29/2020] [Revised: 11/13/2020] [Accepted: 11/13/2020] [Indexed: 12/14/2022] Open
Abstract
The influenza A virus is a human pathogen causing respiratory infections. The ability of this virus to trigger seasonal epidemics and sporadic pandemics is a result of its high genetic variability, leading to the ineffectiveness of vaccinations and current therapies. The source of this variability is the accumulation of mutations in viral genes and reassortment enabled by its segmented genome. The latter process can induce major changes and the production of new strains with pandemic potential. However, not all genetic combinations are tolerated and lead to the assembly of complete infectious virions. Reports have shown that viral RNA segments co-segregate in particular circumstances. This tendency is a consequence of the complex and selective genome packaging process, which takes place in the final stages of the viral replication cycle. It has been shown that genome packaging is governed by RNA–RNA interactions. Intersegment contacts create a network, characterized by the presence of common and strain-specific interaction sites. Recent studies have revealed certain RNA regions, and conserved secondary structure motifs within them, which may play functional roles in virion assembly. Growing knowledge on RNA structure and interactions facilitates our understanding of the appearance of new genome variants, and may allow for the prediction of potential reassortment outcomes and the emergence of new strains in the future.
Collapse
|
22
|
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.
Collapse
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
| | | |
Collapse
|
23
|
Selective flexible packaging pathways of the segmented genome of influenza A virus. Nat Commun 2020; 11:4355. [PMID: 32859915 PMCID: PMC7455735 DOI: 10.1038/s41467-020-18108-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 07/30/2020] [Indexed: 12/20/2022] Open
Abstract
The genome of influenza A viruses (IAV) is encoded in eight distinct viral ribonucleoproteins (vRNPs) that consist of negative sense viral RNA (vRNA) covered by the IAV nucleoprotein. Previous studies strongly support a selective packaging model by which vRNP segments are bundling to an octameric complex, which is integrated into budding virions. However, the pathway(s) generating a complete genome bundle is not known. We here use a multiplexed FISH assay to monitor all eight vRNAs in parallel in human lung epithelial cells. Analysis of 3.9 × 105 spots of colocalizing vRNAs provides quantitative insights into segment composition of vRNP complexes and, thus, implications for bundling routes. The complexes rarely contain multiple copies of a specific segment. The data suggest a selective packaging mechanism with limited flexibility by which vRNPs assemble into a complete IAV genome. We surmise that this flexibility forms an essential basis for the development of reassortant viruses with pandemic potential.
Collapse
|
24
|
|
25
|
Abstract
The genome of the influenza virus consists of eight distinct single-stranded RNA segments, each encoding proteins essential for the viral life cycle. When the virus infects a host cell, these segments must be replicated and packaged into new budding virions. The viral genome is assembled with remarkably high fidelity: experiments reveal that most virions contain precisely one copy of each of the eight RNA segments. Cell-biological studies suggest that genome assembly is mediated by specific reversible and irreversible interactions between the RNA segments and their associated proteins. However, the precise inter-segment interaction network remains unresolved. Here, we computationally predict that tree-like irreversible interaction networks guarantee high-fidelity genome assembly, while cyclic interaction networks lead to futile or frustrated off-pathway products. We test our prediction against multiple experimental datasets. We find that tree-like networks capture the nearest-neighbour statistics of RNA segments in packaged virions, as observed by electron tomography. Just eight tree-like networks (of a possible 262 144) optimally capture both the nearest-neighbour data and independently measured RNA–RNA binding and co-localization propensities. These eight do not include the previously proposed hub-and-spoke and linear networks. Rather, each predicted network combines hub-like and linear features, consistent with evolutionary models of interaction gain and loss.
Collapse
Affiliation(s)
- Nida Farheen
- Indian Institute of Science Education and Research, Pune 411008, India
| | - Mukund Thattai
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| |
Collapse
|
26
|
Shafiuddin M, Boon ACM. RNA Sequence Features Are at the Core of Influenza A Virus Genome Packaging. J Mol Biol 2019; 431:4217-4228. [PMID: 30914291 PMCID: PMC6756997 DOI: 10.1016/j.jmb.2019.03.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 02/18/2019] [Accepted: 03/11/2019] [Indexed: 11/23/2022]
Abstract
The influenza A virus (IAV), a respiratory pathogen for humans, poses serious medical and economic challenges to global healthcare systems. The IAV genome, consisting of eight single-stranded viral RNA segments, is incorporated into virions by a complex process known as genome packaging. Specific RNA sequences within the viral RNA segments serve as signals that are necessary for genome packaging. Although efficient packaging is a prerequisite for viral infectivity, many of the mechanistic details about this process are still missing. In this review, we discuss the recent advances toward the understanding of IAV genome packaging and focus on the RNA features that play a role in this process.
