四川石渠县牦牛源蜱感染巴尔通体的分子流行病学调查

Molecular detection of Bartonella infection in ixodid ticks collected from yaks in Shiqu County of Sichuan Province

为了解四川省石渠县牦牛体表寄生蜱的种类及其巴尔通体的感染情况。采集牦牛体表的蜱,经形态学初步鉴定后,提取蜱总DNA,PCR扩增蜱细胞色素氧化酶Ⅰ(COⅠ)基因和巴尔通体 gltA 基因,对阳性产物测序、比对,并构建系统进化树,从而确定蜱及其携带巴尔通体的种类。结果表明:在石渠县4个乡共采集到蜱818只,其中西藏革蜱占78.97%(646/818)、青海血蜱占21.03%(172/818);蜱巴尔通体的总感染率为30.07%,其中阿日扎乡、麻甲乡、德荣玛乡、长须干玛乡蜱巴尔通体的感染率分别为4.76%、76.79%、12.50%、17.95%,麻甲乡西藏革蜱巴尔通体感染率显著高于其他地点( P <0.01),麻甲乡青海血蜱巴尔通体感染率(79.07%)高于西藏革蜱(69.23%),但无显著差异( P >0.05)。经比对分析,总共得到3条序列(uncultured Bartonella sp. shiqu 1,uncultured Bartonella sp. shiqu 2和uncultured Bartonella sp. shiqu 3)。遗传进化分析显示,uncultured Bartonella sp. shiqu 1和uncultured Bartonella sp. shiqu 2与未定种的 Bartonella spp. RF124HAIN (FJ464240)亲缘关系最近;uncultured Bartonella sp. Shiqu 3与对人有致病性的 Bartonella melophagi 亲缘关系最近。综上,石渠县存在西藏革蜱和青海血蜱,蜱巴尔通体感染率较高,并且具有感染人的风险。

In order to investigate tick species and its Bartonella infection from yaks in Shiqu County of Sichuan Province, the ticks collected from yaks were classified by morphological identification. The total DNA of ticks was extracted and partial sequences of CO Ⅰ and gltA gene of ticks and Bartonella were amplified by PCR, respectively. The positive products were sequenced and compared through the NCBI database. Phylogenetic tree was constructed based on CO Ⅰ and gltA for determination species of ticks and Bartonella , respectively. A total of 818 ticks were collected from 4 villages in Shiqu County and only Dermacentor everestianus (78.97%, 646/818) and Haemphysalis qinghaiensis (21.03%, 172/818) were found. The total infection rate of Bartonella in ticks was 30.07% and the infection rates of Arizha, Maga, Derongma and Changxuganma townships were 4.76%, 76.79%, 12.50% and 17.95%, respectively. Compared with other villages, the infection rate of Bartonella in Maga was higher ( P <0.01). In Maga, no significant difference was observed ( P >0.05), though the infection rate of Bartonella in Haemphysalis qinghaiensis (79.07%)was higher than that in Dermacentor everestianus (69.23%). At last, three sequences of gltA were obtained (uncultured Bartonella sp. shiqu 1, uncultured Bartonella sp. shiqu 2 and uncultured Bartonella sp. Shiqu 3). Phylogenetic analysis showed that uncultured Bartonella sp. Shiqu 1 and uncultured Bartonella sp. Shiqu 2 had the closest relationship with the undetermined Bartonella spp. RF124HAIN (FJ464240) and uncultured Bartonella sp. Shiqu 3 had the closest relationship with the human pathogenic Bartonella melophagi. At present, Dermacentor everestianus and Haemphysalis qinghaiensis were found in Shiqu County with high infection of Bartonella , and there existed high risk of human infection.