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Zhang Z, Zhang H, Xu L, Guo X, Wang W, Ji Y, Lin C, Wang Y, Wang X. Selective usage of ANP32 proteins by influenza B virus polymerase: Implications in determination of host range. PLoS Pathog 2020; 16:e1008989. [PMID: 33045004 PMCID: PMC7580981 DOI: 10.1371/journal.ppat.1008989] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 10/22/2020] [Accepted: 09/17/2020] [Indexed: 11/18/2022] Open
Abstract
The influenza B virus (IBV) causes seasonal influenza and has accounted for an increasing proportion of influenza outbreaks. IBV mainly causes human infections and has not been found to spread in poultry. The replication mechanism and the determinants of interspecies transmission of IBV are largely unknown. In this study, we found that the host ANP32 proteins are required for the function of the IBV polymerase. Human ANP32A/B strongly supports IBV replication, while ANP32E has a limited role. Unlike human ANP32A/B, chicken ANP32A has low support activity to IBV polymerase because of a unique 33-amino-acid insert, which, in contrast, exhibits species specific support to avian influenza A virus (IAV) replication. Chicken ANP32B and ANP32E have even lower activity compared with human ANP32B/E due to specific amino acid substitutions at sites 129–130. We further revealed that the sites 129–130 affect the binding ability of ANP32B/E to IBV polymerase, while the 33-amino-acid insert of chicken ANP32A reduces its binding stability and affinity. Taken together, the features of avian ANP32 proteins limited their abilities to support IBV polymerase, which could prevent efficient replication of IBV in chicken cells. Our results illustrate roles of ANP32 proteins in supporting IBV replication and may help to understand the ineffective replication of IBV in birds. Influenza B viruses infect humans and few other mammals, but fairly rare in birds. Here we found that IBV requires the involvement of host ANP32 proteins in the replication process, in which ANP32A and ANP32B play major roles and can fully support polymerase activity independently, while ANP32E gives only limited support to IBV polymerase because of certain substitutions compared with ANP32A/B. Chicken ANP32A has a 33-amino-acid insert not present in mammals and provides better support to avian IAV polymerase, but this insert impairs its support for IBV polymerase activity. Chicken ANP32B and ANP32E have even lower support to IBV polymerase due to specific inactive mutations at sites 129/130. Our findings reveal an important role for ANP32 proteins in IBV polymerase activity and suggest the possible molecular basis of adaptation and restriction of IBV infection in different species.
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Affiliation(s)
- Zhenyu Zhang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, P. R. China
| | - Haili Zhang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, P. R. China
| | - Ling Xu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, P. R. China
| | - Xing Guo
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, P. R. China
| | - Wenfei Wang
- School of Life Science, Northeast Agricultural University, Harbin, P. R. China
| | - Yujie Ji
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, P. R. China
| | - Chaohui Lin
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, P. R. China
| | - Yujie Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, P. R. China
| | - Xiaojun Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, P. R. China
- * E-mail:
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Abed Y, Fage C, Lagüe P, Carbonneau J, Papenburg J, Vinh DC, Boivin G. Reduced Susceptibility to Neuraminidase Inhibitors in Influenza B Isolate, Canada. Emerg Infect Dis 2019; 25:838-840. [PMID: 30882323 PMCID: PMC6433030 DOI: 10.3201/eid2504.181554] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We identified an influenza B isolate harboring a Gly407Ser neuraminidase substitution in an immunocompromised patient in Canada before antiviral therapy. This mutation mediated reduced susceptibility to oseltamivir, zanamivir, and peramivir, most likely by preventing interaction with the catalytic Arg374 residue. The potential emergence of such variants emphasizes the need for new antivirals.
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Yoshino R, Yasuo N, Sekijima M. Molecular Dynamics Simulation reveals the mechanism by which the Influenza Cap-dependent Endonuclease acquires resistance against Baloxavir marboxil. Sci Rep 2019; 9:17464. [PMID: 31767949 PMCID: PMC6877583 DOI: 10.1038/s41598-019-53945-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 10/24/2019] [Indexed: 12/11/2022] Open
Abstract
Baloxavir marboxil (BXM), an antiviral drug for influenza virus, inhibits RNA replication by binding to RNA replication cap-dependent endonuclease (CEN) of influenza A and B viruses. Although this drug was only approved by the FDA in October 2018, drug resistant viruses have already been detected from clinical trials owing to an I38 mutation of CEN. To investigate the reduction of drug sensitivity by the I38 mutant variants, we performed a molecular dynamics (MD) simulation on the CEN-BXM complex structure to analyze variations in the mode of interaction. Our simulation results suggest that the side chain methyl group of I38 in CEN engages in a CH-pi interaction with the aromatic ring of BXM. This interaction is abolished in various I38 mutant variants. Moreover, MD simulation on various mutation models and binding free energy prediction by MM/GBSA method suggest that the I38 mutation precludes any interaction with the aromatic ring of BXA and thereby reduces BXA sensitivity.
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Affiliation(s)
- Ryunosuke Yoshino
- Transborder Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
- Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Nobuaki Yasuo
- Advanced Computational Drug Discovery Unit, Tokyo Institute of Technology, 4259-J3-23 Nagatsutacho, Midori-ku, Yokohama, Kanagawa, 226-8501, Japan
| | - Masakazu Sekijima
- Advanced Computational Drug Discovery Unit, Tokyo Institute of Technology, 4259-J3-23 Nagatsutacho, Midori-ku, Yokohama, Kanagawa, 226-8501, Japan.
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Huang CT, Hung CY, Hseih YC, Chang CS, Velu AB, He YC, Huang YL, Chen TA, Chen TC, Lin CY, Lin YC, Shih SR, Dutta A. Effect of aloin on viral neuraminidase and hemagglutinin-specific T cell immunity in acute influenza. Phytomedicine 2019; 64:152904. [PMID: 31454654 DOI: 10.1016/j.phymed.2019.152904] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 03/27/2019] [Accepted: 03/29/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Millions of people are infected by the influenza virus worldwide every year. Current selections of anti-influenza agents are limited and their effectiveness and drug resistance are still of concern. PURPOSE Investigation on in vitro and in vivo effect of aloin from Aloe vera leaves against influenza virus infection. METHODS In vitro antiviral property of aloin was measured by plaque reduction assay in which MDCK cells were infected with oseltamivir-sensitive A(H1N1)pdm09, oseltamivir-resistant A(H1N1)pdm09, H1N1 or H3N2 influenza A or with influenza B viruses in the presence of aloin. In vivo activity was tested in H1N1 influenza virus infected mice. Aloin-mediated inhibition of influenza neuraminidase activity was tested by MUNANA assay. Aloin treatment-mediated modulation of anti-influenza immunity was tested by the study of hemagglutinin-specific T cells in vivo. RESULTS Aloin significantly reduced in vitro infection by all the tested strains of influenza viruses, including oseltamivir-resistant A(H1N1)pdm09 influenza viruses, with an average IC50 value 91.83 ± 18.97 μM. In H1N1 influenza virus infected mice, aloin treatment (intraperitoneal, once daily for 5 days) reduced virus load in the lungs and attenuated body weight loss and mortality. Adjuvant aloin treatment also improved the outcome with delayed oseltamivir treatment. Aloin inhibited viral neuraminidase and impeded neuraminidase-mediated TGF-β activation. Viral neuraminidase mediated immune suppression with TGF-β was constrained and influenza hemagglutinin-specific T cell immunity was increased. There was more infiltration of hemagglutinin-specific CD4+ and CD8+ T cells in the lungs and their production of effector cytokines IFN-γ and TNF-α was boosted. CONCLUSION Aloin from Aloe vera leaves is a potent anti-influenza compound that inhibits viral neuraminidase activity, even of the oseltamivir-resistant influenza virus. With suppression of this virus machinery, aloin boosts host immunity with augmented hemagglutinin-specific T cell response to the infection. In addition, in the context of compromised benefit with delayed oseltamivir treatment, adjuvant aloin treatment ameliorates the disease and improves survival. Taken together, aloin has the potential to be further evaluated for clinical applications in human influenza.
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MESH Headings
- Aloe/chemistry
- Animals
- Antiviral Agents/pharmacology
- Cell Line
- Drug Resistance, Viral
- Emodin/analogs & derivatives
- Emodin/pharmacology
- Hemagglutinins/immunology
- Humans
- Influenza A Virus, H1N1 Subtype/drug effects
- Influenza A Virus, H1N1 Subtype/enzymology
- Influenza A Virus, H1N1 Subtype/immunology
- Influenza A Virus, H3N2 Subtype/drug effects
- Influenza A Virus, H3N2 Subtype/enzymology
- Influenza A Virus, H3N2 Subtype/immunology
- Influenza B virus/drug effects
- Influenza B virus/enzymology
- Influenza B virus/immunology
- Influenza, Human/drug therapy
- Influenza, Human/immunology
- Influenza, Human/virology
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Neuraminidase/antagonists & inhibitors
- Oseltamivir/pharmacology
- Plant Leaves/chemistry
- T-Lymphocytes/drug effects
- T-Lymphocytes/immunology
- Viral Proteins/antagonists & inhibitors
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Affiliation(s)
- Ching-Tai Huang
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Guishan- 33333, Taoyuan City, Taiwan; College of Medicine, Chang Gung University, Guishan-33333, Taoyuan City, Taiwan
| | - Chen-Yiu Hung
- Department of Thoracic Medicine, Chang Gung Memorial Hospital, Guishan-33333, Taoyuan City, Taiwan
| | - Yu-Chia Hseih
- Division of Pediatric Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Guishan- 33333, Taoyuan City, Taiwan
| | - Chia-Shiang Chang
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Guishan- 33333, Taoyuan City, Taiwan
| | - Arul Balaji Velu
- Research Center for Emerging Viral Infections and Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Guishan- 33333, Taoyuan City, Taiwan
| | - Yueh-Chia He
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Guishan- 33333, Taoyuan City, Taiwan
| | - Yu-Lin Huang
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Guishan- 33333, Taoyuan City, Taiwan
| | - Ting-An Chen
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Guishan- 33333, Taoyuan City, Taiwan
| | - Tse-Ching Chen
- College of Medicine, Chang Gung University, Guishan-33333, Taoyuan City, Taiwan; Department of Pathology, Chang Gung Memorial Hospital, Guishan-33333, Taoyuan City, Taiwan
| | - Chun-Yen Lin
- College of Medicine, Chang Gung University, Guishan-33333, Taoyuan City, Taiwan; Division of Hepatogastroenterology, Department of Medicine, Chang Gung Memorial Hospital, Guishan- 33333, Taoyuan City, Taiwan
| | - Yung-Chang Lin
- College of Medicine, Chang Gung University, Guishan-33333, Taoyuan City, Taiwan; Division of Hematology and Oncology, Department of Medicine, Chang Gung Memorial Hospital, Guishan- 33333, Taoyuan City, Taiwan
| | - Shin-Ru Shih
- Research Center for Emerging Viral Infections and Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Guishan- 33333, Taoyuan City, Taiwan
| | - Avijit Dutta
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Guishan- 33333, Taoyuan City, Taiwan.
