1
|
Arragain B, Krischuns T, Pelosse M, Drncova P, Blackledge M, Naffakh N, Cusack S. Structures of influenza A and B replication complexes give insight into avian to human host adaptation and reveal a role of ANP32 as an electrostatic chaperone for the apo-polymerase. Nat Commun 2024; 15:6910. [PMID: 39160148 DOI: 10.1038/s41467-024-51007-3] [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: 02/08/2024] [Accepted: 07/16/2024] [Indexed: 08/21/2024] Open
Abstract
Replication of influenza viral RNA depends on at least two viral polymerases, a parental replicase and an encapsidase, and cellular factor ANP32. ANP32 comprises an LRR domain and a long C-terminal low complexity acidic region (LCAR). Here we present evidence suggesting that ANP32 is recruited to the replication complex as an electrostatic chaperone that stabilises the encapsidase moiety within apo-polymerase symmetric dimers that are distinct for influenza A and B polymerases. The ANP32 bound encapsidase, then forms the asymmetric replication complex with the replicase, which is embedded in a parental ribonucleoprotein particle (RNP). Cryo-EM structures reveal the architecture of the influenza A and B replication complexes and the likely trajectory of the nascent RNA product into the encapsidase. The cryo-EM map of the FluB replication complex shows extra density attributable to the ANP32 LCAR wrapping around and stabilising the apo-encapsidase conformation. These structures give new insight into the various mutations that adapt avian strain polymerases to use the distinct ANP32 in mammalian cells.
Collapse
Affiliation(s)
- Benoît Arragain
- European Molecular Biology Laboratory, Grenoble, Cedex 9, France
| | - Tim Krischuns
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, RNA Biology of Influenza Virus, Paris, France
- Heidelberg University, Department of Infectious Diseases, Virology, Schaller Research Group, Heidelberg, Germany
| | - Martin Pelosse
- European Molecular Biology Laboratory, Grenoble, Cedex 9, France
| | - Petra Drncova
- European Molecular Biology Laboratory, Grenoble, Cedex 9, France
| | - Martin Blackledge
- Institut de Biologie Structurale, Université Grenoble-Alpes-CEA-CNRS UMR5075, Grenoble, France
| | - Nadia Naffakh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, RNA Biology of Influenza Virus, Paris, France
| | - Stephen Cusack
- European Molecular Biology Laboratory, Grenoble, Cedex 9, France.
| |
Collapse
|
2
|
Zhao L, Li S, Deng L, Zhang Y, Jiang C, Wei Y, Xia J, Ping J. Host-specific SRSF7 regulates polymerase activity and replication of influenza A virus. Microbes Infect 2024:105401. [PMID: 39134172 DOI: 10.1016/j.micinf.2024.105401] [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: 02/07/2024] [Revised: 05/19/2024] [Accepted: 08/01/2024] [Indexed: 08/17/2024]
Abstract
Avian influenza viruses crossing the host barrier to infect humans have caused great panic in human society and seriously threatened public health. Herein, we revealed that knockdown of SRSF7 significantly down-regulated influenza virus titers and viral protein expression. We further observed for the first time that human SRSF7, but not avian SRSF7, significantly inhibited polymerase activity (PB2627E). Molecular mapping demonstrated that amino acids 206 to 228 of human SRSF7 play a decisive role in regulating the polymerase activity, which contains the amino acid motif absent in avian SRSF7. Importantly, our results illustrated that the PB2627K-encoding influenza virus induces SRSF7 protein degradation more strongly via the lysosome pathway and not via the proteasome pathway. Functional enrichment analysis of SRSF7-related KEGG pathways indicated that SRSF7 is closely related to cell growth and death. Lastly, our results showed that knocking down SRSF7 interferes with normal polymerase activity. Taken together, our results advance our understanding of interspecies transmission and our findings point out new targets for the development of drugs preventing or treating influenza virus infection.
Collapse
Affiliation(s)
- Lingcai Zhao
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Shengmin Li
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Lulu Deng
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Yijia Zhang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Chenfeng Jiang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Yurong Wei
- Xinjiang Key Laboratory of Animal Infectious Diseases, Institute of Veterinary Medicine, Xinjiang Academy of Animal Sciences, Urumqi, 830013, China.
| | - Jun Xia
- Key Laboratory of Herbivore Disease Prevention and Control, (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs, China.
