Table 3.
Pairwise comparison of nucleotides and amino acids of the S1 gene of Chinese IBV TA03 with 4/91 pathogenic and attenuated strains.
| Strains | 87 (29) | 179 (60) | 283 (95) | 319 (107) | 825 (275) | 1491 (497) | 1522 (508) | 1574 (525) | 1589 (530) |
|---|---|---|---|---|---|---|---|---|---|
| 4/91 attenuated | C (Y) | T (V) | G (A) | T (F) | T (T) | C (N) | A (I) | A (Q) | C (P) |
| 4/91 pathogenic | C (Y) | T (V) | T (S) | T (F) | T (T) | C (N) | G (V) | A (Q) | T (L) |
| TA03 | T (Y) | C (A) | T (S) | C (L) | C (T) | T (N) | G (V) | G (R) | T (L) |
We compared nucleotides and deduced amino acids (in parentheses) from the ATG encoding the translational start to the cleavage recognition site. No deletions or insertions were found in the S1 genes of the three IBV strains. Of the nine mutations, three (283, 1522 and 1589) were the same as the 4/91 pathogenic strain and the other six were different from both the 4/91 pathogenic and the attenuated strains. Three (87, 825 and 1491) of the mutations were synonymous and did not result in amino acid substitutions. GenBank accession numbers: 4/91 pathogenic strain, AF093794 and 4/91 attenuated strain, AF093793. Y, tyrosine; V, valine; A, alanine; S, serine; T, threonine; F, phenylalanine; L, leucine; N, asparagine; I, isoleucine; Q, glutamine; R, arginine; P, proline.