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Fluorescence-based Neuraminidase Inhibition Assay to Assess the Susceptibility of Influenza Viruses to The Neuraminidase Inhibitor Class of Antivirals
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Published on: April 15, 2017

Amantadine resistance in clinical influenza A (H3N2) and (H1N1) virus isolates

R M Pemberton, R Jennings, C W Potter

    The Journal of Antimicrobial Chemotherapy
    |October 1, 1986
    PubMed

    Insights

    Influenza A virus isolates show varying susceptibility to amantadine antiviral medication. More recent influenza A strains exhibit a higher incidence of amantadine resistance, impacting treatment options.

    Area of Science:

    • Virology
    • Antimicrobial Resistance

    Background:

    • Influenza A viruses are a significant cause of seasonal epidemics and occasional pandemics.
    • Amantadine is an antiviral drug historically used for influenza A treatment and prophylaxis.
    • Emergence of antiviral resistance can limit the effectiveness of influenza therapies.

    Purpose of the Study:

    • To assess the susceptibility of contemporary influenza A virus isolates to amantadine.
    • To investigate the genetic basis and phenotypic characteristics of amantadine resistance in influenza A viruses.

    Main Methods:

    • Susceptibility testing of 39 influenza A (H1N1 and H3N2) isolates using allantois-on-shell (AOS) cultures.
    • Titration of isolates in the presence of varying amantadine concentrations (2.5 mg/l and 25 mg/l).
    • Derivation and characterization of cloned viruses from resistant isolates via limiting dilution passage.

    Main Results:

    • A spectrum of amantadine susceptibility was observed among the influenza A isolates.
    • One isolate demonstrated complete resistance at 25 mg/l amantadine.
    • Cloned viruses derived from resistant isolates displayed heterogeneous amantadine resistance phenotypes.
    • A trend towards increased amantadine resistance in more recent influenza A virus isolates was noted.

    Conclusions:

    • Contemporary influenza A virus isolates exhibit varying levels of amantadine resistance.
    • The study identified heterogeneity in amantadine resistance phenotypes within virus clones.
    • Increasing amantadine resistance in recent influenza A strains may necessitate alternative antiviral strategies.

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