Sequence analyses at mitochondrial and nuclear loci reveal a novel Theileria sp. and aid in the phylogenetic resolution of piroplasms from Australian marsupials and ticks
Sequence analyses at mitochondrial and nuclear loci reveal a novel Theileria sp. and aid in the phylogenetic resolution of piroplasms from Australian marsupials and ticks
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DOI：
10.1371/journal.pone.0225822
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发表时间：
2019-12-18
期刊：
影响因子：
3.7
通讯作者：
Irwin, Peter J.
中科院分区：
文献类型：
--
作者：
Barbosa, Amanda D.;Austen, Jill;Irwin, Peter J.
梨质体目包括两个主要科：巴贝斯蚊科和巴贝斯蚊科，它们含有世界范围内具有兽医和医学重要性的蜱传病原体。虽然目前只发现了包含梨质寄生虫的三个属（巴贝虫、胞虫和伊氏菌），但对18S rRNA （18S）基因的系统发育研究表明，这些生物至少代表了十个谱系，其中一个谱系包括来自澳大利亚有袋动物和蜱虫的相对独特和高度多样化的伊氏菌。作为单独分析18S序列的替代方法，线粒体基因测序已被证明对阐明某些类群间的进化关系是有用的。本研究旨在利用多种遗传标记（18S、细胞色素c、氧化酶亚基III （cox3）和细胞色素B (cytB)）和显微镜技术，对澳大利亚本土哺乳动物和蜱的螺质进行表征。为此，从东部袋狸（Bettongia gaimardi）、东部袋狸（Dasyurus viverrinus）、东部灰袋鼠（Macropus giganteus）、沼泽小袋鼠（Wallabia bicolor）、短尾矮袋鼠（Setonix brachyurus）和Gilbert potoroo (Potorous gilbertii) 6种有袋类动物的32只动物中获得了几乎完整的piroplasm-18S序列。检测到的生物代表了8种新的伊勒菌基因型，它们在主要的有袋动物分支中形成了5个亚分支，其中包括先前报道的澳大利亚有袋动物和壁虱衍生的伊勒菌。在18世纪选择的新的和以前描述的澳大利亚梨质也首次成功地在cox3和cytB位点上进行了表征，并证实了澳大利亚本土伊勒菌在一个独立的、得到良好支持的分支中的地位。cox3和cytB基因的分析也有助于澳大利亚梨质虫分支的分类分辨。重要的是，显微镜和多个位点的分子分析导致了一种独特的梨质物种的发现，它与澳大利亚有袋动物Theileria聚集在一起，我们建议将其命名为Theileria lupei n. sp。
The order Piroplasmida encompasses two main families: Babesiidae and Theileriidae, containing tick-borne pathogens of veterinary and medical importance worldwide. While only three genera (Babesia, Cytauxzoon and Theileria) comprising piroplasm parasites are currently recognised, phylogenetic studies at the 18S rRNA (18S) gene suggest that these organisms represent at least ten lineages, one of which comprises the relatively unique and highly diverse Theileria spp. from Australian marsupials and ticks. As an alternative to analysing 18S sequences alone, sequencing of mitochondrial genes has proven to be useful for the elucidation of evolutionary relationships amongst some groups of piroplasms. This research aimed to characterise piroplasms from Australian native mammals and ticks using multiple genetic markers (18S, cytochrome c, oxidase subunit III (cox3) and cytochrome B (cytB)) and microscopy. For this, nearly complete piroplasm-18S sequences were obtained from 32 animals belonging to six marsupial species: eastern bettong (Bettongia gaimardi), eastern quoll (Dasyurus viverrinus), eastern grey kangaroo (Macropus giganteus), swamp wallaby (Wallabia bicolor), quokka (Setonix brachyurus) and Gilbert's potoroo (Potorous gilbertii). The organisms detected represented eight novel Theileria genotypes, which formed five sub-clades within the main marsupial clade containing previously reported Australian marsupial and tick-derived Theileria spp. A selection of both novel and previously described Australian piroplasms at the 18S were also successfully characterised, for the first time, at the cox3 and cytB loci, and corroborated the position of Australian native theilerias in a separate, well-supported clade. Analyses of the cox3 and cytB genes also aided in the taxonomic resolution within the clade of Australian Piroplasmida. Importantly, microscopy and molecular analysis at multiple loci led to the discovery of a unique piroplasm species that clustered with the Australian marsupial theilerias, for which we propose the name Theileria lupei n. sp.