Figure. A) Representative result from conventional PCR that used H274r primer for oseltamivir-sensitive and Y274r primer for oseltamivir-resistant detection in samples isolated from human plasma (P), tiger (T), and Vietnamese patient (V). Plasmids containing N1 fragments obtained from PCR-based mutagenesis for wild-type H274 (Wt) and mutant Y274 (Mt) were used as positive controls in each reaction. (N, no template control; M, 100-bp molecular marker.) B) Semiquantitative data on the ability of the assay to detect subpopulations of the resistant variants. The 2 control plasmids were mixed at wild-type:variant ratios of 108:102 (lanes 1 and 8), 107:103 (lanes 2 and 9), 106:104 (lanes 3 and 10), 105:105 (lanes 4 and 11), 104:106 (lanes 5 and 12), 103:107 (lanes 6 and 13), and 102:108 (lanes 7 and 14).