以18SrRNA基因为分子标记的微小隐孢子虫系统发育研究

Molecular phylogeny of Cryptosporidium parvum based on 18SrRNA gene sequence

目的以18SrRNA基因为分子标记对分离自我国人和牛,以及澳大利亚和美国不同宿主来源微小隐孢子虫的系统发育进行探讨。方法用PCR扩增我国两个虫株的18SrRNA基因片段并进行序列测定,与登录于GenBank的澳、美两国虫株的相应序列进行比对。用NJ法构建分子系统树进行系统发育分析。结果分离自我国的小牛虫株(JLC)与GenBank中3个牛源虫株(澳大利亚的C1,美国的UCP和AUCP-1)亲缘关系近,位于系统发育树的同一枝;分离自我国的人源虫株(JSH)与澳大利亚鼠源虫株(M24)同源,共同位于系统发育树的另一枝。结论本研究中微小隐孢子虫株间亲缘关系的远近似主要由宿主因素决定,而受地理位置的影响较小。

Objective To approach on the systematic phylogeny of Cryptosporidium parvum isolates derived from China, Australia and America. Methods 18SrRNA gene segments of 2 Chinese isolates were amplified by PCR and sequenced. The sequences were then aligned with those from the corresponsive isolates accessed in GenBank. A molecular phylogeny tree was constructed with NJ method and analyzed. Results The Chinese isolate from calf was identical with 3 bovine isolates （2 from America,1 from Australia）, and they were branched in a same cluster of the phylogeny tree. The other Chinese isolate from human was quite close to an Australia isolate from mouse and they were together in another cluster. Condusion The genetic relationships between the C. parvurn isolates are mainly determined by host origins, while the geographic factor may play a less role.