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Stadlbauer D, Zhu X, McMahon M, Turner JS, Wohlbold TJ, Schmitz AJ, Strohmeier S, Yu W, Nachbagauer R, Mudd PA, Wilson IA, Ellebedy AH, Krammer F. Broadly protective human antibodies that target the active site of influenza virus neuraminidase. Science 2019; 366:499-504. [PMID: 31649200 PMCID: PMC7105897 DOI: 10.1126/science.aay0678] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 09/27/2019] [Indexed: 12/21/2022]
Abstract
Better vaccines against influenza virus are urgently needed to provide broader protection against diverse strains, subtypes, and types. Such efforts are assisted by the identification of novel broadly neutralizing epitopes targeted by protective antibodies. Influenza vaccine development has largely focused on the hemagglutinin, but the other major surface antigen, the neuraminidase, has reemerged as a potential target for universal vaccines. We describe three human monoclonal antibodies isolated from an H3N2-infected donor that bind with exceptional breadth to multiple different influenza A and B virus neuraminidases. These antibodies neutralize the virus, mediate effector functions, are broadly protective in vivo, and inhibit neuraminidase activity by directly binding to the active site. Structural and functional characterization of these antibodies will inform the development of neuraminidase-based universal vaccines against influenza virus.
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Affiliation(s)
- Daniel Stadlbauer
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Department of Biotechnology, University of Natural Resources and Life Sciences, A-1190 Vienna, Austria
| | - Xueyong Zhu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Meagan McMahon
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Jackson S Turner
- Division of Immunobiology, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Teddy J Wohlbold
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Department of Pediatrics, Columbia Irving Medical Center, New York, NY 10032, USA
- NewYork-Presbyterian Morgan Stanley Children's Hospital, New York, NY 10032, USA
| | - Aaron J Schmitz
- Division of Immunobiology, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Shirin Strohmeier
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Wenli Yu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Raffael Nachbagauer
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Philip A Mudd
- Division of Emergency Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ian A Wilson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ali H Ellebedy
- Division of Immunobiology, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Florian Krammer
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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6
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Baloxavir marboxil (Xofluza) for treatment of influenza. Med Lett Drugs Ther 2018; 60:193-6. [PMID: 30653474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
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7
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Tewawong N, Vichiwattana P, Korkong S, Klinfueng S, Suntronwong N, Thongmee T, Theamboonlers A, Vongpunsawad S, Poovorawan Y. Evolution of the neuraminidase gene of seasonal influenza A and B viruses in Thailand between 2010 and 2015. PLoS One 2017; 12:e0175655. [PMID: 28410396 PMCID: PMC5391933 DOI: 10.1371/journal.pone.0175655] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 03/29/2017] [Indexed: 11/28/2022] Open
Abstract
The neuraminidase inhibitors (NAIs) oseltamivir and zanamivir are commonly used for the treatment and control of influenza A and B virus infection. However, the emergence of new influenza virus strains with reduced susceptibility to NAIs may appear with the use of these antivirals or even naturally. We therefore screened the neuraminidase (NA) sequences of seasonal influenza virus A(H1N1), A(H1N1)pdm09, A(H3N2), and influenza B virus strains identified in Thailand for the presence of substitutions previously reported to reduce susceptibility to NAIs. We initially examined oseltamivir resistance (characterized by the H275Y mutation in the NA gene) in 485 A(H1N1)pdm09 strains circulating in Thailand and found that 0.82% (4/485) had this substitution. To further evaluate the evolution of the NA gene, we also randomly selected 98 A(H1N1)pdm09, 158 A(H3N2), and 69 influenza B virus strains for NA gene amplification and sequencing, which revealed various amino acid mutations in the active site of the NA protein previously shown to be associated with reduced susceptibility to NAIs. Phylogenetic analysis of the influenza virus strains from this study and elsewhere around the world, together with the estimations of nucleotide substitution rates and selection pressure, and the predictions of B-cell epitopes and N-linked glycosylation sites all provided evidence for the ongoing evolution of NA. The overall rates of NA evolution for influenza A viruses were higher than for influenza B virus at the nucleotide level, although influenza B virus possessed more genealogical diversity than that of influenza A viruses. The continual surveillance of the antigenic changes associated with the NA protein will not only contribute to the influenza virus database but may also provide a better understanding of selection pressure exerted by antiviral use.
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MESH Headings
- Drug Resistance, Viral/genetics
- Epitopes, B-Lymphocyte/immunology
- Evolution, Molecular
- Genotype
- Glycosylation
- Humans
- Influenza A Virus, H1N1 Subtype/drug effects
- Influenza A Virus, H1N1 Subtype/enzymology
- Influenza A Virus, H1N1 Subtype/genetics
- Influenza A Virus, H3N2 Subtype/drug effects
- Influenza A Virus, H3N2 Subtype/enzymology
- Influenza A Virus, H3N2 Subtype/genetics
- Influenza B virus/drug effects
- Influenza B virus/enzymology
- Influenza B virus/genetics
- Influenza, Human/drug therapy
- Influenza, Human/epidemiology
- Influenza, Human/virology
- Neuraminidase/classification
- Neuraminidase/genetics
- Neuraminidase/metabolism
- Oseltamivir/pharmacology
- Oseltamivir/therapeutic use
- Phylogeny
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Seasons
- Thailand/epidemiology
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Affiliation(s)
- Nipaporn Tewawong
- Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Preeyaporn Vichiwattana
- Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Sumeth Korkong
- Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Sirapa Klinfueng
- Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Nungruthai Suntronwong
- Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Thanunrat Thongmee
- Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Apiradee Theamboonlers
- Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Sompong Vongpunsawad
- Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Yong Poovorawan
- Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- * E-mail:
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8
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Pascua PNQ, Marathe BM, Burnham AJ, Vogel P, Webby RJ, Webster RG, Govorkova EA. Competitive Fitness of Influenza B Viruses Possessing E119A and H274Y Neuraminidase Inhibitor Resistance-Associated Substitutions in Ferrets. PLoS One 2016; 11:e0159847. [PMID: 27466813 PMCID: PMC4965113 DOI: 10.1371/journal.pone.0159847] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 07/09/2016] [Indexed: 11/30/2022] Open
Abstract
Neuraminidase (NA) inhibitors (NAIs) are the only antiviral drugs recommended for influenza treatment and prophylaxis. Although NAI-resistant influenza B viruses that could pose a threat to public health have been reported in the field, their fitness is poorly understood. We evaluated in ferrets the pathogenicity and relative fitness of reverse genetics (rg)-generated influenza B/Yamanashi/166/1998-like viruses containing E119A or H274Y NA substitutions (N2 numbering). Ferrets inoculated with NAI-susceptible rg-wild-type (rg-WT) or NAI-resistant (rg-E119A or rg-H274Y) viruses developed mild infections. Growth of rg-E119A virus in the nasal cavities was delayed, but the high titers at 3 days post-inoculation (dpi) were comparable to those of the rg-WT and rg-H274Y viruses (3.6-4.1 log10TCID50/mL). No virus persisted beyond 5 dpi and replication did not extend to the trachea or lungs. Positive virus antigen-staining of the nasal turbinate epithelium was intermittent with the rg-WT and rg-H274Y viruses; whereas antigen-staining for the rg-E119A virus was more diffuse. Virus populations in ferrets coinoculated with NAI-susceptible and -resistant viruses (1:1 mixture) remained heterogeneous at 5 dpi but were predominantly rg-WT (>70%). Although the E119A substitution was associated with delayed replication in ferrets, the H274Y substitution did not measurably affect viral growth properties. These data suggest that rg-H274Y has undiminished fitness in single virus inoculations, but neither rg-E119A nor rg-H274Y gained a fitness advantage over rg-WT in direct competition experiments without antiviral drug pressure. Taken together, our data suggest the following order of relative fitness in a ferret animal model: rg-WT > rg-H274Y > rg-E119A.
