title: Generation and Characterization of Recombinant Influenza A(H1N1) Viruses Resistant to Neuraminidase Inhibitors.
abstract: OBJECTIVE
  To examine the effect of neuraminidase (NA) mutations on the NA inhibitor (NAI) resistance phenotype, the recombinant influenza A/Chungbuk/4448/2008(H1N1) virus isolated in South Korea during the 2008-2009 season was generated by reverse genetics.
  
  
  METHODS
  Site-directed mutagenesis was introduced on the NA gene of A/Chungbuk/4448/2008(H1N1) virus, and a total of 23 single, double, and triple mutants were generated. Resistance phenotype of these recombinant viruses was determined by NA-inhibition (NAI) assays based on a fluorometric method using two NAIs (oseltamivir and zanamivir).
  
  
  RESULTS
  NA-inhibition assays showed that all the single and double mutants containing the Y275 except the single Y275-E119V mutant conferred important levels of resistance to oseltamivir, whereas all the single, double, and triple mutants containing the E119V mutation were associated with the resistance to zanamivir.
  
  
  CONCLUSIONS
  Considering the effect of mutations in NA gene on the resistance to NAIs, it is important to monitor the possible emergence and dissemination of multidrug-resistant variants in the human population due to amino acid changes at NA gene as well as to develop novel NAIs.
authors: Division of Arboviruses, Korea National Institute of Health, Osong, Korea.
authors: Wooyoung
authors: W
authors: Choi
authors: Division of Influenza Virus, Korea National Institute of Health, Osong, Korea.
authors: Jin-Young
authors: JY
authors: Shin
authors: SK Chemicals, Seongnam, Korea.
authors: Hwan-Eui
authors: HE
authors: Jeong
authors: Division of Influenza Virus, Korea National Institute of Health, Osong, Korea.
authors: Mi-Jin
authors: MJ
authors: Jeong
authors: Division of Influenza Virus, Korea National Institute of Health, Osong, Korea.
authors: Su-Jin
authors: SJ
authors: Kim
authors: Division of Influenza Virus, Korea National Institute of Health, Osong, Korea.
authors: Joo-Yeon
authors: JY
authors: Lee
authors: Division of Influenza Virus, Korea National Institute of Health, Osong, Korea.
authors: Chun
authors: C
authors: Kang
keywords: influenza virus; neuraminidase inhibitors; recombinant drug-resistant virus; reverse genetics