| | - Jihui Ping
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
| |
Collapse
|
3
|
Bonomini A, Felicetti T, Pacetti M, Bertagnin C, Coletti A, Giammarino F, De Angelis M, Poggialini F, Macchiarulo A, Sabatini S, Mercorelli B, Nencioni L, Vicenti I, Dreassi E, Cecchetti V, Tabarrini O, Loregian A, Massari S. Optimization of potent, broad-spectrum, and specific anti-influenza compounds targeting RNA polymerase PA-PB1 heterodimerization. Eur J Med Chem 2024; 277:116737. [PMID: 39153334 DOI: 10.1016/j.ejmech.2024.116737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2024] [Revised: 07/30/2024] [Accepted: 08/01/2024] [Indexed: 08/19/2024]
Abstract
Influenza viruses (IV) are single-stranded RNA viruses with a negative-sense genome and have the potential to cause pandemics. While vaccines exist for influenza, their protection is only partial. Additionally, there is only a limited number of approved anti-IV drugs, which are associated to emergence of drug resistance. To address these issues, for years we have focused on the development of small-molecules that can interfere with the heterodimerization of PA and PB1 subunits of the IV RNA-dependent RNA polymerase (RdRP). In this study, starting from a cycloheptathiophene-3-carboxamide compound that we recently identified, we performed iterative cycles of medicinal chemistry optimization that led to the identification of compounds 43 and 45 with activity in the nanomolar range against circulating A and B strains of IV. Mechanistic studies demonstrated the ability of 43 and 45 to interfere with viral RdRP activity by disrupting PA-PB1 subunits heterodimerization and to bind to the PA C-terminal domain through biophysical assays. Most important, ADME studies of 45 also showed an improvement in the pharmacokinetic profile with respect to the starting hit.
Collapse
Affiliation(s)
- Anna Bonomini
- Department of Molecular Medicine, University of Padua, 35121, Padua, Italy
| | - Tommaso Felicetti
- Department of Pharmaceutical Sciences, University of Perugia, 06123, Perugia, Italy
| | - Martina Pacetti
- Department of Pharmaceutical Sciences, University of Perugia, 06123, Perugia, Italy
| | - Chiara Bertagnin
- Department of Molecular Medicine, University of Padua, 35121, Padua, Italy
| | - Alice Coletti
- Department of Pharmaceutical Sciences, University of Perugia, 06123, Perugia, Italy
| | - Federica Giammarino
- Department of Medical Biotechnologies, University of Siena, 53100, Siena, Italy
| | - Marta De Angelis
- Department of Public Health and Infectious Diseases, Laboratory Affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, 00185, Rome, Italy
| | - Federica Poggialini
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, 53100, Siena, Italy
| | - Antonio Macchiarulo
- Department of Pharmaceutical Sciences, University of Perugia, 06123, Perugia, Italy
| | - Stefano Sabatini
- Department of Pharmaceutical Sciences, University of Perugia, 06123, Perugia, Italy
| | | | - Lucia Nencioni
- Department of Public Health and Infectious Diseases, Laboratory Affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, 00185, Rome, Italy
| | - Ilaria Vicenti
- Department of Medical Biotechnologies, University of Siena, 53100, Siena, Italy
| | - Elena Dreassi
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, 53100, Siena, Italy
| | - Violetta Cecchetti
- Department of Pharmaceutical Sciences, University of Perugia, 06123, Perugia, Italy
| | - Oriana Tabarrini
- Department of Pharmaceutical Sciences, University of Perugia, 06123, Perugia, Italy
| | - Arianna Loregian
- Department of Molecular Medicine, University of Padua, 35121, Padua, Italy.
| | - Serena Massari
- Department of Pharmaceutical Sciences, University of Perugia, 06123, Perugia, Italy.
| |
Collapse
|
4
|
Dupont M, Krischuns T, Gianetto QG, Paisant S, Bonazza S, Brault JB, Douché T, Arragain B, Florez-Prada A, Perez-Perri J, Hentze M, Cusack S, Matondo M, Isel C, Courtney D, Naffakh N. The RBPome of influenza A virus NP-mRNA reveals a role for TDP-43 in viral replication. Nucleic Acids Res 2024; 52:7188-7210. [PMID: 38686810 PMCID: PMC11229366 DOI: 10.1093/nar/gkae291] [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: 03/17/2023] [Revised: 03/22/2024] [Accepted: 04/05/2024] [Indexed: 05/02/2024] Open
Abstract
Genome-wide approaches have significantly advanced our knowledge of the repertoire of RNA-binding proteins (RBPs) that associate with cellular polyadenylated mRNAs within eukaryotic cells. Recent studies focusing on the RBP interactomes of viral mRNAs, notably SARS-Cov-2, have revealed both similarities and differences between the RBP profiles of viral and cellular mRNAs. However, the RBPome of influenza virus mRNAs remains unexplored. Herein, we identify RBPs that associate with the viral mRNA encoding the nucleoprotein (NP) of an influenza A virus. Focusing on TDP-43, we show that it binds several influenza mRNAs beyond the NP-mRNA, and that its depletion results in lower levels of viral mRNAs and proteins within infected cells, and a decreased yield of infectious viral particles. We provide evidence that the viral polymerase recruits TDP-43 onto viral mRNAs through a direct interaction with the disordered C-terminal domain of TDP-43. Notably, other RBPs found to be associated with influenza virus mRNAs also interact with the viral polymerase, which points to a role of the polymerase in orchestrating the assembly of viral messenger ribonucleoproteins.
