TABLE 3.

Comparison of oseltamivir IC50 values in cell culture assays and in the sialidase enzyme assay for clinical isolates of influenza viruses

Virus typeVirusaIC50 in plaque reduction assayb (nM)IC50 in sialidase enzyme assay (nM)
MDCK cellsST6Gal I- expressing cells
H3N21>1,000100.5
2>1,000100.5
3>1,000100.3
4>1,000100.2
5>1,000100.3
6>1,000101.2
H1N17>1,000106.8
8>1,000108.4
91,00010072.9
10>1,00010012.5
11>1,000105.6
12>1,000108.4
B13>1,0001,000109.3
14>1,0001,000131.3
15>1,0001,000214.9
16>1,0001,00059.6
17>1,0001,00089.5
  • a Viruses were isolated from clinical specimens in MDCK cells. The influenza viruses listed were isolated from patients prior to treatment.

  • b The inhibitory concentration at which the plaque size is reduced by more than 50% compared with the no-drug negative control.