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Din GU, Hasham K, Amjad MN, Hu Y. Natural History of Influenza B Virus-Current Knowledge on Treatment, Resistance and Therapeutic Options. Curr Issues Mol Biol 2023; 46:183-199. [PMID: 38248316 PMCID: PMC10814056 DOI: 10.3390/cimb46010014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/08/2023] [Accepted: 12/13/2023] [Indexed: 01/23/2024] Open
Abstract
Influenza B virus (IBV) significantly impacts the health and the economy of the global population. WHO global health estimates project 1 billion flu cases annually, with 3 to 5 million resulting in severe disease and 0.3 to 0.5 million influenza-related deaths worldwide. Influenza B virus epidemics result in significant economic losses due to healthcare expenses, reduced workforce productivity, and strain on healthcare systems. Influenza B virus epidemics, such as the 1987-1988 Yamagata lineage outbreak and the 2001-2002 Victoria lineage outbreak, had a significant global impact. IBV's fast mutation and replication rates facilitate rapid adaptation to the environment, enabling the evasion of existing immunity and the development of resistance to virus-targeting treatments. This leads to annual outbreaks and necessitates the development of new vaccination formulations. This review aims to elucidate IBV's evolutionary genomic organization and life cycle and provide an overview of anti-IBV drugs, resistance, treatment options, and prospects for IBV biology, emphasizing challenges in preventing and treating IBV infection.
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Affiliation(s)
- Ghayyas Ud Din
- CAS Key Laboratory of Molecular Virology & Immunology, Institutional Center for Shared Technologies and Facilities, Pathogen Discovery and Big Data Platform, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, No. 320 Yueyang Road, Shanghai 200031, China; (G.U.D.)
- University of Chinese Academy of Sciences, Beijing 100040, China
| | - Kinza Hasham
- Sundas Molecular Analysis Center, Sundas Foundation Gujranwala Punjab Pakistan, Gujranwala 50250, Pakistan
| | - Muhammad Nabeel Amjad
- CAS Key Laboratory of Molecular Virology & Immunology, Institutional Center for Shared Technologies and Facilities, Pathogen Discovery and Big Data Platform, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, No. 320 Yueyang Road, Shanghai 200031, China; (G.U.D.)
- University of Chinese Academy of Sciences, Beijing 100040, China
| | - Yihong Hu
- CAS Key Laboratory of Molecular Virology & Immunology, Institutional Center for Shared Technologies and Facilities, Pathogen Discovery and Big Data Platform, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, No. 320 Yueyang Road, Shanghai 200031, China; (G.U.D.)
- University of Chinese Academy of Sciences, Beijing 100040, China
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Tang YS, Lo CY, Mok CKP, Chan PKS, Shaw PC. The Extended C-Terminal Region of Influenza C Virus Nucleoprotein Is Important for Nuclear Import and Ribonucleoprotein Activity. J Virol 2019; 93:e02048-18. [PMID: 30814281 PMCID: PMC6475786 DOI: 10.1128/jvi.02048-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 02/15/2019] [Indexed: 02/06/2023] Open
Abstract
The influenza C virus (ICV) is a human-pathogenic agent, and the infections are frequently identified in children. Compared to influenza A and B viruses, the nucleoprotein of ICV (NPC) has an extended C-terminal region of which the functional significance is ill defined. We observed that the nuclear localization signals (NLSs) found on the nucleoproteins of influenza A and B virus subtypes are absent at corresponding positions on ICV. Instead, we found that a long bipartite nuclear localization signal resides at the extended C-terminal region, spanning from R513 to K549. Our experimental data determined that the KKMK motif within this region plays important roles in both nuclear import and polymerase activity. Similar to the influenza A viruses, NPC also binds to multiple human importin α isoforms. Taken together, our results enhance the understanding of the virus-host interaction of the influenza C virus.IMPORTANCE As a member of the Orthomyxoviridae family, the polymerase complex of the influenza C virus structurally resembles its influenza A and influenza B virus counterparts, but the nucleoprotein differs by possessing an extra C-terminal region. We have characterized this region in view of nuclear import and interaction with the importin α protein family. Our results demonstrate the functional significance of a previously uncharacterized region on Orthomyxoviridae nucleoprotein (NP). Based on this work, we propose that importin α binding to influenza C virus NP is regulated by a long bipartite nuclear localization signal. Since the sequence of influenza D virus NP shares high homology to that of the influenza C virus, this work will also shed light on how influenza D virus NP functions.
