#Cholesterol #binding to the transmembrane region of a group 2 HA of #Influenza virus is essential for virus replication affecting both virus assembly and HA’s #fusion activity (J Virol., abstract)

[Source: Journal of Virology, full page: (LINK). Abstract, edited.]

Cholesterol binding to the transmembrane region of a group 2 HA of Influenza virus is essential for virus replication affecting both virus assembly and HA’s fusion activity

Bodan Hu, Chris Tina Höfer, Christoph Thiele, Michael Veit

DOI: 10.1128/JVI.00555-19

 

ABSTRACT

Hemagglutinin (HA) of Influenza virus is incorporated into cholesterol enriched, nanodomains of the plasma membrane. Phylogenetic group 2 HAs contain the conserved cholesterol consensus motif (CCM) YKLW in the transmembrane region. We previously reported that mutations in the CCM retarded intracellular transport of HA and decreased its nanodomain association. Here we analyzed whether cholesterol interacts with the CCM. Incorporation of photocholesterol into HA was significantly reduced if the whole CCM is replaced by alanine, both using immunoprecipitated HA and when HA is embedded in the membrane. Next, we used reverse genetics to investigate the significance of the CCM for virus replication. No virus was rescued if the whole motif is exchanged (YKLW4A); single (LA) or double (YK2A and LW2A) mutated virus showed decreased titers and a comparative fitness disadvantage. In polarized cells transport of HA mutants to the apical membrane was not disturbed. Reduced amounts of HA and cholesterol were incorporated into the viral membrane. Mutant viruses exhibit a decrease in hemolysis, which is only partially corrected if the membrane is replenished with cholesterol. More specifically, viruses have a defect in hemifusion as demonstrated by fluorescence dequenching. Cells expressing HA-YKLW4A fuse with erythrocytes, but the number of events are reduced. Even after acidification unfused erythrocytes remain cell-bound, a phenomenon not observed with wildtype HA. We conclude that cholesterol-binding to a group 2 HA is essential for virus replication. It has pleiotropic effects on virus assembly and membrane fusion, mainly on lipid mixing and possibly a preceding step.

 

IMPORTANCE

The glycoprotein hemagglutinin (HA) is a major pathogenicity factor of Influenza viruses. Whereas the structure and function of HA’s ectodomain is known in great detail, similar data for the membrane-anchoring part of the protein are missing. Here we demonstrate that the transmembrane region of a group 2 HA interacts with cholesterol, the major lipid of the plasma membrane and the defining element of the viral budding site nanodomains of the plama membrane. The cholesterol binding motif is essential for virus replication. Its partial removal affects various steps of the viral life cycle, such as assembly of new virus particles and their subsequent cell entry via membrane fusion. A cholesterol-binding pocket in group 2 HAs might be a promising target for a small lipophilic drug that inactivates the virus.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Influenza A; Viral pathogenesis.

——

Advertisements

#Association of #severe #influenza virus infections with CD226 (DNAM-1) #variants (J Infect Dis., abstract)

[Source: Journal of Infectious Diseases, full page: (LINK). Abstract, edited.]

Association of severe influenza virus infections with CD226 (DNAM-1) variants

Monika Redlberger-Fritz, Hannes Vietzen, Elisabeth Puchhammer-Stöckl

The Journal of Infectious Diseases, jiz270, https://doi.org/10.1093/infdis/jiz270

Published: 21 May 2019

 

Abstract

NK-cell response against influenza viruses partly depends on expression of CD112, a ligand for NK-cell receptor CD226 (DNAM-1). We analyzed whether distinct CD226 variants are associated with influenza disease severity. Comparison between 145 patients hospitalized with severe influenza at intensive care units (ICU) with 139 matched influenza-positive outpatients showed that especially presence of the rs763362 G allele (GG, AG) was associated with occurrence of severe influenza infections (p=0.0076). Also a higher frequency of the rs727088 G allele and rs763361 T allele were observed in the ICU group. Thus, CD226 variants may contribute to the severity of influenza virus disease.

severe influenza, CD226, CD226 variants and disease severity, CD226 and influenza

Issue Section: Brief Report

This content is only available as a PDF.

© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Keywords: Influenza A; Genetics.

