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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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Li L, Liu T, Wang Q, Ding Y, Jiang Y, Wu Z, Wang X, Dou H, Jia Y, Jiao B. Genetic characterization and whole-genome sequencing-based genetic analysis of influenza virus in Jining City during 2021-2022. Front Microbiol 2023; 14:1196451. [PMID: 37426015 PMCID: PMC10324579 DOI: 10.3389/fmicb.2023.1196451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/02/2023] [Indexed: 07/11/2023] Open
Abstract
Background The influenza virus poses a significant threat to global public health due to its high mutation rate. Continuous surveillance, development of new vaccines, and public health measures are crucial in managing and mitigating the impact of influenza outbreaks. Methods Nasal swabs were collected from individuals with influenza-like symptoms in Jining City during 2021-2022. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect influenza A viruses, followed by isolation using MDCK cells. Additionally, nucleic acid detection was performed to identify influenza A H1N1, seasonal H3N2, B/Victoria, and B/Yamagata strains. Whole-genome sequencing was conducted on 24 influenza virus strains, and subsequent analyses included characterization, phylogenetic construction, mutation analysis, and assessment of nucleotide diversity. Results A total of 1,543 throat swab samples were collected. The study revealed the dominance of the B/Victoria influenza virus in Jining during 2021-2022. Whole-genome sequencing showed co-prevalence of B/Victoria influenza viruses in the branches of Victoria clade 1A.3a.1 and Victoria clade 1A.3a.2, with a higher incidence observed in winter and spring. Comparative analysis demonstrated lower similarity in the HA, MP, and PB2 gene segments of the 24 sequenced influenza virus strains compared to the Northern Hemisphere vaccine strain B/Washington/02/2019. Mutations were identified in all antigenic epitopes of the HA protein at R133G, N150K, and N197D, and the 17-sequence antigenic epitopes exhibited more than 4 amino acid variation sites, resulting in antigenic drift. Moreover, one sequence had a D197N mutation in the NA protein, while seven sequences had a K338R mutation in the PA protein. Conclusion This study highlights the predominant presence of B/Victoria influenza strain in Jining from 2021 to 2022. The analysis also identified amino acid site variations in the antigenic epitopes, contributing to antigenic drift.
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Affiliation(s)
- Libo Li
- Department of Laboratory, Jining Center for Disease Control and Prevention, Jining, China
| | - Tiantian Liu
- Department of Laboratory, Jining Center for Disease Control and Prevention, Jining, China
| | - Qingchuan Wang
- Department of Medicine, Jining Municipal Government Hospital, Jining, China
| | - Yi Ding
- Department of Laboratory, Jining Center for Disease Control and Prevention, Jining, China
| | - Yajuan Jiang
- Department of Laboratory, Jining Center for Disease Control and Prevention, Jining, China
| | - Zengding Wu
- Department of AI and Bioinformatics, Nanjing Chengshi BioTech (TheraRNA) Co., Ltd., Nanjing, China
| | - Xiaoyu Wang
- Department of Laboratory, Jining Center for Disease Control and Prevention, Jining, China
| | - Huixin Dou
- Department of Laboratory, Jining Center for Disease Control and Prevention, Jining, China
| | - Yongjian Jia
- Department of Laboratory, Jining Center for Disease Control and Prevention, Jining, China
| | - Boyan Jiao
- Department of Laboratory, Jining Center for Disease Control and Prevention, Jining, China
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AbuBakar U, Amrani L, Kamarulzaman FA, Karsani SA, Hassandarvish P, Khairat JE. Avian Influenza Virus Tropism in Humans. Viruses 2023; 15:833. [PMID: 37112812 PMCID: PMC10142937 DOI: 10.3390/v15040833] [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: 02/04/2023] [Revised: 03/12/2023] [Accepted: 03/17/2023] [Indexed: 03/29/2023] Open
Abstract
An influenza pandemic happens when a novel influenza A virus is able to infect and transmit efficiently to a new, distinct host species. Although the exact timing of pandemics is uncertain, it is known that both viral and host factors play a role in their emergence. Species-specific interactions between the virus and the host cell determine the virus tropism, including binding and entering cells, replicating the viral RNA genome within the host cell nucleus, assembling, maturing and releasing the virus to neighboring cells, tissues or organs before transmitting it between individuals. The influenza A virus has a vast and antigenically varied reservoir. In wild aquatic birds, the infection is typically asymptomatic. Avian influenza virus (AIV) can cross into new species, and occasionally it can acquire the ability to transmit from human to human. A pandemic might occur if a new influenza virus acquires enough adaptive mutations to maintain transmission between people. This review highlights the key determinants AIV must achieve to initiate a human pandemic and describes how AIV mutates to establish tropism and stable human adaptation. Understanding the tropism of AIV may be crucial in preventing virus transmission in humans and may help the design of vaccines, antivirals and therapeutic agents against the virus.
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Affiliation(s)
- Umarqayum AbuBakar
- Institute of Biological Sciences (ISB), Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Lina Amrani
- Institute of Biological Sciences (ISB), Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Farah Ayuni Kamarulzaman
- Institute of Biological Sciences (ISB), Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Saiful Anuar Karsani
- Institute of Biological Sciences (ISB), Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Pouya Hassandarvish
- Tropical Infectious Diseases Research and Education Center, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Jasmine Elanie Khairat
- Institute of Biological Sciences (ISB), Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia
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Kashyap T, Murray J, Walker CJ, Chang H, Tamir S, Hou B, Shacham S, Kauffman MG, Tripp RA, Landesman Y. Selinexor, a novel selective inhibitor of nuclear export, reduces SARS-CoV-2 infection and protects the respiratory system in vivo. Antiviral Res 2021; 192:105115. [PMID: 34157321 PMCID: PMC8213878 DOI: 10.1016/j.antiviral.2021.105115] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 06/01/2021] [Indexed: 02/07/2023]
Abstract
The novel coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the recent global pandemic. The nuclear export protein (XPO1) has a direct role in the export of SARS-CoV proteins including ORF3b, ORF9b, and nucleocapsid. Inhibition of XPO1 induces anti-inflammatory, anti-viral, and antioxidant pathways. Selinexor is an FDA-approved XPO1 inhibitor. Through bioinformatics analysis, we predicted nuclear export sequences in the ACE-2 protein and confirmed by in vitro testing that inhibition of XPO1 with selinexor induces nuclear localization of ACE-2. Administration of selinexor inhibited viral infection prophylactically as well as therapeutically in vitro. In a ferret model of COVID-19, selinexor treatment reduced viral load in the lungs and protected against tissue damage in the nasal turbinates and lungs in vivo. Our studies demonstrated that selinexor downregulated the pro-inflammatory cytokines IL-1β, IL-6, IL-10, IFN-γ, TNF-α, and GMCSF, commonly associated with the cytokine storm observed in COVID-19 patients. Our findings indicate that nuclear export is critical for SARS-CoV-2 infection and for COVID-19 pathology and suggest that inhibition of XPO1 by selinexor could be a viable anti-viral treatment option.
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Affiliation(s)
| | - Jackelyn Murray
- University of Georgia College of Veterinary Medicine, Athens, GA, USA
| | | | - Hua Chang
- Karyopharm Therapeutics, Newton, MA, USA
| | | | - Bing Hou
- Antengene Corporation Co., Ltd., Shaoxing, PR China
| | | | | | - Ralph A Tripp
- University of Georgia College of Veterinary Medicine, Athens, GA, USA
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Jaiswal N, Agarwal N, Poluri KM, Kumar D. Effect of urea concentration on instant refolding of Nuclear Export Protein (NEP) from Influenza-A virus H1N1: A solution NMR based investigation. Int J Biol Macromol 2020; 165:2508-2519. [PMID: 33470198 DOI: 10.1016/j.ijbiomac.2020.10.146] [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: 08/26/2019] [Revised: 08/12/2020] [Accepted: 10/18/2020] [Indexed: 01/14/2023]
Abstract
Nuclear-export-protein (NEP) plays multiple-functions during influenza virus replication-cycle and shows unique pattern of conserved residues, which altogether make NEP a potential target for developing novel anti-influenza drugs. However, the mechanistic structural biology of NEP has not been fully characterized so far owing to its tendency to aggregate in solution. As structural information is important to guide rational drug-discovery process; therefore, procedural optimization efforts are going on to achieve properly folded NEP in sub-millimolar concentrations for solution-NMR investigations. As a first step in this direction, the refolding-cum-aggregation behavior of recombinant-NEP with N-terminal purification-tag (referred here as NEPN) at different urea-concentrations has been investigated here by NMR-based methods. Several attempts were made to refold denatured NEP-N through step-dialysis. However, owing to its strong tendency to aggregate, excessive precipitation was observed at sub-higher levels of urea concentration (5.0 ± 1.0 M). Finally, we used drip-dilution method with 10.5 M urea-denatured NEP-N and were able to refold NEP-N instantly. The amide 1H dispersion of 3.6 ppm (6.6-10.2 ppm) in the 15N-HSQC-spectra of instantly refolded NEP-N confirmed the folded state. This successful instant-refolding of NEP-N has been reported for the first-time and the underlying mechanism has been rationalized through establishing the complete backbone-resonance-assignments of NEP-N at 9.7 M urea-denatured state.
