我国部分地区蜱中莱姆病螺旋体的检测与基因分型研究

Detection and genotyping of Borrelia burgdorferi sensu lato in ticks from some areas of China

目的对我国部分地区的多种蜱类进行莱姆病螺旋体的检测和基因分型。方法选择我国黑龙江、吉林和浙江省部分林区为调查点,采集当地蜱类,用巢式PCR法进行检测,阳性产物进行限制性片段长度多态性(RFLP)分析和单链构象多态性(SSCP)分析,确定莱姆病螺旋体的基因型。结果共检测蜱512只,阳性126只,阳性率24.61%。其中吉林全沟硬蜱带菌率为37.00%,黑龙江全沟硬蜱带菌率为20.87%,浙江长角血蜱带菌率为28.07%。RFLP分析表明,蜱中莱姆病螺旋体包括B.garinii和B.afzelii两种基因型。SSCP分析显示为7种亚型,其中B.garinii分为5个亚型,B.afzelii分为2个亚型。发现有3只蜱同时感染不同基因(亚)型莱姆病螺旋体。结论证实B.garinii和B.afzelii基因型为我国莱姆病螺旋体的优势基因型,并在我国蜱中发现莱姆病螺旋体不同基因(亚)型的混合感染。

Objective To detect and identify the genotype of Borrelia burgdorferi in ticks from some areas of China. Methods 512 ticks were collected from Heilongjiang Province, Jilin Province and Zhejiang Province, China. On the basis of 5S-23S rRNA intergenic spacer, a nested-PCR method was developed and applied to detect B. burgdorferi in ticks. Restriction fragment length polymorphism（RFLP） and single-strand conformation polymorphism（SSCP） analysis based on 5S-23S rRNA intergenic spacer of B. burgdorferi were applied for determination of B. burgdorferi genotype. Resuits Out of 512 ticks examined, 216 ticks were positive for B. burgdorferi with an infection rate of 24.61%. The infection rate was higher in I. persulcatus（37.00%） from Jilin Province than that from Heilongjiang Province（20.87% ,P =0.02）. In Zhejiang Province, the infection rate in H. longicornis （28.07%） was higher than that in the other ticks （13.24% ,P=0.02）. RFLP methods showed that B. burgdorferi in ticks belonged to either B. garinii or B. afzelii. And as determined by SSCP analysis, they were respectively suhclassfied into 5 and 2 different genotypes. Furthermore, coinfections of different genotypes were found in 3 individual ticks. Conclusion The findings further confirmed the dominance of B. garinii and B. afzelii in China. Coinfections of different genotypes are found at the first time in ticks collected from China.