——

Sequential #Immunization With Live-Attenuated Chimeric #Hemagglutinin-Based Vaccines Confers #Heterosubtypic Immunity Against #Influenza A Viruses in a Preclinical Ferret Model (Front Immunol., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Front Immunol. 2019 Apr 10;10:756. doi: 10.3389/fimmu.2019.00756. eCollection 2019.

Sequential Immunization With Live-Attenuated Chimeric Hemagglutinin-Based Vaccines Confers Heterosubtypic Immunity Against Influenza A Viruses in a Preclinical Ferret Model.

Liu WC1,2, Nachbagauer R1, Stadlbauer D1, Solórzano A1, Berlanda-Scorza F3, García-Sastre A1,2,4, Palese P1,4, Krammer F1, Albrecht RA1,2.

Author information: 1 Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States. 2 Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States. 3 PATH US, Seattle, WA, United States. 4 Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States.

 

Abstract

Due to continuous antigenic drift and occasional antigenic shift, influenza viruses escape from human adaptive immunity resulting in significant morbidity and mortality in humans. Therefore, to avoid the need for annual reformulation and readministration of seasonal influenza virus vaccines, we are developing a novel chimeric hemagglutinin (cHA)-based universal influenza virus vaccine, which is comprised of sequential immunization with antigens containing a conserved stalk domain derived from a circulating pandemic H1N1 strain in combination with “exotic” head domains. Here, we show that this prime-boost sequential immunization strategy redirects antibody responses toward the conserved stalk region. We compared the vaccine efficacy elicited by distinct vaccination approaches in the preclinical ferret model of influenza. All ferrets immunized with cHA-based vaccines developed stalk-specific and broadly cross-reactive antibody responses. Two consecutive vaccinations with live-attenuated influenza viruses (LAIV-LAIV) conferred superior protection against pH1N1 and H6N1 challenge infection. Sequential immunization with LAIV followed by inactivated influenza vaccine (LAIV-IIV regimen) also induced robust antibody responses. Importantly, the LAIV-LAIV immunization regimen also induced HA stalk-specific CD4+IFN-γ+ and CD8+IFN-γ+ effector T cell responses in peripheral blood that were recalled by pH1N1 viral challenge. The findings from this preclinical study suggest that an LAIV-LAIV vaccination regimen would be more efficient in providing broadly protective immunity against influenza virus infection as compared to other approaches tested here.

KEYWORDS: chimeric hemagglutinin; ferret; heterosubtypic protection; live-attenuated influenza vaccine; stalk antibody; universal influenza virus vaccine

PMID: 31105689 PMCID: PMC6499175 DOI: 10.3389/fimmu.2019.00756

Keywords: Influenza A; Vaccines; Animal models.

——

#Baloxavir marboxil, a novel cap-dependent endonuclease inhibitor potently suppresses #influenza virus #replication and represents therapeutic effects in both immunocompetent and immunocompromised mouse models (PLoS One, abstract)

[Source: PLoS One, full page: (LINK). Abstract, edited.]

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Baloxavir marboxil, a novel cap-dependent endonuclease inhibitor potently suppresses influenza virus replication and represents therapeutic effects in both immunocompetent and immunocompromised mouse models

Keita Fukao, Yoshinori Ando, Takeshi Noshi, Mitsutaka Kitano, Takahiro Noda, Makoto Kawai, Ryu Yoshida, Akihiko Sato, Takao Shishido , Akira Naito

Published: May 20, 2019 / DOI: https://doi.org/10.1371/journal.pone.0217307

 

Abstract

Baloxavir marboxil (BXM) is an orally available small molecule inhibitor of cap-dependent endonuclease (CEN), an essential enzyme in the initiation of mRNA synthesis of influenza viruses. In the present study, we evaluated the efficacy of BXM against influenza virus infection in mouse models. Single-day oral administration of BXM completely prevented mortality due to infection with influenza A and B virus in mice. Moreover, 5-day repeated administration of BXM was more effective for reducing mortality and body weight loss in mice infected with influenza A virus than oseltamivir phosphate (OSP), even when the treatment was delayed up to 96 hours post infection (p.i.). Notably, administration of BXM, starting at 72 hours p.i. led to significant decrease in virus titers of >2-log10 reduction compared to the vehicle control within 24 hours after administration. Virus reduction in the lung was significantly greater than that observed with OSP. In addition, profound and sustained reduction of virus titer was observed in the immunocompromised mouse model without emergence of variants possessing treatment-emergent amino acid substitutions in the target protein. In our immunocompetent and immunocompromised mouse models, delayed treatment with BXM resulted in rapid and potent reduction in infectious virus titer and prevention of signs of influenza infection, suggesting that BXM could extend the therapeutic window for patients with influenza virus infection regardless of the host immune status.