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Affiliation(s)
- Nancy Jaiswal
- Centre of Biomedical Research, SGPGIMS Campus, Lucknow 226014, India; Dr. APJ Abdul Kalam Technical University, IET Campus, Sitapur Road, Lucknow, Uttar Pradesh, India
| | - Nipanshu Agarwal
- Department of Biotechnology and Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
| | - Krishna Mohan Poluri
- Department of Biotechnology and Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
| | - Dinesh Kumar
- Centre of Biomedical Research, SGPGIMS Campus, Lucknow 226014, India.
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Establishment of a Reverse Genetics System for Influenza D Virus. J Virol 2020; 94:JVI.01767-19. [PMID: 32102883 DOI: 10.1128/jvi.01767-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 02/03/2020] [Indexed: 12/22/2022] Open
Abstract
Influenza D virus (IDV) was initially isolated in the United States in 2011. IDV is distributed worldwide and is one of the causative agents of the bovine respiratory disease complex (BRDC), which causes high morbidity and mortality in feedlot cattle. The molecular mechanisms of IDV pathogenicity are still unknown. Reverse genetics systems are vital tools not only for studying the biology of viruses, but also for use in applications such as recombinant vaccine viruses. Here, we report the establishment of a plasmid-based reverse genetics system for IDV. We first verified that the 3'-terminal nucleotide of each 7-segmented genomic RNA contained uracil (U), contrary to previous reports, and we were then able to successfully generate recombinant IDV by cotransfecting 7 plasmids containing these genomic RNAs along with 4 plasmids expressing polymerase proteins and nucleoprotein into human rectal tumor 18G (HRT-18G) cells. The recombinant virus had a growth deficit compared to the wild-type virus, and we determined the reason for this growth difference by examining the genomic RNA content of the viral particles. We found that the recombinant virus incorporated an unbalanced ratio of viral RNA segments into particles compared to that of the wild-type virus, and thus we adjusted the amount of each plasmid used in transfection to obtain a recombinant virus with the same replicative capacity as the wild-type virus. Our work here in establishing a reverse genetics system for IDV will have a broad range of applications, including uses in studies focused on better understanding IDV replication and pathogenicity, as well as in those contributing to the development of BRDC countermeasures.IMPORTANCE The bovine respiratory disease complex (BRDC) causes high mortality and morbidity in cattle, causing economic losses worldwide. Influenza D virus (IDV) is considered to be a causative agent of the BRDC. Here, we developed a reverse genetics system that allows for the generation of IDV from cloned cDNAs and the introduction of mutations into the IDV genome. This reverse genetics system will become a powerful tool for use in studies related to understanding the molecular mechanisms of viral replication and pathogenicity and will also lead to the development of new countermeasures against the BRDC.
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Sederdahl BK, Williams JV. Epidemiology and Clinical Characteristics of Influenza C Virus. Viruses 2020; 12:E89. [PMID: 31941041 PMCID: PMC7019359 DOI: 10.3390/v12010089] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/06/2020] [Accepted: 01/07/2020] [Indexed: 12/14/2022] Open
Abstract
Influenza C virus (ICV) is a common yet under-recognized cause of acute respiratory illness. ICV seropositivity has been found to be as high as 90% by 7-10 years of age, suggesting that most people are exposed to ICV at least once during childhood. Due to difficulty detecting ICV by cell culture, epidemiologic studies of ICV likely have underestimated the burden of ICV infection and disease. Recent development of highly sensitive RT-PCR has facilitated epidemiologic studies that provide further insights into the prevalence, seasonality, and course of ICV infection. In this review, we summarize the epidemiology and clinical characteristics of ICV.
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Affiliation(s)
- Bethany K. Sederdahl
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA;
| | - John V. Williams
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA;
- Institute for Infection, Inflammation, and Immunity in Children (i4Kids), University of Pittsburgh, Pittsburgh, PA 15224, USA
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Sreenivasan CC, Thomas M, Kaushik RS, Wang D, Li F. Influenza A in Bovine Species: A Narrative Literature Review. Viruses 2019; 11:v11060561. [PMID: 31213032 PMCID: PMC6631717 DOI: 10.3390/v11060561] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 12/17/2022] Open
Abstract
It is quite intriguing that bovines were largely unaffected by influenza A, even though most of the domesticated and wild animals/birds at the human-animal interface succumbed to infection over the past few decades. Influenza A occurs on a very infrequent basis in bovine species and hence bovines were not considered to be susceptible hosts for influenza until the emergence of influenza D. This review describes a multifaceted chronological review of literature on influenza in cattle which comprises mainly of the natural infections/outbreaks, experimental studies, and pathological and seroepidemiological aspects of influenza A that have occurred in the past. The review also sheds light on the bovine models used in vitro and in vivo for influenza-related studies over recent years. Despite a few natural cases in the mid-twentieth century and seroprevalence of human, swine, and avian influenza viruses in bovines, the evolution and host adaptation of influenza A virus (IAV) in this species suffered a serious hindrance until the novel influenza D virus (IDV) emerged recently in cattle across the world. Supposedly, certain bovine host factors, particularly some serum components and secretory proteins, were reported to have anti-influenza properties, which could be an attributing factor for the resilient nature of bovines to IAV. Further studies are needed to identify the host-specific factors contributing to the differential pathogenetic mechanisms and disease progression of IAV in bovines compared to other susceptible mammalian hosts.
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Affiliation(s)
- Chithra C Sreenivasan
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA.
| | - Milton Thomas
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD 57007, USA.
| | - Radhey S Kaushik
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA.
| | - Dan Wang
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA.
- BioSystems Networks and Translational Research Center (BioSNTR), Brookings, SD 57007, USA.
| | - Feng Li
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA.
- BioSystems Networks and Translational Research Center (BioSNTR), Brookings, SD 57007, USA.
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Mathew C, Ghildyal R. CRM1 Inhibitors for Antiviral Therapy. Front Microbiol 2017; 8:1171. [PMID: 28702009 PMCID: PMC5487384 DOI: 10.3389/fmicb.2017.01171] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 06/08/2017] [Indexed: 12/22/2022] Open
Abstract
Infectious diseases are a major global concern and despite major advancements in medical research, still cause significant morbidity and mortality. Progress in antiviral therapy is particularly hindered by appearance of mutants capable of overcoming the effects of drugs targeting viral components. Alternatively, development of drugs targeting host proteins essential for completion of viral lifecycle holds potential as a viable strategy for antiviral therapy. Nucleocytoplasmic trafficking pathways in particular are involved in several pathological conditions including cancer and viral infections, where hijacking or alteration of function of key transporter proteins, such as Chromosome Region Maintenance1 (CRM1) is observed. Overexpression of CRM1-mediated nuclear export is evident in several solid and hematological malignancies. Interestingly, CRM1-mediated nuclear export of viral components is crucial in various stages of the viral lifecycle and assembly. This review summarizes the role of CRM1 in cancer and selected viruses. Leptomycin B (LMB) is the prototypical inhibitor of CRM1 potent against various cancer cell lines overexpressing CRM1 and in limiting viral infections at nanomolar concentrations in vitro. However, the irreversible shutdown of nuclear export results in high cytotoxicity and limited efficacy in vivo. This has prompted search for synthetic and natural CRM1 inhibitors that can potentially be developed as broadly active antivirals, some of which are summarized in this review.
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Affiliation(s)
| | - Reena Ghildyal
- Respiratory Virology Group, Centre for Research in Therapeutic Solutions, Health Research Institute, University of CanberraCanberra, ACT, Australia
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Wu X, Wu X, Sun Q, Zhang C, Yang S, Li L, Jia Z. Progress of small molecular inhibitors in the development of anti-influenza virus agents. Am J Cancer Res 2017; 7:826-845. [PMID: 28382157 PMCID: PMC5381247 DOI: 10.7150/thno.17071] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 11/18/2016] [Indexed: 02/05/2023] Open
Abstract
The influenza pandemic is a major threat to human health, and highly aggressive strains such as H1N1, H5N1 and H7N9 have emphasized the need for therapeutic strategies to combat these pathogens. Influenza anti-viral agents, especially active small molecular inhibitors play important roles in controlling pandemics while vaccines are developed. Currently, only a few drugs, which function as influenza neuraminidase (NA) inhibitors and M2 ion channel protein inhibitors, are approved in clinical. However, the acquired resistance against current anti-influenza drugs and the emerging mutations of influenza virus itself remain the major challenging unmet medical needs for influenza treatment. It is highly desirable to identify novel anti-influenza agents. This paper reviews the progress of small molecular inhibitors act as antiviral agents, which include hemagglutinin (HA) inhibitors, RNA-dependent RNA polymerase (RdRp) inhibitors, NA inhibitors and M2 ion channel protein inhibitors etc. Moreover, we also summarize new, recently reported potential targets and discuss strategies for the development of new anti-influenza virus drugs.
