Hunan Provincial Key Laboratory of Protein Engineering in Animal Vaccines, College of Veterinary Medicine, Hunan Agricultural University, Changsha, Hunan Province, 410128, China.
Department of Zoology, University of Swabi, Swabi, 23430, Khyber Pakhtunkhwa, Pakistan.
Vet Parasitol. 2021 Aug;296:109476. doi: 10.1016/j.vetpar.2021.109476. Epub 2021 May 28.
Capillariid nematode is a group of endoparasites of vertebrates with a complex taxonomy, causing significant economic losses to poultry industry. The taxonomic status of the genus Eucoleus remained controversial for several decades. Mitochondrial (mt) DNA provides useful genetic markers for accurate identification of species, but complete mt genome sequences have been lacking for any Capillariid nematodes. In the present study, we decoded the complete mt genome of E. annulatus and examined its phylogenetic relationship with selected members of the class Enoplea nematodes. The circular mt genome of E. annulatus was 14,118 bp, encoded 37 genes with a single non-coding region and showed substantial gene rearrangements (especially tRNA genes) compared to other nematodes studied to date. The complete mt genome of E. annulatus showed a clear A + T bias in nucleotide composition. The number of A (5404) was approximately equal to T (5405) and the GC-skew was negative on average (-0.073). Phylogenetic analyses based on 18S rDNA placed Eucoleus spp. well apart from each other and supported the proposal that Eucoleus and Capillaria are two distinct genera. Similarly, Bayesian inference (BI) and Maximum likelihood (ML) phylogenies based on mtDNA sequences revealed that the family Capillariidae is more closely related to the family Trichuridae than to the family Trichinellidae. This is the first report of the complete mt genome of capillariid nematodes, and it will provide additional genetic markers for studying the molecular epidemiology, population genetics and systematics of capillariid nematodes and should have implications for the molecular diagnosis, prevention, and control of capillariosis in animals.
毛细线虫是一类具有复杂分类学的脊椎动物内寄生虫，给家禽业造成了重大的经济损失。Eucoleus 属的分类地位几十年来一直存在争议。线粒体 (mt) DNA 为准确鉴定物种提供了有用的遗传标记，但迄今尚无任何毛细线虫的完整 mt 基因组序列。在本研究中，我们解码了 E. annulatus 的完整 mt 基因组，并检查了它与所选的 Enoplea 类线虫成员的系统发育关系。E. annulatus 的圆形 mt 基因组长 14118 bp，编码 37 个基因，与迄今研究的其他线虫相比，存在大量基因重排（尤其是 tRNA 基因）。E. annulatus 的完整 mt 基因组在核苷酸组成上表现出明显的 A + T 偏向性。A（5404）的数量大致等于 T（5405），GC 倾斜平均值为负值（-0.073）。基于 18S rDNA 的系统发育分析将 Eucoleus spp. 彼此分开，并支持 Eucoleus 和 Capillaria 是两个不同属的提议。同样，基于 mtDNA 序列的贝叶斯推断 (BI) 和最大似然 (ML) 系统发育分析表明，Capillariidae 科与 Trichuridae 科比 Trichinellidae 科更密切相关。这是毛细线虫完整 mt 基因组的首次报道，它将为研究毛细线虫的分子流行病学、种群遗传学和系统发育学提供额外的遗传标记，并且应该对动物毛细线虫病的分子诊断、预防和控制具有重要意义。
