Lopez F A, Manglicmot J, Schmidt T M, Yeh C, Smith H V, Relman D A
Infectious Diseases Section, Louisiana State University School of Medicine, New Orleans, LA 7012, USA.
J Infect Dis. 1999 Mar;179(3):670-6. doi: 10.1086/314645.
Cyclospora organisms are intestinal pathogens of humans that are increasingly recognized in many parts of the world; yet, the reservoirs and host range remain poorly defined. Analysis of 18S ribosomal DNA (rDNA) suggests that the human-associated Cyclospora species (Cyc-hu) is most closely related to the Eimeria species, which are host species-specific. Recently, oocysts identical to those of Cyc-hu were detected in baboon fecal specimens from Tanzania. The 18S rDNA from 3 of these baboon-associated oocyst specimens was amplified and sequenced. Phylogenetic analysis indicated that these baboon-associated Cyclospora-like organisms (Cyc-bab) are nearly identical to each other and are distinct from Cyc-hu (1.6%-1.7% dissimilar); however, these Cyc-bab organisms are the closest known relatives of Cyc-hu. Together, these primate-associated cyclosporans constitute a coherent clade within the diverse group of Eimeria species. These findings raise important questions about the evolutionary relationships of the eimeriids and Cyc-hu host range and should lead to improved polymerase chain reaction-based diagnostics.
环孢子虫是人类肠道病原体，在世界许多地区日益受到关注；然而，其储存宿主和宿主范围仍不明确。对18S核糖体DNA（rDNA）的分析表明，与人类相关的环孢子虫物种（Cyc-hu）与艾美耳属物种关系最为密切，后者具有宿主物种特异性。最近，在来自坦桑尼亚的狒狒粪便样本中检测到了与Cyc-hu相同的卵囊。对其中3个与狒狒相关的卵囊样本的18S rDNA进行了扩增和测序。系统发育分析表明，这些与狒狒相关的环孢子虫样生物（Cyc-bab）彼此几乎相同，且与Cyc-hu不同（差异为1.6%-1.7%）；然而，这些Cyc-bab生物是已知与Cyc-hu关系最密切的亲属。这些与灵长类相关的环孢子虫共同构成了艾美耳属物种多样化群体中的一个连贯分支。这些发现提出了关于艾美耳科生物与Cyc-hu宿主范围进化关系的重要问题，并应有助于改进基于聚合酶链反应的诊断方法。
