Phylogenetic analysis based on 28S rRNA of Babesia spp. in ruminants in China.

Molecular phylogenetic analyses are mainly based on the small ribosomal RNA subunit (18S rRNA), internal transcribed spacer regions, and other molecular markers. We compared the phylogenetic relationships of Babesia spp. using large subunit ribosomal RNA, i.e., 28S rRNA, and the united 28S + 18S rRNA sequence fragments from 11 isolates of Babesia spp. collected in China. Due to sequence length and variability, the 28S rRNA gene contained more information than the 18S rRNA gene and could be used to elucidate the phlyogenetic relationships of B. motasi, B. major, and B. bovis. Thus, 28S rRNA is another candidate marker that can be used for the phylogenetic analysis of Babesia spp. However, the united fragment (28S + 18S) analysis provided better supported phylogenetic relationships than single genes for Babesia spp. in China.