Tessema M Z, Koets A P, Rutten V P, Gruys E
Department of Pathology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
Vet Q. 2001 Nov;23(4):153-62. doi: 10.1080/01652176.2001.9695105.
Paratuberculosis is a chronic, progressive disease of mainly ruminants caused by the facultative intracellular bacterium, Mycobacterium avium subsp. paratuberculosis. Infection usually occurs in young animals through oral uptake of food contaminated with the organisms. The ingested bacteria are transcytosed through M-cells overlying the Peyer's patches and are released in the stroma, where they are taken up by macrophages. Inside the macrophage, the mycobacteria resist enzymatic and toxic degradation and multiply until the infected macrophage ruptures. The thick, lipid-rich cell envelope is mainly responsible for micobacterial resistance. In addition to its barrier effect, which provides protections, the mycobacterial cell wall also contains several biologically active components that down-regulate the bactericidal function of macrophages. The basic survival strategy of pathogenic mycobacteria can be viewed at three levels: selective use of relatively safe entry pathways that do not trigger oxidative attack, modification of the intracellular trafficking of mycobacteria-containing phagosomes, and modulation of the cooperation between the innate and specific immunity. In doing so, pathogenic mycobacteria are successful intracellular organisms that survive and multiply inside macrophages. Current understanding about the survival strategies of M. a. paratuberculosis and its implications in the epidemiology, diagnosis, and control of the disease are discussed.
副结核病是一种主要发生在反刍动物身上的慢性、进行性疾病，由兼性胞内细菌鸟分枝杆菌副结核亚种引起。感染通常发生在幼龄动物，通过口服摄入被该病原体污染的食物。摄入的细菌通过覆盖派尔集合淋巴结的M细胞进行转胞吞作用，并在基质中释放，然后被巨噬细胞摄取。在巨噬细胞内，分枝杆菌抵抗酶解和毒性降解并繁殖，直到被感染的巨噬细胞破裂。厚实、富含脂质的细胞壁主要负责分枝杆菌的抗性。除了其提供保护的屏障作用外，分枝杆菌细胞壁还含有几种生物活性成分，可下调巨噬细胞的杀菌功能。致病性分枝杆菌的基本生存策略可从三个层面来看：选择性使用不会引发氧化攻击的相对安全的进入途径、改变含分枝杆菌吞噬体的细胞内运输过程，以及调节固有免疫和特异性免疫之间的协作。通过这些方式，致病性分枝杆菌成为在巨噬细胞内存活和繁殖的成功胞内生物。本文讨论了目前对鸟分枝杆菌副结核亚种生存策略及其在该疾病流行病学、诊断和控制方面的影响的认识。
