用半套式PCR检测蜱和啮齿动物中查菲埃立克体

目的　了解福建西北部林区查菲埃立克体 (Ehrlichiachaffeensis)的存在情况。方法　用 16SrRNA基因特异引物进行半套式PCR ,检测从福建武夷山和宁化采集的蜱类及野生动物中的查菲埃立克体DNA ,然后对有代表性的标本的扩增产物进行克隆和序列测定 ,并与GenBank中注册的核苷酸序列进行同源性比较。结果　从该地区的越原血蜱 ,野鼠(褐家鼠、黄毛鼠、黄胸鼠、社鼠、小家鼠 )和野兔的脾脏和 /或血块中均扩增出了查菲埃立克体的特异片段。越原血蜱成蜱 2 40组 (6 16只 ) ,31组阳性 ,最小阳性率 5 0 %。野鼠脾脏标本 39份 ,2 2份阳性。野鼠和野兔血块标本共 35份 ,14份阳性。 390bp的PCR产物经克隆、测序后分析发现其DNA序列与美国查菲埃立克体分离株对应位置一致。结论　福建西北部林区可能存在人单核细胞埃立克体病的自然疫源地。

DETECTION OF EHRLICHIA CHAFFEENSIS IN TICKS AND RODENTS USING SEMI-NESTED PCR

Aim To investigate the presence of Ehrlichia chaffeensis in the forest area of northwestern Fujian Province Methods Specific primers derived from 16S rRNA gene were used in semi nested PCR(HE1/PER2 and HE1/HE3)to detect E chaffeensis DNA in ticks and rodent hosts collected from Wuyishan city and Ninghua county of Fujian province PCR products of representative samples were cloned and sequenced The sequence was compared with nucleotide database of GenBank for maximal homology Results Adult Haemaphysalis yeni ticks,wild rats(Rattus norvegicus、Rattus losea、Rattus flavipectus、Rattus niviventer、Mus musculus),and Lepus sinensis were found positive for E chaffeensis DNA Of the 616(240pools)adult Haemaphysalis yeni examined,31 pools were positive at a minimum prevalence of 5 0% In addition,the semi nested PCR detected E chaffeensis DNA in 22 of 39(56 4%)spleen specimens of rats,12 of 31(38 7%)blood samples of rats,and in 2 of 4 blood samples of hare,respectively The sequence of the 390bp fragment amplified from representative samples of H yeni and rodent were indentical to the corresponding part of American strains of E chaffeensis Conclusion The findings of the present study imply that the natural foci of human monocytic ehrlichiosis may exist in northwestern Fujian Province