Table 2. Coupled residue pairs in full-length NS3.
| Residue i | Residue j | df | χ2 | P value |
|---|---|---|---|---|
| I18 | K371 | 3 | 37.763 | 0.0000 |
| I18 | Y618 | 5 | 30.335 | 0.0000 |
| I18 | V630 | 3 | 84.483 | 0.0000 |
| S42 | Y56 | 3 | 22.379 | 0.0001 |
| V51 | I170 | 3 | 19.836 | 0.0002 |
| S122 | H246 | 7 | 24.962 | 0.0008 |
| I170 | A263 | 5 | 23.998 | 0.0002 |
| I170 | V630 | 3 | 19.406 | 0.0002 |
| S299 | Y418 | 3 | 96.082 | 0.0000 |
| I303 | D555 | 3 | 53.138 | 0.0000 |
| K371 | V630 | 3 | 99.246 | 0.0000 |
| Y418 | Y618 | 5 | 21.235 | 0.0007 |
| T510 | Y618 | 5 | 31.807 | 0.0000 |
| T510 | T621 | 3 | 61.427 | 0.0000 |
Pairs of positions (i,j) in full-length NS3 of genotype 1b with correlated mutations found to be statistically significant. Results for any two positions i,j are considered significant if P < 0.05 unless: (1) any of the Nn,Ex is less than one, or (2) if more than 20% of the Nn,EX are less than five. If P ≤ 0.001 the results are considered significant even if condition (2) is not met. NEx is the expected number of sequences that contain amino acid X at position i and amino acid Y at position j. A difference between the observed number of sequences that contain amino acid X at position i and amino acid Y at position j, NObs, and NEx may indicate residue coupling. Statistical significance for that is estimated using the χ2 goodness-of-fit test. The significance of the χ2 values depends on the number of degrees of freedom (df).