Onoprienko N N, Pavlovich N V
Mol Gen Mikrobiol Virusol. 2003(3):25-8.
It was demonstrated that the lipopolysaccharides (LPS) preparations, which were isolated from all representatives of Francisella Genus bacteria, i.e. F. tularensis, F. novicida, F. novicida-like and F. philomiragia by using the method of R.P. Darveau, R.E. Hancock (1983), were not toxic for white rats and white mice. A comparative study of toxicity of live F. tularensis bacteria (both wild and LPS-defective strains) made it possible to establish a direct correlation between the toxicity of microbes and LPS chemotype. It was found that only typical strains, which synthesize the wild-type S-LPS, caused the death of white rats and white mice in 24 hours after intraperitoneal contamination (10(9), 10(10) CFU/animal). Live bacteria of F tularensis R-mutants were not able to induce a lethal infection of rats and retained only residual virulence for mice. Other representatives of Francissela genus possessed less pronounced pathogenic properties. Thus, the toxic effect was registered, in case of white rats, only for F. novicida but not for F. novicida-like or F. philomiragia. At the same time, the two last mentioned species displayed a certain degree of virulence at high challenge doses (10(9), 10(10) CFU/animal) in respect to white mice. F. philomiragia, which generated lipoolygosaccharide (LOS) with an unusual structure, was found to be least pathogenic (25-75% of dead mice). The toxicity of bacteria, killed experimentally by different means (heating, UV-light, chloroform, acetone and formalin), was studied to define the role of bacterial proteins in the realisation of F. tularensis toxic potential in vivo. No lethal effect was exerted on experimental animals by killed microbes or purified LPS preparations. Finally, the study results show a priority role of the LPS molecule in the toxic effect of F. tularensis, which is possible in vivo only if structurally valuable molecules of live bacterial cells are available.
结果表明，采用R.P. 达尔维奥、R.E. 汉考克（1983年）的方法从弗朗西斯菌属细菌的所有代表菌株，即土拉弗朗西斯菌、新凶手弗朗西斯菌、类新凶手弗朗西斯菌和嗜肺弗朗西斯菌中分离得到的脂多糖（LPS）制剂，对白鼠和小白鼠无毒。对活的土拉弗朗西斯菌（野生型和LPS缺陷型菌株）的毒性进行比较研究，得以确定微生物毒性与LPS化学型之间的直接关联。结果发现，只有合成野生型S-LPS的典型菌株，在腹腔感染（10⁹、10¹⁰ CFU/动物）后24小时内可导致白鼠和小白鼠死亡。土拉弗朗西斯菌R突变体的活菌无法引发大鼠的致死性感染，对小鼠仅保留残余毒力。弗朗西斯菌属的其他代表菌株致病特性不那么明显。因此，就白鼠而言，仅新凶手弗朗西斯菌表现出毒性作用，而类新凶手弗朗西斯菌或嗜肺弗朗西斯菌则未表现出毒性作用。同时，后两种菌在高接种剂量（10⁹、10¹⁰ CFU/动物）下对小白鼠表现出一定程度的毒力。发现产生具有异常结构的脂寡糖（LOS）的嗜肺弗朗西斯菌致病性最低（25 - 75%的小鼠死亡）。研究了通过不同方式（加热、紫外线、氯仿、丙酮和福尔马林）实验杀灭的细菌的毒性，以确定细菌蛋白在土拉弗朗西斯菌体内毒性潜能实现中的作用。杀灭的微生物或纯化的LPS制剂对实验动物均未产生致死作用。最后，研究结果表明LPS分子在土拉弗朗西斯菌的毒性作用中起首要作用，只有在有活细菌细胞的结构有价值分子时，这种作用才可能在体内发生。