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Affiliation(s)
- Yun-Sang Tang
- School of Life Sciences and Centre for Protein Science and Crystallography, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Chun-Yeung Lo
- School of Life Sciences and Centre for Protein Science and Crystallography, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Chris Ka-Pun Mok
- HKU-Pasteur Research Pole, School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Paul Kay-Sheung Chan
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Pang-Chui Shaw
- School of Life Sciences and Centre for Protein Science and Crystallography, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
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Lee J, Lee S, Kwon YE, Kim YJ, Choi JS. Gene Delivery by PAMAM Dendrimer Conjugated with the Nuclear Localization Signal Peptide Derived from Influenza B Virus Nucleoprotein. Macromol Res 2019. [DOI: 10.1007/s13233-019-7057-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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The structure of the nucleoprotein of Influenza D shows that all Orthomyxoviridae nucleoproteins have a similar NP CORE, with or without a NP TAIL for nuclear transport. Sci Rep 2019; 9:600. [PMID: 30679709 PMCID: PMC6346101 DOI: 10.1038/s41598-018-37306-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 11/30/2018] [Indexed: 02/07/2023] Open
Abstract
This paper focuses on the nucleoprotein (NP) of the newly identified member of the Orthomyxoviridae family, Influenza D virus. To date several X-ray structures of NP of Influenza A (A/NP) and B (B/NP) viruses and of infectious salmon anemia (ISA/NP) virus have been solved. Here we purified, characterized and solved the X-ray structure of the tetrameric D/NP at 2.4 Å resolution. The crystal structure of its core is similar to NP of other Influenza viruses. However, unlike A/NP and B/NP which possess a flexible amino-terminal tail containing nuclear localization signals (NLS) for their nuclear import, D/NP possesses a carboxy-terminal tail (D/NPTAIL). We show that D/NPTAIL harbors a bipartite NLS and designed C-terminal truncated mutants to demonstrate the role of D/NPTAIL for nuclear transport.
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Structural analysis of the complex between influenza B nucleoprotein and human importin-α. Sci Rep 2017; 7:17164. [PMID: 29215074 PMCID: PMC5719345 DOI: 10.1038/s41598-017-17458-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/27/2017] [Indexed: 12/29/2022] Open
Abstract
Influenza viruses are negative strand RNA viruses that replicate in the nucleus of the cell. The viral nucleoprotein (NP) is the major component of the viral ribonucleoprotein. In this paper we show that the NP of influenza B has a long N-terminal tail of 70 residues with intrinsic flexibility. This tail contains the Nuclear Location Signal (NLS). The nuclear trafficking of the viral components mobilizes cellular import factors at different stages, making these host-pathogen interactions promising targets for new therapeutics. NP is imported into the nucleus by the importin-α/β pathway, through a direct interaction with importin-α isoforms. Here we provide a combined nuclear magnetic resonance and small-angle X-ray scattering (NMR/SAXS) analysis to describe the dynamics of the interaction between influenza B NP and the human importin-α. The NP of influenza B does not have a single NLS nor a bipartite NLS but our results suggest that the tail harbors several adjacent NLS sequences, located between residues 30 and 71.
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Wongthida P, Liwnaree B, Wanasen N, Narkpuk J, Jongkaewwattana A. The role of ORF3 accessory protein in replication of cell-adapted porcine epidemic diarrhea virus (PEDV). Arch Virol 2017; 162:2553-2563. [PMID: 28474223 DOI: 10.1007/s00705-017-3390-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 04/19/2017] [Indexed: 12/01/2022]
Abstract
The ORF3 accessory protein has been shown to impede reverse genetics of cell-culture-adapted porcine epidemic diarrhea virus (PEDV). Its absence or truncated variants are also associated with viral attenuation in vivo. Here, three ORF3 variants (ORF3NP12, ORF3NP14 and ORF3RB14) and their truncated counterparts were investigated for their regulatory role in recovery of cell-adapted PEDV in vitro. We demonstrate that ORF3NP12, but not the truncated form, can inhibit recovery of reverse-genetics-derived PEDV when expressed in trans. When testing with other RNA viruses, ORF3 was found to inhibit rescue of porcine respiratory and reproductive syndrome virus (PRRSV), but not of influenza virus. Interestingly, results from mutagenesis of ORF3NP12 suggest that F81 and M167 are responsible for impairing PEDV rescue in vitro. By changing specific residues of ORF3, the recombinant PEDV bearing the modified ORF3NP12 can be productively propagated in VeroE6-APN cells. These results may provide mechanistic insights into ORF3-mediated inhibition of PEDV replication in new host cells.