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Antiviral activity of KR-23502 targeting nuclear export of influenza B virus ribonucleoproteins. Antiviral Res 2016; 134:77-88. [DOI: 10.1016/j.antiviral.2016.07.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 07/24/2016] [Accepted: 07/26/2016] [Indexed: 11/22/2022]
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Matsuzaki Y, Sugawara K, Furuse Y, Shimotai Y, Hongo S, Oshitani H, Mizuta K, Nishimura H. Genetic Lineage and Reassortment of Influenza C Viruses Circulating between 1947 and 2014. J Virol 2016; 90:8251-65. [PMID: 27384661 PMCID: PMC5008092 DOI: 10.1128/jvi.00969-16] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 06/28/2016] [Indexed: 11/20/2022] Open
Abstract
Since influenza C virus was first isolated in 1947, the virus has been only occasionally isolated by cell culture; there are only four strains for which complete genome sequences are registered. Here, we analyzed a total of 106 complete genomes, ranging from the first isolate from 1947 to recent isolates from 2014, to determine the genetic lineages of influenza C virus, the reassortment events, and the rates of nucleotide substitution. The results showed that there are six lineages, named C/Taylor, C/Mississippi, C/Aichi, C/Yamagata, C/Kanagawa, and C/Sao Paulo. They contain both antigenic and genetic lineages of the hemagglutinin-esterase (HE) gene, and the internal genes PB2, PB1, P3, NP, M, and NS are divided into two major lineages, a C/Mississippi/80-related lineage and a C/Yamagata/81-related lineage. Reassortment events were found over the entire period of 68 years. Several outbreaks of influenza C virus between 1990 and 2014 in Japan consisted of reassortant viruses, suggesting that the genomic constellation is related to influenza C virus epidemics. The nucleotide sequences were highly homologous to each other. The minimum percent identity between viruses ranged from 91.1% for the HE gene to 96.1% for the M gene, and the rate of nucleotide substitution for the HE gene was the highest, at 5.20 × 10(-4) substitutions/site/year. These results indicate that reassortment is an important factor that increases the genetic diversity of influenza C virus, resulting in its ability to prevail in humans. IMPORTANCE Influenza C virus is a pathogen that causes acute respiratory illness in children and results in hospitalization of infants. We previously demonstrated (Y. Matsuzaki et al., J Clin Virol 61:87-93, 2014, http://dx.doi.org/10.1016/j.jcv.2014.06.017) that periodic epidemics of this virus occurred in Japan between 1996 and 2014 and that replacement of the dominant antigenic group occurred every several years as a result of selection by herd immunity. However, the antigenicity of the HE glycoprotein is highly stable, and antigenic drift has not occurred for at least 30 years. Here, we analyzed a total of 106 complete genomes spanning 68 years for the first time, and we found that influenza C viruses are circulating worldwide while undergoing reassortment as well as selection by herd immunity, resulting in an increased ability to prevail in humans. The results presented in this study contribute to the understanding of the evolution, including reassortment events, underlying influenza C virus epidemics.
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Affiliation(s)
- Yoko Matsuzaki
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Kanetsu Sugawara
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Yuki Furuse
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yoshitaka Shimotai
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Seiji Hongo
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Hitoshi Oshitani
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Katsumi Mizuta
- Department of Microbiology, Yamagata Prefectural Institute of Public Health, Yamagata, Japan
| | - Hidekazu Nishimura
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Miyagi, Japan
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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: 76] [Impact Index Per Article: 8.4] [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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Perwitasari O, Johnson S, Yan X, Howerth E, Shacham S, Landesman Y, Baloglu E, McCauley D, Tamir S, Tompkins SM, Tripp RA. Verdinexor, a novel selective inhibitor of nuclear export, reduces influenza a virus replication in vitro and in vivo. J Virol 2014; 88:10228-43. [PMID: 24965445 PMCID: PMC4136318 DOI: 10.1128/jvi.01774-14] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Influenza is a global health concern, causing death, morbidity, and economic losses. Chemotherapeutics that target influenza virus are available; however, rapid emergence of drug-resistant strains is common. Therapeutic targeting of host proteins hijacked by influenza virus to facilitate replication is an antiviral strategy to reduce the development of drug resistance. Nuclear export of influenza virus ribonucleoprotein (vRNP) from infected cells has been shown to be mediated by exportin 1 (XPO1) interaction with viral nuclear export protein tethered to vRNP. RNA interference screening has identified XPO1 as a host proinfluenza factor where XPO1 silencing results in reduced influenza virus replication. The Streptomyces metabolite XPO1 inhibitor leptomycin B (LMB) has been shown to limit influenza virus replication in vitro; however, LMB is toxic in vivo, which makes it unsuitable for therapeutic use. In this study, we tested the anti-influenza virus activity of a new class of orally available small-molecule selective inhibitors of nuclear export, specifically, the XPO1 antagonist KPT-335 (verdinexor). Verdinexor was shown to potently and selectively inhibit vRNP export and effectively inhibited the replication of various influenza virus A and B strains in vitro, including pandemic H1N1 virus, highly pathogenic H5N1 avian influenza virus, and the recently emerged H7N9 strain. In vivo, prophylactic and therapeutic administration of verdinexor protected mice against disease pathology following a challenge with influenza virus A/California/04/09 or A/Philippines/2/82-X79, as well as reduced lung viral loads and proinflammatory cytokine expression, while having minimal toxicity. These studies show that verdinexor acts as a novel anti-influenza virus therapeutic agent. IMPORTANCE Antiviral drugs represent important means of influenza virus control. However, substantial resistance to currently approved influenza therapeutic drugs has developed. New antiviral approaches are required to address drug resistance and reduce the burden of influenza virus-related disease. This study addressed critical preclinical studies for the development of verdinexor (KPT-335) as a novel antiviral drug. Verdinexor blocks progeny influenza virus genome nuclear export, thus effectively inhibiting virus replication. Verdinexor was found to limit the replication of various strains of influenza A and B viruses, including a pandemic H1N1 influenza virus strain, a highly pathogenic H5N1 avian influenza virus strain, and a recently emerging H7N9 influenza virus strain. Importantly, oral verdinexor treatments, given prophylactically or therapeutically, were efficacious in limiting lung virus burdens in influenza virus-infected mice, in addition to limiting lung proinflammatory cytokine expression, pathology, and death. Thus, this study demonstrated that verdinexor is efficacious against influenza virus infection in vitro and in vivo.
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Affiliation(s)
- Olivia Perwitasari
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA
| | - Scott Johnson
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA
| | - Xiuzhen Yan
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA
| | - Elizabeth Howerth
- Department of Pathology, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA
| | - Sharon Shacham
- Karyopharm Therapeutics, Inc., Natick, Massachusetts, USA
| | | | - Erkan Baloglu
- Karyopharm Therapeutics, Inc., Natick, Massachusetts, USA
| | | | - Sharon Tamir
- Karyopharm Therapeutics, Inc., Natick, Massachusetts, USA
| | - S Mark Tompkins
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA
| | - Ralph A Tripp
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA
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15
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Cao S, Jiang J, Li J, Li Y, Yang L, Wang S, Yan J, Gao GF, Liu W. Characterization of the nucleocytoplasmic shuttle of the matrix protein of influenza B virus. J Virol 2014; 88:7464-73. [PMID: 24741102 PMCID: PMC4054458 DOI: 10.1128/jvi.00794-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 04/14/2014] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Influenza B virus is an enveloped negative-strand RNA virus that contributes considerably to annual influenza illnesses in human. The matrix protein of influenza B virus (BM1) acts as a cytoplasmic-nuclear shuttling protein during the early and late stages of infection. The mechanism of this intracellular transport of BM1 was revealed through the identification of two leucine-rich CRM1-dependent nuclear export signals (NESs) (3 to 14 amino acids [aa] and 124 to 133 aa), one bipartite nuclear localization signal (NLS) (76 to 94 aa), and two phosphorylation sites (80T and 84S) in BM1. The biological function of the NLS and NES regions were determined through the observation of the intracellular distribution of enhanced green fluorescent protein (EGFP)-tagged signal peptides, and wild-type, NES-mutant, and NLS-mutant EGFP-BM1. Furthermore, the NLS phosphorylation sites 80T and 84S, were found to be required for the nuclear accumulation of EGFP-NLS and for the efficient binding of EGFP-BM1 to human importin-α1. Moreover, all of these regions/sites were required for the generation of viable influenza B virus in a 12-plasmid virus rescue system. IMPORTANCE This study expands our understanding of the life cycle of influenza B virus by defining the dynamic mechanism of the nucleocytoplasmic shuttle of BM1 and could provide a scientific basis for the development of antiviral medication.
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Affiliation(s)
- Shuai Cao
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jingwen Jiang
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Jing Li
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yan Li
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Limin Yang
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Shanshan Wang
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jinghua Yan
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - George F Gao
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China School of Life Sciences, University of Science and Technology of China, Hefei, China Graduate University of Chinese Academy of Sciences, Beijing, China China-Japan Joint Laboratory of Molecular Immunology and Molecular Microbiology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China Research Network of Immunity and Health, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China Office of Director-General, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Wenjun Liu
- Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China School of Life Sciences, University of Science and Technology of China, Hefei, China Graduate University of Chinese Academy of Sciences, Beijing, China China-Japan Joint Laboratory of Molecular Immunology and Molecular Microbiology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
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16
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Dela-Moss LI, Moss WN, Turner DH. Identification of conserved RNA secondary structures at influenza B and C splice sites reveals similarities and differences between influenza A, B, and C. BMC Res Notes 2014; 7:22. [PMID: 24405943 PMCID: PMC3895672 DOI: 10.1186/1756-0500-7-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 01/02/2014] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Influenza B and C are single-stranded RNA viruses that cause yearly epidemics and infections. Knowledge of RNA secondary structure generated by influenza B and C will be helpful in further understanding the role of RNA structure in the progression of influenza infection. FINDINGS All available protein-coding sequences for influenza B and C were analyzed for regions with high potential for functional RNA secondary structure. On the basis of conserved RNA secondary structure with predicted high thermodynamic stability, putative structures were identified that contain splice sites in segment 8 of influenza B and segments 6 and 7 of influenza C. The sequence in segment 6 also contains three unused AUG start codon sites that are sequestered within a hairpin structure. CONCLUSIONS When added to previous studies on influenza A, the results suggest that influenza splicing may share common structural strategies for regulation of splicing. In particular, influenza 3' splice sites are predicted to form secondary structures that can switch conformation to regulate splicing. Thus, these RNA structures present attractive targets for therapeutics aimed at targeting one or the other conformation.
