Demirkan I, Williams H F, Dhawi A, Carter S D, Winstanley C, Bruce K D, Hart C A
Department of Medical Microbiology, University of Liverpool, Liverpool, UK.
J Appl Microbiol. 2006 Oct;101(4):948-55. doi: 10.1111/j.1365-2672.2006.02976.x.
The aim of the study was to characterize a spirochaete isolated from the lesions of a cow with digital dermatitis (DD).
The characterization was on the basis of its light and electron microscopic appearance, enzymic profile and DNA sequence analysis of its flagellin and 16S rRNA genes. The spirochaete was 6-8-microm long and 0.2-0.3 microm in diameter, and possessed seven to eight periplasmic flagella, with three to five helical turns. The enzymic profile of the bacterium resembles, but is not identical to that of Treponema brennaborense. Its flagellin gene sequence was identical to that of Treponema phagedenis but distinct from that of an ovine spirochaete. Analysis of a 1477-bp region of the 16S rRNA genes indicated that this is a Treponema species and that it is indistinguishable from some isolates made from cases of bovine DD in the United States. Finally, electron microscopy revealed the presence of myovirus-like bacteriophage particles in all cultures of the treponeme examined.
The spirochaete isolate was identified as a Treponema species closely related to some isolates from the United States (by 16S rDNA) and to T. phagedenis (by flagellin gene sequence) and is associated with bacteriophage particles.
The fact that the isolates with the same or very similar 16S rDNA sequences have been obtained from cases of bovine DD in cattle in different countries at different times, lends further support to the hypothesis that treponemes play a role in the pathogenesis of this disease.
本研究旨在对从患有指部皮炎(DD)的奶牛病变部位分离出的一种螺旋体进行特性描述。
通过光学显微镜和电子显微镜观察其形态、酶谱分析以及对其鞭毛蛋白和16S rRNA基因进行DNA序列分析来进行特性描述。该螺旋体长6 - 8微米,直径0.2 - 0.3微米,具有七到八条周质鞭毛,有三到五个螺旋圈。该细菌的酶谱与布氏密螺旋体相似,但并不相同。其鞭毛蛋白基因序列与溃蚀性密螺旋体相同,但与一种绵羊螺旋体不同。对16S rRNA基因的1477碱基区域的分析表明,这是一种密螺旋体物种,并且与美国从牛DD病例中分离出的一些菌株无法区分。最后,电子显微镜显示在所检测的所有密螺旋体培养物中都存在类肌病毒噬菌体颗粒。
该螺旋体分离株被鉴定为一种密螺旋体物种,与美国的一些分离株(通过16S rDNA)以及溃蚀性密螺旋体(通过鞭毛蛋白基因序列)密切相关,并且与噬菌体颗粒有关。
在不同时间从不同国家的患牛DD的牛身上获得了具有相同或非常相似的16S rDNA序列的分离株,这一事实进一步支持了密螺旋体在该疾病发病机制中起作用的假说。