Figure 2. Neighbor-joining tree showing relationships between genome segment-2 (Seg-2) from KUW2010/02 with the 25 reference strains of different bluetongue virus (BTV) serotypes. The tree was constructed by using distance matrices, generated by using the p-distance determination algorithm in MEGA 4.1 (500 bootstrap replicates) (12). The 10 evolutionary branching points are indicated by black dots on the tree (along with their bootstrap values), which correlate with the 11 Seg-2 nucleotypes designated A–L. BTV-26 (KUW2010/02),forms a new 12th Seg-2 nucleotype (L). Members of the same Seg-2 nucleotype are characterized by 66.9% identity in their Seg-2 nucleotide sequences; members of different nucleotypes show 61.4% identity in Seg-2 (4). The scale bar indicates the number of substitutions per site. The tree based on the amino acid sequences of viral protein 2 showed very similar topology. GenBank accession numbers of Seg-2 used for comparative analyses: AJ585122–AJ585145, EU839840.