Collapse
Affiliation(s)
- Maud Dupont
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, RNA Biology and Influenza Viruses, Paris, France
| | - Tim Krischuns
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, RNA Biology and Influenza Viruses, Paris, France
| | - Quentin Giai Gianetto
- Institut Pasteur, Université Paris Cité, CNRS UAR2024, Proteomics Platform, Mass Spectrometry for Biology, Paris, France
- Institut Pasteur, Université Paris Cité, Bioinformatics and Biostatistics HUB, Paris, France
| | - Sylvain Paisant
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, RNA Biology and Influenza Viruses, Paris, France
| | - Stefano Bonazza
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, BelfastBT9 7BL, Northern Ireland
| | - Jean-Baptiste Brault
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, RNA Biology and Influenza Viruses, Paris, France
| | - Thibaut Douché
- Institut Pasteur, Université Paris Cité, CNRS UAR2024, Proteomics Platform, Mass Spectrometry for Biology, Paris, France
| | - Benoît Arragain
- European Molecular Biology Laboratory, 38042Grenoble, France
| | | | | | | | - Stephen Cusack
- European Molecular Biology Laboratory, 38042Grenoble, France
| | - Mariette Matondo
- Institut Pasteur, Université Paris Cité, CNRS UAR2024, Proteomics Platform, Mass Spectrometry for Biology, Paris, France
| | - Catherine Isel
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, RNA Biology and Influenza Viruses, Paris, France
| | - David G Courtney
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, BelfastBT9 7BL, Northern Ireland
| | - Nadia Naffakh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, RNA Biology and Influenza Viruses, Paris, France
| |
Collapse
|
5
|
Bessonne M, Morel J, Nevers Q, Da Costa B, Ballandras-Colas A, Chenavier F, Grange M, Roussel A, Crépin T, Delmas B. Antiviral activity of intracellular nanobodies targeting the influenza virus RNA-polymerase core. PLoS Pathog 2024; 20:e1011642. [PMID: 38875296 PMCID: PMC11210859 DOI: 10.1371/journal.ppat.1011642] [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: 08/30/2023] [Revised: 06/27/2024] [Accepted: 05/15/2024] [Indexed: 06/16/2024] Open
Abstract
Influenza viruses transcribe and replicate their genome in the nucleus of the infected cells, two functions that are supported by the viral RNA-dependent RNA-polymerase (FluPol). FluPol displays structural flexibility related to distinct functional states, from an inactive form to conformations competent for replication and transcription. FluPol machinery is constituted by a structurally-invariant core comprising the PB1 subunit stabilized with PA and PB2 domains, whereas the PA endonuclease and PB2 C-domains can pack in different configurations around the core. To get insights into the functioning of FluPol, we selected single-domain nanobodies (VHHs) specific of the influenza A FluPol core. When expressed intracellularly, some of them exhibited inhibitory activity on type A FluPol, but not on the type B one. The most potent VHH (VHH16) binds PA and the PA-PB1 dimer with an affinity below the nanomolar range. Ectopic intracellular expression of VHH16 in virus permissive cells blocks multiplication of different influenza A subtypes, even when induced at late times post-infection. VHH16 was found to interfere with the transport of the PA-PB1 dimer to the nucleus, without affecting its handling by the importin β RanBP5 and subsequent steps in FluPol assembly. Using FluPol mutants selected after passaging in VHH16-expressing cells, we identified the VHH16 binding site at the interface formed by PA residues with the N-terminus of PB1, overlapping or close to binding sites of two host proteins, ANP32A and RNA-polymerase II RPB1 subunit which are critical for virus replication and transcription, respectively. These data suggest that the VHH16 neutralization is likely due to several activities, altering the import of the PA-PB1 dimer into the nucleus as well as inhibiting specifically virus transcription and replication. Thus, the VHH16 binding site represents a new Achilles' heel for FluPol and as such, a potential target for antiviral development.
Collapse
Affiliation(s)
- Mélissa Bessonne
- Unité de Virologie et Immunologie moléculaires, INRAE, Université Paris-Saclay, Jouy-en-Josas, France
| | - Jessica Morel
- Unité de Virologie et Immunologie moléculaires, INRAE, Université Paris-Saclay, Jouy-en-Josas, France
| | - Quentin Nevers
- Unité de Virologie et Immunologie moléculaires, INRAE, Université Paris-Saclay, Jouy-en-Josas, France
| | - Bruno Da Costa
- Unité de Virologie et Immunologie moléculaires, INRAE, Université Paris-Saclay, Jouy-en-Josas, France
| | | | - Florian Chenavier
- Institut de biologie structurale, CNRS, Université de Grenoble, Grenoble, France
| | - Magali Grange
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires (LISM), CNRS, Université d’Aix-Marseille, Marseille, France
| | - Alain Roussel
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires (LISM), CNRS, Université d’Aix-Marseille, Marseille, France
| | - Thibaut Crépin
- Institut de biologie structurale, CNRS, Université de Grenoble, Grenoble, France
| | - Bernard Delmas
- Unité de Virologie et Immunologie moléculaires, INRAE, Université Paris-Saclay, Jouy-en-Josas, France
| |
Collapse
|
6
|
Khanna M, Sharma K, Saxena SK, Sharma JG, Rajput R, Kumar B. Unravelling the interaction between Influenza virus and the nuclear pore complex: insights into viral replication and host immune response. Virusdisease 2024; 35:231-242. [PMID: 39071870 PMCID: PMC11269558 DOI: 10.1007/s13337-024-00879-6] [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: 06/10/2024] [Accepted: 06/21/2024] [Indexed: 07/30/2024] Open
Abstract
Influenza viruses are known to cause severe respiratory infections in humans, often associated with significant morbidity and mortality rates. Virus replication relies on various host factors and pathways, which also determine the virus's infectious potential. Nonetheless, achieving a comprehensive understanding of how the virus interacts with host cellular components is essential for developing effective therapeutic strategies. One of the key components among host factors, the nuclear pore complex (NPC), profoundly affects both the Influenza virus life cycle and the host's antiviral defenses. Serving as the sole gateway connecting the cytoplasm and nucleoplasm, the NPC plays a vital role as a mediator in nucleocytoplasmic trafficking. Upon infection, the virus hijacks and alters the nuclear pore complex and the nuclear receptors. This enables the virus to infiltrate the nucleus and promotes the movement of viral components between the nucleus and cytoplasm. While the nucleus and cytoplasm play pivotal roles in cellular functions, the nuclear pore complex serves as a crucial component in the host's innate immune system, acting as a defense mechanism against virus infection. This review provides a comprehensive overview of the intricate relationship between the Influenza virus and the nuclear pore complex. Furthermore, we emphasize their mutual influence on viral replication and the host's immune responses.