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Affiliation(s)
- Philippe Noriel Q. Pascua
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Bindumadhav M. Marathe
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | | | - Peter Vogel
- Veterinary Pathology Core, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Richard J. Webby
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Robert G. Webster
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Elena A. Govorkova
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
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9
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Thierry E, Guilligay D, Kosinski J, Bock T, Gaudon S, Round A, Pflug A, Hengrung N, El Omari K, Baudin F, Hart DJ, Beck M, Cusack S. Influenza Polymerase Can Adopt an Alternative Configuration Involving a Radical Repacking of PB2 Domains. Mol Cell 2016; 61:125-37. [PMID: 26711008 PMCID: PMC4712189 DOI: 10.1016/j.molcel.2015.11.016] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/13/2015] [Accepted: 11/05/2015] [Indexed: 01/26/2023]
Abstract
Influenza virus polymerase transcribes or replicates the segmented RNA genome (vRNA) into respectively viral mRNA or full-length copies and initiates RNA synthesis by binding the conserved 3' and 5' vRNA ends (the promoter). In recent structures of promoter-bound polymerase, the cap-binding and endonuclease domains are configured for cap snatching, which generates capped transcription primers. Here, we present a FluB polymerase structure with a bound complementary cRNA 5' end that exhibits a major rearrangement of the subdomains within the C-terminal two-thirds of PB2 (PB2-C). Notably, the PB2 nuclear localization signal (NLS)-containing domain translocates ∼90 Å to bind to the endonuclease domain. FluA PB2-C alone and RNA-free FluC polymerase are similarly arranged. Biophysical and cap-dependent endonuclease assays show that in solution the polymerase explores different conformational distributions depending on which RNA is bound. The inherent flexibility of the polymerase allows it to adopt alternative conformations that are likely important during polymerase maturation into active progeny RNPs.
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Affiliation(s)
- Eric Thierry
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Delphine Guilligay
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Jan Kosinski
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Thomas Bock
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Stephanie Gaudon
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Adam Round
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Alexander Pflug
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Narin Hengrung
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK; Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Kamel El Omari
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Florence Baudin
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France; Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Darren J Hart
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Martin Beck
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Stephen Cusack
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France.
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10
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Huang W, Li X, Tan M, Wei H, Cheng Y, Guo J, Wang Z, Xiao N, Wang D, Shu Y. [Susceptibility of Influenza B Viruses to Neuraminidase Inhibitors Isolated during 2013-2014 Influenza Season in Mainland China]. Bing Du Xue Bao 2015; 31:152-156. [PMID: 26164940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Data based on the antiviral-resistant phenotyping characteristics of 884 influenza B viruses circulating in mainland China from October 2013 to March 2014 were analyzed to assess the susceptibility of influenza B viruses to neuraminidase inhibitors. All 884 viruses were sensitive to oseltamivir; two viruses (0.23%) had reduced sensitivity to zanamivir and all other viruses were sensitive to zanamivir. Among the 38 viruses with a B/Victoria lineage, B/Shandong-Kuiwen/1195/2014 exhibited a half-maximal inhibitory concentration (IC50) for zanamivir that was elevated by 5. 12-fold (1.78 nM) compared with neuraminidase inhibitors sensitive to the reference virus (0.34 nM), suggesting that it exhibited reduced inhibition by zanamivir. D35G, N59D and S402T (39, 64 and 399 with N2 number) amino-acid substitutions in the NA gene were detected with no previously reported antiviral-resistant substitutions. Among viruses with the 846 B/Yamagata lineage, B/Hunan-Lingling/350/2013 exhibited a 7.99-fold elevated IC50 for zanamivir (2.72 nM) compared with neuraminidase inhibitors sensitive to the reference virus (0.34 nM), suggesting that it exhibited reduced inhibition by zanamivir. D197N (N2 number), a previously reported antiviral resistant-related amino-acid substitution in the NA gene, was detected in B/Hunan-Lingling/350/2013. These data suggest that recently circulating influenza B viruses in mainland China have retained susceptibility to neuraminidase inhibitors.
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11
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Wang D, Sleeman K, Huang W, Nguyen HT, Levine M, Cheng Y, Li X, Tan M, Xing X, Xu X, Klimov AI, Gubareva LV, Shu Y. Neuraminidase inhibitor susceptibility testing of influenza type B viruses in China during 2010 and 2011 identifies viruses with reduced susceptibility to oseltamivir and zanamivir. Antiviral Res 2012; 97:240-4. [PMID: 23267831 DOI: 10.1016/j.antiviral.2012.12.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 12/09/2012] [Accepted: 12/12/2012] [Indexed: 11/18/2022]
Abstract
Influenza type B viruses are responsible for substantial morbidity and mortality in humans. Antiviral drugs are an important supplement to vaccination for reducing the public health impact of influenza virus infections. Influenza B viruses are not sensitive to M2 inhibitors which limit the current therapeutic options to two neuraminidase inhibitors (NAIs), oseltamivir and zanamivir, which are licensed in many countries. Drug resistance is a public health concern which has necessitated monitoring of influenza virus drug susceptibilities through active global surveillance. Here, we report the results of drug susceptibility surveillance of influenza type B viruses (n=680) collected in mainland China during two calendar years, 2010 and 2011, assessed using functional neuraminidase (NA) inhibition (NI) assays. Four influenza B viruses exhibited reduced susceptibilities to oseltamivir, but not zanamivir, and shared the amino acid substitution I221T (ATC→ACC), at this conserved residue in the NA active site (I222T in N2 numbering). Additionally, a single virus with reduced susceptibility to both oseltamivir and zanamivir was identified and contained an amino acid substitution D197N (GAC→AAC) at another conserved residue in the NA active site (D198N in N2 numbering). This report underlies the importance of continued influenza antiviral susceptibility surveillance globally, even in countries where the use of NAIs has been low or non-existing.
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Affiliation(s)
- Dayan Wang
- Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing, China
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12
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Oiknine-Djian E, Houri-Haddad Y, Weiss EI, Ofek I, Greenbaum E, Hartshorn K, Zakay-Rones Z. High molecular weight constituents of cranberry interfere with influenza virus neuraminidase activity in vitro. Planta Med 2012; 78:962-967. [PMID: 22588835 DOI: 10.1055/s-0031-1298579] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Cranberry juice contains high molecular weight non-dialyzable material (NDM) which was found to inhibit hemagglutination induced by the influenza virus (IV) as well as to neutralize the cytotoxicity of IV in cell cultures. Because influenza virus surface glycoproteins hemagglutinin (HA) and neuraminidase (NA) are involved in viral replication and in the infectious process, we sought in the present study to examine the effect of NDM on neuraminidases which are the target of most anti-influenza drugs today. NDM inhibited the NA enzymatic activity of influenza A and B strains as well as that of Streptococcus pneumoniae. This finding is of importance considering the emergence of influenza isolates resistant to antiviral drugs, reaching 90 % in some places. The anti-NA activity of NDM, evaluated by the MUNANA method and expressed as the concentration required for 50 % inhibition (IC₅₀), was most potent against N1 (IC₅₀, 192 µg/mL), less active against BN and N2 (IC₅₀, 509 µg/mL and 1128 µg/mL, respectively), and moderately active against Streptococcus pneumoniae NA (IC₅₀, 594 µg/mL). The in vitro findings of the present study suggest that cranberry constituents may have a therapeutic potential against both A and B influenza virus infections and might also interfere with the development of secondary bacterial complications.
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Affiliation(s)
- Esther Oiknine-Djian
- Department of Biochemistry and Molecular Biology, Chanock Center of Virology, IMRIC, Hadassah-Hebrew University Medical and Dental Schools, Jerusalem, Israel
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13
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Xu J, Lu G. Evolution of influenza viral neuraminidase (NA) revealed by large-scale sequence analysis. Influenza Other Respir Viruses 2011; 5:405-408. [PMID: 21761592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023] Open
Affiliation(s)
- Jianpeng Xu
- Department of Biology, University of Nebraska at Omaha, Omaha, NE, USA
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14
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L'vov DK, Burtseva EI, Galegov GA, Beliakova NV, Shevchenko ES, Kolobukhina LV, Merkulova LN, Prilipov AG, Leneva IA, Baranov NI, Gorelikov VN, Abramov DD. [Sensitivity of the epidemic and pandemic influenza virus strains to zanamivir (Relenze) in in vitro experiments]. Vopr Virusol 2010; 55:10-14. [PMID: 21381333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The paper presents the results of the first Russian experience in evaluating the sensitivity of the epidemic and pandemic influenza virus strains, circulating in the period 2009-2010, to the anti-neuraminidase drug zanamivir. A complex of studies, including enzyme immunoassay, fluorometric assay and partial sequence of the neuraminidases (NA1 and NA2) from influenza A virus strain, was applied. The findings Indicate that all the test strains, including those resistant to oseltamivir, were susceptible to zanamivir. The latter is recommended by the WHO for the prevention and treatment of influenza in pregnant women.
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15
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Zu M, Zhou D, Gao L, Liu AL, Du GH. [Evaluation of Chinese traditional patent medicines against influenza virus in vitro]. Yao Xue Xue Bao 2010; 45:408-412. [PMID: 21351522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
To study in vitro anti-influenza viral activities of Chinese traditional patent medicines for influenza prevention and treatment, neuraminidase (NA) activity assay was used to examine NA inhibitory activity of 33 Chinese traditional patent medicines through fluorimetric assay, and influenza virus induced cytopathic effect (CPE) inhibition assay was used to verify their anti-influenza viral activities in vitro. The assay results showed that most liquid preparations displayed relatively high NA inhibitory activities, such as Shuanghuanglian oral liquid, Qingkailing oral liquid, Qingre Jiedu oral liquid, and Reduning injection. Among liquid preparations, Shuanghuanglian oral liquid not only displayed the highest NA inhibitory effect, but also exhibited obvious in vitro anti-viral activity in CPE experiment. Among solid preparations, Shuanghuanglian powder for injection showed the highest activity on NA inhibition, and Fufang Yuxingcao tablet showed relatively strong anti-influenza viral activity in CPE cells. From the results, it can be concluded that most Chinese traditional patent medicines possessed NA inhibitory activity, but only a few of them displayed significant in vitro anti-influenza viral activities. These results will provide important information for the isolation of active constituents, and for the clinical uses of Chinese traditional patent medicines for influenza treatment and prevention.
