Ferreira R, Fonseca L S, Lilenbaum W
Department of Medical Microbiology, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Lett Appl Microbiol. 2002;35(3):173-5. doi: 10.1046/j.1472-765x.2002.01149.x.
The aim of this study is to evaluate the AGID serological test for detection of antibodies anti-Mycobacterium paratuberculosis and its possible adoption as diagnostic method in our field conditions.
Bovine serum samples from dairy herds in Rio de Janeiro State, Brazil, were screened for the presence of antibodies against Myco. paratuberculosis using three different ELISA tests. A panel of 48 randomly selected sera were evaluated by an Agarose Gel Immunodiffusion (AGID) test using Protoplasmatic Paratuberculosis Antigen (PPA). AGID results were compared to the standards--the results of the three ELISA tests, and the specificity and sensitivity were calculated.
From 48 sera tested for AGID, 14 (29.17%) were positive and 34 (70.83%) were negative. AGID sensitivity was 57% with two false-positive reactions, and specificity was 92.5% with nine false-negative results. The positive predictive value was calculated in 85.7% for a confidence interval of 95%.
Due to its low sensitivity and specificity rates, AGID test has shown to be unsatisfactory as a screening diagnostic method for subclinical herd infection, but it can be useful as a confirmatory test for clinical suspect animals.
本研究旨在评估琼脂凝胶免疫扩散（AGID）血清学检测法检测副结核分枝杆菌抗体的效果，以及在我们的现场条件下将其用作诊断方法的可能性。
使用三种不同的酶联免疫吸附测定（ELISA）检测法，对巴西里约热内卢州奶牛场的牛血清样本进行副结核分枝杆菌抗体检测。使用原生质副结核抗原（PPA），通过琼脂凝胶免疫扩散（AGID）试验对一组随机选择的48份血清进行评估。将AGID检测结果与标准——三种ELISA检测法的结果进行比较，并计算特异性和敏感性。
在接受AGID检测的48份血清中，14份（29.17%）呈阳性，34份（70.83%）呈阴性。AGID敏感性为57%，有两例假阳性反应，特异性为92.5%，有9例假阴性结果。在95%的置信区间下，阳性预测值计算为85.7%。
由于其低敏感性和特异性率，AGID检测法作为亚临床群体感染的筛查诊断方法并不令人满意，但它可作为临床疑似动物的确证检测法。