Collapse
Affiliation(s)
- Madhu Khanna
- Department of Virology, V.P Chest Institute, University of Delhi, Delhi, India
| | - Kajal Sharma
- Department of Virology, V.P Chest Institute, University of Delhi, Delhi, India
- Department of Biotechnology, Delhi Technological University, Delhi, India
| | - Shailendra K. Saxena
- Centre for Advanced Research (CFAR), Faculty of Medicine, King George’s Medical University (KGMU), Lucknow, India
| | - Jai Gopal Sharma
- Department of Biotechnology, Delhi Technological University, Delhi, India
| | - Roopali Rajput
- Department of Virology, V.P Chest Institute, University of Delhi, Delhi, India
| | - Binod Kumar
- Department of Antiviral Research, Institute of Advanced Virology, Thiruvananthapuram, Kerala India
| |
Collapse
|
7
|
Keown J, Baazaoui A, Šebesta M, Štefl R, Carrique L, Fodor E, Grimes JM. Structural and functional characterization of the interaction between the influenza A virus RNA polymerase and the CTD of host RNA polymerase II. J Virol 2024; 98:e0013824. [PMID: 38563748 PMCID: PMC11092357 DOI: 10.1128/jvi.00138-24] [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: 01/19/2024] [Accepted: 03/10/2024] [Indexed: 04/04/2024] Open
Abstract
Influenza A viruses, causing seasonal epidemics and occasional pandemics, rely on interactions with host proteins for their RNA genome transcription and replication. The viral RNA polymerase utilizes host RNA polymerase II (Pol II) and interacts with the serine 5 phosphorylated (pS5) C-terminal domain (CTD) of Pol II to initiate transcription. Our study, using single-particle electron cryomicroscopy (cryo-EM), reveals the structure of the 1918 pandemic influenza A virus polymerase bound to a synthetic pS5 CTD peptide composed of four heptad repeats mimicking the 52 heptad repeat mammalian Pol II CTD. The structure shows that the CTD peptide binds at the C-terminal domain of the PA viral polymerase subunit (PA-C) and reveals a previously unobserved position of the 627 domain of the PB2 subunit near the CTD. We identify crucial residues of the CTD peptide that mediate interactions with positively charged cavities on PA-C, explaining the preference of the viral polymerase for pS5 CTD. Functional analysis of mutants targeting the CTD-binding site within PA-C reveals reduced transcriptional function or defects in replication, highlighting the multifunctional role of PA-C in viral RNA synthesis. Our study provides insights into the structural and functional aspects of the influenza virus polymerase-host Pol II interaction and identifies a target for antiviral development.IMPORTANCEUnderstanding the intricate interactions between influenza A viruses and host proteins is crucial for developing targeted antiviral strategies. This study employs advanced imaging techniques to uncover the structural nuances of the 1918 pandemic influenza A virus polymerase bound to a specific host protein, shedding light on the vital process of viral RNA synthesis. The study identifies key amino acid residues in the influenza polymerase involved in binding host polymerase II (Pol II) and highlights their role in both viral transcription and genome replication. These findings not only deepen our understanding of the influenza virus life cycle but also pinpoint a potential target for antiviral development. By elucidating the structural and functional aspects of the influenza virus polymerase-host Pol II interaction, this research provides a foundation for designing interventions to disrupt viral replication and transcription, offering promising avenues for future antiviral therapies.