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Affiliation(s)
- Lumbini I Dela-Moss
- Department of Chemistry and Center for RNA Biology, University of Rochester, Rochester, New York 14627-0216, USA
| | - Walter N Moss
- Department of Chemistry and Center for RNA Biology, University of Rochester, Rochester, New York 14627-0216, USA
| | - Douglas H Turner
- Department of Chemistry and Center for RNA Biology, University of Rochester, Rochester, New York 14627-0216, USA
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17
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Ramly RB, Olsen CM, Braaen S, Rimstad E. Infectious salmon anaemia virus nuclear export protein is encoded by a spliced gene product of genomic segment 7. Virus Res 2013; 177:1-10. [DOI: 10.1016/j.virusres.2013.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/01/2013] [Accepted: 07/02/2013] [Indexed: 11/16/2022]
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18
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Hutchinson EC, Denham EM, Thomas B, Trudgian DC, Hester SS, Ridlova G, York A, Turrell L, Fodor E. Mapping the phosphoproteome of influenza A and B viruses by mass spectrometry. PLoS Pathog 2012; 8:e1002993. [PMID: 23144613 PMCID: PMC3493474 DOI: 10.1371/journal.ppat.1002993] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 08/29/2012] [Indexed: 01/06/2023] Open
Abstract
Protein phosphorylation is a common post-translational modification in eukaryotic cells and has a wide range of functional effects. Here, we used mass spectrometry to search for phosphorylated residues in all the proteins of influenza A and B viruses--to the best of our knowledge, the first time such a comprehensive approach has been applied to a virus. We identified 36 novel phosphorylation sites, as well as confirming 3 previously-identified sites. N-terminal processing and ubiquitination of viral proteins was also detected. Phosphorylation was detected in the polymerase proteins (PB2, PB1 and PA), glycoproteins (HA and NA), nucleoprotein (NP), matrix protein (M1), ion channel (M2), non-structural protein (NS1) and nuclear export protein (NEP). Many of the phosphorylation sites detected were conserved between influenza virus genera, indicating the fundamental importance of phosphorylation for all influenza viruses. Their structural context indicates roles for phosphorylation in regulating viral entry and exit (HA and NA); nuclear localisation (PB2, M1, NP, NS1 and, through NP and NEP, of the viral RNA genome); and protein multimerisation (NS1 dimers, M2 tetramers and NP oligomers). Using reverse genetics we show that for NP of influenza A viruses phosphorylation sites in the N-terminal NLS are important for viral growth, whereas mutating sites in the C-terminus has little or no effect. Mutating phosphorylation sites in the oligomerisation domains of NP inhibits viral growth and in some cases transcription and replication of the viral RNA genome. However, constitutive phosphorylation of these sites is not optimal. Taken together, the conservation, structural context and functional significance of phosphorylation sites implies a key role for phosphorylation in influenza biology. By identifying phosphorylation sites throughout the proteomes of influenza A and B viruses we provide a framework for further study of phosphorylation events in the viral life cycle and suggest a range of potential antiviral targets.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- * E-mail:
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19
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A second CRM1-dependent nuclear export signal in the influenza A virus NS2 protein contributes to the nuclear export of viral ribonucleoproteins. J Virol 2012; 87:767-78. [PMID: 23115280 DOI: 10.1128/jvi.06519-11] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Influenza A virus NS2 protein, also called nuclear export protein (NEP), is crucial for the nuclear export of viral ribonucleoproteins. However, the molecular mechanisms of NEP mediation in this process remain incompletely understood. A leucine-rich nuclear export signal (NES2) in NEP, located at the predicted N2 helix of the N-terminal domain, was identified in the present study. NES2 was demonstrated to be a transferable NES, with its nuclear export activity depending on the nuclear export receptor chromosome region maintenance 1 (CRM1)-mediated pathway. The interaction between NEP and CRM1 is coordinately regulated by both the previously reported NES (NES1) and now the new NES2. Deletion of the NES1 enhances the interaction between NEP and CRM1, and deletion of the NES1 and NES2 motifs completely abolishes this interaction. Moreover, NES2 interacts with CRM1 in the mammalian two-hybrid system. Mutant viruses containing NES2 alterations generated by reversed genetics exhibit reduced viral growth and delay in the nuclear export of viral ribonucleoproteins (vRNPs). The NES2 motif is highly conserved in the influenza A and B viruses. The results demonstrate that leucine-rich NES2 is involved in the nuclear export of vRNPs and contributes to the understanding of nucleocytoplasmic transport of influenza virus vRNPs.
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20
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Speranskaya AS, Melnikova NV, Belenikin MS, Dmitriev AA, Oparina NY, Kudryavtseva AV. Genetic diversity and evolution of the influenza C virus. RUSS J GENET+ 2012. [DOI: 10.1134/s1022795412070149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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21
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Ortigoza MB, Dibben O, Maamary J, Martinez-Gil L, Leyva-Grado VH, Abreu P, Ayllon J, Palese P, Shaw ML. A novel small molecule inhibitor of influenza A viruses that targets polymerase function and indirectly induces interferon. PLoS Pathog 2012; 8:e1002668. [PMID: 22577360 PMCID: PMC3343121 DOI: 10.1371/journal.ppat.1002668] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 03/08/2012] [Indexed: 01/09/2023] Open
Abstract
Influenza viruses continue to pose a major public health threat worldwide and options for antiviral therapy are limited by the emergence of drug-resistant virus strains. The antiviral cytokine, interferon (IFN) is an essential mediator of the innate immune response and influenza viruses, like many viruses, have evolved strategies to evade this response, resulting in increased replication and enhanced pathogenicity. A cell-based assay that monitors IFN production was developed and applied in a high-throughput compound screen to identify molecules that restore the IFN response to influenza virus infected cells. We report the identification of compound ASN2, which induces IFN only in the presence of influenza virus infection. ASN2 preferentially inhibits the growth of influenza A viruses, including the 1918 H1N1, 1968 H3N2 and 2009 H1N1 pandemic strains and avian H5N1 virus. In vivo, ASN2 partially protects mice challenged with a lethal dose of influenza A virus. Surprisingly, we found that the antiviral activity of ASN2 is not dependent on IFN production and signaling. Rather, its IFN-inducing property appears to be an indirect effect resulting from ASN2-mediated inhibition of viral polymerase function, and subsequent loss of the expression of the viral IFN antagonist, NS1. Moreover, we identified a single amino acid mutation at position 499 of the influenza virus PB1 protein that confers resistance to ASN2, suggesting that PB1 is the direct target. This two-pronged antiviral mechanism, consisting of direct inhibition of virus replication and simultaneous activation of the host innate immune response, is a unique property not previously described for any single antiviral molecule. Influenza viruses are rapidly developing resistance against available anti-influenza drugs and consequently there is an urgent demand for new treatment approaches. We identified compound ASN2 in a high-throughput screen for molecules that are capable of inducing the antiviral cytokine interferon (IFN) in the presence of influenza virus infection. Normally, influenza virus blocks IFN production, an activity that is dependent on the viral NS1 protein and contributes to the ability of the virus to cause disease in an infected host. We show that ASN2 is a potent inhibitor of influenza A virus and can partially protect infected animals from disease and death. ASN2 acts by targeting influenza virus polymerase function which results in inhibition of virus replication, and as a consequence, NS1 expression. Thus the ability of ASN2 to induce IFN is a “side-effect”, albeit a desirable one, of polymerase inhibition. This combination of directly inhibiting the virus while also stimulating the host immune response is a novel property for an antiviral compound.
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Affiliation(s)
- Mila Brum Ortigoza
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Oliver Dibben
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Jad Maamary
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Luis Martinez-Gil
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Victor H. Leyva-Grado
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Pablo Abreu
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Juan Ayllon
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Peter Palese
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America
- Department of Medicine, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Megan L. Shaw
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America
- * E-mail:
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22
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Furukawa T, Muraki Y, Noda T, Takashita E, Sho R, Sugawara K, Matsuzaki Y, Shimotai Y, Hongo S. Role of the CM2 protein in the influenza C virus replication cycle. J Virol 2011; 85:1322-9. [PMID: 21106743 PMCID: PMC3020500 DOI: 10.1128/jvi.01367-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 11/10/2010] [Indexed: 02/07/2023] Open
Abstract
CM2 is the second membrane protein of influenza C virus. Although its biochemical characteristics, coding strategy, and properties as an ion channel have been extensively studied, the role(s) of CM2 in the virus replication cycle remains to be clarified. In order to elucidate this role, in the present study we generated CM2-deficient influenza C virus-like particles (VLPs) and examined the VLP-producing 293T cells, VLPs, and VLP-infected HMV-II cells. Quantification of viral RNA (vRNA) in the VLPs by real-time PCR revealed that the CM2-deficient VLPs contain approximately one-third of the vRNA found in wild-type VLPs although no significant differences were detected in the expression levels of viral components in VLP-producing cells or in the number and morphology of the generated VLPs. This finding suggests that CM2 is involved in the genome packaging process into VLPs. Furthermore, HMV-II cells infected with CM2-deficient VLPs exhibited significantly reduced reporter gene expression. Although CM2-deficient VLPs could be internalized into HMV-II cells as efficiently as wild-type VLPs, a smaller amount of vRNA was detected in the nuclear fraction of CM2-deficient VLP-infected cells than in that of wild-type VLP-infected cells, suggesting that the uncoating process of the CM2-deficient VLPs in the infected cells did not proceed in an appropriate manner. Taken together, the data obtained in the present study indicate that CM2 has a potential role in the genome packaging and uncoating processes of the virus replication cycle.
