Labruna Marcelo B, Whitworth Ted, Horta Maurício C, Bouyer Donald H, McBride Jere W, Pinter Adriano, Popov Vsevolod, Gennari Solange M, Walker David H
Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA.
J Clin Microbiol. 2004 Jan;42(1):90-8. doi: 10.1128/JCM.42.1.90-98.2004.
Owing to the potential role of the tick Amblyomma cooperi in the enzootic cycle of Rickettsia rickettsii, the etiologic agent of Brazilian spotted fever (BSF), this study evaluated infection by Rickettsia species in A. cooperi ticks collected from an area in Brazil where BSF is endemic. Among a total of 40 A. cooperi adult ticks collected in an area of BSF endemicity in the state of São Paulo, PCR analysis detected DNA of Rickettsia bellii in 16 ticks (40%), and 3 other ticks (7.5%) were positive for a previously unidentified spotted-fever-group (SFG) rickettsia. Cultivation in Vero cell cultures by the shell vial technique with individual A. cooperi ticks resulted in two isolates of R. bellii and one isolate genotypically characterized as an SFG rickettsia. The two R. bellii isolates were established in Vero cell cultures in the laboratory and were confirmed to be R. bellii by molecular analysis of the gltA and 17-kDa protein-encoding genes and by electron microscopic analysis. The SFG rickettsial isolate could not be stably passaged in cell culture in the laboratory, but molecular analysis of early passages suggested that it was closely related to Rickettsia parkeri, Rickettsia africae, and Rickettsia sibirica. These results do not support the role of A. cooperi in the ecology of R. rickettsii in the area studied, but they add two more species of rickettsiae to the poorly developed list of species occurring in ticks in South America.
由于蜱虫巴氏钝缘蜱在巴西立克次体（巴西斑疹热的病原体）的动物疫源循环中可能发挥的作用，本研究评估了从巴西一个巴西斑疹热流行地区采集的巴氏钝缘蜱中感染立克次体属的情况。在圣保罗州巴西斑疹热流行地区采集的总共40只巴氏钝缘蜱成虫中，PCR分析在16只蜱（40%）中检测到贝利立克次体的DNA，另外3只蜱（7.5%）对一种先前未鉴定的斑点热群立克次体呈阳性。采用贝壳瓶技术对单个巴氏钝缘蜱在Vero细胞培养物中进行培养，得到了两株贝利立克次体分离株和一株基因型鉴定为斑点热群立克次体的分离株。这两株贝利立克次体分离株在实验室的Vero细胞培养物中得以建立，并通过对gltA和17-kDa蛋白编码基因的分子分析以及电子显微镜分析确认为贝利立克次体。斑点热群立克次体分离株在实验室的细胞培养中不能稳定传代，但早期传代的分子分析表明它与帕克立克次体、非洲立克次体和西伯利亚立克次体密切相关。这些结果不支持巴氏钝缘蜱在所研究地区巴西立克次体生态学中的作用，但它们为南美洲蜱中出现的种类不多的立克次体名单又增加了两个种类。
