College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, Xinjiang Uygur Autonomous Region, 830052, China.
College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, Xinjiang Uygur Autonomous Region, 830052, China; Xingjiang Key Laboratory of Herbivore Drug Research and Creation, Xinjiang Uygur Autonomous Region, 830052, China; Veterinary Medicine Postdoctoral Research Station of Xinjiang Agricultural University, Urumqi, Xinjiang Uygur Autonomous Region, 830052, China.
Exp Parasitol. 2024 Oct;265:108828. doi: 10.1016/j.exppara.2024.108828. Epub 2024 Aug 17.
In this study, a tick intracellular symbiont, Candidatus Midichloria mitochondrii, was detected in Hyalomma anatolicum from Xinjiang, China. Morphological identification and cytochrome oxidase subunit I sequence alignment were used for molecular identification of the tick species. PCR detection further revealed the presence of endosymbiont C. M. mitochondrii in the tick. Specific primers were designed for Groel and 16S rRNA genes of C. M. mitochondrii for PCR amplification and phylogenetic analysis. To further investigate the vertical transmission characteristics of C. M. mitochondrii, specific primers were designed based on the FabⅠ gene fragment to detect C. M. mitochondrii in different developmental stages and organs of the tick using qPCR. Of the 336 tick specimens collected from the field, 266 samples were identified as H. anatolicum on the basis of morphological characteristics. The gene fragment alignment results of COI confirmed that these ticks were H. anatolicum. The phylogenetic analysis showed that Groel gene of C. M. mitochondrii clustered with Midichloria strains detected in Ixodes ricinus ticks from Italy and Ixodes holocyclus ticks from Australia, with 100% sequence similarity. Furthermore, the 16S rRNA gene of C. M. mitochondrii clusters with the strains isolated from Hyalomma rufipes ticks in Italy, exhibiting the highest degree of homology. qPCR results showed that C. M. mitochondrii was present at all developmental stages of H. anatolicum, with the highest relative abundance in eggs, and lower relative abundance in nymphs and unfed males. With female tick blood feeding, the relative abundance of C. M. mitochondrii increased, and a particularly high relative abundance was detected in the ovaries of engorged female ticks. This study provides information for studying the survival adaptability of H. anatolicum, and provides data for further investigation of the mechanisms regulating tick endosymbionts in ticks, enriching the reference materials for comprehensive prevention and control of tick-borne diseases.
在中国新疆的璃眼蜱（Hyalomma anatolicum）中检测到一种 tick 细胞内共生体，候选密立根立克次体（Candidatus Midichloria mitochondrii）。使用形态学鉴定和细胞色素氧化酶亚基 I 序列比对进行蜱种的分子鉴定。PCR 检测进一步显示 tick 中存在共生体 C. M. mitochondrii。为了对 C. M. mitochondrii 的垂直传播特征进行进一步研究，根据 FabⅠ基因片段设计了特异性引物，用于使用 qPCR 检测 tick 不同发育阶段和器官中的 C. M. mitochondrii。从野外采集的 336 个 tick 标本中，根据形态特征鉴定出 266 个为 H. anatolicum。COI 基因片段比对结果证实这些 tick 为 H. anatolicum。系统发育分析显示，候选密立根立克次体的 Groel 基因与意大利的硬蜱（Ixodes ricinus）和澳大利亚的全沟硬蜱（Ixodes holocyclus）中检测到的密立根立克次体菌株聚类，具有 100%的序列相似性。此外，候选密立根立克次体的 16S rRNA 基因与意大利的璃眼蜱（Hyalomma rufipes）分离株聚类，具有最高的同源性。qPCR 结果表明候选密立根立克次体存在于 H. anatolicum 的所有发育阶段，在卵中相对丰度最高，在若虫和未吸血雄性中相对丰度较低。随着雌性 tick 吸血，候选密立根立克次体的相对丰度增加，在饱血雌 tick 的卵巢中检测到相对丰度特别高。本研究为研究 H. anatolicum 的生存适应性提供了信息，并为进一步研究调节 tick 共生体的 tick 内共生机制提供了数据，丰富了 tick 病综合防治的参考资料。