___

Citation: Fukao K, Ando Y, Noshi T, Kitano M, Noda T, Kawai M, et al. (2019) Baloxavir marboxil, a novel cap-dependent endonuclease inhibitor potently suppresses influenza virus replication and represents therapeutic effects in both immunocompetent and immunocompromised mouse models. PLoS ONE 14(5): e0217307. https://doi.org/10.1371/journal.pone.0217307

Editor: Stefan Pöhlmann, Deutsches Primatenzentrum GmbH – Leibniz-Institut fur Primatenforschung, GERMANY

Received: February 8, 2019; Accepted: May 8, 2019; Published: May 20, 2019

Copyright: © 2019 Fukao et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: This study was sponsored by Shionogi and Co., Ltd (Osaka, Japan), manufacturer/licensee of baloxavir marboxil. The sponsor provided support in the form of salaries for authors [KF, YA, TN, MK, TN, MK, RY, AS, TS and AN], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: All authors are employees of Shionogi and Co., Ltd or Shionogi TechnoAdvance Research, Co., Ltd, an affiliation of Shionogi. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Keywords: Influenza A; Antivirals; Baloxavir Marboxil; Animal Models.

——

#Effectiveness of the #Neuraminidase #Inhibitors: The Supporting #Evidence Increases (J Infect Dis., summary)

[Source: The Journal of Infectious Diseases, full page: (LINK). Summary, edited.]

Effectiveness of the Neuraminidase Inhibitors: The Supporting Evidence Increases

Arnold S Monto

The Journal of Infectious Diseases, jiz157, https://doi.org/10.1093/infdis/jiz157

Published: 20 May 2019

Issue Section: Editorial Commentary

___

The neuraminidase inhibitors (NAIs) zanamivir and oseltamivir were the first in that class of influenza antivirals to receive approval by the Food and Drug Administration, with both approved at the turn of the last century [1, 2] The regulatory approvals, for both prophylaxis and treatment of uncomplicated influenza, occurred after standard review of studies. The 2 drugs target nearby sites in the enzymatically active pocket of the virus but are very different in their route of administration and pharmacokinetics [1, 2]. Despite these differences, the results of the clinical trials of both were remarkably similar in terms of the characteristics of prophylactic efficacy and of treatment effects. Recruitment of cases to the treatment studies was based on clinical criteria but was limited to the influenza season; these cases were the intent-to-treat population [3–5]. The studies were done before use of polymerase chain reaction analysis had become accepted for influenza diagnosis, so the standard method of detecting the infecting virus was by cell culture.

(…)

___

Notes

Potential conflicts of interest.

A. S. M. reports personal fees from Roche outside the submitted work. The author has submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Keywords: Antivirals; Oseltamivir; Zanamivir; Peramivir; Influenza A; Pandemic Influenza.

——

A Site of #Vulnerability on the #Influenza Virus #Hemagglutinin Head Domain Trimer Interface (Cell, abstract)

[Source: Cell, full page: (LINK). Abstract, edited.]

Cell. 2019 May 16;177(5):1136-1152.e18. doi: 10.1016/j.cell.2019.04.011.

A Site of Vulnerability on the Influenza Virus Hemagglutinin Head Domain Trimer Interface.

Bangaru S1, Lang S2, Schotsaert M3, Vanderven HA4, Zhu X2, Kose N5, Bombardi R5, Finn JA1, Kent SJ4, Gilchuk P5, Gilchuk I5, Turner HL2, García-Sastre A6, Li S7, Ward AB2, Wilson IA8, Crowe JE Jr9.

Author information: 1 Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA. 2 Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. 3 Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. 4 Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia. 5 The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA. 6 Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. 7 Department of Medicine and Biomedical Sciences, School of Medicine, University of California, San Diego, CA 92093, USA. 8 Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. Electronic address: wilson@scripps.edu. 9 Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA. Electronic address: james.crowe@vanderbilt.edu.