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MESH Headings
- Animals
- Antiviral Agents/pharmacology
- Cell Line
- Cytopathogenic Effect, Viral/drug effects
- Dogs
- Dose-Response Relationship, Drug
- Drugs, Chinese Herbal/administration & dosage
- Drugs, Chinese Herbal/isolation & purification
- Drugs, Chinese Herbal/pharmacology
- Influenza A Virus, H1N1 Subtype/drug effects
- Influenza A Virus, H1N1 Subtype/enzymology
- Influenza A Virus, H3N2 Subtype/drug effects
- Influenza A Virus, H3N2 Subtype/enzymology
- Influenza B virus/drug effects
- Influenza B virus/enzymology
- Medicine, Chinese Traditional
- Neuraminidase/antagonists & inhibitors
- Neuraminidase/metabolism
- Plants, Medicinal/chemistry
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Affiliation(s)
- Mian Zu
- Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
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16
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Dominiak PM, Volkov A, Dominiak AP, Jarzembska KN, Coppens P. Combining crystallographic information and an aspherical-atom data bank in the evaluation of the electrostatic interaction energy in an enzyme-substrate complex: influenza neuraminidase inhibition. Acta Crystallogr D Biol Crystallogr 2009; 65:485-99. [PMID: 19390154 PMCID: PMC2672818 DOI: 10.1107/s0907444909009433] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Accepted: 03/13/2009] [Indexed: 11/11/2022]
Abstract
Although electrostatic interactions contribute only a part of the interaction energies between macromolecules, unlike dispersion forces they are highly directional and therefore dominate the nature of molecular packing in crystals and in biological complexes and contribute significantly to differences in inhibition strength among related enzyme inhibitors. In the reported study, a wide range of complexes of influenza neuraminidases with inhibitor molecules (sialic acid derivatives and others) have been analyzed using charge densities from a transferable aspherical-atom data bank. The strongest interactions of the residues are with the acidic group at the C2 position of the inhibitor ( approximately -300 kJ mol(-1) for -COO(-) in non-aromatic inhibitors, approximately -120-210 kJ mol(-1) for -COO(-) in aromatic inhibitors and approximately -450 kJ mol(-1) for -PO(3)(2-)) and with the amino and guanidine groups at C4 ( approximately -250 kJ mol(-1)). Other groups contribute less than approximately 100 kJ mol(-1). Residues Glu119, Asp151, Glu227, Glu276 and Arg371 show the largest variation in electrostatic energies of interaction with different groups of inhibitors, which points to their important role in the inhibitor recognition. The Arg292-->Lys mutation reduces the electrostatic interactions of the enzyme with the acidic group at C2 for all inhibitors that have been studied (SIA, DAN, 4AM, ZMR, G20, G28, G39 and BCZ), but enhances the interactions with the glycerol group at C6 for inhibitors that contain it. This is in agreement with the lower level of resistance of the mutated virus to glycerol-containing inhibitors compared with the more hydrophobic derivatives.
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Affiliation(s)
- Paulina M. Dominiak
- Department of Chemistry, State University of New York at Buffalo, NY 14260, USA
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warszawa, Poland
| | - Anatoliy Volkov
- Department of Chemistry, State University of New York at Buffalo, NY 14260, USA
| | - Adam P. Dominiak
- Department of Chemistry, State University of New York at Buffalo, NY 14260, USA
| | | | - Philip Coppens
- Department of Chemistry, State University of New York at Buffalo, NY 14260, USA
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17
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Reina J. [Peramivir. A new and potent neuraminidase inhibitor for the treatment of influenza]. Rev Esp Quimioter 2006; 19:317-22. [PMID: 17235399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Affiliation(s)
- J Reina
- Unidad de Virología, Servicio de Microbiología Clínica, Hospital Universitario Son Dureta, Palma de Mallorca.
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18
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Ferraris O, Kessler N, Lina B. Sensitivity of influenza viruses to zanamivir and oseltamivir: a study performed on viruses circulating in France prior to the introduction of neuraminidase inhibitors in clinical practice. Antiviral Res 2006; 68:43-8. [PMID: 16125799 DOI: 10.1016/j.antiviral.2005.07.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Revised: 07/13/2005] [Accepted: 07/13/2005] [Indexed: 01/01/2023]
Abstract
Influenza virus neuraminidase inhibitors (NAIs) were introduced in clinical practice in various parts of the world since 1999 but were only scarcely distributed in France. Prior to the generalization of zanamivir and oseltamivir utilization in our country, we decided to test a large panel of influenza strains to establish the baseline sensitivity of these viruses to anti-neuraminidase drugs, based upon a fluorometric neuraminidase enzymatic test. Our study was performed on clinical samples collected by practitioners of the GROG network (Groupe Régional d'Observation de la Grippe) in the south of France during the 2002-2003 influenza season. Out of 355 isolates tested in the fluorometric neuraminidase activity assay, 267 isolates could be included in inhibition assay against anti-neuraminidase drugs. Differences in IC50 range were found according to the subtype and the anti-neuraminidase drug. Influenza B and A/H1N1 viruses appeared to be more sensitive to zanamivir than to oseltamivir (mean B IC50 values: 4.19 nM versus 13 nM; mean H1N1 IC50 values: 0.92 nM versus 1.34 nM), while A/H1N2 and A/H3N2 viruses were more sensitive to oseltamivir than to zanamivir (mean H3N2 IC50 values: 0.67 nM versus 2.28 nM; mean H1N2 IC50 values: 0.9 nM versus 3.09 nM). Out of 128 N2 carrying isolates, 10 isolates had zanamivir or oseltamivir IC50 values in upper limits compared to their respective data range. Sequencing of the neuraminidase of these outliers N2 highlighted several mutations, but none of them were associated with resistance to neuraminidase inhibitors.
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Affiliation(s)
- O Ferraris
- Laboratoire de Virologie, Centre National de Référence pour la Grippe (France-Sud), Domaine Rockefeller, 8 Avenue Rockefeller, 69373 Lyon cedex 08, France.
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19
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Abstract
Neuraminidase (NA) is one of the most important targets to screen the drugs of anti-influenza virus A and B. After virtual screening approaches were applied to a compound database which possesses more than 10000 compound structures, 160 compounds were selected for bioactivity assay, then a High Throughput Screening (HTS) model established for influenza virus NA inhibitors was applied to detect these compounds. Finally, three compounds among them displayed higher inhibitory activities, the range of their IC50 was from 0.1 micromol/L to 3 micromol/L. Their structural scaffolds are novel and different from those of NA inhibitors approved for influenza treatment, and will be useful for the design and research of new NA inhibitors. The result indicated that the combination of virtual screening with HTS was very significant to drug screening and drug discovery.
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Affiliation(s)
- Ailin Liu
- Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
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20
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Maring CJ, Stoll VS, Zhao C, Sun M, Krueger AC, Stewart KD, Madigan DL, Kati WM, Xu Y, Carrick RJ, Montgomery DA, Kempf-Grote A, Marsh KC, Molla A, Steffy KR, Sham HL, Laver WG, Gu YG, Kempf DJ, Kohlbrenner WE. Structure-based characterization and optimization of novel hydrophobic binding interactions in a series of pyrrolidine influenza neuraminidase inhibitors. J Med Chem 2005; 48:3980-90. [PMID: 15943472 DOI: 10.1021/jm049276y] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structure-activity relationship (SAR) of a novel hydrophobic binding interaction within a subsite of the influenza neuraminidase (NA) active site was characterized and optimized for a series of trisubstituted pyrrolidine inhibitors modified at the 4-position. Previously, potent inhibitors have targeted this subsite with hydrophilic substituents such as amines and guanidines. Inhibitor-bound crystal structures revealed that hydrophobic substituents with sp(2) hybridization could achieve optimal interactions by virtue of a low-energy binding conformation and favorable pi-stacking interactions with the residue Glu119. From a lead methyl ester, investigation of five-membered heteroaromatic substituents at C-4 produced a 3-pyrazolyl analogue that improved activity by making a targeted hydrogen bond with Trp178. The SAR of substituted vinyl substituents at C-4 produced a Z-propenyl analogue with improved activity over the lead methyl ester. The C-1 ethyl ester prodrugs of the substituted C-4 vinyl analogues gave compounds with excellent oral bioavailability (F > 60%) when dosed in rat.
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Affiliation(s)
- Clarence J Maring
- Department of Infectious Disease Research and Advanced Technology, Global Pharmaceutical R & D, Abbott Laboratories, Abbott Park, Illinois 60064, USA.
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21
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Macdonald SJF, Cameron R, Demaine DA, Fenton RJ, Foster G, Gower D, Hamblin JN, Hamilton S, Hart GJ, Hill AP, Inglis GGA, Jin B, Jones HT, McConnell DB, McKimm-Breschkin J, Mills G, Nguyen V, Owens IJ, Parry N, Shanahan SE, Smith D, Watson KG, Wu WY, Tucker SP. Dimeric Zanamivir Conjugates with Various Linking Groups Are Potent, Long-Lasting Inhibitors of Influenza Neuraminidase Including H5N1 Avian Influenza. J Med Chem 2005; 48:2964-71. [PMID: 15828835 DOI: 10.1021/jm040891b] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis, antiviral and pharmacokinetic properties of zanamivir (ZMV) dimers 8 and 13 are described. The compounds are highly potent neuraminidase (NA) inhibitors which, along with dimer 3, are being investigated as potential second generation inhaled therapies both for the treatment of influenza and for prophylactic use. They show outstanding activity in a 1 week mouse influenza prophylaxis assay, and compared with ZMV, high concentrations of 8 and 13 are found in rat lung tissue after 1 week. Retention of compounds in rat lung tissue correlated both with molecular weight (excluding 3 and 15) and with a capacity factor K' derived from immobilized artificial membrane (IAM) chromatography (including 3 and 15). Pharmacokinetic parameters for 3, 8 and 13 in rats show the compounds have short to moderate plasma half-lives, low clearances and low volumes of distribution. Dimer 3 shows NA inhibitory activity against N1 viruses including the recent highly pathogenic H5N1 A/Chicken/Vietnam/8/2004. In plaque reduction assays, 3, 8 and 13 show good to outstanding potency against a panel of nine flu A and B virus strains. Consistent with its shorter and more rigid linking group, dimer 8 has been successfully crystallized.
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Affiliation(s)
- Simon J F Macdonald
- GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom.
