Figure 2. Detection of Q136K substitution in NA by sequencing in primary samples and virus isolates. Arrows indicate the first peak of the codon encoding amino acid position 136. Comparison of the sequence chromatogram showed a mixed population of bases in both original clinical samples and virus isolates, with a dominant peak for 136K (AAG) mutants, compared with wild-type 136Q (CAG) viruses. NA, neuraminidase.