TABLE 2.
Susceptibilities of the avian, swine, and human influenza viruses of the N1 NA subtype to the NA inhibitor oseltamivir
| Species | Susceptibilitya | IC50 range (nM)b | No. of isolates (% of total) | Mean IC50 ± SD (nM) |
|---|---|---|---|---|
| Ducks | High | 0.81-4.91 | 12 (18.5) | 2.97 ± 1.49 |
| Moderate | 5.11-40.57 | 50 (77) | 12.85 ± 8.82 | |
| Reduced | 51.61-102.25 | 4 (6) | 77.43 ± 26.99 | |
| Shorebirds/gulls | High | 0.5-4.6 | 9 (31) | 2.80 ± 1.34 |
| Moderate | 5.59-45.82 | 15 (52) | 13.57 ± 9.62 | |
| Reduced | 52.85-154.43 | 5 (17) | 92.76 ± 36.59 | |
| Swine | High | 0.33-2.56 | 15 (100) | 1.44 ± 0.81 |
| Moderate | NAc | 0 | NA | |
| Reduced | NA | 0 | NA | |
| Humans | Sensitive | 0.89-2.12 | 14 (82) | 1.40 ± 0.36 |
| Resistant | 2,588.92-2,887.63 | 3 (17) | 2,725.1 ± 151.1 |
a
Susceptibilities of influenza viruses to oseltamivir were recorded as high (mean IC50, 0.5 to 5.0 nM), moderate (mean IC50, 5.1 to 50.0 nM), or reduced (mean IC50, 50 to ≥100 nM).
b
The NA inhibition assay was performed with viruses standardized to equivalent NA activity and incubated with NAIs at concentrations of 0.00005 to 100 μM with MUNANA as a substrate. The IC50 was determined by plotting the dose-response curve of inhibition of NA activity as a function of the compound concentration. Values are from at least three independent determinations.
c
NA, not applicable.