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22
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Jackson D, Barclay W, Zürcher T. Characterization of recombinant influenza B viruses with key neuraminidase inhibitor resistance mutations. J Antimicrob Chemother 2005; 55:162-9. [PMID: 15665027 DOI: 10.1093/jac/dkh528] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES AND METHODS An influenza B virus plasmid-based rescue system was used to introduce site-specific mutations, previously observed in neuraminidase (NA) inhibitor-resistant viruses, into the NA protein of six recombinant viruses. Three mutations observed only among in vitro selected zanamivir-resistant influenza A mutants were introduced into the B/Beijing/1/87 virus NA protein, to change residue E116 to glycine, alanine or aspartic acid. Residue E116 was also mutated to valine, a mutation found in the clinic among oseltamivir-resistant viruses. An arginine to lysine change at position 291 (292 N2 numbering) mimicked that seen frequently in influenza A N2 clinical isolates resistant to oseltamivir. Similarly, an arginine to lysine change at position 149 (152 in N2 numbering) was made to reproduce the change found in the only reported zanamivir-resistant clinical isolate of influenza B virus. In vitro selection and prolonged treatment in the clinic leads to resistance pathways that require compensatory mutations in the haemagglutinin gene, but these appear not to be important for mutants isolated from immunocompetent patients. The reverse genetics system was therefore used to generate mutants containing only the NA mutation. RESULTS AND CONCLUSIONS With the exception of a virus containing the E116G mutation, mutant viruses were attenuated to different levels in comparison with wild-type virus. This attenuation was a result of altered NA activity or stability depending on the introduced mutation. Mutant viruses displayed increased resistance to zanamivir, oseltamivir and peramivir, with certain viruses displaying cross-resistance to all three drugs.
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Affiliation(s)
- David Jackson
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, PO Box 228, Reading RG6 6AJ
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23
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Puzelli S, Frezza F, Fabiani C, Ansaldi F, Campitelli L, Lin YP, Gregory V, Bennett M, D'Agaro P, Campello C, Crovari P, Hay A, Donatelli I. Changes in the hemagglutinins and neuraminidases of human influenza B viruses isolated in Italy during the 2001-02, 2002-03, and 2003-04 seasons. J Med Virol 2005; 74:629-40. [PMID: 15484280 DOI: 10.1002/jmv.20225] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Throughout most of the last decade, B/Yamagata/16/88-lineage influenza viruses were predominant among the B isolates circulating worldwide, whereas B/Victoria/2/87-lineage viruses were isolated infrequently and restricted geographically to eastern Asia. During the 2001-02 influenza season, B/Victoria/2/87-lineage viruses re-emerged in North America and Europe and spread worldwide. Virological surveillance in Italy during that season showed wide circulation of influenza B viruses, of which most were antigenically related to the B/Sichuan/379/99 (Yamagata-lineage) vaccine strain, together with a smaller number of B viruses antigenically similar to B/HongKong/330/01, a recent B/Victoria/2/87-lineage antigenic variant. In the subsequent 2002-03 epidemic season, B viruses with a Victoria-lineage hemagglutinin (HA), more closely related to that of B/Shandong/7/97, were isolated exclusively. Similar strains have continued to predominate among the few B viruses isolated in Italy during last season (2003-04), although most influenza B viruses, isolated sporadically elsewhere in Europe, again belong to the Yamagata-lineage. In the present study, phylogenetic analyses of the HA and neuraminidase (NA) genes of representative B strains, isolated throughout Italy during 2001-04, showed that during the first influenza season the NA genes, as well as the HA genes, separated into the two distinct clades, the Yamagata- and Victoria-lineages, and showed no evidence of genetic reassortment. On the contrary, all the B viruses isolated in the 2002-03 and most of those isolated in the 2003-04 epidemic season were "Victoria HA-Yamagata NA" reassortants similar to those isolated in other parts of the world, showing that these reassortants became established in the human population. The frequency of reassortment between HA and NA of distinct lineages and sublineages highlights again the importance of detailed molecular analyses of both surface glycoproteins in understanding the evolution of influenza B viruses.
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Affiliation(s)
- Simona Puzelli
- Laboratory of Virology, National Influenza Centre, Istituto Superiore di Sanità, Rome, Italy
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24
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Abstract
A wide use of inhibitors of influenza virus neuraminidase (NAIs) to control influenza in humans demands a better understanding of the mechanisms involved in the resistance emergence. In vitro studies demonstrate that both neuraminidase (NA) and hemagglutinin (HA) influence virus susceptibility to NAIs. Drug resistance conferred due to changes in the NA could be monitored in the NA inhibition assays. Zanamivir-selected viruses acquired the NA substitutions at residues 119 and 292; oseltamivir-selected--at 274 and 292; peramivir-selected--at 292; and A-315675-selected--at 119. The HA binding efficiency and therefore susceptibility to NAIs are affected by the amino acids forming the HA receptor-binding site, the location and number of oligosaccharide chains, and structure of the neuraminic acid-containing cellular receptors. The lack of suitable cell culture-based assays hampers the assessment of virus susceptibility in humans. Emergence of the viruses with the NAI-induced substitutions in the NA is uncommon in drug-treated humans, however a compromised state of the immune system promotes emergence of drug resistance. In vivo, the zanamivir-selected mutant contained a substitution at 152 (B/NA); the oseltamivir-selected mutants-at residues 119 (A/N2), 198 (B/NA), 274 (A/N1), and 292 (A/N2). Substitutions in the NA were often accompanied by impairment of virus infectivity and virulence in animal models. Because of complexity of mechanisms of virus resistance, further analysis of the viruses recovered from the drug-treated humans is warranted.
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Affiliation(s)
- Larisa V Gubareva
- Department of Internal Medicine, University of Virginia Health Sciences Center, P.O. Box 800473, Charlottesville, VA, USA.
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25
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Lommer BS, Ali SM, Bajpai SN, Brouillette WJ, Air GM, Luo M. A benzoic acid inhibitor induces a novel conformational change in the active site ofInfluenza B virusneuraminidase. Acta Crystallogr D Biol Crystallogr 2004; 60:1017-23. [PMID: 15159560 DOI: 10.1107/s0907444904006225] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2004] [Accepted: 03/16/2004] [Indexed: 11/10/2022]
Abstract
Owing to the highly conserved nature of its active site, Influenza B virus neuraminidase (NA) has emerged as a major target for the design of novel anti-influenza drugs. A benzene-ring scaffold has been used in place of the pyranose ring of sialic acid to develop simpler NA inhibitors that contain a minimal number of chiral centers. A new compound belonging to this series, BANA 207, showed significant improvement in inhibitory activity against Influenza B virus NA compared with its parent compound. Here, the structural analysis of a complex of BANA 207 with influenza virus B/Lee/40 NA is reported. The results indicate that BANA 207 forms an unexpected interaction with the crucial active-site residue Glu275 that stabilizes the side chain of this residue in a conformation previously unobserved in NA-inhibitor complexes. This change in the side-chain orientation of Glu275 alters the topology of the triglycerol pocket, which accommodates an additional lipophilic substitution at the benzene ring and may provide an explanation for the increased activity of BANA 207 against Influenza B virus NA.
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Affiliation(s)
- Barbara S Lommer
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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26
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McSharry JJ, McDonough AC, Olson BA, Drusano GL. Phenotypic drug susceptibility assay for influenza virus neuraminidase inhibitors. Clin Diagn Lab Immunol 2004; 11:21-8. [PMID: 14715540 PMCID: PMC321328 DOI: 10.1128/cdli.11.1.21-28.2004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A flow cytometric (fluorescence-activated cell sorter [FACS]) assay was developed for analysis of the drug susceptibilities of wild-type and drug-resistant influenza A and B virus laboratory strains and clinical isolates for the neuraminidase (NA) inhibitors oseltamivir carboxylate, zanamivir, and peramivir. The drug susceptibilities of wild-type influenza viruses and those with mutations in the hemagglutinin (HA) and/or NA genes rendering them resistant to one or more of the NA inhibitors were easily determined with the FACS assay. The drug concentrations that reduced the number of virus-infected cells or the number of PFU by 50% as determined by the FACS assay were similar to those obtained with the more time-consuming and labor-intensive virus yield reduction assay. The NA inhibition (NAI) assay confirmed the resistance patterns demonstrated by the FACS and virus yield assays for drug-resistant influenza viruses with mutations in the NA gene. However, only the FACS and virus yield assays detected NA inhibitor-resistant influenza viruses with mutations in the HA gene but not in the NA gene. The FACS assay is more rapid and less labor-intensive than the virus yield assay and just as quantitative. The FACS assay determines the drug susceptibilities of influenza viruses with mutations in either the HA or NA genes, making the assay more broadly useful than the NAI assay for measuring the in vitro susceptibilities of influenza viruses for NA inhibitors. However, since only viruses with mutations in the NA gene that lead to resistance to the NA inhibitors correlate with clinical resistance, this in vitro assay should not be used in the clinical setting to determine resistance to NA inhibitors. The assay may be useful for determining the in vivo susceptibilities of other compounds effective against influenza A and B viruses.
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Affiliation(s)
- James J McSharry
- Center for Immunology and Microbial Disease and Clinical Research Initiative, Albany Medical College, Albany, New York 12208, USA.
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27
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Kaji M. [Neuraminidase inhibitor, anti-influenzal agent--mechanism of action, and how to use clinically]. Nihon Rinsho 2003; 61:1975-9. [PMID: 14619441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
Neuraminidase inhibitor has changed the treatment of influenza dramatically. The drug is effective for both influenza A and B whereas amantadine, another anti-influenzal agent, inhibits influenza A virus infection but not B. Neuraminidase inhibitor blocks the process of release of influenza virus from infected cells and inhibit the virus transmission to the neighboring cells. Neuraminidase inhibitor improves the symptoms of influenza and shortens the duration of illness. It is emphasized that this drug should be given within forty-eight hours after the onset, and it must be not noted that the possibility of the drug resistant virus although it is observed infrequently. Prophylactic use of the drug is also discussed.
