Detection of Francisella strains and Francisella-like endosymbionts in ticks in some regions of China

doi:10.11853/j.issn.1003.8280.2021.06.020

Abstract

Abstract: Objective To detect Francisella strains and Francisella-like endosymbionts (FLEs) in ticks in China. Methods We selected Liaoning province, Xinjiang Uygur Autonomous Region, and Hubei province as sampling sites, which are located in Northeast, Northwest, and South Central China, respectively. A total of 715 ticks were collected, including 627 Haemaphysalis longicornis and 88 Hyalomma asiaticum ticks. For all the collected ticks, we amplified the 16S rRNA gene and tul4 gene to detect Francisella strains and FLEs. We performed sequencing and homology alignment on PCR products with amplified target fragments, and conducted a phylogenetic analysis with published sequences of Francisella and FLEs in GenBank. Results Five of 24 Ha. longicornis pools from Liaoyang, Liaoning province harbored F. tularensis, showing a minimum prevalence of 2.12% (5/236) in Ha. longicornis ticks from Liaoyang. The prevalence of FLEs was 3.39% (8/236) in Ha. longicornis from Liaoyang, 32.95% (58/176) in Ha. longicornis from Shenyang, Liaoning province, 41.86% (90/215) in Ha. longicornis from Wuhan, Hubei province, and 100% (88/88) in Hy. asiaticum from Bole, Xinjiang Uygur Autonomous Region. The phylogenic analyses based on the 16S rRNA and tul4 genes indicated that FLEs in China had high genetic diversity and significant differences with other known FLEs in the world. Conclusion It is the first time to discover FLEs in Ha. longicornis. FLEs from Ha. longicornis and Hy. asiaticum ticks in China compose a separate lineage, suggesting that these FLEs may be newly discovered.

Key words: Francisella-like endosymbiont, Francisella tularensis, Haemaphysalis longicornis, Hyalomma asiaticum, Tick, Phylogeny

摘要： 目的了解弗朗西斯菌属和弗朗西斯菌属（类）内共生体（弗类共生体）在我国蜱中的携带情况。方法在我国东北、西北和中南地区，分别选取辽宁省、新疆维吾尔自治区（新疆）和湖北省作为采样点，共采蜱715只，包括长角血蜱627只和亚洲璃眼蜱88只。对所有采集蜱，首先通过扩增16S rRNA基因和tul4基因来检测弗朗西斯菌属和弗类共生体。然后，对有目的片段扩增的PCR产物进行测序和同源性比对，并与网上已公布的弗朗西斯菌属和弗类共生体的序列进行系统进化分析。结果在辽阳市采获的24组长角血蜱中有5组土拉弗朗西斯菌（土拉菌）阳性，土拉菌的最小携带率为2.12%（5/236）。辽阳、沈阳和武汉市的长角血蜱、以及新疆博乐市的亚洲璃眼蜱，弗类共生体的携带率分别为3.39%（8/236）、32.95%（58/176）、41.86%（90/215）和100%（88/88）。16S rRNA基因和tul4基因的系统进化分析均显示，中国弗类共生体具有高度的遗传多样性，和世界其他已知弗类共生体有显著差异。结论首次在长角血蜱中发现弗类共生体。我国长角血蜱和亚洲璃眼蜱中的弗类共生体形成单独的谱系，提示这些弗类共生体可能是新发现的。

关键词: 弗类共生体, 土拉弗朗西斯菌, 长角血蜱, 亚洲璃眼蜱, 蜱, 系统进化

CLC Number:

R378.99

WANG Yan-hua, SUN Ying-wei, MAO Ling-ling, WANG Zi-jiang, ZHANG Jia-yong, ZHANG Ji-bo, PENG Yao, XIA Lian-xu. Detection of Francisella strains and Francisella-like endosymbionts in ticks in some regions of China[J]. Chinese Journal of Vector Biology and Control, 2021, 32(6): 756-762.

王艳华, 孙英伟, 毛玲玲, 王子江, 张家勇, 张稷博, 彭遥, 夏连续. 我国部分地区蜱体弗朗西斯菌属和弗类共生体的检测研究[J]. 中国媒介生物学及控制杂志, 2021, 32(6): 756-762.

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