Figure 2.

Phylogenetic analysis of the nucleotide sequences of the representative strains of infectious bursal disease virus (IBDV) in China. (a) Nine genogroups based on the hypervariable region (HVR) of VP2 gene in segment A. (b) Five genogroups based on the B-marker of the VP1 gene in segment B. The trees are generated by the maximum-likelihood method using MEGA7 software and are visualized using iTOL. The trees are drawn to scale with branch lengths measured in the number of substitutions per site. Only branches supported by a bootstrap value above 60% are displayed. A total of 86 representative strains isolated in China and 29 (VP2) or 13 (VP1) reference strains are involved in this analysis. All Chinese strains are highlighted with a solid circle (●), of which 13 stains with segment-reassortant characteristics are marked with a solid triangle (▲).