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Affiliation(s)
- Takatoshi Furukawa
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan, Department of Public Health, Yamagata University Graduate School of Medical Science, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
| | - Yasushi Muraki
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan, Department of Public Health, Yamagata University Graduate School of Medical Science, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
| | - Takeshi Noda
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan, Department of Public Health, Yamagata University Graduate School of Medical Science, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
| | - Emi Takashita
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan, Department of Public Health, Yamagata University Graduate School of Medical Science, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
| | - Ri Sho
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan, Department of Public Health, Yamagata University Graduate School of Medical Science, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
| | - Kanetsu Sugawara
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan, Department of Public Health, Yamagata University Graduate School of Medical Science, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
| | - Yoko Matsuzaki
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan, Department of Public Health, Yamagata University Graduate School of Medical Science, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
| | - Yoshitaka Shimotai
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan, Department of Public Health, Yamagata University Graduate School of Medical Science, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
| | - Seiji Hongo
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan, Department of Public Health, Yamagata University Graduate School of Medical Science, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
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23
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Gayer CP, Craig DH, Flanigan TL, Reed TD, Cress DE, Basson MD. ERK regulates strain-induced migration and proliferation from different subcellular locations. J Cell Biochem 2010; 109:711-25. [PMID: 20069571 DOI: 10.1002/jcb.22450] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Repetitive deformation like that engendered by peristalsis or villous motility stimulates intestinal epithelial proliferation on collagenous substrates and motility across fibronectin, each requiring ERK. We hypothesized that ERK acts differently at different intracellular sites. We stably transfected Caco-2 cells with ERK decoy expression vectors that permit ERK activation but interfere with its downstream signaling. Targeting sequences constrained the decoy inside or outside the nucleus. We assayed proliferation by cell counting and migration by circular wound closure with or without 10% repetitive deformation at 10 cycles/min. Confocal microscopy confirmed localization of the fusion proteins. Inhibition of phosphorylation of cytoplasmic RSK or nuclear Elk confirmed functionality. Both the nuclear-localized and cytosolic-localized ERK decoys prevented deformation-induced proliferation on collagen. Deformation-induced migration on fibronectin was prevented by constraining the decoy in the nucleus but not in the cytosol. Like the nuclear-localized ERK decoy, a Sef-overexpressing adenovirus that sequesters ERK in the cytoplasm also blocked the motogenic and mitogenic effects of strain. Inhibiting RSK or reducing Elk ablated both the mitogenic and motogenic effects of strain. RSK isoform reduction revealed isoform specificity. These results suggest that ERK must translocate to the nucleus to stimulate cell motility while ERK must act in both the cytosol and the nucleus to stimulate proliferation in response to strain. Selectively targeting ERK within different subcellular compartments may modulate or replace physical force effects on the intestinal mucosa to maintain the intestinal mucosal barrier in settings when peristalsis or villous motility are altered and fibronectin is deposited into injured tissue.
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24
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Muraki Y, Furukawa T, Kohno Y, Matsuzaki Y, Takashita E, Sugawara K, Hongo S. Influenza C virus NS1 protein upregulates the splicing of viral mRNAs. J Virol 2010; 84:1957-66. [PMID: 20007279 PMCID: PMC2812400 DOI: 10.1128/jvi.01627-09] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Accepted: 11/25/2009] [Indexed: 11/20/2022] Open
Abstract
Pre-mRNAs of the influenza A virus M and NS genes are poorly spliced in virus-infected cells. By contrast, in influenza C virus-infected cells, the predominant transcript from the M gene is spliced mRNA. The present study was performed to investigate the mechanism by which influenza C virus M gene-specific mRNA (M mRNA) is readily spliced. The ratio of M1 encoded by a spliced M mRNA to CM2 encoded by an unspliced M mRNA in influenza C virus-infected cells was about 10 times larger than that in M gene-transfected cells, suggesting that a viral protein(s) other than M gene translational products facilitates viral mRNA splicing. RNase protection assays showed that the splicing of M mRNA in infected cells was much higher than that in M gene-transfected cells. The unspliced and spliced mRNAs of the influenza C virus NS gene encode two nonstructural (NS) proteins, NS1(C/NS1) and NS2(C/NS2), respectively. The introduction of premature translational termination into the NS gene, which blocked the synthesis of the C/NS1 and C/NS2 proteins, drastically reduced the splicing of NS mRNA, raising the possibility that C/NS1 or C/NS2 enhances viral mRNA splicing. The splicing of influenza C virus M mRNA was increased by coexpression of C/NS1, whereas it was reduced by coexpression of the influenza A virus NS1 protein (A/NS1). The splicing of influenza A virus M mRNA was also increased by coexpression of C/NS1, though it was inhibited by that of A/NS1. These results suggest that influenza C virus NS1, but not A/NS1, can upregulate viral mRNA splicing.
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Affiliation(s)
- Yasushi Muraki
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, Drug Analysis Department, Kashima Laboratory, Toxicological Science Division, Medi-Chem Business Segment, Mitsubishi Chemical Medience Corporation, Sunayama 14, Kamisu-City, Ibaraki, 314-0255, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan
| | - Takatoshi Furukawa
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, Drug Analysis Department, Kashima Laboratory, Toxicological Science Division, Medi-Chem Business Segment, Mitsubishi Chemical Medience Corporation, Sunayama 14, Kamisu-City, Ibaraki, 314-0255, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan
| | - Yoshihiko Kohno
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, Drug Analysis Department, Kashima Laboratory, Toxicological Science Division, Medi-Chem Business Segment, Mitsubishi Chemical Medience Corporation, Sunayama 14, Kamisu-City, Ibaraki, 314-0255, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan
| | - Yoko Matsuzaki
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, Drug Analysis Department, Kashima Laboratory, Toxicological Science Division, Medi-Chem Business Segment, Mitsubishi Chemical Medience Corporation, Sunayama 14, Kamisu-City, Ibaraki, 314-0255, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan
| | - Emi Takashita
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, Drug Analysis Department, Kashima Laboratory, Toxicological Science Division, Medi-Chem Business Segment, Mitsubishi Chemical Medience Corporation, Sunayama 14, Kamisu-City, Ibaraki, 314-0255, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan
| | - Kanetsu Sugawara
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, Drug Analysis Department, Kashima Laboratory, Toxicological Science Division, Medi-Chem Business Segment, Mitsubishi Chemical Medience Corporation, Sunayama 14, Kamisu-City, Ibaraki, 314-0255, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan
| | - Seiji Hongo
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Iida-Nishi, Yamagata 990-9585, Japan, Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan, Drug Analysis Department, Kashima Laboratory, Toxicological Science Division, Medi-Chem Business Segment, Mitsubishi Chemical Medience Corporation, Sunayama 14, Kamisu-City, Ibaraki, 314-0255, Japan, Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan
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Lee JH, Kim SH, Pascua PNQ, Song MS, Baek YH, Jin X, Choi JK, Kim CJ, Kim H, Choi YK. Direct interaction of cellular hnRNP-F and NS1 of influenza A virus accelerates viral replication by modulation of viral transcriptional activity and host gene expression. Virology 2009; 397:89-99. [PMID: 19926108 DOI: 10.1016/j.virol.2009.10.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 09/18/2009] [Accepted: 10/27/2009] [Indexed: 01/01/2023]
Abstract
To investigate novel NS1-interacting proteins, we conducted a yeast two-hybrid analysis, followed by co-immunoprecipitation assays. We identified heterogeneous nuclear ribonucleoprotein F (hnRNP-F) as a cellular protein interacting with NS1 during influenza A virus infection. Co-precipitation assays suggest that interaction between hnRNP-F and NS1 is a common and direct event among human or avian influenza viruses. NS1 and hnRNP-F co-localize in the nucleus of host cells, and the RNA-binding domain of NS1 directly interacts with the GY-rich region of hnRNP-F determined by GST pull-down assays with truncated proteins. Importantly, hnRNP-F expression levels in host cells indicate regulatory role on virus replication. hnRNP-F depletion by small interfering RNA (siRNA) shows 10- to 100-fold increases in virus titers corresponding to enhanced viral RNA polymerase activity. Our results delineate novel mechanism of action by which NS1 accelerates influenza virus replication by modulating normal cellular mRNA processes through direct interaction with cellular hnRNP-F protein.
