奶牛温氏附红细胞体16S rRNA基因的克隆及系统进化分析

Cloning and phylogenetic analysis of 16S rRNA gene of E. wenyoni in cow

无菌采集感染温氏附红细胞体(E.wenyoni)的牛血液,抽提E.wenyoni基因组DNA,参考GenBank发表的E.wenyoni16S rRNA基因序列(AF016546),设计1对特异性引物,扩增并克隆E.wenyoni16S rRNA部分基因,基因产物大小为1 005 bp。序列比较结果显示,所测序列与参考序列(AF016546)同源性最高,达97.9%。系统发育分析表明,所测序列与支原体属病原代表种的序列接近,同源性约为70%,而与无浆体科病原代表种的序列相差较远,同源性约为50%。可见,E.wenyoni应归为支原体属,而不应属于立克次氏体目、无浆体科。

The genomic DNA was extracted from blood sample with E. wenyoni, a sequence of 1 005 bp of the 16S rRNA in E. wenyoni were amplified and cloned by using a pair of special primers which was designed according to the sequence in GenBank（AF016546）. The determined sequence was most similar to that of AF016546 （similarity levei,97.9% ）. Phylogenetic analysis indicated that it was more similar to those of Mycoplasrna spp. （homology level,about 70% ）, but was farther from Anaplasma spp. （homology level, about 50% ）. These data indicated that E. wenyoni seems to belong to Mycoplasma,but not Rickettsiales,Anaplasmataceae.