TABLE 4.

Characterization of extreme and mild outliers among A(H3N2) viruses from three previous seasons

SeasonStrainMean IC50 ± SD (nM)bOutlier(s)/drug(s)cNA mutation(s)dAccession no.
OseltamivirZanamivir
2006-2007A/Texas/12/2007a9.18 ± 0.78e0.96 ± 0.46E/OE119VEU516111
2006-2007A/Montana/8/20073.50 ± 0.06191.94 ± 11.83fM/O, E/ZD151V/DEU516195
2004-2005A/Argentina/135/20051.52 ± 0.2862.49 ± 32.89M/O, E/ZD151VEU879077
2006-2007A/Canada/270/20071.18 ± 0.3947.60 ± 19.58E/ZD151A/DEU879074
2004-2005A/Oman/6943/20050.74 ± 0.2833.79 ± 2.39E/ZD151AEU879069
2006-2007A/Canada/83/20060.90 ± 0.4115.12 ± 5.76M/ZV165I, H274NEU879070
2006-2007A/Canada/309/20071.64 ± 0.5114.31 ± 4.78M/O, M/ZG248R, K249EEU879076
2004-2005A/Singapore/8/20051.15 ± 0.0813.98 ± 1.37M/ZD151NEU879072
2006-2007A/Canada/281/20071.39 ± 0.3612.80 ± 4.24M/ZD151N, K249EEU879067
2004-2005A/Hong Kong/4653/20051.00 ± 0.1812.28 ± 1.19M/ZD151N, S315G, L338SEU879075
2004-2005A/Singapore/2/20051.07 ± 0.2110.76 ± 5.56M/ZA27S, D151N/D, K249E, V313AEU879068
2006-2007A/Canada/267/20071.40 ± 0.1810.66 ± 3.31M/ZD251GEU879065
2005-2006A/Santiago/9491/20062.78 ± 2.779.54 ± 2.08M/O, M/ZD151NEU879071
2006-2007A/Canada/9/20060.46 ± 0.268.92 ± 2.99gM/ZD151G/DEU879066
2006-2007A/Canada/1210/20060.61 ± 0.348.02 ± 2.88gM/ZD151G/DEU879073
  • a Resistant virus.

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

  • c E, extreme; M, mild; O, oseltamivir (IC50 values >1.50 nM); Z, zanamivir (IC50 values >9.20 nM).

  • d Boldface type indicates a mutation at the NA active site.

  • e A 57-fold increase in IC50 to oseltamivir compared to that of the matching virus A/Washington/1/2007 (accession no. EU100650).

  • f A 164-fold increase in IC50 to zanamivir compared to that of the matching virus A/Brazil/80/2007 (accession no. EU879087).

  • g IC50s were below the cutoff after retesting.