Pérez V, Tellechea J, Badiola J J, Gutiérrez M, García Marín J F
Departamento de Patología Animal, Facultad de Veterinaria, Universidad de Zaragoza, Spain.
Am J Vet Res. 1997 Aug;58(8):799-803.
To investigate the relation between lesions and serologic response in sheep with naturally acquired paratuberculosis and to evaluate the efficacy of agar gel immunodiffusion (AGID) and ELISA as diagnostic tests.
134 adult sheep, culled by the owner from flocks with history of severe chronic weight loss.
Before euthanasia, blood samples were collected and serum was obtained. AGID and ELISA were performed, using a protoplasmic antigen of Mycobacterium paratuberculosis. Sensitivity and specificity of these techniques were evaluated, using histopathologic findings as a reference. Histologic studies were carried out focusing on specimens containing intestinal organized lymphoid tissue.
Of the sheep examined, 46.3% had lesions that were classified in 5 categories, according to their location, extension, cellular types, and presence of acid-fast bacilli. Regarding serologic test results, 37.1% of sheep with lesions had a positive AGID result, and all sheep without lesions had negative results. However, ELISA positivity was slightly greater--48.4% of sheep with lesions; however, by use of ELISA, 11.1% of sheep without lesions had positive results.
A close relation between pathologic findings and serologic response was determined, especially between presence of acid-fast bacilli (potentially heavily shedding sheep) in the intestinal lesions and positivity to serologic tests, especially AGID.
On the basis of these results, together with its high specificity, reliability, and the difficulty of fecal specimen culture in sheep, AGID is proposed as a useful tool for seeking evidence of paratuberculosis in live sheep, and therefore, is suggested as the basis for control programs in areas in which the disease is a serious threat to sheep production.
研究自然感染副结核病绵羊的病变与血清学反应之间的关系，并评估琼脂凝胶免疫扩散试验（AGID）和酶联免疫吸附测定（ELISA）作为诊断检测方法的有效性。
134只成年绵羊，由畜主从有严重慢性体重减轻病史的羊群中挑选出来进行扑杀。
在实施安乐死之前，采集血样并分离血清。使用副结核分枝杆菌原生质抗原来进行AGID和ELISA检测。以组织病理学检查结果作为参考，评估这些检测技术的敏感性和特异性。组织学研究聚焦于含有肠道有组织淋巴样组织的标本。
在所检查的绵羊中，46.3%有病变，根据病变的位置、范围、细胞类型以及抗酸杆菌的存在情况分为5类。关于血清学检测结果，有病变的绵羊中37.1%的AGID检测结果为阳性，所有无病变的绵羊检测结果均为阴性。然而，ELISA检测的阳性率略高——有病变的绵羊中48.4%呈阳性；不过，使用ELISA检测时，无病变的绵羊中有11.1%呈阳性。
确定了病理检查结果与血清学反应之间存在密切关系，尤其是肠道病变中抗酸杆菌（可能是大量排菌的绵羊）的存在与血清学检测阳性，特别是AGID检测阳性之间的关系。
基于这些结果，以及AGID检测的高特异性、可靠性，加之绵羊粪便标本培养困难，AGID被推荐为在活羊中查找副结核病证据的有用工具，因此，建议将其作为在该病对绵羊生产构成严重威胁的地区实施防控计划的依据。