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Affiliation(s)
- Masahide Kaji
- Department of Internal Medicine, Kurume University Medical Center
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28
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Katinger D, Romanova J, Ferko B, Fekete H, Egorov A. Effect of a single mutation in neuraminidase on the properties of Influenza B virus isolates. Arch Virol 2003; 149:173-81. [PMID: 14689282 DOI: 10.1007/s00705-003-0203-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2003] [Revised: 01/01/2003] [Accepted: 07/17/2003] [Indexed: 11/28/2022]
Abstract
Two strains of Influenza B virus were isolated in Vero cells. Subclones with improved efficiency of plaque formation were selected. The activity of the neuraminidase (NA) of the two subclones compared to their respective isolates dropped 20- and 100-fold, respectively. Both subclones had a common mutation in segment 6 leading to a change from Asp to Asn at position 457 in the NA. This mutation destroyed a salt bridge of the contact surface between the monomers, thereby causing the loss in enzymatic activity. The decreased NA activity caused improved plaque formation but had no significant impact on the replication in liquid culture.
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Affiliation(s)
- D Katinger
- Polymun Scientific GmbH, Vienna, Austria.
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29
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Brouillette WJ, Bajpai SN, Ali SM, Velu SE, Atigadda VR, Lommer BS, Finley JB, Luo M, Air GM. Pyrrolidinobenzoic acid inhibitors of influenza virus neuraminidase: modifications of essential pyrrolidinone ring substituents. Bioorg Med Chem 2003; 11:2739-49. [PMID: 12788348 DOI: 10.1016/s0968-0896(03)00271-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We recently reported the first benzoic acid, 1-[4-carboxy-2-(3-pentylamino)phenyl]-5,5-bis(hydroxymethyl)pyrrolidin-2-one (8), that is a potent inhibitor of avian influenza A neuraminidase (N9) and, unlike other reported potent neuraminidase inhibitors, does not contain a basic aliphatic amine or guanidine nor a simple N-acetyl grouping. However, 8 was a poor inhibitor of influenza B neuraminidase. In the present study we further evaluated 8 as an inhibitor of human influenza A NA isolates, and it was effective against N2NA but found to be 160-fold less active against N1NA. We also synthesized analogues of 8 involving moderate modifications of essential substituents on the pyrrolidinone ring. Specifically, the aminomethyl (9), hydroxyethyl (10), and aminoethyl (11) analogues were prepared. Only the most conservative change (compound 9) resulted in continued effective inhibition of influenza A, in addition to a noteworthy increase in the activity of 9 for N1NA. The effectiveness of 9 against influenza B neuraminidase was furthermore improved 10-fold relative to 8, but this activity remained 50-fold poorer than for type A NA.
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Affiliation(s)
- Wayne J Brouillette
- Department of Chemistry, 901 14th Street South, CHEM 201, The University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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30
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Baum EZ, Wagaman PC, Ly L, Turchi I, Le J, Bucher D, Bush K. A point mutation in influenza B neuraminidase confers resistance to peramivir and loss of slow binding. Antiviral Res 2003; 59:13-22. [PMID: 12834856 DOI: 10.1016/s0166-3542(03)00011-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The influenza neuraminidase (NA) inhibitors peramivir, oseltamivir, and zanamivir are potent inhibitors of NAs from both influenza A and B strains. In general, these inhibitors are slow, tight binders of NA, exhibiting time-dependent inhibition. A mutant of influenza virus B/Yamagata/16/88 which was resistant to peramivir was generated by passage of the virus in tissue culture, in the presence of increasing concentrations (0.1-120 microM over 15 passages) of the compound. Whereas the wild type (WT) virus was inhibited by peramivir with an EC(50) value of 0.10 microM, virus isolated at passages 3 and 15 displayed EC(50) values of 10 and >50 microM, respectively. Passage 3 virus contained 3 hemagglutinin (HA) mutations, but no NA mutation. Passage 15 (P15R) virus contained an additional 3 HA mutations, plus the NA mutation His273Tyr. The mechanism of inhibition of WT and P15R NA by peramivir was examined in enzyme assays. The WT and P15R NAs displayed IC(50) values of 8.4+/-0.4 and 127+/-16 nM, respectively, for peramivir. Peramivir inhibited the WT enzyme in a time-dependent fashion, with a K(i) value of 0.066+/-0.002nM. In contrast, the P15R enzyme did not display the property of slow binding and was inhibited competitively with a K(i) value of 4.69+/-0.44nM. Molecular modeling suggested that His273 was relatively distant from peramivir (>5A) in the NA active site, but that Tyr273 introduced a repulsive interaction between the enzyme and inhibitor, which may have been responsible for peramivir resistance.
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Affiliation(s)
- Ellen Z Baum
- Johnson & Johnson Pharmaceutical Research & Development, L.L.C., Raritan, NJ 08869, USA.
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31
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Achyuthan KE, Pence LM, Appleman JR, Shimasaki CD. ZstatFlu-II test: a chemiluminescent neuraminidase assay for influenza viral diagnostics. LUMINESCENCE 2003; 18:131-9. [PMID: 12701088 DOI: 10.1002/bio.714] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The ZstatFlu-II test is a highly sensitive, specific, rapid, point-of-care chemiluminescent diagnostic test for influenza infection. Influenza viral neuraminidase-specific substrate, spiroadamantyl-1,2-dioxetane-4,7-dimethoxy-N-acetyl-neuraminic acid, is at the core of the ZstatFlu-II Test. The enzymatic reaction was carried out at 25 degrees C and neutral pH, representing the optimum assay conditions for influenza types A and B viral neuraminidases. The results were outputted on a Polaroid trade mark High Speed Detector Film. Positive results appeared as a '+'-shaped white film image; negative results produced no image. The 'glow' kinetics, facilitated by a unique combination of light enhancers, also 'tuned' the wavelength of emission to match the spectral properties of the film. The substrate hydrolysed non-enzymatically at acid pH or at temperatures above 25 degrees C. In order to minimize false positives, the ZstatFlu-II Test was formatted with 0.3-0.4 K(m) substrate and freezing the test kit until use. The pH optimization of the ZstatFlu-II test is discussed with reference to model compounds of sialyl-glycosides. A nucleophilic attack or an electrostatic stabilization of a developing carbonium ion under the influence of the adjacent carboxyl group was probably responsible for non-enzymatic hydrolysis of the substrate. Intramolecular general acid catalysis is proposed as a mechanism for the lability of the O-glycosidic linkage of the substrate.
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32
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Parkes KEB, Ermert P, Fässler J, Ives J, Martin JA, Merrett JH, Obrecht D, Williams G, Klumpp K. Use of a pharmacophore model to discover a new class of influenza endonuclease inhibitors. J Med Chem 2003; 46:1153-64. [PMID: 12646026 DOI: 10.1021/jm020334u] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Data from both our own and literature studies of the biochemistry and inhibition of influenza virus endonuclease was combined with data on the mechanism of action and the likely active site mechanism to propose a pharmacophore. The pharmacophore was used to design a novel structural class of inhibitors, some of which were found to have activities similar to that of known influenza endonuclease inhibitors and were also antiviral in cell culture.
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Affiliation(s)
- Kevin E B Parkes
- Roche Discovery Welwyn, 40 Broadwater Road, Welwyn Garden City, Herts, AL7 3AY, UK.
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33
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Birch L, Murray CW, Hartshorn MJ, Tickle IJ, Verdonk ML. Sensitivity of molecular docking to induced fit effects in influenza virus neuraminidase. J Comput Aided Mol Des 2002; 16:855-69. [PMID: 12825619 DOI: 10.1023/a:1023844626572] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Many proteins undergo small side chain or even backbone movements on binding of different ligands into the same protein structure. This is known as induced fit and is potentially problematic for virtual screening of databases against protein targets. In this report we investigate the limits of the rigid protein approximation used by the docking program, GOLD, through cross-docking using protein structures of influenza neuraminidase. Neuraminidase is known to exhibit small but significant induced fit effects on ligand binding. Some neuraminidase crystal structures caused concern due to the bound ligand conformation and GOLD performed poorly on these complexes. A 'clean' set, which contained unique, unambiguous complexes, was defined. For this set, the lowest energy structure was correctly docked (i.e. RMSD < 1.5 A away from the crystal reference structure) in 84% of proteins, and the most promiscuous protein (1mwe) was able to dock all 15 ligands accurately including those that normally required an induced fit movement. This is considerably better than the 70% success rate seen with GOLD against general validation sets. Inclusion of specific water molecules involved in water-mediated hydrogen bonds did not significantly improve the docking performance for ligands that formed water-mediated contacts but it did prevent docking of ligands that displaced these waters. Our data supports the use of a single protein structure for virtual screening with GOLD in some applications involving induced fit effects, although care must be taken to identify the protein structure that performs best against a wide variety of ligands. The performance of GOLD was significantly better than the GOLD implementation of ChemScore and the reasons for this are discussed. Overall, GOLD has shown itself to be an extremely good, robust docking program for this system.
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Affiliation(s)
- Louise Birch
- The University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
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34
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Abstract
The recovery of recombinant influenza A virus entirely from cDNA was recently described (9, 19). We adapted the technique for engineering influenza B virus and generated a mutant bearing an amino acid change E116G in the viral neuraminidase which was resistant in vitro to the neuraminidase inhibitor zanamivir. The method also facilitates rapid isolation of single-gene reassortants suitable as vaccine seeds and will aid further investigations of unique features of influenza B virus.