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Affiliation(s)
- Phonphimon Wongthida
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin Rd., Klong Nueng, Klong Luang, Pathum Thani, 12120, Thailand
| | - Benjamas Liwnaree
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin Rd., Klong Nueng, Klong Luang, Pathum Thani, 12120, Thailand
| | - Nanchaya Wanasen
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin Rd., Klong Nueng, Klong Luang, Pathum Thani, 12120, Thailand
| | - Jaraspim Narkpuk
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin Rd., Klong Nueng, Klong Luang, Pathum Thani, 12120, Thailand
| | - Anan Jongkaewwattana
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin Rd., Klong Nueng, Klong Luang, Pathum Thani, 12120, Thailand.
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Nogales A, Baker SF, Domm W, Martínez-Sobrido L. Development and applications of single-cycle infectious influenza A virus (sciIAV). Virus Res 2016; 216:26-40. [PMID: 26220478 PMCID: PMC4728073 DOI: 10.1016/j.virusres.2015.07.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Revised: 07/05/2015] [Accepted: 07/13/2015] [Indexed: 02/06/2023]
Abstract
The diverse host range, high transmissibility, and rapid evolution of influenza A viruses justify the importance of containing pathogenic viruses studied in the laboratory. Other than physically or mechanically changing influenza A virus containment procedures, modifying the virus to only replicate for a single round of infection similarly ensures safety and consequently decreases the level of biosafety containment required to study highly pathogenic members in the virus family. This biological containment is more ideal because it is less apt to computer, machine, or human error. With many necessary proteins that can be deleted, generation of single-cycle infectious influenza A viruses (sciIAV) can be achieved using a variety of approaches. Here, we review the recent burst in sciIAV generation and summarize the applications and findings on this important human pathogen using biocontained viral mimics.
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Affiliation(s)
- Aitor Nogales
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States
| | - Steven F Baker
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States
| | - William Domm
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States
| | - Luis Martínez-Sobrido
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States.
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Sobhy H. A Review of Functional Motifs Utilized by Viruses. Proteomes 2016; 4:proteomes4010003. [PMID: 28248213 PMCID: PMC5217368 DOI: 10.3390/proteomes4010003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 01/07/2016] [Accepted: 01/13/2016] [Indexed: 01/05/2023] Open
Abstract
Short linear motifs (SLiM) are short peptides that facilitate protein function and protein-protein interactions. Viruses utilize these motifs to enter into the host, interact with cellular proteins, or egress from host cells. Studying functional motifs may help to predict protein characteristics, interactions, or the putative cellular role of a protein. In virology, it may reveal aspects of the virus tropism and help find antiviral therapeutics. This review highlights the recent understanding of functional motifs utilized by viruses. Special attention was paid to the function of proteins harboring these motifs, and viruses encoding these proteins. The review highlights motifs involved in (i) immune response and post-translational modifications (e.g., ubiquitylation, SUMOylation or ISGylation); (ii) virus-host cell interactions, including virus attachment, entry, fusion, egress and nuclear trafficking; (iii) virulence and antiviral activities; (iv) virion structure; and (v) low-complexity regions (LCRs) or motifs enriched with residues (Xaa-rich motifs).
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Affiliation(s)
- Haitham Sobhy
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden.
