Takai S, Fukunaga N, Ochiai S, Imai Y, Sasaki Y, Tsubaki S, Sekizaki T
Department of Animal Hygiene, School of Veterinary Medicine and Animal Sciences, Kitasato University, Aomori, Japan.
J Clin Microbiol. 1996 Apr;34(4):1034-7. doi: 10.1128/jcm.34.4.1034-1037.1996.
We recently reported the existence of Rhodococcus equi isolates with at least three virulence levels, isolated from AIDS patients: virulent R. equi having 15- to 17-kDa antigens that kills mice with 10(6) cells, intermediately virulent R. equi having a 20-kDa antigen that kills mice with 10(7) cells, and avirulent R. equi that does not kill mice with 10(8) cells or more (S. Takai, Y. Imai, N. Fukunaga, Y. Uchida, K. Kamisawa, Y. Sasaki, S. Tsubaki, and T. Sekizaki, J. Infect. Dis. 172:1306-1311, 1995). Virulent R. equi having the 15- to 17-kDa antigens has been isolated frequently from horses and their environment, but the source of intermediately virulent R. equi having the 20-kDa antigen is poorly understood. There are many reports of the isolation of R. equi from the lymph nodes of pigs with and without lesions resembling those of tuberculosis. Therefore, we analyzed antigens of R. equi isolates from the submaxillary lymph nodes of pigs by immunoblotting with monoclonal antibodies against these virulence-associated antigens. Immunoblots of whole-cell antigen preparations of R. equi pig isolates revealed the presence of the 20-kDa antigen in almost all the pig isolates studied, and these isolates were intermediately virulent for mice. We also demonstrated that the expression of the 20-kDa antigen and its pathogenicity in mice were associated strongly with the presence of five large, distinct plasmids of 70 to 95 kb; two of the five plasmids from pig isolates were the same sizes as those from human isolates. These results suggest that R. equi having the 20-kDa antigen exists in the submaxillary lymph nodes of pigs and that the source of infection in some human cases might be associated with pigs and their environment.
具有15至17 kDa抗原的强毒力马红球菌，用10⁶个细胞可致小鼠死亡；具有20 kDa抗原的中等毒力马红球菌，用10⁷个细胞可致小鼠死亡；无毒力马红球菌，用10⁸个或更多细胞也不会致小鼠死亡（S. Takai、Y. Imai、N. Fukunaga、Y. Uchida、K. Kamisawa、Y. Sasaki、S. Tsubaki和T. Sekizaki，《传染病杂志》172:1306 - 1311，1995年）。具有15至17 kDa抗原的强毒力马红球菌经常从马及其环境中分离得到，但对具有20 kDa抗原的中等毒力马红球菌的来源了解甚少。有许多关于从有或无类似结核病变的猪的淋巴结中分离出马红球菌的报道。因此，我们用针对这些与毒力相关抗原的单克隆抗体通过免疫印迹法分析了从猪的颌下淋巴结分离出的马红球菌分离株的抗原。马红球菌猪分离株全细胞抗原制剂的免疫印迹显示，在所研究的几乎所有猪分离株中都存在20 kDa抗原，并且这些分离株对小鼠具有中等毒力。我们还证明，20 kDa抗原的表达及其在小鼠中的致病性与五个大小为70至95 kb的大型不同质粒的存在密切相关；来自猪分离株的五个质粒中的两个与来自人类分离株的质粒大小相同。这些结果表明，具有20 kDa抗原的马红球菌存在于猪的颌下淋巴结中，并且在一些人类病例中的感染源可能与猪及其环境有关。
