Figure 3
(a) Sequence alignment of NA genes from the WT and Tamiflu-resistant viruses to confirm the genotype at position 275, performed using one-step RT-PCR. The red arrow indicates the mutated amino acid in Tamiflu-resistant NA compared with WT NA when histidine (H) at position 275 is replaced by tyrosine (Y). NA inhibition tests of (b) oseltamivir phosphate (TamifluTM) and (c) oseltamivir hexylthiol (OHT) for the WT (black) and Tamiflu-resistant enzymes (red) using a commercial fluorescence-based NA inhibition assay kit. The relative NA activity was calculated from the fluorescence intensity ratio of treated to nontreated virus (0 mM) and the average values were plotted (n = 3).