Collapse
Affiliation(s)
- Jeremy Keown
- Division of Structural Biology, Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Alaa Baazaoui
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Marek Šebesta
- CEITEC–Central European Institute of Technology, Masaryk University, Brno, Czechia
| | - Richard Štefl
- CEITEC–Central European Institute of Technology, Masaryk University, Brno, Czechia
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czechia
| | - Loïc Carrique
- Division of Structural Biology, Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Jonathan M. Grimes
- Division of Structural Biology, Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
8
|
Liu C, Hu L, Dong G, Zhang Y, Ferreira da Silva-Júnior E, Liu X, Menéndez-Arias L, Zhan P. Emerging drug design strategies in anti-influenza drug discovery. Acta Pharm Sin B 2023; 13:4715-4732. [PMID: 38045039 PMCID: PMC10692392 DOI: 10.1016/j.apsb.2023.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 07/12/2023] [Accepted: 08/03/2023] [Indexed: 12/05/2023] Open
Abstract
Influenza is an acute respiratory infection caused by influenza viruses (IFV), According to the World Health Organization (WHO), seasonal IFV epidemics result in approximately 3-5 million cases of severe illness, leading to about half a million deaths worldwide, along with severe economic losses and social burdens. Unfortunately, frequent mutations in IFV lead to a certain lag in vaccine development as well as resistance to existing antiviral drugs. Therefore, it is of great importance to develop anti-IFV drugs with high efficiency against wild-type and resistant strains, needed in the fight against current and future outbreaks caused by different IFV strains. In this review, we summarize general strategies used for the discovery and development of antiviral agents targeting multiple IFV strains (including those resistant to available drugs). Structure-based drug design, mechanism-based drug design, multivalent interaction-based drug design and drug repurposing are amongst the most relevant strategies that provide a framework for the development of antiviral drugs targeting IFV.
Collapse
Affiliation(s)
- Chuanfeng Liu
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Lide Hu
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Guanyu Dong
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Ying Zhang
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Edeildo Ferreira da Silva-Júnior
- Laboratory of Medicinal Chemistry, Institute of Pharmaceutical Sciences, Federal University of Alagoas, Maceió 57072-970, Alagoas, Brazil
| | - Xinyong Liu
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Luis Menéndez-Arias
- Centro de Biología Molecular “Severo Ochoa” (Consejo Superior de Investigaciones Científicas & Universidad Autónoma de Madrid), Madrid 28049, Spain
| | - Peng Zhan
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| |
Collapse
|
9
|
A structural understanding of influenza virus genome replication. Trends Microbiol 2023; 31:308-319. [PMID: 36336541 DOI: 10.1016/j.tim.2022.09.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/27/2022] [Accepted: 09/30/2022] [Indexed: 11/06/2022]
Abstract
Influenza virus contains a single-stranded negative-sense RNA genome. Replication of the genome is carried out by the viral RNA-dependent RNA polymerase in the context of the viral ribonucleoprotein (RNP) complex, through a positive-sense complementary RNA intermediate. Genome replication is tightly controlled through interactions with accessory viral and host factors. Propelled by developments in recombinant protein expression, and technical improvements in X-ray crystallography and cryo-electron microscopy, snapshots of the replication process have been captured. Here, we review how recent structural data shed light on the molecular mechanisms of influenza virus genome replication, in particular, encapsidation of nascent RNA, de novo RNP assembly, and regulation of replication initiation through interactions with host and viral cues.
Collapse
|
10
|
The ubiquitination landscape of the influenza A virus polymerase. Nat Commun 2023; 14:787. [PMID: 36774438 PMCID: PMC9922279 DOI: 10.1038/s41467-023-36389-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 01/30/2023] [Indexed: 02/13/2023] Open
Abstract
During influenza A virus (IAV) infections, viral proteins are targeted by cellular E3 ligases for modification with ubiquitin. Here, we decipher and functionally explore the ubiquitination landscape of the IAV polymerase proteins during infection of human alveolar epithelial cells by applying mass spectrometry analysis of immuno-purified K-ε-GG (di-glycyl)-remnant-bearing peptides. We have identified 59 modified lysines across the three subunits, PB2, PB1 and PA of the viral polymerase of which 17 distinctively affect mRNA transcription, vRNA replication and the generation of recombinant viruses via non-proteolytic mechanisms. Moreover, further functional and in silico analysis indicate that ubiquitination at K578 in the PB1 thumb domain is mechanistically linked to dynamic structural transitions of the viral polymerase that are required for vRNA replication. Mutations K578A and K578R differentially affect the generation of recombinant viruses by impeding cRNA and vRNA synthesis, NP binding as well as polymerase dimerization. Collectively, our results demonstrate that the ubiquitin-mediated charge neutralization at PB1-K578 disrupts the interaction to an unstructured loop in the PB2 N-terminus that is required to coordinate polymerase dimerization and facilitate vRNA replication. This provides evidence that IAV exploits the cellular ubiquitin system to modulate the activity of the viral polymerase for viral replication.
