FIG 2.

Yield of NAI-susceptible and -resistant influenza B virus populations following coinfection of NHBE cells. Multicycle growth curves after coinfection of NHBE cells with mixtures of NAI-susceptible and -resistant influenza B viruses grown either without drug pressure, with oseltamivir (1 or 10 μM), or with zanamivir (1 or 10 μM) are shown. NAI-susceptible rg-WT and rg-E119A (A), rg-D198E (B), rg-I222T (C), rg-H274Y (D), rg-N294S (E), and rg-R371K (F) at an MOI of 0.01 PFU/cell were mixed 50:50 and then used to infect NHBE cells at a final MOI of 0.02 PFU/cell. Virus yield in MDCK cells was determined by the TCID₅₀ assay at 33°C and expressed as log₁₀ TCID₅₀/ml. Total virus yield was determined by performing AUC analysis of the viral load at 24, 48, and 72 h p.i. Each data point represents the mean ± SD from two or three independent experiments. The limit of detection was 0.75 log₁₀ TCID₅₀/ml. Abbreviations: OSE, oseltamivir; ZAN, zanamivir.