Table 5. LRT tests and codons under positive selection for HA1 sequences of egg-adapted human A(H1N1) influenza viruses between 1933-1979.
| LRT (2Δl) (p-values) | Positively selected sites1 | |||
| 1933∼1979 (32 strains) | M2a | M2a-M1a | 17.02 (0.0002) | 77 (95.8%), 225 (98.8%) |
| M8 | M8-M7 | 20.30 (0.0000) | 77 (98.7%), 225 (99.6%), 227 (97.7%) | |
| M8-M8a | 16.74 (0.0000) | |||
| 1947∼1957 (12 strains) | M2a | M2a-M1a | 20.0 (0.0000) | 143 (99.3%), 264 (99.6%) |
| M8 | M8-M7 | 20.30 (0.0000) | 143 (99.6%), 166 (95.1%), 264 (99.7%) | |
| M8-M8a | 19.98 (0.0000) | |||
| 1948∼1979 (17 strains) | M2a | M2a-M1a | 8.58 (0.0137) | 225 (99.1%) |
| M8 | M8-M7 | 8.84 (0.0120) | 225 (99.8%) | |
| M8-M8a | 8.54 (0.0017) | |||
1
Positively selected sites from PAML 4.0 [45] using Bayes Empirical Bayes analysis [72]. Only codons with greater than 95% posterior probabilities to be under positive selection were listed with the corresponding posterior probabilities shown in parentheses. Highlighted in bold were codons that were not associated with egg-adapted substitutions [62], [63], [64].