TABLE 3.

Characterization of extreme and mild outliers among A(H1N1) viruses from three previous seasonsa

SeasonStrainMean IC50 ± SDc (nM)Outlier(s)/drug(s)dNA mutation(s)eAccession no.
OseltamivirZanamivir
2005-2006A/Zhejiang/Xiangshan522/2006b131.85 ± 31.552.56 ± 0.01E/OH274YEU879082
2006-2007A/Georgia/20/2006b383.01 ± 143.69f2.55 ± 1.02E/OH274YEU516197i
2006-2007A/Massachusetts/5/2007b258.48 ± 41.56g1.71 ± 0.28E/OH274YEU516028
2006-2007A/Texas/31/2007b285.56 ± 18.051.14 ± 0.33E/OH274YEU516027
2006-2007A/Minnesota/23/2007b225.61 ± 13.850.99 ± 0.05E/OH274YEU516141
2006-2007A/Gansu/Chenguan/1129/2007b126.89 ± 1.960.49 ± 0.25E/OH274YEU879064
2005-2006A/Guangdongluohu/1232/20068.76 ± 4.682.33 ± 1.47M/OD79G, S247GEU879081
2006-2007A/Hubei/Jiangan/1251/20066.75 ± 5.2413.50 ± 12.24M/Z, M/OH126NEU879078
2006-2007A/Thailand/708/20064.51 ± 1.362.76 ± 0.01hM/ONoneEU879083
2005-2006A/Zhejiang/Xiaocheng/1345/20064.21 ± 0.680.54 ± 0.12M/OS247GEU879079
2005-2006A/Thailand/674/20061.95 ± 0.697.12 ± 3.64M/ZG248REU879080
  • a Includes viruses collected from 1 October 2004 to 30 September 2007.

  • b Resistant virus.

  • c Mean IC50 ± SD values were calculated from data collected from at least three independent experiments.

  • d E, extreme; M, mild; O, oseltamivir (IC50s > 2.89 nM); Z, zanamivir (IC50s > 3.89 nM).

  • e Boldface type indicates a mutation in the NA active site.

  • f A 638-fold increase in the IC50 for oseltamivir compared to that of the matching virus A/Georgia/17/2006 (accession no. EU100630).

  • g A 1,616-fold increase in IC50 for oseltamivir compared to that of the matching virus A/Massachusetts/6/2006 (accession no. EU100634).

  • h IC50s were below the cutoff after retesting.

  • i Additional sequences for this virus are those of accession no. EU516198 and EU516199.