Kurade N P, Tripathi B N, Rajukumar K, Parihar N S
Division of Pathology, Indian Veterinary Research Institute, Izatnagar 243 122, Uttar Pradesh, India.
Vet Pathol. 2004 Jul;41(4):378-87. doi: 10.1354/vp.41-4-378.
Understanding pathogenesis during progressive stages of infection by Mycobacterium avium subsp. paratuberculosis (MAP) and finding suitable methods for its diagnosis are key to the control of Johne's disease in animals. Paratuberculosis was experimentally produced in 20 crossbred lambs by oral administration of MAP to study the sequential development of lesions between 10 and 330 days postinfection and to assess commonly used diagnostic methods such as bacterial culture, lymphocyte stimulation test (LST), and enzyme-linked immunosorbent assay (ELISA) during progressive stages of infection. Histologic lesions were classified into four grades from grade 1 (least severe) to grade 4 (most severe) on the basis of location of granulomatous lesions in different regions and layers of intestines, their association with intestinal lymphoid tissues, pattern and distribution of lesions, types of cellular infiltration, and presence of acid-fast bacilli. It is evident that infection first establishes in lymphoid tissues of the small intestine, possibly at multiple sites, producing segmental lesions and from there spreads to lamina propria and local lymph nodes. Wide variability in the histologic lesions in relation to postinfection periods and initial tropism of MAP to the intestinal lymphoid tissues (Peyer's patches) suggests a differential susceptibility of young animals, possibly because of compositional phenotypic variation of Peyer's patches influencing subsequent course of infection. Histopathology was found to be a better indicator of paratuberculous infection than bacteriology in sheep. The LST (reflecting the cellular immune response) and ELISA (reflecting the humoral immune response) had overall sensitivities of 65% (11 of 17) and 42% (8 of 19), respectively, in sheep with different types of pathology but when employed together could detect about 88% of infected animals.
了解鸟分枝杆菌副结核亚种（MAP）感染进展阶段的发病机制并找到合适的诊断方法是控制动物副结核病的关键。通过给20只杂交羔羊口服MAP来实验性地诱发副结核病，以研究感染后10至330天病变的连续发展，并评估感染进展阶段常用的诊断方法，如细菌培养、淋巴细胞刺激试验（LST）和酶联免疫吸附测定（ELISA）。根据肉芽肿性病变在肠道不同区域和层次的位置、它们与肠道淋巴组织的关联、病变的模式和分布、细胞浸润类型以及抗酸杆菌的存在情况，将组织学病变分为从1级（最轻微）到4级（最严重）的四个等级。显然，感染首先在小肠的淋巴组织中建立，可能在多个部位，产生节段性病变，然后从那里扩散到固有层和局部淋巴结。与感染后时期以及MAP对肠道淋巴组织（派伊尔氏淋巴集结）的初始嗜性相关的组织学病变存在广泛差异，这表明幼龄动物的易感性不同，可能是因为派伊尔氏淋巴集结的组成表型变异影响了后续的感染过程。在绵羊中，组织病理学被发现是比细菌学更好的副结核感染指标。LST（反映细胞免疫反应）和ELISA（反映体液免疫反应）在患有不同类型病理学的绵羊中的总体敏感性分别为65%（17只中的11只）和42%（19只中的8只），但当一起使用时可以检测出约88%的感染动物。
