Sánchez B, Monteón V, Reyes P A, Espinoza B
Departamento de Inmunología, Instituto de Investigaciones Biomédicas (IIB), Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico.
Arch Med Res. 2001 Sep-Oct;32(5):382-8. doi: 10.1016/s0188-4409(01)00303-4.
This report describes two assays for the detection of anti-Trypanosoma cruzi antibodies using Mexican strains of the parasite and the concordance with two assays previously evaluated at the Instituto Nacional de Cardiología Ignacio Chávez in Mexico City.
Micro-enzyme-linked immunosorbent assay (ELISA) and Western blot were used for the detection of T. cruzi antibodies with a total extract of epimastigote from Ninoa and Queretaro, which are Mexican strains of T. cruzi. To standardize these methods, a total of 246 serum samples was used. In addition, sera from six confirmed Mexican chronic individuals in the asymptomatic phase were also used for comparison with the Argentinean antigen.
ELISA was 100% specific in that no false positive results were found with sera of both healthy individuals and non-Chagasic cardiopaths. Sera from individuals infected with Leishmania sp. showed approximately 16% of cross-reaction with ELISA. The test showed a positive predictive value of 90% and a negative predictive value of 100%. Western blot was also a highly sensitive test for detecting chronic Chagasic symptomatic patients from Mexico because no false negative results were obtained. Furthermore, it was possible to use Western blot to detect seven immunodominant antigens of approximately 30, 32, 40, 42, 65, 70, and 83 kDa. Concordance with two previous standardized tests at the Instituto Nacional de Cardiología showed a Kappa index of 0.96, indicating high concordance between the results obtained at these two laboratories. Finally, ELISA using Ninoa antigen extract was more sensitive than ELISA with an Argentinean extract, which failed to detect individuals in the chronic asymptomatic phase (undetermined phase) of infection.
This study indicates that ELISA and Western blot using Ninoa and/or Queretaro extracts of T. cruzi as antigens are useful tools in the detection of individuals who have been exposed to T. cruzi both in the undetermined/asymptomatic and symptomatic phases. More concordance studies such as this are recommended to obtain an accurate Chagas diagnostic test and to determine the real prevalence of this disease in Mexico.
本报告描述了两种使用墨西哥株寄生虫检测抗克氏锥虫抗体的检测方法，以及与先前在墨西哥城伊格纳西奥·查韦斯国家心脏病学研究所评估的两种检测方法的一致性。
采用微酶联免疫吸附测定法（ELISA）和蛋白质印迹法，用来自尼诺亚和克雷塔罗的墨西哥株克氏锥虫的前鞭毛体总提取物检测克氏锥虫抗体。为了标准化这些方法，共使用了246份血清样本。此外，还使用了6名确诊的墨西哥无症状期慢性患者的血清与阿根廷抗原进行比较。
ELISA具有100%的特异性，即健康个体和非查加斯心肌病患者的血清均未出现假阳性结果。感染利什曼原虫属的个体血清与ELISA显示约16%的交叉反应。该检测的阳性预测值为90%，阴性预测值为100%。蛋白质印迹法也是检测墨西哥慢性查加斯病有症状患者的高灵敏度检测方法，因为未获得假阴性结果。此外，蛋白质印迹法能够检测到大约30、32、40、42、65、70和83 kDa的7种免疫显性抗原。与国家心脏病学研究所之前的两种标准化检测方法的一致性显示卡帕指数为0.96，表明这两个实验室获得的结果之间具有高度一致性。最后，使用尼诺亚抗原提取物的ELISA比使用阿根廷提取物的ELISA更灵敏，后者未能检测到感染慢性无症状期（未确定期）的个体。
本研究表明，以尼诺亚和/或克雷塔罗克氏锥虫提取物作为抗原的ELISA和蛋白质印迹法是检测处于未确定/无症状期和有症状期的克氏锥虫暴露个体的有用工具。建议开展更多此类一致性研究，以获得准确的恰加斯病诊断检测方法，并确定该疾病在墨西哥的实际流行率。
