Table 3. Results of the evolutionary analysis of the neuraminidase (NA) gene of the N1pdm, N1av, N2dk, and N2hu95 lineages.
The best-fitting substitution model M1a and M2a indicates neutral/negative selection and positive selection, respectively. The global ω ratio indicates average dN/dS ratio of the sequences. The positions in which positive selection occurred are given, and the positions are numbered from the first methionine. The TempEst correlation coefficient indicates how well the sequences are accumulating nucleotide changes proportionally to elapsed time. The substitution rate was calculated based on the length of the NA gene (1413nts) and represents the number of substitutions for the entire gene per year.
| N1pdm | N1av | N2dk | N2hu95 | |
|---|---|---|---|---|
| Probability of M1a/M2a (%) | 90/10 | 73/27 | 88/12 | 88/12 |
| Global ω ratio | 0.24 | 0.15 | 0.17 | 0.18 |
| Positions with positive Hu-Lection | - | - | - | - |
| TempEst correlation coefficient | 0.88 | 0.68 | 0.75 | 0.62 |
| Substitution rate (per site per year) | 3.9 × 10−3 | 5.9 × 10−3 | 4.4 × 10−3 | N.A |