Abstract:

Objective To detect the infection of Francisella and Francisella-like endosymbiont(FLEs)in Haemaphysalis longicornis from Liaoning province. Methods In July 2013, 357 H. longicornis collected in Liaoning province were divided into 38 groups, and cultured for Francisella tularensis. Detection of Francisella and FLEs was performed using nested polymerase chain reaction(PCR)assays based on the amplification of 16S rRNA. The PCR products amplified with target fragment were sequenced, and then their nucleotide sequences obtained were aligned and performed phylogenetic analysis with published sequences of Francisella and FLEs in GenBank. Results In the sequenced 13 groups of H. longicornis, 5 groups belonged to F. tularensis, other 8 to FLEs. It was calculated that the minimum carrying rate with F. tularensis in H. longicornis from Helan town was 2.12%. The phylogenetic analysis indicated that 5 groups were assigned to a clade of F. tularensis, and the rest 8 groups to main clade with FLEs. Conclusion The current work is the first detection of the infection of F. tularensi and FLEs in H. longicornis from Liaoning province, which serves a warning to the health department within the region to do further risk assessment on the emergence of tularemia.

Key words: Francisella, Francisella tularensis, Haemaphysalis longicornis, Polymerase chain reaction

摘要：

目的 检测辽宁省长角血蜱中弗朗西斯菌属及其内共生体的携带情况。方法 2013年7月，在辽宁省采集长角血蜱357只共分成38组，进行土拉弗朗西斯菌（土拉菌）的特异培养和弗朗西斯菌属及其共生体16S rRNA的巢式PCR检测。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朗西斯菌属（类）内共生体的序列进行系统进化分析。结果 有测序结果的13组蜱中，5组为土拉菌，8组为弗朗西斯菌属（类）内共生体。由此推算，河栏镇长角血蜱对于土拉菌的最小携带率为2.12%。系统进化分析显示，5组蜱和土拉菌聚在一个分支上，其余8组和弗朗西斯菌属（类）内共生体聚在一个主干分支上。结论 首次发现辽宁省长角血蜱携带土拉菌及弗朗西斯菌属（类）内共生体，对于提醒当地卫生部门做好土拉热防控具有一定意义。

关键词: 弗朗西斯菌属, 土拉弗朗西斯菌, 长角血蜱, 聚合酶链反应