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Affiliation(s)
- David Jackson
- University of Reading, Whiteknights, Reading RG6 6AJ. GlaxoSmithKline Medicine Research Centre, Stevenage SG1 2NY, United Kingdom
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35
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Guo Y, Wen L, Wang M, Zhang Y, Guo J, Li Z. [A novel test for diagnosis of influenza]. Zhonghua Shi Yan He Lin Chuang Bing Du Xue Za Zhi 2002; 16:207-10. [PMID: 12665920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
OBJECTIVE To set up a novel, simple, sensitive, specific, repeatable and rapid assay for diagnosis of influenza. METHODS Monolayers of MDCK cells were inoculated with the specimens for amplifying viral yield, the feature of receptors on cell surface was changed by treatment of neuraminidases of influenza A and B viruses. Afterward, based on the lectin binds to receptors on cell surface with strict specificity,the phenomenon of red blood cell aggregation was observed under the conventional microscope. Finally, the tested results could be determined by the extent of red blood cell aggregation. RESULTS There was a complete (%) consistency rate (100%) for viral isolation between new and routine tests. In general, the results were detected with new assay within 20 h. The sensitivity of new assay was over 100-10,000 times higher than that of routine method. Meanwhile, the novel test could not only be used for rapid diagnosis in the clinic, but also be used for influenza surveillance. The best concentration of red blood cells was 1 in the detection assay. The testing result was not effected by red blood cells taken from either different red blood cell type of human or different individual of guinea pigs. CONCLUSIONS The novel method has several advantages: simple, high sensitivity and specificity, accurate and suitable for multiple purposes.
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Affiliation(s)
- Yuanji Guo
- National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100052, China
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36
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Honda T, Masuda T, Yoshida S, Arai M, Kobayashi Y, Yamashita M. Synthesis and anti-influenza virus activity of 4-guanidino-7-substituted Neu5Ac2en derivatives. Bioorg Med Chem Lett 2002; 12:1921-4. [PMID: 12113809 DOI: 10.1016/s0960-894x(02)00328-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Substitution of 7-OH by small hydrophobic groups on zanamivir resulted in the retaining of low nanomolar inhibitory activities against not only influenza A virus sialidase but also influenza A virus in cell culture. These compounds were prepared by treatment of the corresponding 7-substituted sialic acids derived from 4-modified N-acetyl-D-mannosamine (ManNAc) using enzyme-catalyzed aldol condensation.
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Affiliation(s)
- Takeshi Honda
- Medicinal Chemistry Research Laboratories, Sankyo Co., Ltd., 1-2-58 Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan.
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37
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Abstract
Forty-two influenza A and 23 influenza B isolates collected from untreated subjects during the 1999-2000 influenza season in Canada were tested for their susceptibility to three neuraminidase inhibitors (zanamivir, oseltamivir carboxylate and RWJ-270201 or BCX-1812) using a chemiluminescent neuraminidase assay. Influenza B isolates were less susceptible than A viruses to all tested drugs. RWJ-270201 was the most potent drug against both influenza A(H3N2) (mean IC(50): 0.60 nM) and B (mean IC(50): 0.87 nM) viruses. Oseltamivir carboxylate was more active than zanamivir for influenza A(H3N2) isolates (mean IC(50): 0.73 vs. 2.09 nM) whereas it was less potent against B viruses (mean IC(50): 11.53 vs. 4.15 nM).
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Affiliation(s)
- Guy Boivin
- Research Center in Infectious Diseases, CHUQ-CHUL, Room RC-709, 2705 Blvd. Laurier, Sainte-Foy, Québec, Canada G1V4G2.
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38
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Kati WM, Montgomery D, Carrick R, Gubareva L, Maring C, McDaniel K, Steffy K, Molla A, Hayden F, Kempf D, Kohlbrenner W. In vitro characterization of A-315675, a highly potent inhibitor of A and B strain influenza virus neuraminidases and influenza virus replication. Antimicrob Agents Chemother 2002; 46:1014-21. [PMID: 11897583 PMCID: PMC127111 DOI: 10.1128/aac.46.4.1014-1021.2002] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A-315675 is a novel, pyrrolidine-based compound that was evaluated in this study for its ability to inhibit A and B strain influenza virus neuraminidases in enzyme assays and influenza virus replication in cell culture. A-315675 effectively inhibited influenza A N1, N2, and N9 and B strain neuraminidases with inhibitor constant (K(i)) values between 0.024 and 0.31 nM. These values were comparable to or lower than the K(i) values measured for oseltamivir carboxylate (GS4071), zanamivir, and BCX-1812, except for the N1 enzymes that were found to be the most sensitive to BCX-1812. The time-dependent inhibition of neuraminidase catalytic activity observed with A-315675 is likely due to its very low rate of dissociation from the active site of neuraminidase. The half times for dissociation of A-315675 from B/Memphis/3/89 and A/Tokyo/3/67 (H3N2) influenza virus neuraminidases of 10 to 12 h are significantly slower than the half times measured for oseltamivir carboxylate (33 to 60 min). A-315675 inhibited the replication of several laboratory strains of influenza virus in cell culture with potencies that were comparable or superior to those for oseltamivir carboxylate and BCX-1812, except for the A/H1N1 viruses that were found to be two- to fourfold more susceptible to BCX-1812. A-315675 and oseltamivir carboxylate exhibited comparable potencies against a panel of A/H1N1 and A/H3N2 influenza virus clinical isolates, but A-315675 was found to be significantly more potent than oseltamivir carboxylate against the B strain isolates. The favorable in vitro results relative to other clinically effective agents provide strong support for the further investigation of A-315675 as a potential therapy for influenza virus infections.
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Affiliation(s)
- Warren M Kati
- Antiviral Drug Discovery Research, Abbott Laboratories, Abbott Park, Illinois 60064-6217, USA.
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39
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Abstract
Zanamivir is licensed for influenza treatment, but may also play a role in prophylaxis either alone or in combination with vaccine in epidemic periods. We conducted a double blind placebo controlled trial to investigate the effect of zanamivir treatment on the humoral immune response to influenza vaccine. Forty young healthy volunteers were vaccinated with licensed trivalent influenza vaccine and received 20 mg zanamivir (24 subjects) or placebo (16 subjects) daily for a period of 14 days. No significant differences were observed in the magnitude or the time course of the antibody response to the influenza H3N2 and B strains between the two groups, in contrast the placebo group responded with higher antibody titres to the H1N1. Our results suggest that during an influenza epidemic, volunteers would only need to continue zanamivir treatment for the initial 12 days after vaccination whilst the vaccine induced protective antibody response developed.
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Affiliation(s)
- R J Cox
- Department of Molecular Biology, University of Bergen, N-5020, Bergen, Norway.
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40
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Abstract
The influenza virus neuraminidase (NA) is an enzyme essential for viral infection and offers a potential target for antiviral drug development. We aimed our research at the synthesis of non-carbohydrate molecules able to inhibit NA as transition-state analogues. Aromatic sialic acid analogues (compound 5 and compound 10) were synthesised in good yields starting from commercially available benzoic acids using a suitable synthetic strategy.
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Affiliation(s)
- A Bianco
- Dipartimento di Chimica, Università La Sapienza, Rome, Italy.
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41
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Wyatt PG, Coomber BA, Evans DN, Jack TI, Fulton HE, Wonacott AJ, Colman P, Varghese J. Sialidase inhibitors related to zanamivir. Further SAR studies of 4-amino-4H-pyran-2-carboxylic acid-6-propylamides. Bioorg Med Chem Lett 2001; 11:669-73. [PMID: 11266166 DOI: 10.1016/s0960-894x(01)00019-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
SAR investigations of the 4- and 5-positions of a series of 4-amino-4H-pyran-2-carboxylic acid 6-carboxamides are reported. Potent inhibitors of influenza A sialidase with marked selectivity over the influenza B enzyme were obtained when the basic 4-amino substituent was replaced by hydroxyl or even deleted. Modifications at the 5-position exhibited a tight steric requirement, with trifluoroacetamide being optimal.
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Affiliation(s)
- P G Wyatt
- Department of Medicinal Chemistry, Glaxo Wellcome Medicines Research Centre, Stevenage, Herts, UK.
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42
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Lalezari J, Campion K, Keene O, Silagy C. Zanamivir for the treatment of influenza A and B infection in high-risk patients: a pooled analysis of randomized controlled trials. Arch Intern Med 2001; 161:212-7. [PMID: 11176734 DOI: 10.1001/archinte.161.2.212] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Influenza can cause significant morbidity and mortality, particularly in patients considered to be at high risk (such as the elderly and those with chronic disease) of developing influenza-related complications. Data on the efficacy of zanamivir in high-risk patients are lacking because individual studies recruited a limited number of these patients. METHODS A retrospective pooled analysis of data from high-risk patients in studies completed before or during the 1998-1999 winter season was performed to investigate the efficacy and safety of inhaled zanamivir (10 mg twice daily for 5 days) for the treatment of confirmed influenza. All studies were randomized, double-blind, and placebo-controlled with 21- to 28-day follow-up. A total of 2751 patients was recruited. Of these, 321 (12%) were considered high risk and 154 were randomized to zanamivir. The median time to alleviation of influenza symptoms and time to return to normal activities were the main outcome measures. RESULTS Zanamivir-treated high-risk patients had a treatment benefit of 2.5 days compared with those given placebo (P = .015). Patients treated with zanamivir returned to normal activities 3.0 days earlier (P = .022) and had an 11% reduction (P = .039) in the median total symptom score over 1 to 5 days relative to those taking placebo. In addition, zanamivir reduced the incidence of complications requiring antibiotic use by 43% relative to placebo users (P = .045). Adverse events reported were of a similar nature and frequency between the two groups. CONCLUSION This pooled analysis shows that zanamivir is an effective and well-tolerated treatment for influenza in patients considered at high-risk of developing influenza-related complications.
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Affiliation(s)
- J Lalezari
- Quest Clinical Research, 2300 Sutter St, Suite 202, San Francisco, Calif 94115, USA.
