Available online 22 December 2012
In Press, Accepted Manuscript — Note to users
Neuraminidase Inhibitor Susceptibility Testing of Influenza Type B Viruses in China during 2010 and 2011 Identifies Viruses with Reduced Susceptibility to Oseltamivir and Zanamivir
Dayan Wanga, 1,
Katrina Sleemanb, 1,
Weijuan Huanga, 1,
Ha T. Nguyenb, c,
Marnie Levineb, c,
Alexander I. Klimovb,
Larisa V. Gubarevab,
Yuelong Shua, Corresponding author contact information, E-mail the corresponding author
a Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing, China
b Virus Surveillance and Diagnosis Branch, Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
c Battelle, Atlanta, Georgia, USA
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.
► We report the drug resistance in country with low or non-existing NAI use. ► Influenza B Viruses with reduced susceptibility to NAIs were identified. ► I222T and D197N mutation in NA gene was identified in China for the first time.