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Koutsakos M, Nguyen THO, Barclay WS, Kedzierska K. Knowns and unknowns of influenza B viruses. Future Microbiol 2015; 11:119-35. [PMID: 26684590 DOI: 10.2217/fmb.15.120] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Influenza B viruses (IBVs) circulate annually along with influenza A (IAV) strains during seasonal epidemics. IBV can dominate influenza seasons and cause severe disease, particularly in children and adolescents. Research has revealed interesting aspects of IBV and highlighted the importance of these viruses in clinical settings. Yet, many important questions remain unanswered. In this review, the clinical relevance of IBV is emphasized, unique features in epidemiology, host range and virology are highlighted and gaps in knowledge pinpointed. Multiple aspects of IBV epidemiology, evolution, virology and immunology are discussed. Future research into IBV is needed to understand how we can prevent severe disease in high-risk groups, especially children and elderly.
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Affiliation(s)
- Marios Koutsakos
- Department of Microbiology & Immunology, University of Melbourne, at the Peter Doherty Institute for Infection & Immunity, Parkville VIC 3010, Australia
| | - Thi H O Nguyen
- Department of Microbiology & Immunology, University of Melbourne, at the Peter Doherty Institute for Infection & Immunity, Parkville VIC 3010, Australia
| | - Wendy S Barclay
- Section of Virology, Faculty of Medicine, Wright Fleming Institute, Imperial College London, Norfolk Place, London W2 1PG, UK
| | - Katherine Kedzierska
- Department of Microbiology & Immunology, University of Melbourne, at the Peter Doherty Institute for Infection & Immunity, Parkville VIC 3010, Australia
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Liu M, Lam MKH, Zhang Q, Elderfield R, Barclay WS, Shaw PC. The Functional Study of the N-Terminal Region of Influenza B Virus Nucleoprotein. PLoS One 2015; 10:e0137802. [PMID: 26368391 PMCID: PMC4569402 DOI: 10.1371/journal.pone.0137802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 08/21/2015] [Indexed: 11/18/2022] Open
Abstract
Influenza nucleoprotein (NP) is a major component of the ribonucleoprotein (vRNP) in influenza virus, which functions for the transcription and replication of viral genome. Compared to the nucleoprotein of influenza A (ANP), the N-terminal region of influenza B nucleoprotein (BNP) is much extended. By virus reconstitution, we found that the first 38 residues are essential for viral growth. We further illustrated the function of BNP by mini-genome reconstitution, fluorescence microscopy, electron microscopy, light scattering and gel shift. Results show that the N terminus is involved in the formation of both higher homo-oligomers of BNP and BNP-RNA complex.
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Affiliation(s)
- Ming Liu
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Mandy Ka-Han Lam
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Qinfen Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Ruth Elderfield
- Section of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Wendy S. Barclay
- Section of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Pang-Chui Shaw
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
- * E-mail:
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Jengarn J, Wongthida P, Wanasen N, Frantz PN, Wanitchang A, Jongkaewwattana A. Genetic manipulation of porcine epidemic diarrhoea virus recovered from a full-length infectious cDNA clone. J Gen Virol 2015; 96:2206-2218. [PMID: 25979733 DOI: 10.1099/vir.0.000184] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Porcine epidemic diarrhoea virus (PEDV) causes acute diarrhoea and dehydration in swine of all ages, with significant mortality in neonatal pigs. The recent rise of PEDV outbreaks in Asia and North America warrants an urgent search for effective vaccines. However, PEDV vaccine research has been hampered by difficulties in isolating and propagating the virus in mammalian cells, thereby complicating the recovery of infectious PEDV using a full-length infectious clone. Here, we engineered VeroE6 cells to stably express porcine aminopeptidase N (pAPN) and used them as a platform to obtain a high-growth variant of PEDV, termed PEDVAVCT12. Subsequently, the full-length cDNA clone was constructed by assembling contiguous cDNA fragments encompassing the complete genome of PEDVAVCT12 in a bacterial artificial chromosome. Infectious PEDV could be recovered, and the rescued virus displayed phenotypic properties identical to the parental virus. Interestingly, we found that PEDVAVCT12 contained a C-terminal deletion of the spike gene, resulting in disruption of the ORF3 start codon. When a functional ORF3 gene was restored, the recombinant virus could not be rescued, suggesting that ORF3 could suppress PEDV replication in vitro. In addition, a high-growth and genetically stable recombinant PEDV expressing a foreign protein could be rescued by replacing the ORF3 gene with the mCherry gene. Together, the results of this study provide a means to generate genetically defined PEDV as a promising vaccine candidate.
