• Open Access

Neuraminidase inhibitor susceptibility surveillance of influenza viruses circulating worldwide during the 2011 Southern Hemisphere season

Authors

  • Margaret Okomo-Adhiambo,

    1. Virus Surveillance and Diagnosis Branch, Influenza Division, National Center for Immunization and Respiratory Diseases, WHO Collaborating Center for Surveillance, Epidemiology and Control of Influenza, Centers for Disease Control and Prevention, Atlanta, GA, USA
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    • These authors contributed equally to this work.
  • Katrina Sleeman,

    1. Virus Surveillance and Diagnosis Branch, Influenza Division, National Center for Immunization and Respiratory Diseases, WHO Collaborating Center for Surveillance, Epidemiology and Control of Influenza, Centers for Disease Control and Prevention, Atlanta, GA, USA
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    • These authors contributed equally to this work.
  • Colleen Lysén,

    1. Virus Surveillance and Diagnosis Branch, Influenza Division, National Center for Immunization and Respiratory Diseases, WHO Collaborating Center for Surveillance, Epidemiology and Control of Influenza, Centers for Disease Control and Prevention, Atlanta, GA, USA
    2. Battelle Memorial Institute, Atlanta, GA, USA
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  • Ha T. Nguyen,

    1. Virus Surveillance and Diagnosis Branch, Influenza Division, National Center for Immunization and Respiratory Diseases, WHO Collaborating Center for Surveillance, Epidemiology and Control of Influenza, Centers for Disease Control and Prevention, Atlanta, GA, USA
    2. Battelle Memorial Institute, Atlanta, GA, USA
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  • Xiyan Xu,

    1. Virus Surveillance and Diagnosis Branch, Influenza Division, National Center for Immunization and Respiratory Diseases, WHO Collaborating Center for Surveillance, Epidemiology and Control of Influenza, Centers for Disease Control and Prevention, Atlanta, GA, USA
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  • Yan Li,

    1. Influenza and Respiratory Viruses Section, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
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  • Alexander I. Klimov,

    1. Virus Surveillance and Diagnosis Branch, Influenza Division, National Center for Immunization and Respiratory Diseases, WHO Collaborating Center for Surveillance, Epidemiology and Control of Influenza, Centers for Disease Control and Prevention, Atlanta, GA, USA
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  • Larisa V. Gubareva

    Corresponding author
    • Virus Surveillance and Diagnosis Branch, Influenza Division, National Center for Immunization and Respiratory Diseases, WHO Collaborating Center for Surveillance, Epidemiology and Control of Influenza, Centers for Disease Control and Prevention, Atlanta, GA, USA
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Correspondence: Larisa V. Gubareva, Mail Stop G-16, 1600 Clifton Road, Atlanta, GA 30333, USA.

E-mail: lgubareva@cdc.gov

Abstract

Background

Neuraminidase (NA) inhibitors (NAIs) are currently the only antivirals effective against influenza infections due to widespread resistance to M2 inhibitors.

Methods

Influenza A and B viruses (n = 1079) collected worldwide between April 01, 2011, and September 30, 2011, were assessed for susceptibility to FDA-approved NAIs, oseltamivir and zanamivir, and investigational peramivir, using the fluorescent-based NA-Fluor™ Influenza Neuraminidase Assay Kit. A subset of viruses (n = 98) were tested for susceptibility to the investigational NAI, laninamivir.

Results

Influenza A(H1N1)pdm09 viruses (n = 326) were sensitive to all NAIs, except for two (0·6%) with H275Y (N1 numbering; H274Y in N2 numbering) substitution, which exhibited elevated IC50s for oseltamivir and peramivir, and a third with previously unreported N325K substitution, exhibiting reduced susceptibility to oseltamivir. Influenza A(H3N2) viruses (n = 407) were sensitive to all NAIs. Influenza B viruses (n = 346) were sensitive to all NAIs, except two (0·6%) with H273Y (N1 numbering; H274Y in N2 numbering) substitution, exhibiting reduced susceptibility to oseltamivir and peramivir, and one with previously unreported G140R and N144K substitutions, exhibiting reduced susceptibility to oseltamivir, zanamivir, and peramivir. All influenza A and B viruses were sensitive to laninamivir. It is unknown whether substitutions N325K, G140R, and N144K were present in the virus prior to culturing because clinical specimens were unavailable for testing.

Conclusions

This study summarizes NAI susceptibility of influenza viruses circulating worldwide during the 2011 Southern Hemisphere (SH) season, assessed using the NA-Fluor™ Kit. Despite low resistance to NAIs among tested influenza viruses, constant surveillance of influenza virus susceptibility to NAIs should be emphasized.

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