Insights into the phylogenetic relationships and drug targets of Babesia isolates infective to small ruminants from the mitochondrial genomes.

Xiaoxing Wang, Jinming Wang, Junlong Liu, Aihong Liu, Xin He, Quanjia Xiang, Youquan Li, Hong Yin, Jianxun Luo, Guiquan Guan

Parasites & vectors 2020 Jul 29

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Babesiosis, a tick-borne disease caused by protozoans of the genus Babesia, is widespread in subtropical and tropical countries. Mitochondria are essential organelles that are responsible for energy transduction and metabolism, calcium homeostasis and cell signaling. Mitochondrial genomes could provide new insights to help elucidate and investigate the biological features, genetic evolution and classification of the protozoans. Nevertheless, there are limited data on the mitochondrial genomes of ovine Babesia spp. in China. Herein, we sequenced, assembled and annotated the mitochondrial genomes of six ovine Babesia isolates; analyzed the genome size, gene content, genome structure and cytochrome b (cytb) amino acid sequences and performed comparative mitochondrial genomics and phylogenomic analyses among apicomplexan parasites. The mitochondrial genomes range from 5767 to 5946 bp in length with a linear form and contain three protein-encoding genes, cytochrome c oxidase subunit 1 (cox1), cytochrome c oxidase subunit 3 (cox3) and cytb, six large subunit rRNA genes (LSU) and two terminal inverted repeats (TIR) on both ends. The cytb gene sequence analysis indicated the binding site of anti-Babesia drugs that targeted the cytochrome bc1 complex. Babesia microti and Babesia rodhaini have a dual flip-flop inversion of 184-1082 bp, whereas other Babesia spp. and Theileria spp. have one pair of TIRs, 25-1563 bp. Phylogenetic analysis indicated that the six ovine Babesia isolates were divided into two clades, Babesia sp. and Babesia motasi. Babesia motasi isolates were further separated into two small clades (B. motasi Hebei/Ningxian and B. motasi Tianzhu/Lintan). The data provided new insights into the taxonomic relationships and drug targets of apicomplexan parasites.

Citation

Xiaoxing Wang, Jinming Wang, Junlong Liu, Aihong Liu, Xin He, Quanjia Xiang, Youquan Li, Hong Yin, Jianxun Luo, Guiquan Guan. Insights into the phylogenetic relationships and drug targets of Babesia isolates infective to small ruminants from the mitochondrial genomes. Parasites & vectors. 2020 Jul 29;13(1):378