Live-cell fluorescence imaging of cells transfected with NAI-resistant NA genes.

<p>Zanamivir-resistant mutation (Q136K) or oseltamivir-resistant mutation (H275Y) were introduced in NA gene of zanamivir and oseltamivir-sensitive virus A/USSR/92/1977 (H1N1). The NA genes were transfected to COS7 cells. After 24 hr, the NA-expressed cells were incubated with 100 nM zanamivir or oseltamivir in an SFM at 37°C for 5 min. Then, BTP3-Neu5Ac (20 μM for final concentration) was added to cell culture medium at 37°C for 5 min. Fluorescent images of the cells were observed under UV irradiation by using a fluorescence microscope. A scale bar indicates 200 μm.