Raymond Claudine R, Conlan J Wayne
National Research Council Canada, Institute for Biological Sciences, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada.
Microb Pathog. 2009 Apr;46(4):231-4. doi: 10.1016/j.micpath.2009.01.002. Epub 2009 Feb 7.
The type A and B subspecies of Francisella tularensis cause severe disease, tularemia, in humans. However, only the former can be lethal especially if inhaled. It is likely that non-lethal infection is due at least in part to the ability of innate host defenses to control pathogen growth whilst acquired immunity develops. Most common small laboratory animals rapidly succumb to clinical strains of F. tularensis and are, therefore, poor models with which to study innate immunity. In an attempt to improve upon this situation in the present study, Sprague-Dawley and Fischer 344 rats were examined for their ability to combat challenge with type A and B strains of the pathogen. Sprague-Dawley rats were significantly more resistant than Fischer rats to infection with either subspecies. This correlated with the ability of Sprague-Dawley rats to arrest the growth of the pathogen at both the site of challenge and at sites of disseminated infection. The rapidity with which F. tularensis kills susceptible rats and the early onset of control of infection in resistant rats suggests that differences in innate immunity account for these disparate outcomes. Thus, the rat might be a more useful model for studying innate immunity to virulent F. tularensis than other small mammals.
土拉弗朗西斯菌的A亚种和B亚种可导致人类患上严重疾病——兔热病。然而，只有前者可能致命，尤其是通过吸入感染时。非致命性感染很可能至少部分归因于在获得性免疫形成过程中，宿主先天防御系统控制病原体生长的能力。大多数常见的小型实验动物会迅速死于土拉弗朗西斯菌的临床菌株感染，因此，它们是研究先天免疫的较差模型。为了在本研究中改善这种情况，研究人员检测了斯普拉格-道利大鼠和费希尔344大鼠对抗该病原体A亚种和B亚种攻击的能力。斯普拉格-道利大鼠比费希尔大鼠对这两个亚种的感染具有更强的抵抗力。这与斯普拉格-道利大鼠在攻击部位和播散性感染部位阻止病原体生长的能力相关。土拉弗朗西斯菌杀死易感大鼠的速度以及抗性大鼠感染控制的早期出现表明，先天免疫的差异导致了这些不同的结果。因此，与其他小型哺乳动物相比，大鼠可能是研究对毒性土拉弗朗西斯菌先天免疫的更有用模型。
