Fig. 1.

Phylogenetic tree showing partial S1 gene relationships between Korean IBV isolates and reference strains. ClustalW alignment method for S1 nucleotide positions 1–1611 corresponding to those of strain Massachusetts (GenBank accession number X04722). The unrooted phylogenetic trees were generated by the distance-based neighbor-joining method and the Kimura-2 parameter model using MEGA 3.1. Reliability of the trees was assessed by bootstrap analysis in 1000 replications. Bootstrap values >90% are displayed above the branch nodes. Viruses isolated in the present study are in bold, and the K2parent (K2/01) is underlined.