Tkachuk-Saad O, Prescott J
Department of Veterinary Microbiology and Immunology, University of Guelph, Ontario, Canada.
J Clin Microbiol. 1991 Dec;29(12):2696-700. doi: 10.1128/jcm.29.12.2696-2700.1991.
Fifty-four strains of Rhodococcus equi from different clinical sources (mainly horses and pigs) were examined for their plasmid content by two screening methods. Plasmids were detected in 49 of 54 strains. A plasmid of approximately 80 kb was isolated from 21 of 22 isolates from horses and 20 of 28 isolates from pigs, and a 105-kb plasmid was isolated from 7 of 28 isolates from pigs. The 80-kb plasmid was significantly associated with strains of equine rather than porcine origin, and the 105-kb plasmid was significantly associated with strains of porcine origin. The type strain, ATCC 6939, consistently failed to yield a plasmid. Restriction enzyme analysis of purified plasmid DNA confirmed the relatedness of the 80-kb plasmids isolated from strains of equine and porcine origin. More differences between the restriction patterns of plasmids from strains isolated from horses and from pigs than among strains from either species were observed. Restriction enzyme analysis also showed relatedness of the 105-kb plasmid to the 80-kb plasmid. Three strains shown by others to be virulent in horses or mice possessed the 80-kb plasmid, whereas three other strains not virulent for horses or mice lacked the plasmid, although one had the 105-kb plasmid. There was a significant but not perfect association between the presence of the 80-kb plasmid and production of a diffuse 17.5-kDa thermoregulated, virulence-associated protein. Further study is needed to determine whether this plasmid is associated with virulence in R. equi.
采用两种筛选方法，对来自不同临床来源（主要是马和猪）的54株马红球菌进行了质粒含量检测。在54株菌株中，有49株检测到了质粒。从22株马源分离株中的21株以及28株猪源分离株中的20株中分离出了一个约80 kb的质粒，从28株猪源分离株中的7株中分离出了一个105 kb的质粒。80 kb的质粒与马源菌株显著相关，而非猪源菌株；105 kb的质粒与猪源菌株显著相关。模式菌株ATCC 6939一直未能产生质粒。对纯化的质粒DNA进行限制性内切酶分析，证实了从马源和猪源菌株中分离出的80 kb质粒具有相关性。观察到马源菌株和猪源菌株的质粒限制性图谱之间的差异比同一物种内菌株之间的差异更多。限制性内切酶分析还显示105 kb质粒与80 kb质粒具有相关性。其他研究表明，在马或小鼠中具有毒力的3株菌株含有80 kb的质粒，而另外3株对马或小鼠无毒力的菌株则缺乏该质粒，尽管其中一株含有105 kb的质粒。80 kb质粒的存在与一种弥散性的17.5 kDa温度调节的、与毒力相关的蛋白的产生之间存在显著但并不完全的关联。需要进一步研究以确定该质粒是否与马红球菌的毒力相关。
