我国南方蜱样本中发现犬埃立克体DNA

EHRLICHIA CAINS DNA FOUND IN TICKS IN THE SOUTH OF CHINA

目的调查我国南方蜱样本埃立克体感染情况。方法用已发表的埃立克体16SrRNA基因的属特异引物和自行设计的犬埃立克体种特异引物，对广东、广西和海南部分地区采集的蜱样本进行PCR检测，并将阳性PCR产物克隆测序，结果通过Internet提交到美国国立医学图书馆／国家健康研究所的站点，利用BLAST对核酸数据库进行同源性检索。结果从广东采集的血红扇头蜱和广西采集的微小牛蜱样本中扩增出埃文克体452bp特异片段和大埃立克体的555bp特异片段。测序和检索结果证实这些片段均为犬埃立克体，并且两种蜱中的埃立克体DNA片段有至少4bp差异。结论这是首次在我国发现犬埃立克体病原线索。微小牛蜱也能携带犬埃立克体。表明我国极有可能存在该病的自然疫源地，有必要进行深入研究。

Aim To investigate the ticks infected by Ehrlichia in the South of China. Method Tick samples collectedfrom Guangdong,Guangxi,Hainan province were detected by polymerase chain reaction using primers spectific for Ehilichiaand Ehrlichia canis designed based on their 16SrRNA gene. Positive products of PCR were coloned and sequenced. The resultswere submitted to National Library of Medicine/National Institutes of Health of America by internet and searched the homol-ogous sequences from GenBank,EMBL, DDBJ, PDB nucle0tide database by BLAST. Result 452base pairs (bp) DNA frag-ments specific for Ehrlichia and 555bp for E. canis were amplified from Rhipicephalus sanguineu collected from Guangdong andBoophilus microplus from Guangxi. The results of BLAST search of the sequence showed the DNA fragments were fromE. canis. The two fragments of E. canis amplified from the different ticks are distinct in 4bp at least- Conclusion This is thefirst time to find the pathogenic evidence of the existence of E. canis in our country,and the first time to show the presence ofthe E. canis in Boophilus microplus. It indicates that there may have the nature infective spots of E. canis in the country.