Zúñiga E, Montes C, Barbieri G, Gruppi A
Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas (UNC), Cordoba, 5000, Argentina.
Clin Immunol. 1999 Oct;93(1):81-9. doi: 10.1006/clim.1999.4744.
The aim of this work was to study the antibody response of acute and chronic chagasic patients against a Trypanosoma cruzi alkaline fraction (FI) in comparison with the reactivity against a T. cruzi acidic antigen, the main cystein proteinase of the parasite named cruzipain, and "natural" antigens. FI-specific antibodies were detected only during the acute phase of the infection and IgM was the main isotype produced, whereas cruzipain-specific antibodies were detected during all phases of the infection. By means of immunoblot and sequencing analysis we identified a 47-kDa FI proteic band recognized by IgM from acute chagasic patients as the T. cruzi glutamate dehydrogenase (GluDH). Furthermore, the antibody response against isolated GluDH showed similar characteristics as the one against FI. We also observed a strict association between the reactivity of IgM against FI and GluDH and IgM natural antibodies. However, reactivity against these alkaline antigens was not modified after absorption of natural antibodies in sera from acute chagasic patients, indicating that these parasite antigens are not recognized by the polyspecific natural antibodies. The most important goal of this report is that for the first time the T. cruzi antigen isoelectric point has been associated with its ability to trigger immunological memory, raising a novel antigen property that should be considered in the selection of antigens used in Chagas' disease diagnostic test and in the design of a vaccine against T. cruzi infection.
本研究旨在比较急性和慢性恰加斯病患者针对克氏锥虫碱性组分（FI）的抗体反应，以及与针对克氏锥虫酸性抗原（该寄生虫主要的半胱氨酸蛋白酶，即克鲁斯蛋白酶）和“天然”抗原的反应性。仅在感染急性期检测到FI特异性抗体，且产生的主要同种型为IgM，而在感染的所有阶段均检测到克鲁斯蛋白酶特异性抗体。通过免疫印迹和测序分析，我们鉴定出一条47 kDa的FI蛋白条带，急性恰加斯病患者的IgM可识别该条带，其为克氏锥虫谷氨酸脱氢酶（GluDH）。此外，针对分离出的GluDH的抗体反应表现出与针对FI的抗体反应相似的特征。我们还观察到IgM针对FI和GluDH的反应性与IgM天然抗体之间存在紧密关联。然而，急性恰加斯病患者血清中的天然抗体吸收后，针对这些碱性抗原的反应性并未改变，这表明这些寄生虫抗原未被多特异性天然抗体识别。本报告最重要的目标是，首次将克氏锥虫抗原的等电点与其触发免疫记忆的能力联系起来，提出了一种新的抗原特性，在恰加斯病诊断试验所用抗原的选择以及针对克氏锥虫感染的疫苗设计中应予以考虑。