Collapse
Affiliation(s)
- Md Shafiuddin
- Department of Internal Medicine, Washington University in Saint Louis School of Medicine, St. Louis, MO 63110, USA
| | - Adrianus C M Boon
- Department of Internal Medicine, Washington University in Saint Louis School of Medicine, St. Louis, MO 63110, USA; Department of Molecular Microbiology and Microbial Pathogenesis, Washington University in Saint Louis School of Medicine, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University in Saint Louis School of Medicine, St. Louis, MO 63110, USA.
| |
Collapse
|
27
|
Abstract
RNA viruses carry out selective packaging of their genomes in a variety of ways, many involving a genomic packaging signal. The first coronavirus packaging signal was discovered nearly thirty years ago, but how it functions remains incompletely understood. This review addresses the current state of knowledge of coronavirus genome packaging, which has mainly been studied in two prototype species, mouse hepatitis virus and transmissible gastroenteritis virus. Despite the progress that has been made in the mapping and characterization of some packaging signals, there is conflicting evidence as to whether the viral nucleocapsid protein or the membrane protein plays the primary role in packaging signal recognition. The different models for the mechanism of genomic RNA packaging that have been prompted by these competing views are described. Also discussed is the recent exciting discovery that selective coronavirus genome packaging is critical for in vivo evasion of the host innate immune response. Selective incorporation of the coronavirus genome into virions is mediated by a cis-acting RNA packaging signal. Packaging signals vary across different coronavirus genera and lineages. Different lines of evidence attribute packaging signal recognition to either the nucleocapsid or the membrane protein. Selective coronavirus genome packaging plays a role in evasion of host innate immunity.
Collapse
Affiliation(s)
- Paul S Masters
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201, United States.
| |
Collapse
|
28
|
Newburn LR, White KA. Trans-Acting RNA-RNA Interactions in Segmented RNA Viruses. Viruses 2019; 11:v11080751. [PMID: 31416187 PMCID: PMC6723669 DOI: 10.3390/v11080751] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 08/08/2019] [Accepted: 08/11/2019] [Indexed: 12/18/2022] Open
Abstract
RNA viruses represent a large and important group of pathogens that infect a broad range of hosts. Segmented RNA viruses are a subclass of this group that encode their genomes in two or more molecules and package all of their RNA segments in a single virus particle. These divided genomes come in different forms, including double-stranded RNA, coding-sense single-stranded RNA, and noncoding single-stranded RNA. Genera that possess these genome types include, respectively, Orbivirus (e.g., Bluetongue virus), Dianthovirus (e.g., Red clover necrotic mosaic virus) and Alphainfluenzavirus (e.g., Influenza A virus). Despite their distinct genomic features and diverse host ranges (i.e., animals, plants, and humans, respectively) each of these viruses uses trans-acting RNA–RNA interactions (tRRIs) to facilitate co-packaging of their segmented genome. The tRRIs occur between different viral genome segments and direct the selective packaging of a complete genome complement. Here we explore the current state of understanding of tRRI-mediated co-packaging in the abovementioned viruses and examine other known and potential functions for this class of RNA–RNA interaction.
Collapse
Affiliation(s)
- Laura R Newburn
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada
| | - K Andrew White
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada.
| |
Collapse
|
29
|
Lakdawala SS, Lee N, Brooke CB. Teaching an Old Virus New Tricks: A Review on New Approaches to Study Age-Old Questions in Influenza Biology. J Mol Biol 2019; 431:4247-4258. [PMID: 31051174 DOI: 10.1016/j.jmb.2019.04.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 04/12/2019] [Accepted: 04/23/2019] [Indexed: 01/31/2023]
Abstract
Influenza viruses have been studied for over 80 years, yet much about the basic viral lifecycle remain unknown. However, new imaging, biochemical, and sequencing techniques have revealed significant insight into many age-old questions of influenza virus biology. In this review, we will cover the role of imaging techniques to describe unique aspects of influenza virus assembly, biochemical techniques to study viral genomic organization, and next-generation sequencing to explore influenza genomic evolution. Our goal is to provide a brief overview of how emerging techniques are being used to answer basic questions about influenza viruses. This is not a comprehensive list of emerging techniques, rather ones that we feel will continue to make significant contributions to field of influenza biology.
Collapse
Affiliation(s)
- Seema S Lakdawala
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, School of Medicine Pittsburgh, PA 15219, USA.
| | - Nara Lee
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, School of Medicine Pittsburgh, PA 15219, USA.
| | - Christopher B Brooke
- Department of Microbiology, University of Illinois at Urbana-Champaign, Champaign, IL 61801, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Champaign, IL 61801, USA.
| |
Collapse
|