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

Abstract

Background 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. Methods 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. Results 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 ( cox 1), cytochrome c oxidase subunit 3 ( cox 3) 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 bc 1 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). Conclusions The data provided new insights into the taxonomic relationships and drug targets of apicomplexan parasites.

Mitochondrial Genomic Landscape: A Portrait of the Mitochondrial Genome 40 Years after the First Complete Sequence

“…Excluding multipartite mtDNAs, the shortest complete mitogenomes in our dataset belong to three different Chinese isolates of the genus Babesia , an apicomplexan taxon that causes babesiosis, a tick-transmitted disease. Their linear mitogenome ranges from 5767 bp to 5790 bp and it encodes for nine genes: three protein coding genes and six rRNA genes [ 146 ]. The shortest metazoan mitogenome was the Ctenophora Mnemiopsis leidyi , which resulted in only 10326 pb long: this is mostly due to the absence of tRNA genes, to the scarcity of intergenic nucleotides, and to the relocation of atp6 to the nuclear genome [ 79 ].…”

First record of Babesia and Theileria parasites in ticks from Kassena‐Nankana, Ghana

“…More investigations will be needed to determine the effects of B. occultans on cattle production in Ghana and effective control measures adopted to prevent infection spread. causing disease in sheep and goats and has a significant economic impact on small ruminant production (Liu et al, 2007;Wang et al, 2020). Infections by the pathogen are usually asymptomatic (Liu et al, 2007), hence in a resource-limited setting like Ghana, it is possible infections will go unnoticed or unreported.…”

Chromosome-level genome assembly of Babesia caballi reveals diversity of multigene families among Babesia species

“…In contrast, in another study based on β-tubulin and cox3 sequences, B. caballi and B. bigemina located in the same clade and B. bovis appeared outside of them [ 9 ]. Another phylogenetic analysis using cox1 and cytb sequences was also conducted [ 10 ] but more genes are required to reach a consensus.…”

“…Another inconsistency is observed from a morphological point of view. It is known that there are the ridge structures on the surface of B. bovis- infected erythrocytes and they are involved in cytoadhesion and capillary sequestration [ 10 – 12 ]. In contrast, neither ridge structures nor sequestration are observed for B. bigemina [ 13 ].…”