Fig. 1

Neighbor-joining phylogenetic tree based on BLV env gene complete sequences (1548 bp) from China and around the world. Strains identified in our study in China are identified with filled circles (●) for genotype 4 (in red) and open circles (○) for genotype 6 (in green). Genotypes shown on the right are according to Yang et al. [6]. The numbers at the branches show bootstrap support (1000 replicates). The bar at the bottom of the figure denotes distance