Figure 4.

TSN did not inhibit the hemagglutinin (HA) or neuraminidase (NA) activity of influenza A virus strains A/PR/8/34 and H3N2. (A) Influenza virus A/PR/8/34 (upper two lanes) and H3N2 (lower two lanes) were diluted with PBS to 4 HAU and mixed with serially diluted concentrations (up to 250 µM) of TSN for 1 h at 4°C in duplicate. Chicken RBCs in PBS (0.5% w/v) were added and incubated for 1 h at room temperature. The plates were then photographed. (B) Influenza virus A/PR/8/34 or H3N2 in assay buffer was incubated with serially diluted TSN or the known NA inhibitor zanamivir (0.8 µM) as a positive control for 30 min at 37°C. After 1-h incubation with NA-Fluor substrate at 37°C, NA activity was measured by fluorescence spectrometry. Data are presented as mean ± SD of three replicates for three independent experiments.