TABLE 7.
Comparison of in vitro and in vivo susceptibility data for influenza virus clinical isolates
Virus | NA assay IC50 (ng/ml)a | Plaque assay IC50 (μg/ml) | Ferret nasal-wash virus titers (EDAUC10 mg/kg)b |
---|---|---|---|
2871 D2 (influenza B) | 2.1 ± 0.85 | 5.7 ± 6.63 | 0.82 |
7241 D1 (influenza A/H3N2) | Cc | >100 | 0.02 |
7249 D1 (influenza A/H3N2) | 0.9 ± 0.14 | >100 | 0.1 |
A/Mississippi/1/85 (H3N2) | 1.3 | 0.0047 | 0.32 |
B/Victoria/102/85 | 1.3 | 0.0017 | 0.59 |
Although numbers are small, a rank correlation coefficient of 0.95 (P = 0.0513) was observed on comparison of the NA assay and the in vivo assay.
AUC10, the concentration of zanamivir that inhibits nasal virus titers by 90% (calculated as 10% of the AUC), was determined as a measure of susceptibility to zanamivir. ED, effective dose.
NA activity was too low to assay.