中文摘要：

根据GenBank上已发表的环孢子虫序列设计并合成2对引物，利用巢式PCR技术对首次在牛体内发现的形态学特征与人环孢子虫极为相似的牛源环孢子虫的18SrRNA基因进行了扩增，并以KpnⅠ酶对PCR产物进行RFLP分析；扩增出的片段纯化后克隆至pGEM-T Easy载体，对阳性克隆进行序列测定并对测序结果进行了同源性及系统发育分析。结果显示，扩增的18SrRNA基因片段大小为501bp，不含KpnⅠ酶切位点，与对照的艾美尔球虫的酶切图谱明显不同。序列同源性及系统发育分析显示该牛源环孢子虫与环孢子虫同源性最高，系统树中位于同一分支，可以确定其为一种环孢子虫。

英文摘要：

According to the published sequence of the rRNA gene of Cyclospora in GenBank, two pairs of primers were designed to amplify the 18S rRNA of the Cyclospora-like organism, found in dairy cattle from China by nest PCR. The nest PCR amplicons was RFLP analyzed with Kpn Ⅰ and the positive amplicons was cloned into pGEM-T Easy vector, The insert was successfully sequenced, and the result revealed that the insert was 501 bp in length. The dairy cattle-associated Cyclospora-like organism was identified as a Cyclospora spp based on the phylogenetic analysis.