Collapse
|
11
|
Malet H, Williams HM, Cusack S, Rosenthal M. The mechanism of genome replication and transcription in bunyaviruses. PLoS Pathog 2023; 19:e1011060. [PMID: 36634042 PMCID: PMC9836281 DOI: 10.1371/journal.ppat.1011060] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Bunyaviruses are negative sense, single-strand RNA viruses that infect a wide range of vertebrate, invertebrate and plant hosts. WHO lists three bunyavirus diseases as priority diseases requiring urgent development of medical countermeasures highlighting their high epidemic potential. While the viral large (L) protein containing the RNA-dependent RNA polymerase is a key enzyme in the viral replication cycle and therefore a suitable drug target, our knowledge on the structure and activities of this multifunctional protein has, until recently, been very limited. However, in the last few years, facilitated by the technical advances in the field of cryogenic electron microscopy, many structures of bunyavirus L proteins have been solved. These structures significantly enhance our mechanistic understanding of bunyavirus genome replication and transcription processes and highlight differences and commonalities between the L proteins of different bunyavirus families. Here, we provide a review of our current understanding of genome replication and transcription in bunyaviruses with a focus on the viral L protein. Further, we compare within bunyaviruses and with the related influenza virus polymerase complex and highlight open questions.
Collapse
Affiliation(s)
- Hélène Malet
- University Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
- Institut Universitaire de France (IUF), Paris, France
| | - Harry M. Williams
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
| | | | - Maria Rosenthal
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Discovery Research ScreeningPort, Hamburg, Germany
- * E-mail:
| |
Collapse
|
12
|
Zhao L, Zhao Y, Liu Q, Huang J, Lu Y, Ping J. DDX5/METTL3-METTL14/YTHDF2 Axis Regulates Replication of Influenza A Virus. Microbiol Spectr 2022; 10:e0109822. [PMID: 35583334 PMCID: PMC9241928 DOI: 10.1128/spectrum.01098-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 04/28/2022] [Indexed: 12/14/2022] Open
Abstract
DEAD-box helicase 5 (DDX5), a member of the DEAD/H-box helicases, is known to participate in all aspects of RNA metabolism. However, its regulatory effect in antiviral innate immunity during replication of influenza virus remains unclear. Herein, we found that human DDX5 promotes replication of influenza virus in A549 cells. Moreover, our results further revealed that DDX5 relies on its N terminus to interact with the nucleoprotein (NP) of influenza virus, which is independent of RNA. Of course, we also observed colocalization of DDX5 with NP in the context of transfection or infection. However, influenza virus infection had no significant effect on the protein expression and nucleocytoplasmic distribution of DDX5. Importantly, we found that DDX5 suppresses antiviral innate immunity induced by influenza virus infection. Mechanistically, DDX5 downregulated the mRNA levels of interferon beta (IFN-β), interleukin 6 (IL-6), and DHX58 via the METTL3-METTL14/YTHDF2 axis. We revealed that DDX5 bound antiviral transcripts and regulated immune responses through YTHDF2-dependent mRNA decay. Taken together, our data demonstrate that the DDX5/METTL3-METTL14/YTHDF2 axis regulates the replication of influenza A virus. IMPORTANCE The replication and transcription of influenza virus depends on the participation of many host factors in cells. Exploring the relationship between viruses and host factors will help us fully understand the characteristics and pathogenic mechanisms of influenza viruses. In this study, we showed that DDX5 interacted with the NP of influenza virus. We demonstrated that DDX5 downregulated the expression of IFN-β and IL-6 and the transcription of antiviral genes downstream from IFN-β in influenza virus-infected A549 cells. Additionally, DDX5 downregulated the mRNA levels of antiviral transcripts via the METTL3-METTL14/YTHDF2 axis. Our findings provide a novel perspective to understand the mechanism by which DDX5 regulates antiviral immunity.
Collapse
Affiliation(s)
- Lingcai Zhao
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yongzhen Zhao
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Qingzheng Liu
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jingjin Huang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yuanlu Lu
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jihui Ping
- MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| |
Collapse
|
13
|
Krischuns T, Isel C, Drncova P, Lukarska M, Pflug A, Paisant S, Navratil V, Cusack S, Naffakh N. Type B and type A influenza polymerases have evolved distinct binding interfaces to recruit the RNA polymerase II CTD. PLoS Pathog 2022; 18:e1010328. [PMID: 35605026 PMCID: PMC9242477 DOI: 10.1371/journal.ppat.1010328] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 06/29/2022] [Accepted: 04/09/2022] [Indexed: 01/05/2023] Open
Abstract
During annual influenza epidemics, influenza B viruses (IBVs) co-circulate with influenza A viruses (IAVs), can become predominant and cause severe morbidity and mortality. Phylogenetic analyses suggest that IAVs (primarily avian viruses) and IBVs (primarily human viruses) have diverged over long time scales. Identifying their common and distinctive features is an effective approach to increase knowledge about the molecular details of influenza infection. The virus-encoded RNA-dependent RNA polymerases (FluPolB and FluPolA) are PB1-PB2-PA heterotrimers that perform transcription and replication of the viral genome in the nucleus of infected cells. Initiation of viral mRNA synthesis requires a direct association of FluPol with the host RNA polymerase II (RNAP II), in particular the repetitive C-terminal domain (CTD) of the major RNAP II subunit, to enable "cap-snatching" whereby 5'-capped oligomers derived from nascent RNAP II transcripts are pirated to prime viral transcription. Here, we present the first high-resolution co-crystal structure of FluPolB bound to a CTD mimicking peptide at a binding site crossing from PA to PB2. By performing structure-based mutagenesis of FluPolB and FluPolA followed by a systematic investigation of FluPol-CTD binding, FluPol activity and viral phenotype, we demonstrate that IBVs and IAVs have evolved distinct binding interfaces to recruit the RNAP II CTD, despite the CTD sequence being highly conserved across host species. We find that the PB2 627 subdomain, a major determinant of FluPol-host cell interactions and IAV host-range, is involved in CTD-binding for IBVs but not for IAVs, and we show that FluPolB and FluPolA bind to the host RNAP II independently of the CTD. Altogether, our results suggest that the CTD-binding modes of IAV and IBV may represent avian- and human-optimized binding modes, respectively, and that their divergent evolution was shaped by the broader interaction network between the FluPol and the host transcriptional machinery.