 

Abstract

Here, we describe the discovery of a naturally occurring human antibody (Ab), FluA-20, that recognizes a new site of vulnerability on the hemagglutinin (HA) head domain and reacts with most influenza A viruses. Structural characterization of FluA-20 with H1 and H3 head domains revealed a novel epitope in the HA trimer interface, suggesting previously unrecognized dynamic features of the trimeric HA protein. The critical HA residues recognized by FluA-20 remain conserved across most subtypes of influenza A viruses, which explains the Ab’s extraordinary breadth. The Ab rapidly disrupted the integrity of HA protein trimers, inhibited cell-to-cell spread of virus in culture, and protected mice against challenge with viruses of H1N1, H3N2, H5N1, or H7N9 subtypes when used as prophylaxis or therapy. The FluA-20 Ab has uncovered an exceedingly conserved protective determinant in the influenza HA head domain trimer interface that is an unexpected new target for anti-influenza therapeutics and vaccines.

Copyright © 2019 Elsevier Inc. All rights reserved.

KEYWORDS: B-lymphocytes; antibodies; antibody-dependent cell cytotoxicity; antigen-antibody reactions; hemagglutinin glycoproteins; influenza A virus; influenza virus; monoclonal; viral

PMID: 31100268 DOI: 10.1016/j.cell.2019.04.011

Keywords: Influenza A; H1N1; H3N2; H5N1; H7N9; Monoclonal antibodies; Animal models.

——-

Protective role for the N-terminal domain of α-dystroglycan in #Influenza A virus #proliferation (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Protective role for the N-terminal domain of α-dystroglycan in Influenza A virus proliferation

Jessica C. de Greef, Bram Slütter, Mary E. Anderson, Rebecca Hamlyn, Raul O’Campo Landa, Ellison J. McNutt, Yuji Hara, Lecia L. Pewe, David Venzke, Kiichiro Matsumura, Fumiaki Saito, John T. Harty, and Kevin P. Campbell

PNAS first published May 16, 2019 / DOI: https://doi.org/10.1073/pnas.1904493116

Contributed by Kevin P. Campbell, April 16, 2019 (sent for review March 20, 2019; reviewed by Andrea Brancaccio and Jamey D. Marth)

 

Significance

Influenza A virus (IAV) is a major cause of respiratory infections. We show that mice lacking the N-terminal domain of α-dystroglycan (α-DGN) exhibit significantly higher viral titers in the lungs after IAV infection. In addition, we show that overexpression of α-DGN in the lungs, both prior and during IAV infection, significantly reduces viral load and that recombinant α-DGN disrupts hemagglutination mediated by the influenza virus. Collectively, we uncover a protective role for α-DGN in IAV proliferation, suggesting it may have antiviral properties and could potentially be used as a treatment for IAV infection. As α-DGN levels are altered in more (inflammatory) disease states, this insight opens new avenues of investigation into the role of α-DGN in inflammation.

 

Abstract

α-Dystroglycan (α-DG) is a highly glycosylated basement membrane receptor that is cleaved by the proprotein convertase furin, which releases its N-terminal domain (α-DGN). Before cleavage, α-DGN interacts with the glycosyltransferase LARGE1 and initiates functional O-glycosylation of the mucin-like domain of α-DG. Notably, α-DGN has been detected in a wide variety of human bodily fluids, but the physiological significance of secreted α-DGN remains unknown. Here, we show that mice lacking α-DGN exhibit significantly higher viral titers in the lungs after Influenza A virus (IAV) infection (strain A/Puerto Rico/8/1934 H1N1), suggesting an inability to control virus load. Consistent with this, overexpression of α-DGN before infection or intranasal treatment with recombinant α-DGN prior and during infection, significantly reduced IAV titers in the lungs of wild-type mice. Hemagglutination inhibition assays using recombinant α-DGN showed in vitro neutralization of IAV. Collectively, our results support a protective role for α-DGN in IAV proliferation.

α-dystroglycan – influenza A virus – inflammation

Keywords: Influenza A; Immunopathology; Viral Pathogenesis.

——