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Affiliation(s)
- Jun Han Lee
- College of Medicine and Medical Research Institute, Chungbuk National University, 12 Gaeshin-Dong Heungduk-Ku, Cheongju 361-763, Republic of Korea
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26
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Robb NC, Smith M, Vreede FT, Fodor E. NS2/NEP protein regulates transcription and replication of the influenza virus RNA genome. J Gen Virol 2009; 90:1398-1407. [PMID: 19264657 DOI: 10.1099/vir.0.009639-0] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The influenza virus RNA polymerase transcribes the negative-sense viral RNA segments (vRNA) into mRNA and replicates them via complementary RNA (cRNA) intermediates into more copies of vRNA. It is not clear how the relative amounts of the three RNA products, mRNA, cRNA and vRNA, are regulated during the viral life cycle. We found that in viral ribonucleoprotein (vRNP) reconstitution assays involving only the minimal components required for viral transcription and replication (the RNA polymerase, the nucleoprotein and a vRNA template), the relative levels of accumulation of RNA products differed from those observed in infected cells, suggesting a regulatory role for additional viral proteins. Expression of the viral NS2/NEP protein in RNP reconstitution assays affected viral RNA levels by reducing the accumulation of transcription products and increasing the accumulation of replication products to more closely resemble those found during viral infection. This effect was functionally conserved in influenza A and B viruses and was influenza-virus-type-specific, demonstrating that the NS2/NEP protein changes RNA levels by specific alteration of the viral transcription and replication machinery, rather than through an indirect effect on the host cell. Although NS2/NEP has been shown previously to play a role in the nucleocytoplasmic export of viral RNPs, deletion of the nuclear export sequence region that is required for its transport function did not affect the ability of the protein to regulate RNA levels. A role for the NS2/NEP protein in the regulation of influenza virus transcription and replication that is independent of its viral RNP export function is proposed.
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Affiliation(s)
- Nicole C Robb
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Matt Smith
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Frank T Vreede
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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Kohno Y, Muraki Y, Matsuzaki Y, Takashita E, Sugawara K, Hongo S. Intracellular localization of influenza C virus NS2 protein (NEP) in infected cells and its incorporation into virions. Arch Virol 2009; 154:235-43. [PMID: 19130168 DOI: 10.1007/s00705-008-0292-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Accepted: 11/29/2008] [Indexed: 11/25/2022]
Abstract
RNA segment 7 of influenza C virus encodes two non-structural (NS) proteins, NS1 and NS2. The influenza C virus NS2 protein has been proposed to possess nuclear export activity like that of influenza A and B virus NS2 proteins (NEP). In the present study, we investigated the kinetics and localization of the NS2 protein in influenza C virus-infected cells, and analysed whether NS2 is present in virions. Immunofluorescent staining analysis of the infected cells indicated that NS2 was localized in the nucleus immediately after synthesis and predominantly in the cytoplasm in the later stages of infection. Confocal microscopy revealed that a part of the NS2 protein was colocalized with nucleoprotein NP/vRNP in the cytoplasm and on the cell membrane in the late stages of infection. The NS2 protein was detected in influenza C virions purified by gradient centrifugations and/or affinity chromatography. Trypsin treatment demonstrated that the NS2 protein was present inside the viral envelope. Furthermore, glycerol gradient analysis of detergent-solubilized virions revealed that the NS2 protein cosedimented with vRNPs. These data suggest that the influenza C virus NS2 protein is incorporated into virions, where it associates with vRNP.
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Affiliation(s)
- Yoshihiko Kohno
- Department of Bacteriology, Faculty of Medicine, Yamagata University, Iida-Nishi, Yamagata 990-9585, Japan
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28
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García-Rosado E, Markussen T, Kileng O, Baekkevold ES, Robertsen B, Mjaaland S, Rimstad E. Molecular and functional characterization of two infectious salmon anaemia virus (ISAV) proteins with type I interferon antagonizing activity. Virus Res 2008; 133:228-38. [PMID: 18304672 DOI: 10.1016/j.virusres.2008.01.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 01/11/2008] [Accepted: 01/12/2008] [Indexed: 12/25/2022]
Abstract
In this study we characterize two proteins encoded by the two smallest genomic segments of the piscine orthomyxovirus infectious salmon anaemia virus (ISAV). Both proteins, encoded by the un-spliced ORF from genomic segment 7 (s7ORF1) and the larger ORF from segment 8 (s8ORF2), are involved in modulation of the type I interferon (IFN) response. The data suggests that the s7ORF1 protein is collinearly encoded, non-structural, contains no nuclear localisation signals, localises mainly to the cytoplasmic perinuclear area and does not bind single- or double-stranded RNA. On the other hand, genomic segment 8 uses a bicistronic coding strategy and the encoded s8ORF2 protein is a structural component of the viral particle. This protein contains two nuclear localisation signals, has a predominantly nuclear localisation, binds both double-stranded RNA and poly-A tailed single-stranded RNA, but not double-stranded DNA. In poly I:C stimulated salmon cells both ISAV proteins independently down-regulate the type I IFN promoter activity. Thus, ISAV counteracts the type I IFN response by the action of at least two of its gene products, rather than just one, as appears to be the case for other known members of the Orthomyxoviridae.
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Affiliation(s)
- Esther García-Rosado
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., N-0033 Oslo, Norway.
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29
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Ghanem A, Mayer D, Chase G, Tegge W, Frank R, Kochs G, García-Sastre A, Schwemmle M. Peptide-mediated interference with influenza A virus polymerase. J Virol 2007; 81:7801-4. [PMID: 17494067 PMCID: PMC1933368 DOI: 10.1128/jvi.00724-07] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The assembly of the polymerase complex of influenza A virus from the three viral polymerase subunits PB1, PB2, and PA is required for viral RNA synthesis. We show that peptides which specifically bind to the protein-protein interaction domains in the subunits responsible for complex formation interfere with polymerase complex assembly and inhibit viral replication. Specifically, we provide evidence that a 25-amino-acid peptide corresponding to the PA-binding domain of PB1 blocks the polymerase activity of influenza A virus and inhibits viral spread. Targeting polymerase subunit interactions therefore provides a novel strategy to develop antiviral compounds against influenza A virus or other viruses.
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Affiliation(s)
- Alexander Ghanem
- Department of Virology, Institute for Medical Microbiology and Hygiene, University of Freiburg, Hermann-Herder-Strasse 11, D-79104 Freiburg, Germany
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Kibenge FSB, Xu H, Kibenge MJT, Qian B, Joseph T. Characterization of gene expression on genomic segment 7 of infectious salmon anaemia virus. Virol J 2007; 4:34. [PMID: 17394643 PMCID: PMC1851003 DOI: 10.1186/1743-422x-4-34] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Accepted: 03/29/2007] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Infectious salmon anaemia (ISA) virus (ISAV), an important pathogen of fish that causes disease accompanied by high mortality in marine-farmed Atlantic salmon, is the only species in the genus Isavirus, one of the five genera of the Orthomyxoviridae family. The Isavirus genome consists of eight single-stranded RNA species, and the virions have two surface glycoproteins; haemagglutinin-esterase (HE) protein encoded on segment 6 and fusion (F) protein encoded on segment 5. Based on the initial demonstration of two 5'-coterminal mRNA transcripts by RT-PCR, ISAV genomic segment 7 was suggested to share a similar coding strategy with segment 7 of influenza A virus, encoding two proteins. However, there appears to be confusion as to the protein sizes predicted from the two open reading frames (ORFs) of ISAV segment 7 which has in turn led to confusion of the predicted protein functions. The primary goal of the present work was to clone and express these two ORFs in order to assess whether the predicted protein sizes match those of the expressed proteins so as to clarify the coding assignments, and thereby identify any additional structural proteins of ISAV. RESULTS In the present study we show that ISAV segment 7 encodes 3 proteins with estimated molecular masses of 32, 18, and 9.5 kDa. The 18-kDa and 9.5-kDa products are based on removal of an intron each from the primary transcript (7-ORF1) so that the translation continues in the +2 and +3 reading frames, respectively. The segment 7-ORF1/3 product is variably truncated in the sequence of ISAV isolates of the European genotype. All three proteins are recognized by rabbit antiserum against the 32-kDa product of the primary transcript, as they all share the N-terminal 22 amino acids. This antiserum detected a single 35-kDa protein in Western blots of purified virus, and immunoprecipitated a 32-kDa protein in ISAV-infected TO cells. Immunofluorescence staining of infected cells with the same antiserum revealed the protein(s) to be localized in the cytoplasm. Vaccination of farmed Atlantic salmon with the 32-kDa protein resulted in a higher survival rate than what was attainable with the HE protein, albeit a moderate protection against the low ISAV challenge. CONCLUSION Collectively, our observations suggest that the product of ISAV segment 7 primary transcript (7-ORF1) is a structural protein. The 18-kDa (7-ORF1/2) protein is identified as the putative ISAV nuclear export protein based on the presence of nuclear export signals. The function of the 9.5-kDa (7-ORF1/3) protein is not presently known.
