Effect of chaotropes in Chagas disease and leishmaniasis cross-reacting serology assays for epidemiological surveys

Abstract INTRODUCTION: Serological cross-reactivity between leishmaniasis and Chagas disease, especially at low titers, leads to difficulties of the seroepidemiological interpretation. METHODS: We have studied the ability of urea as a chaotrope to select high-avidity antibodies in IgG ELISA, thus reducing low-avidity IgG cross-reactivity in serologically positive samples in both assays. RESULTS: Using 0.5M urea for diluting the sample efficiently defined leishmaniasis or double infections in high-avidity IgG ELISA and eliminated false-positive results. CONCLUSIONS: The use of a chaotropic diluting agent is useful for improving the specificity of Chagas disease and leishmaniasis immunoassays.

引言：利什曼病与恰加斯病之间存在血清学交叉反应（serological cross-reactivity），尤其在低滴度（low titers）情况下，这给血清流行病学解读（seroepidemiological interpretation）带来了显著困难。方法：本研究探讨了以尿素（urea）作为离液剂（chaotrope），在IgG酶联免疫吸附试验（IgG ELISA）中筛选高亲和力抗体（high-avidity antibodies）的效果，以此在两项检测中降低血清学阳性样本内的低亲和力IgG交叉反应。结果：采用0.5M尿素稀释样本，可在高亲和力IgG ELISA中有效区分利什曼病或双重感染，并消除假阳性结果（false-positive results）。结论：使用离液稀释剂（chaotropic diluting agent）可有效提升恰加斯病与利什曼病免疫测定（immunoassays）的特异性。