Collapse
Affiliation(s)
- Tim Krischuns
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Unité Biologie des ARN et Virus Influenza, Paris, France
| | - Catherine Isel
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Unité Biologie des ARN et Virus Influenza, Paris, France
| | - Petra Drncova
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, Grenoble, France
| | - Maria Lukarska
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, Grenoble, France
| | - Alexander Pflug
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, Grenoble, France
| | - Sylvain Paisant
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Unité Biologie des ARN et Virus Influenza, Paris, France
| | - Vincent Navratil
- PRABI, Rhône Alpes Bioinformatics Center, UCBL, Lyon1, Université de Lyon, Lyon, France
| | - Stephen Cusack
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, Grenoble, France
- * E-mail: (SC); (NN)
| | - Nadia Naffakh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Unité Biologie des ARN et Virus Influenza, Paris, France
- * E-mail: (SC); (NN)
| |
Collapse
|
14
|
The Influenza Virus RNA-Polymerase and the Host RNA-Polymerase II: RPB4 Is Targeted by a PB2 Domain That Is Involved in Viral Transcription. Viruses 2022; 14:v14030518. [PMID: 35336925 PMCID: PMC8950122 DOI: 10.3390/v14030518] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 02/28/2022] [Accepted: 03/01/2022] [Indexed: 12/10/2022] Open
Abstract
Influenza virus transcription is catalyzed by the viral RNA-polymerase (FluPol) through a cap-snatching activity. The snatching of the cap of cellular mRNA by FluPol is preceded by its binding to the flexible C-terminal domain (CTD) of the RPB1 subunit of RNA-polymerase II (Pol II). To better understand how FluPol brings the 3′-end of the genomic RNAs in close proximity to the host-derived primer, we hypothesized that FluPol may recognize additional Pol II subunits/domains to ensure cap-snatching. Using binary complementation assays between the Pol II and influenza A FluPol subunits and their structural domains, we revealed an interaction between the N-third domain of PB2 and RPB4. This interaction was confirmed by a co-immunoprecipitation assay and was found to occur with the homologous domains of influenza B and C FluPols. The N-half domain of RPB4 was found to be critical in this interaction. Punctual mutants generated at conserved positions between influenza A, B, and C FluPols in the N-third domain of PB2 exhibited strong transcriptional activity defects. These results suggest that FluPol interacts with several domains of Pol II (the CTD to bind Pol II), initiating host transcription and a second transcription on RPB4 to locate FluPol at the proximity of the 5′-end of nascent host mRNA.
Collapse
|
15
|
Winston DS, Boehr DD. Allosteric and dynamic control of RNA-dependent RNA polymerase function and fidelity. Enzymes 2021; 49:149-193. [PMID: 34696831 DOI: 10.1016/bs.enz.2021.06.001] [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] [Indexed: 06/13/2023]
Abstract
All RNA viruses encode an RNA-dependent RNA polymerase (RdRp) responsible for genome replication. It is now recognized that enzymes in general, and RdRps specifically, are dynamic macromolecular machines such that their moving parts, including active site loops, play direct functional roles. While X-ray crystallography has provided deep insight into structural elements important for RdRp function, this methodology generally provides only static snapshots, and so is limited in its ability to report on dynamic fluctuations away from the lowest energy conformation. Nuclear magnetic resonance (NMR), molecular dynamics (MD) simulations and other biophysical techniques have brought new insight into RdRp function by their ability to characterize the trajectories, kinetics and thermodynamics of conformational motions. In particular, these methodologies have identified coordinated motions among conserved structural motifs necessary for nucleotide selection and incorporation. Disruption of these motions through amino acid substitutions or inhibitor binding impairs RdRp function. Understanding and re-engineering these motions thus provides exciting new avenues for anti-viral strategies. This chapter outlines the basics of these methodologies, summarizes the dynamic motions observed in different RdRps important for nucleotide selection and incorporation, and illustrates how this information can be leveraged towards rational vaccine strain development and anti-viral drug design.