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43
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Shimizu H. [The rapid detection kit based on neuraminidase activity of influenza virus]. Nihon Rinsho 2000; 58:2234-7. [PMID: 11225310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
The ZstatFlu test(ZymeTx, USA) is a rapid detection kit for influenza types A and B virus. This test is based upon the reaction between viral neuraminidase from influenza viruses and chromogenic substrate. The positive specimen of influenza type A or B virus cleave the substrate and produce a blue colored product. The ZstatFlu was evaluated by a prototype viruses, isolated viruses and clinical specimens. At result, this kit was reactive for all human influenza type A and B virus. No cross reactivity was detected with other respiratory viruses, including parainfluenza type 1, 2, 3 and mumps viruses with neuraminidase activity. Throat swabs were used for the test. By comparison with cell culture and RT-PCR. The sensitivity and the specificity was 77.0% and 90.2% respectively. The ZstatFlu should be useful for the rapid diagnosis of influenza virus infection.
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Affiliation(s)
- H Shimizu
- Kawasaki City Institute of Public Health
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Babu YS, Chand P, Bantia S, Kotian P, Dehghani A, El-Kattan Y, Lin TH, Hutchison TL, Elliott AJ, Parker CD, Ananth SL, Horn LL, Laver GW, Montgomery JA. BCX-1812 (RWJ-270201): discovery of a novel, highly potent, orally active, and selective influenza neuraminidase inhibitor through structure-based drug design. J Med Chem 2000; 43:3482-6. [PMID: 11000002 DOI: 10.1021/jm0002679] [Citation(s) in RCA: 276] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Y S Babu
- BioCryst Pharmaceuticals, Inc., 2190 Parkway Lake Drive, Birmingham, Alabama 35244, USA.
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Lew W, Wu H, Chen X, Graves BJ, Escarpe PA, MacArthur HL, Mendel DB, Kim CU. Carbocyclic influenza neuraminidase inhibitors possessing a C3-cyclic amine side chain: synthesis and inhibitory activity. Bioorg Med Chem Lett 2000; 10:1257-60. [PMID: 10866394 DOI: 10.1016/s0960-894x(00)00214-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
As part of our continuing work in the area of influenza neuraminidase inhibitors, a series of C3-aza inhibitors possessing a cyclic amine side chain was synthesized and evaluated for influenza neuraminidase inhibitory activity. Analogues possessing a six-, seven- and eight-membered ring, 4c-e, respectively, at the C3 position exhibited excellent influenza B neuraminidase inhibition.
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Affiliation(s)
- W Lew
- Gilead Sciences Inc., Foster City, CA 94404, USA.
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Noyola DE, Clark B, O'Donnell FT, Atmar RL, Greer J, Demmler GJ. Comparison of a new neuraminidase detection assay with an enzyme immunoassay, immunofluorescence, and culture for rapid detection of influenza A and B viruses in nasal wash specimens. J Clin Microbiol 2000; 38:1161-5. [PMID: 10699013 PMCID: PMC86363 DOI: 10.1128/jcm.38.3.1161-1165.2000] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The performance of a new, rapid, easy-to-perform assay based on neuraminidase enzyme activity for detection of influenza virus types A and B was compared to detection by culture, indirect immunofluorescence, and enzyme immunoassay in 479 nasal wash specimens from children with respiratory infections. Compared to isolation of influenza virus by culture, the neuraminidase assay had a sensitivity of 70.1%, specificity of 92.4%, positive predictive value of 76.3%, and negative predictive value of 89.9%. There was a higher sensitivity for the detection of influenza A virus (76.4%) than for influenza B virus (40.9%). Indirect immunofluorescence showed a sensitivity of 59.8% and specificity of 97% compared to culture isolation for detection of influenza A and B viruses. Enzyme immunoassay showed a sensitivity of 89.7% and specificity of 98.1% for the detection of influenza A alone. The quality of the nasal wash specimen had a significant effect on the detection of influenza virus by all of the assays. A strong response of the neuraminidase assay was more likely to represent a culture-confirmed influenza infection. This new rapid neuraminidase assay was useful for the detection of influenza A and B viruses in nasal wash specimens.
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Affiliation(s)
- D E Noyola
- Departments of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.
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Abstract
A prototype version of a new diagnostic assay for influenza A and B (Zstat Flutrade mark) based on detection of viral neuraminidase was evaluated and compared to culture in 196 clinical samples. Children with respiratory illnesses were prospectively evaluated at a pediatrician's office and at a large children's hospital using the neuraminidase assay and viral culture performed on respiratory secretions. Influenza virus was isolated from 51 samples and 83 were positive by the neuraminidase assay. When compared to culture the sensitivity of the assay was 96%, specificity was 77%, positive predictive value was 59%, and negative predictive value was 98%. Testing in the laboratory of pure cultures of bacteria and non-influenza viruses frequently found in the respiratory tract showed 0% cross-reactivity with the neuraminidase assay and 100% specificity for influenza virus in vitro. This new assay provided useful information for the preliminary diagnosis of influenza A and B infections and appears to be suitable for both point-of-care use in the physician's office and rapid diagnosis in a virology laboratory. The high sensitivity makes it particularly useful as a screening test for exclusion of influenza A and B infections. To confirm the diagnosis and exclude a false-positive result, as well as to determine the influenza virus type, a viral culture may be considered.
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Affiliation(s)
- D E Noyola
- Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, 6621 Fannin, MC 3-2371, Houston, TX 77030, USA
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Abstract
With the clinical development of anti-viral agents, monitoring for the continued susceptibility of wild-type strains has become important in disease management. Various methods have been used to monitor viral susceptibility; the advantages and disadvantages of which depend on the virus, the target and the scale of the research being undertaken. The plaque-reduction assay is valuable for measuring susceptibility of most viruses but is not ideal for large-scale monitoring. Yield-reduction, measuring specific virus antigens, and dye-uptake assays, measuring virus cytopathic effects, are more suitable for high-throughput requirements, but the IC(50) value (the concentration that inhibits 50% of virus) varies with the viral inoculum. Surveillance of influenza susceptibility to rimantadine/amantadine in the clinic has predominantly used EIA-based assays, since plaquing of influenza clinical isolates is variable. With development of the influenza NA inhibitors it became apparent that current cell-based assays were unsuitable for monitoring susceptibility to this new class of drugs. Variability may result from virus spread directly from cell to cell in culture by-passing the NA function. Furthermore, mutations selected in the HA, while not apparently contributing to phenotypic resistance in vivo, may result in cell-culture based resistance, and may mask NA resistance in cell culture by modifying receptor-binding specificity. One important distinction between NA inhibitors and other antiviral enzyme inhibitors is that both target enzyme and inhibitor work extracellularly. NA assays are therefore most representative of the in vivo situation for monitoring susceptibility, supported by HA sequencing. As the clinical use of NA inhibitors escalates, a major change will be required in approaches used to monitor susceptibility of influenza isolates in virology laboratories world-wide.
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Affiliation(s)
- M Tisdale
- Clinical Virology and Surrogates Unit, Glaxo Wellcome Research & Development, Gunnels Wood Road, Stevenage SG1 2NY, UK
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Mitamura K, Yamazaki M, Kimura K, Sugaya N, Nirasawa M, Takahashi K, Shimizu H, Hirai Y, Watanabe S, Imai M. [Evaluation of the rapid detection test for influenza A and B viruses using neuraminidase activity]. Kansenshogaku Zasshi 2000; 74:12-6. [PMID: 10695289 DOI: 10.11150/kansenshogakuzasshi1970.74.12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The ZstatFlu test (ZymeTx, USA) is a rapid detection kit for influenza A and B viruses. This test is based upon the reaction between viral neuraminidase from influenza viruses and a chromogenic substrate. The clinical performance of the ZstatFlu test was determined by comparison with viral isolation in cell culture. A total of 176 respiratory specimens from 172 pediatric patients with influenza like illnesses during the 1998/99 season were tested. Influenza viruses were recovered from 97 specimens (type A: 6, type B: 91) in cell culture. ZstatFlu demonstrated 67.4% sensitivity (29/43) and 62.7% specificity (37/59) for throat swabs. Of the 22 ZstatFlu-positive, culture-negative throat swabs tested by RT-PCR, 18 were positive by RT-PCR. ZstatFlu showed 48.1% sensitivity (26/54) and 90.0% specificity (18/20) for nasopharyngeal aspirates. Of the two ZstatFlu-positive, culture-negative nasopharyngeal aspirates tested by HI titer of paired sera, one showed a 4-fold increase of HI titer. Nasopharyngeal aspirates therefore showed lower sensitivity than throat swabs at this test, different from EIA test kits such as Directigen FluA or FLU OIA. Overall, only 5 specimens were false positive by the ZstatFlu test. Therefore, this test demonstrated high specificity and positive predictive value. In conclusion, the ZstatFlu test is useful for the rapid detection of influenza A and B viruses to identify patients who need antiviral treatment.
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Affiliation(s)
- K Mitamura
- Department of Pediatrics, Nippon Kokan Hospital
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Abstract
Influenza A and B viruses do not form reassortants with each other, presumably due to selection at either the RNA or protein level. Although differences in the promoter sequences of type A and B viruses have been studied, selection at the protein level has not been addressed. In this paper we describe experiments to determine whether differences in structure and/or function of the neuraminidase (NA) protein preclude formation of A/B NA reassortants. Influenza type A (N9) NA or B/Lee/40 NA expressed from plasmids can support multicycle growth of a NA-deficient type A virus (NWS-Mvi), indicating that their function in tissue culture is similar. To determine whether the type A or B NA supplied in trans can be incorporated into the virion of NWS-Mvi, the virus grown in NA-expressing cells was purified by sucrose gradient centrifugation. In each case there was a peak of NA activity coincident with the virus peak, indicating that some NA protein is packaged into the virion. The experiments suggest that, in spite of large sequence differences, the functions of the head, stalk, signal-anchor, and cytoplasmic domains of type A and B NAs are similar in tissue culture. Thus, lack of formation of A/B NA reassortant viruses is not due to restriction at the protein level.
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Affiliation(s)
- A A Ghate
- Department of Biochemistry, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, 73190, USA
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