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Affiliation(s)
- Juggragarn Jengarn
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani 12120, Thailand
| | - Phonphimon Wongthida
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani 12120, Thailand
| | - Nanchaya Wanasen
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani 12120, Thailand
| | - Phanramphoei Namprachan Frantz
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani 12120, Thailand
| | - Asawin Wanitchang
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani 12120, Thailand
| | - Anan Jongkaewwattana
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani 12120, Thailand
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The N terminus of the influenza B virus nucleoprotein is essential for virus viability, nuclear localization, and optimal transcription and replication of the viral genome. J Virol 2014; 88:12326-38. [PMID: 25122787 DOI: 10.1128/jvi.01542-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
UNLABELLED The nucleoprotein (NP) of influenza viruses is a multifunctional protein with essential roles throughout viral replication. Despite influenza A and B viruses belonging to separate genera of the Orthomyxoviridae family, their NP proteins share a relatively high level of sequence conservation. However, NP of influenza B viruses (BNP) contains an evolutionarily conserved N-terminal 50-amino-acid extension that is absent from NP of influenza A viruses. There is conflicting evidence as to the functions of the BNP N-terminal extension; however, this has never been assessed in the context of viral infection. We have used reverse genetics to assess the significance of this region on the functions of BNP and virus viability. The truncation of more than three amino acids prevented virus recovery, suggesting that the N-terminal extension is essential for virus viability. Mutational analysis indicated that multiple regions of the protein are involved in the nuclear localization of BNP, with the entire N-terminal extension required for this to function efficiently. Viruses containing mutations in the first 10 residues of BNP demonstrated few differences in nuclear localization; however, the viruses exhibited significant reductions in viral mRNA transcription and genome replication, resulting in significantly attenuated phenotypes. Mutations introduced to ablate a previously reported nuclear localization signal also resulted in a significant decrease in mRNA production during early stages of viral replication. Overall, our results demonstrate that the N-terminal extension of BNP is essential to virus viability not only for directing nuclear localization of BNP but also for regulating viral mRNA transcription and genome replication. IMPORTANCE The multifunctional NP of influenza viruses has roles throughout the viral replication cycle; therefore, it is essential for virus viability. Despite high levels of homology between the NP of influenza A and B viruses, the NP of influenza B virus contains an evolutionarily conserved 50-amino-acid N-terminal extension that is absent from the NP of influenza A viruses. In this study, we show that this N-terminal extension is essential for virus viability, and we confirm and expand upon recent findings that this region of BNP is required for nuclear localization of the protein. Furthermore, we demonstrate for the first time that the N terminus of BNP is involved in regulating viral mRNA transcription and replication of the viral genome. As the NP of influenza A virus lacks this N-terminal extension, these viruses may have evolved separate mechanisms to regulate these processes.
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Jaru-ampornpan P, Narkpuk J, Wanitchang A, Jongkaewwattana A. Nucleoprotein of influenza B virus binds to its type A counterpart and disrupts influenza A viral polymerase complex formation. Biochem Biophys Res Commun 2013; 443:296-300. [PMID: 24309113 DOI: 10.1016/j.bbrc.2013.11.100] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 11/24/2013] [Indexed: 11/17/2022]
Abstract
Upon co-infection with influenza B virus (FluB), influenza A virus (FluA) replication is substantially impaired. Previously, we have shown that the nucleoprotein of FluB (BNP) can inhibit FluA polymerase machinery, retarding the growth of FluA. However, the molecular mechanism underlying this inhibitory action awaited further investigation. Here, we provide evidence that BNP hinders the proper formation of FluA polymerase complex by competitively binding to the nucleoprotein of FluA. To exert this inhibitory effect, BNP must be localized in the nucleus. The interaction does not require the presence of the viral RNA but needs an intact BNP RNA-binding motif. The results highlight the novel role of BNP as an anti-influenza A viral agent and provide insights into the mechanism of intertypic interference.
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Affiliation(s)
- Peera Jaru-ampornpan
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani, Thailand.
| | - Jaraspim Narkpuk
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani, Thailand
| | - Asawin Wanitchang
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani, Thailand
| | - Anan Jongkaewwattana
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani, Thailand.
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