西藏亚东县西藏血蜱携带微生物群落情况及主要病原体进化分析

Microbial community and genetic homology of Anaplasma harbored by Haemaphysalis tibetensis collected in Yadong county,Tibet Autonomous Region

目的了解西藏自治区亚东县西藏血蜱携带微生物群落的情况及主要病原体无形体的分型。方法2022年5月在亚东县采集寄生于牦牛身上的蜱虫样本141只。根据硬蜱线粒体16S rDNA基因扩增序列进行分子鉴定以确定蜱种。采用Illumina Novaseq 6000平台对西藏血蜱进行高通量测序,将测序得到的原始数据处理后对其进行组装、基因预测、丰度分析和分类学预测。利用巢式PCR扩增无形体的16S rDNA基因片段并测序及进行序列的遗传进化分析。结果121只成蜱样本鉴定为西藏血蜱。非冗余数据集经NCBI-NR数据库比对进行物种注释后,最常见的微生物种类是真核生物(19.78%)和细菌(13.54%)。在细菌中,优势门分别是变形杆菌门、拟杆菌门和厚壁菌门;优势属分别是无形体属、锥虫属、冷杆菌属和立克次体属;优势种分别是嗜吞噬细胞无形体、泰勒虫和斑点热群立克次体。无形体的系统发育树与绵羊无形体遗传距离最近,具有较高的同源性。结论西藏自治区亚东县地区优势蜱种为西藏血蜱。无形体的主要分型为绵羊无形体。当地人畜暴露在多种蜱传病原体中,存在潜在蜱传疾病的威胁,应针对性加强对蜱的监测和预防控制工作。

Objective To genetically characterize microbial community and Anaplasma–a major pathogen harbored by Haemaphysalis tibetensis collected in Yadong county,Tibet Autonomous Region.Methods Totally 141 ticks parasitizing on yaks were collected in Yadong county in May 2022 and the species of the ticks were identified according to amplified sequences of mitochondrial 16s rDNA of Ixodes.High-throughput sequencing was carried on the identified Haemaphysalis tibetensis using the Illumina Novaseq 6000 platform.The resulting raw data underwent processing for assembly,gene prediction,abundance analysis,and taxonomic prediction.The 16S rDNA gene fragment of Anaplasma was amplified and sequenced with nested PCR for phylogenetic analysis.Results Out of 141 adult tick samples collected,121 were positively identified as Haemaphysalis tibetensis.According to species annotation with the National Center for Biotechnology Information(NCBI)-NR database,the most prevalent microorganisms were eukaryotes(19.78%)and bacteria(13.54%),with the dominant genera of Anaplasma,Trypanosoma,Psychrobacter,and Rickettsia and the dominant species of phagocytophilum group,Trypanosoma theileri,and spotted fever group rickettsia.Among the bacterial florae,the dominant phyla were Proteobacteria,Bacteroidetes,and Firmicutes.The phylogenetic analysis revealed a high homology of the tick-born Anaplasma and Anaplasma ovis.Conclusion In the research area,the dominant tick species parasitizing on yaks in this region is the Haemaphysalis tibetensis and the major genotype of the tick-born Anaplasma is Anaplasma ovis.The results suggest that local residents and livestock could be exposed to various tick-borne pathogens and targeted surveillance and preventive measures against tick-borne diseases should be enhanced.