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TWiV 396: Influenza viruses with Peter Palese

3 July 2016 by Vincent Racaniello

TWiVVincent speaks with Peter Palese about his illustrious career in virology, from early work on neuraminidases to universal influenza virus vaccines, on episode #396 of the science show This Week in Virology.

You can find TWiV #396 at microbe.tv/twiv, or listen below.

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Filed Under: This Week in Virology Tagged With: aerosol transmission, ferret, Flu, gain of function, H5N1, influenza, influenza virus, neuraminidase, relenza, swine flu, tamiflu, universal vaccine, vaccine, viral, virology, virus, viruses

The neuraminidase of influenza virus

5 November 2013 by Vincent Racaniello

influenza virusThe influenza virus particle is made up of the viral RNA genome wrapped in a lipid membrane (illustrated). The membrane, or envelope, contains three different kinds of viral proteins. The hemagglutinin molecule (HA, blue) attaches to cell receptors and initiates the process of virus entry into cells. I have written about the HA and its function during infection (article one and two) but not about the neuraminidase (NA, red) or M2 (purple) proteins. Let’s first tackle NA.

An important function of the NA protein is to remove sialic acid from glycoproteins. Sialic acid is present on many cell surface proteins as well as on the viral glycoproteins; it is the cell receptor to which influenza virus attaches via the HA protein. The sialic acids on the HA and NA are removed as the proteins move to the cell surface through the secretory pathway. Newly released virus particles can still potentially aggregate by binding of an HA to sialic acid present on the cell surface. Years ago Peter Palese showed that influenza virus forms aggregates at the cell surface when the viral neuraminidase is inactivated. The NA is therefore an enzyme that is essential for release of progeny virus particles from the surface of an infected cell.

The NA protein also functions during entry of virus into the respiratory tract. The epithelial cells of the respiratory tract are bathed in mucus, a complex protective coating that contains many sialic acid-containing glycoproteins. When influenza virions enter the respiratory tract, they are trapped in mucus where they bind sialic acids. This interaction would prevent the viruses from binding to a susceptible cell were it not for the action of the NA protein which cleaves sialic acids from glycoproteins. When the virus particle encounters a cell, it binds the sialic acid-containing receptor and is rapidly taken into the cell before the NA protein can cleave the carbohydrate from the cell surface.

The essential nature of the NA for virus production has been exploited to develop new drugs designed to inhibit viral release. Both Tamiflu (Oseltamivir) and Relenza (Zanamivir) are structural mimics of sialic acid that bind tightly in the active site of the NA enzyme. When bound to drug, the NA cannot remove sialic acids from the cell surface, and consequently newly synthesized virus remains immobilized. The result is an inhibition of virus infection because virions cannot spread from one cell to another.

This article is part of Influenza 101, a series of posts about influenza virus biology and pathogenesis.

Filed Under: Basic virology, Information Tagged With: glycoprotein, influenza, neuraminidase, relenza, sialic acid, spread, tamiflu, viral, virology, virus

TWiV 223: EEEV and the serpent

10 March 2013 by Vincent Racaniello

On episode #223 of the science show This Week in Virology, Vincent, Alan, and Kathy discuss new influenza virus NA inhibitors, detection of EEEV antibody and RNA in snakes, and replication of the coronavirus EMC in human airway epithelial cells.

You can find TWiV #223 at www.microbe.tv/twiv.

Filed Under: This Week in Virology Tagged With: alphavirus, coronavirus EMC, eastern equine encephalitis virus, EEEV, human airway epithelial cells, influenza, neuraminidase, relenza, snakes, tamiflu, togavirus, viral, virology, virus, zoonotic

Frederick Hayden on influenza antivirals

31 January 2011 by Vincent Racaniello

Frederick Hayden, Professor of Medicine and Pathology, University of Virginia School of Medicine, U.K., has focused on the use of antiviral agents to prevent and treat respiratory viral infections. His interests range from the use of in vitro assays to study viral susceptibility and antiviral mechanisms of action, to clinical trials utilizing experimentally induced and naturally occurring infections. Work from his laboratory includes the demonstration that intranasal administration of interferons can prevent transmission of rhinovirus colds, studies of transmission of drug-resistant influenza A viruses in families, and the antiviral activity and clinical use of influenza neuraminidase inhibitors. His laboratory currently focuses on the application of nucleic acid hybridization to study rhinovirus pathogenesis, elucidating the phenotypic and genotypic basis of antiviral drug resistance in rhinovirus and influenza viruses, and clinical testing candidate antiviral agents for influenza and rhinovirus infections.

I discussed the use of antiviral drugs to treat influenza with Dr. Hayden during ICAAC Boston 2010, as part of TWiV 99. View the video below, or at YouTube.

Filed Under: Information Tagged With: antivirals, frederick hayden, icaac, influenza, neuraminidase, relenza, tamiflu, viral, virology, virus

TWiV 99: ICAAC Boston 2010

19 September 2010 by Vincent Racaniello

Host: Vincent Racaniello

Vincent tours the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in Boston, speaking with exhibitors and visitors, including Professors Derek Smith, Michael Schmidt, Frederick Hayden, and Myra McClure.

Many thanks to Chris Condayan and Ray Ortega of the American Society for Microbiology for recording and editing this episode.

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Click the arrow above to play, or right-click to download TWiV #99 (45 MB .mp3, 62 minutes)

Subscribe to TWiV (free) in iTunes , at the Zune Marketplace, by the RSS feed, or by email, or listen on your mobile device with Stitcher Radio.

Links for this episode:

  • 50th ICAAC
  • ICAAC daily press conference videos (including Prof. Myra McClure)
  • Antigenic cartography
  • Antimicrobial properties of copper
  • Video of this episode – download .mp4 (1.99 GB) or .wmv (935 MB) or view below

Send your virology questions and comments (email or mp3 file) to twiv@microbe.tv or leave voicemail at Skype: twivpodcast. You can also post articles that you would like us to discuss at microbeworld.org and tag them with twiv.

Filed Under: This Week in Virology Tagged With: antigenic cartography, antigenic drift, antiviral, bacteria, CFS, chronic fatigue syndrome, conference, copper, icaac, influenza, pandemic, podcast, racaniello, relenza, swine flu, tamiflu, TWiV, viral, virology, virus, xmrv

Virology lecture #21: Antivirals

7 May 2010 by Vincent Racaniello

Download: .wmv (349 MB) | .mp4 (90 MB)

Visit the virology W3310 home page for a complete list of course resources.

Filed Under: Basic virology, Information Tagged With: acyclovir, antiviral drug, HIV, influenza, lecture, relenza, tamiflu, viral, virology, virus, w3310

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by Vincent Racaniello

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