Collapse
Affiliation(s)
- Dennis S Winston
- Department of Chemistry, The Pennsylvania State University, University Park, PA, United States
| | - David D Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, PA, United States.
| |
Collapse
|
16
|
Plant EP, Ye Z. A Codon-Pair Bias Associated With Network Interactions in Influenza A, B, and C Genomes. Front Genet 2021; 12:699141. [PMID: 34295355 PMCID: PMC8290168 DOI: 10.3389/fgene.2021.699141] [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: 04/22/2021] [Accepted: 06/16/2021] [Indexed: 11/13/2022] Open
Abstract
A new codon-pair bias present in the genomes of different types of influenza virus is described. Codons with fewer network interactions are more frequency paired together than other codon-pairs in influenza A, B, and C genomes. A shared feature among three different influenza types suggests an evolutionary bias. Codon-pair preference can affect both speed of protein translation and RNA structure. This newly identified bias may provide insight into drivers of virus evolution.
Collapse
Affiliation(s)
- Ewan P Plant
- Laboratory of Pediatric and Respiratory Viral Disease, Office of Vaccines Research and Review, CBER, FDA, Silver Spring, MD, United States
| | - Zhiping Ye
- Laboratory of Pediatric and Respiratory Viral Disease, Office of Vaccines Research and Review, CBER, FDA, Silver Spring, MD, United States
| |
Collapse
|
17
|
Weis S, te Velthuis AJW. Influenza Virus RNA Synthesis and the Innate Immune Response. Viruses 2021; 13:v13050780. [PMID: 33924859 PMCID: PMC8146608 DOI: 10.3390/v13050780] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 04/25/2021] [Accepted: 04/25/2021] [Indexed: 12/25/2022] Open
Abstract
Infection with influenza A and B viruses results in a mild to severe respiratory tract infection. It is widely accepted that many factors affect the severity of influenza disease, including viral replication, host adaptation, innate immune signalling, pre-existing immunity, and secondary infections. In this review, we will focus on the interplay between influenza virus RNA synthesis and the detection of influenza virus RNA by our innate immune system. Specifically, we will discuss the generation of various RNA species, host pathogen receptors, and host shut-off. In addition, we will also address outstanding questions that currently limit our knowledge of influenza virus replication and host adaption. Understanding the molecular mechanisms underlying these factors is essential for assessing the pandemic potential of future influenza virus outbreaks.
Collapse
|
18
|
Russell CJ. Hemagglutinin Stability and Its Impact on Influenza A Virus Infectivity, Pathogenicity, and Transmissibility in Avians, Mice, Swine, Seals, Ferrets, and Humans. Viruses 2021; 13:746. [PMID: 33923198 PMCID: PMC8145662 DOI: 10.3390/v13050746] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/21/2021] [Accepted: 04/23/2021] [Indexed: 12/13/2022] Open
Abstract
Genetically diverse influenza A viruses (IAVs) circulate in wild aquatic birds. From this reservoir, IAVs sporadically cause outbreaks, epidemics, and pandemics in wild and domestic avians, wild land and sea mammals, horses, canines, felines, swine, humans, and other species. One molecular trait shown to modulate IAV host range is the stability of the hemagglutinin (HA) surface glycoprotein. The HA protein is the major antigen and during virus entry, this trimeric envelope glycoprotein binds sialic acid-containing receptors before being triggered by endosomal low pH to undergo irreversible structural changes that cause membrane fusion. The HA proteins from different IAV isolates can vary in the pH at which HA protein structural changes are triggered, the protein causes membrane fusion, or outside the cell the virion becomes inactivated. HA activation pH values generally range from pH 4.8 to 6.2. Human-adapted HA proteins tend to have relatively stable HA proteins activated at pH 5.5 or below. Here, studies are reviewed that report HA stability values and investigate the biological impact of variations in HA stability on replication, pathogenicity, and transmissibility in experimental animal models. Overall, a stabilized HA protein appears to be necessary for human pandemic potential and should be considered when assessing human pandemic risk.
Collapse
Affiliation(s)
- Charles J Russell
- Department of Infectious Diseases, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105-3678, USA
| |
Collapse
|
19
|
The influenza virus RNA polymerase as an innate immune agonist and antagonist. Cell Mol Life Sci 2021; 78:7237-7256. [PMID: 34677644 PMCID: PMC8532088 DOI: 10.1007/s00018-021-03957-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/16/2021] [Accepted: 09/29/2021] [Indexed: 12/16/2022]
Abstract
Influenza A viruses cause a mild-to-severe respiratory disease that affects millions of people each year. One of the many determinants of disease outcome is the innate immune response to the viral infection. While antiviral responses are essential for viral clearance, excessive innate immune activation promotes lung damage and disease. The influenza A virus RNA polymerase is one of viral proteins that affect innate immune activation during infection, but the mechanisms behind this activity are not well understood. In this review, we discuss how the viral RNA polymerase can both activate and suppress innate immune responses by either producing immunostimulatory RNA species or directly targeting the components of the innate immune signalling pathway, respectively. Furthermore, we provide a comprehensive overview of the polymerase residues, and their mutations, associated with changes in innate immune activation, and discuss their putative effects on polymerase function based on recent advances in our understanding of the influenza A virus RNA polymerase structure.
Collapse
|