Phylogenetic analysis of Babesia species in China based on Cytochrome b (COB) gene

In this study, a mitochondrial marker consisting of an approximately 550-bp region of the Cytochrome b genes (COB) was amplified by polymerase chain reaction (PCR) and sequenced from individual Babesia species. Sequence variation between Babesia species from China was 1.6-30.8%. The constructed phylogenetic tree based on the three unlinked gene sequences (partial COB gene, 18S rDNA and ITS) that evolve at different rates by the method of Neighbor-joining revealed the phylogenetic relationship of Babesia species in China compared with other published corresponding sequences from Babesia species. These data indicate that the 18S rDNA more reliably distinguish the deeper branches among some Babesia species than the partial COB gene and ITS, however, the partial COB gene sequence is better for recognizing close lineages among some Babesia species than the 18S rDNA and ITS sequences. So the combined phylogenetic analysis based on the multiple unlinked loci with different evolving rates can facilitate to establish the more reliable phylogenetic relationship of the Babesia genus. The data could be applicable for the survey of parasite dynamics, epidemiological studies as well as prevention and control of the disease.