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Affiliation(s)
- Frederick SB Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, P.E.I., C1A 4P3, Canada
| | - Hongtao Xu
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, P.E.I., C1A 4P3, Canada
- McGill AIDS Centre, Jewish General Hospital, 3755 Cote Ste Catherine Road, Montreal, Quebec, H3T 1E2, Canada
| | - Molly JT Kibenge
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, P.E.I., C1A 4P3, Canada
| | - Biao Qian
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, P.E.I., C1A 4P3, Canada
| | - Tomy Joseph
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, P.E.I., C1A 4P3, Canada
- Laboratory of Infectious Diseases, NIAID, NIH, Bldg 50, Room 6132 50 South Drive, MSC 8007, Bethesda, MD 20892, USA
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Sugawara K, Muraki Y, Takashita E, Matsuzaki Y, Hongo S. Conformational maturation of the nucleoprotein synthesized in influenza C virus-infected cells. Virus Res 2006; 122:45-52. [PMID: 16870298 DOI: 10.1016/j.virusres.2006.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 06/09/2006] [Accepted: 06/12/2006] [Indexed: 11/20/2022]
Abstract
The conformational maturation of the influenza C virus nucleoprotein (NP) synthesized in infected cells was investigated. Monoclonal antibodies (mAbs) that have previously been characterized [Sugawara, K., Nishimura, H., Hongo, S., Kitame, F., Nakamura, K., 1991. Antigenic characterization of the nucleoprotein and matrix protein of influenza C virus with monoclonal antibodies. J. Gen. Virol. 72, 103-109] enabled this molecular maturation to be detected. Both pulse-labeled and chased NPs could equally retain high reactivity with H31 mAb recognizing a linear epitope on the NP molecule. However, pulse-labeled NP showed three- to four-fold lower reactivity with H27 mAb recognizing a conformational epitope, compared to chased NP. Sedimentation analyses by sucrose gradient centrifugation revealed that the mature NP could readily participate in nucleocapsid formation while the immature NP was free. The immature NP was rapidly transported into the nucleus and its maturation seemed to occur after or during translocation into the nucleus. A single expression of NP cDNA in COS-1 cells demonstrated that the NP maturation was an intrinsic feature of the NP molecule without relation to other viral components.
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Affiliation(s)
- Kanetsu Sugawara
- Department of Infectious Diseases, Yamagata University School of Medicine, Iida-Nishi, Yamagata 990-9585, Japan.
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Glaser L, Stevens J, Zamarin D, Wilson IA, García-Sastre A, Tumpey TM, Basler CF, Taubenberger JK, Palese P. A single amino acid substitution in 1918 influenza virus hemagglutinin changes receptor binding specificity. J Virol 2005; 79:11533-6. [PMID: 16103207 PMCID: PMC1193621 DOI: 10.1128/jvi.79.17.11533-11536.2005] [Citation(s) in RCA: 303] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The receptor binding specificity of influenza viruses may be important for host restriction of human and avian viruses. Here, we show that the hemagglutinin (HA) of the virus that caused the 1918 influenza pandemic has strain-specific differences in its receptor binding specificity. The A/South Carolina/1/18 HA preferentially binds the alpha2,6 sialic acid (human) cellular receptor, whereas the A/New York/1/18 HA, which differs by only one amino acid, binds both the alpha2,6 and the alpha2,3 sialic acid (avian) cellular receptors. Compared to the conserved consensus sequence in the receptor binding site of avian HAs, only a single amino acid at position 190 was changed in the A/New York/1/18 HA. Mutation of this single amino acid back to the avian consensus resulted in a preference for the avian receptor.
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Affiliation(s)
- Laurel Glaser
- Department of Microbiology, Mount Sinai School of Medicine, New York, NY 10029, USA
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33
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Iwatsuki-Horimoto K, Horimoto T, Fujii Y, Kawaoka Y. Generation of influenza A virus NS2 (NEP) mutants with an altered nuclear export signal sequence. J Virol 2004; 78:10149-55. [PMID: 15331747 PMCID: PMC514982 DOI: 10.1128/jvi.78.18.10149-10155.2004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Accepted: 05/04/2004] [Indexed: 11/20/2022] Open
Abstract
The NS2 (NEP) protein of influenza A virus contains a highly conserved nuclear export signal (NES) motif in its amino-terminal region (12ILMRMSKMQL21, A/WSN/33), which is thought to be required for nuclear export of viral ribonucleoprotein complexes (vRNPs) mediated by a cellular export factor, CRM1. However, simultaneous replacement of three hydrophobic residues in the NES with alanine does not affect NS2 (NEP) binding to CRM1, although the virus with these mutations is not viable. To determine the extent of sequence conservation required by the NS2 (NEP) NES for its export function during viral replication, we randomly introduced mutations by degenerative mutagenesis into the region of NS cDNA encoding the NS2 (NEP) NES and then attempted to generate mutant viruses containing these alterations by reverse genetics. Sequence analysis of the recovered viruses showed that although some of the mutants possessed amino acids other than those conserved in the NES, hydrophobicity within this motif was maintained. Nuclear export of vRNPs representing all of the mutant viruses was completely inhibited in the presence of a CRM1 inhibitor, leptomycin B, as was the transport of wild-type virus, indicating that the CRM1-mediated pathway is responsible for the nuclear export of both wild-type and mutant vRNPs. The vRNPs of some of the mutant viruses were exported in a delayed manner, resulting in limited viral growth in cell culture and in mice. These results suggest that the NES motif may be an attractive target for the introduction of attenuating mutations in the production of live vaccine viruses.
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Affiliation(s)
- Kiyoko Iwatsuki-Horimoto
- Department of Microbiology and Immunology, Division of Virology, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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34
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Muraki Y, Washioka H, Sugawara K, Matsuzaki Y, Takashita E, Hongo S. Identification of an amino acid residue on influenza C virus M1 protein responsible for formation of the cord-like structures of the virus. J Gen Virol 2004; 85:1885-1893. [PMID: 15218173 DOI: 10.1099/vir.0.79937-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Influenza C virus-like particles (VLPs) have been generated from cloned cDNAs. A cDNA of the green fluorescent protein (GFP) gene in antisense orientation was flanked by the 5' and 3' non-coding regions of RNA segment 5 of the influenza C virus. The cDNA cassette was inserted between an RNA polymerase I promoter and terminator of the Pol I vector. This plasmid DNA was transfected into 293T cells together with plasmids encoding virus proteins of C/Ann Arbor/1/50 or C/Yamagata/1/88. Transfer of the supernatants of the transfected 293T cells to HMV-II cells resulted in GFP expression in the HMV-II cells. The quantification of the GFP-positive HMV-II cells indicated the presence of approximately 10(6) VLPs (ml supernatant)(-1). Cords 50-300 microm in length were observed on transfected 293T cells, although the cords were not observed when the plasmid for M1 protein of C/Ann Arbor/1/50 was replaced with that of C/Taylor/1233/47. A series of transfection experiments with plasmids encoding M1 mutants of C/Ann Arbor/1/50 or C/Taylor/1233/47 showed that an amino acid at residue 24 of the M1 protein is responsible for cord formation. This finding provides direct evidence for a previous hypothesis that M1 protein is involved in the formation of cord-like structures protruding from the C/Yamagata/1/88-infected cells. Evidence was obtained by electron microscopy that transfected cells bearing cords produced filamentous VLPs, suggesting the potential role of the M1 protein in determining the filamentous/spherical morphology of influenza C virus.
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Affiliation(s)
- Yasushi Muraki
- Department of Bacteriology, Yamagata University School of Medicine, Iida-Nishi, Yamagata 990-9585, Japan
| | - Hiroshi Washioka
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-Nishi, Yamagata 990-9585, Japan
| | - Kanetsu Sugawara
- Department of Bacteriology, Yamagata University School of Medicine, Iida-Nishi, Yamagata 990-9585, Japan
| | - Yoko Matsuzaki
- Department of Bacteriology, Yamagata University School of Medicine, Iida-Nishi, Yamagata 990-9585, Japan
| | - Emi Takashita
- Department of Bacteriology, Yamagata University School of Medicine, Iida-Nishi, Yamagata 990-9585, Japan
| | - Seiji Hongo
- Department of Bacteriology, Yamagata University School of Medicine, Iida-Nishi, Yamagata 990-9585, Japan
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35
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Akarsu H, Burmeister WP, Petosa C, Petit I, Müller CW, Ruigrok RWH, Baudin F. Crystal structure of the M1 protein-binding domain of the influenza A virus nuclear export protein (NEP/NS2). EMBO J 2003; 22:4646-55. [PMID: 12970177 PMCID: PMC212717 DOI: 10.1093/emboj/cdg449] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
During influenza virus infection, viral ribonucleoproteins (vRNPs) are replicated in the nucleus and must be exported to the cytoplasm before assembling into mature viral particles. Nuclear export is mediated by the cellular protein Crm1 and putatively by the viral protein NEP/NS2. Proteolytic cleavage of NEP defines an N-terminal domain which mediates RanGTP-dependent binding to Crm1 and a C-terminal domain which binds to the viral matrix protein M1. The 2.6 A crystal structure of the C-terminal domain reveals an amphipathic helical hairpin which dimerizes as a four-helix bundle. The NEP-M1 interaction involves two critical epitopes: an exposed tryptophan (Trp78) surrounded by a cluster of glutamate residues on NEP, and the basic nuclear localization signal (NLS) of M1. Implications for vRNP export are discussed.
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Affiliation(s)
- Hatice Akarsu
- EMBL Grenoble Outstation, BP 181, 38042 Grenoble cedex 9, France
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Vodeiko GM, McInnis J, Chizhikov V, Levandowski RA. Genetic and phenotypic analysis of reassortants of high growth and low growth strains of influenza B virus. Vaccine 2003; 21:3867-74. [PMID: 12922121 DOI: 10.1016/s0264-410x(03)00312-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The yield of influenza virus in eggs is critical to influenza vaccine production and availability, but the contribution of specific genes to the growth properties of influenza B viruses is not well understood. Influenza B/Beijing/184/93 and B/Shangdong/7/97 were chosen for study because B/Shangdong/7/97 replicated to several fold higher titers in eggs than B/Beijing/184/93 as demonstrated by hemagglutination titers and EID50. A reassortant with the HA, NP and PB2 genes from B/Beijing/184/93 and all other genes from B/Shangdong/7/97 had the high growth phenotype of B/Shangdong/7/97 in eggs, which suggests that NS, M, NA, PB1 or PA, or a combination of these genes derived from B/Shangdong/7/97 were needed for the high growth phenotype of the reassortants. A high degree of homology was found among the genetic sequences of B/Beijing/184/93, B/Shangdong/7/97, and other influenza B viruses. However, differences potentially related to growth characteristics were suggested by analysis of the deduced amino acid (AA) sequences of four genes: NS (NS1, NS2), M (BM2), NA (NA, NB) and PB1. The studies identify multiple genes that may affect growth of influenza B viruses in eggs.
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Affiliation(s)
- G M Vodeiko
- Laboratory of Pediatric and Respiratory Viral Diseases, Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics and Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
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Cros JF, Palese P. Trafficking of viral genomic RNA into and out of the nucleus: influenza, Thogoto and Borna disease viruses. Virus Res 2003; 95:3-12. [PMID: 12921991 DOI: 10.1016/s0168-1702(03)00159-x] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Most RNA viruses that lack a DNA phase replicate in the cytoplasm. However, several negative-stranded RNA viruses such as influenza, Thogoto, and Borna disease viruses replicate their RNAs in the nucleus, taking advantage of the host cell's nuclear machinery. A challenge faced by these viruses is the trafficking of viral components into and out of the nucleus through the nuclear membrane. The genomic RNAs of these viruses associate with proteins to form large complexes called viral ribonucleoproteins (vRNPs), which exceed the size limit for passive diffusion through the nuclear pore complex (NPC). To insure efficient transport across the nuclear membrane, these viruses use nuclear import and export signals exposed on the vRNPs. These signals recruit the cellular import and export complexes, which are responsible for the translocation of the vRNPs through the NPC. The ability to control the direction of vRNP trafficking throughout the viral life cycle is critical. Various mechanisms, ranging from simple post-translational modification to complex, sequential masking-and-exposure of localization signals, are used to insure the proper movement of the vRNPs.
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Affiliation(s)
- Jerome F Cros
- Department of Microbiology, Mount Sinai School of Medicine, New York, NY 10029, USA
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Flandorfer A, García-Sastre A, Basler CF, Palese P. Chimeric influenza A viruses with a functional influenza B virus neuraminidase or hemagglutinin. J Virol 2003; 77:9116-23. [PMID: 12915528 PMCID: PMC187417 DOI: 10.1128/jvi.77.17.9116-9123.2003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2003] [Accepted: 06/03/2003] [Indexed: 12/13/2022] Open
Abstract
Reassortment of influenza A and B viruses has never been observed in vivo or in vitro. Using reverse genetics techniques, we generated recombinant influenza A/WSN/33 (WSN) viruses carrying the neuraminidase (NA) of influenza B virus. Chimeric viruses expressing the full-length influenza B/Yamagata/16/88 virus NA grew to titers similar to that of wild-type influenza WSN virus. Recombinant viruses in which the cytoplasmic tail or the cytoplasmic tail and the transmembrane domain of the type B NA were replaced with those of the type A NA were impaired in tissue culture. This finding correlates with reduced NA content in virions. We also generated a recombinant influenza A virus expressing a chimeric hemagglutinin (HA) protein in which the ectodomain is derived from type B/Yamagata/16/88 virus HA, whereas both the cytoplasmic and the transmembrane domains are derived from type A/WSN virus HA. This A/B chimeric HA virus did not grow efficiently in MDCK cells. However, after serial passage we obtained a virus population that grew to titers as high as wild-type influenza A virus in MDCK cells. One amino acid change in position 545 (H545Y) was found to be responsible for the enhanced growth characteristics of the passaged virus. Taken together, we show here that the absence of reassortment between influenza viruses belonging to different A and B types is not due to spike glycoprotein incompatibility at the level of the full-length NA or of the HA ectodomain.
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Affiliation(s)
- Astrid Flandorfer
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029, USA
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Hoffmann E, Mahmood K, Yang CF, Webster RG, Greenberg HB, Kemble G. Rescue of influenza B virus from eight plasmids. Proc Natl Acad Sci U S A 2002; 99:11411-6. [PMID: 12172012 PMCID: PMC123270 DOI: 10.1073/pnas.172393399] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2002] [Indexed: 11/18/2022] Open
Abstract
Influenza B virus causes a significant amount of morbidity and mortality, yet the systems to produce high yield inactivated vaccines for these viruses have lagged behind the development of those for influenza A virus. We have established a plasmid-only reverse genetics system for the generation of recombinant influenza B virus that facilitates the generation of vaccine viruses without the need for time consuming coinfection and selection procedures currently required to produce reassortants. We cloned the eight viral cDNAs of influenza B/Yamanashi/166/98, which yields relatively high titers in embryonated chicken eggs, between RNA polymerase I and RNA polymerase II transcription units. Virus was detected as early as 3 days after transfection of cocultured COS7 and Madin-Darby canine kidney cells and achieved levels of 10(6)-10(7) plaque-forming units per ml of cell supernatant 6 days after transfection. The full-length sequence of the recombinant virus after passage into embryonated chicken eggs was identical to that of the input plasmids. To improve the utility of the eight-plasmid system for generating 6 + 2 reassortants from recently circulating influenza B strains, we optimized the reverse transcriptase-PCR for cloning of the hemagglutinin (HA) and neuraminidase (NA) segments. The six internal genes of B/Yamanashi/166/98 were used as the backbone to generate 6 + 2 reassortants including the HA and NA gene segments from B/Victoria/504/2000, B/Hong Kong/330/2001, and B/Hawaii/10/2001. Our results demonstrate that the eight-plasmid system can be used for the generation of high yields of influenza B virus vaccines expressing current HA and NA glycoproteins from either of the two lineages of influenza B virus.
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Affiliation(s)
- Erich Hoffmann
- MedImmune Vaccines, 297 North Bernardo Avenue, Mountain View, CA 94043, USA.
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40
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Portela A, Digard P. The influenza virus nucleoprotein: a multifunctional RNA-binding protein pivotal to virus replication. J Gen Virol 2002; 83:723-734. [PMID: 11907320 DOI: 10.1099/0022-1317-83-4-723] [Citation(s) in RCA: 371] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
All viruses with negative-sense RNA genomes encode a single-strand RNA-binding nucleoprotein (NP). The primary function of NP is to encapsidate the virus genome for the purposes of RNA transcription, replication and packaging. The purpose of this review is to illustrate using the influenza virus NP as a well-studied example that the molecule is much more than a structural RNA-binding protein, but also functions as a key adapter molecule between virus and host cell processes. It does so through the ability to interact with a wide variety of viral and cellular macromolecules, including RNA, itself, two subunits of the viral RNA-dependent RNA polymerase and the viral matrix protein. NP also interacts with cellular polypeptides, including actin, components of the nuclear import and export apparatus and a nuclear RNA helicase. The evidence for the existence of each of these activities and their possible roles in transcription, replication and intracellular trafficking of the virus genome is considered.
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Affiliation(s)
- Agustín Portela
- División de Productos Biológicos y Biotecnología, Agencia Española del Medicamento, Majadahonda 28220, Madrid, Spain1
| | - Paul Digard
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK2
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Abstract
The cellular nuclear transport machinery relies on the assembly of specialized transport complexes between soluble transport receptors, transport substrates, and additional accessory proteins. This study focuses on the structural characteristics of influenza virus protein NS2 (NEP), which interacts with the nuclear export machinery during viral replication, and has been proposed to act as an adapter molecule between the nuclear export machinery and the viral ribonucleoprotein complex. For this purpose, we have purified recombinant NS2 under nondenaturing conditions, and have investigated its structure and aggregation state using optical spectroscopy, differential scanning calorimetry, as well as hydrodynamic techniques. Our results indicate that isolated NS2 exists as a monomer in solution, and adopts a compact, but very flexible conformation, which shows characteristics of the molten globule state under near physiological conditions. Proteolytic sensitivity suggests that, despite its overall plasticity, the structure of NS2 is heterogeneous. While the C terminus of the protein adopts a relatively rigid conformation, its N terminus, which is recognized by the nuclear export machinery, exists in a highly mobile and exposed state. It is proposed that the flexibility observed in the nuclear export domain of NS2 is an important element in the recognition of substrate proteins by the nuclear export machinery.
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MESH Headings
- Acrylamide/pharmacology
- Calorimetry, Differential Scanning
- Cell Nucleus/metabolism
- Chromatography, Gel
- Circular Dichroism
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- Escherichia coli/metabolism
- Guanidine/pharmacology
- Isoelectric Focusing
- Kinetics
- Orthomyxoviridae/chemistry
- Protein Binding
- Protein Conformation
- Protein Folding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Recombinant Proteins/metabolism
- Spectrometry, Fluorescence
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Spectrophotometry
- Spectroscopy, Fourier Transform Infrared
- Temperature
- Ultracentrifugation
- Viral Nonstructural Proteins/chemistry
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Affiliation(s)
- Barbara S Lommer
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294-4400, USA
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