Araujo F G, Guptill D
Am J Trop Med Hyg. 1984 May;33(3):362-71. doi: 10.4269/ajtmh.1984.33.362.
Antigens derived from the amastigote or the epimastigote stages of Trypanosoma cruzi and prepared by sonication or formalinization were examined and compared in the immunofluorescent antibody (IFA) test and enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to the parasite in sera of infected humans. The results revealed that antigens derived of amastigotes from cell cultures can be used for the detection of antibodies to T. cruzi in both tests. In the IFA test, 46.3% of the sera had higher titers with amastigote antigens, 41.5% had equal titers with antigens from both stages, and 12.2% had higher titers with epimastigote antigens. In the ELISA, 43.9% had higher titers with amastigote antigens, 43.9% had equal titers with antigens of both stages and 12.2% had higher titers with the epimastigote antigens. The differences in titers, however, were not of a magnitude sufficient to indicate a higher sensitivity for the amastigote antigens. The ELISA was performed successfully with formalinized or sonicated organisms of both stages. The use of formalinized parasites introduces a new advantage over previously reported ELISA methods. Formalinized antigens are easier to prepare and can be stored for prolonged periods of time at 4 degrees C. The reason for the higher titers with amastigote antigens was examined by using 125I-labeled antigens to determine the binding of antigens to the plastic solid-phase used in the ELISA and to compare the antigens of each stage that could be immunoprecipitated by antibodies to T. cruzi. The ability of amastigote antigens to bind to the plastic solid phase appeared to be slightly higher than that of epimastigote antigens although the differences were not statistically significant. On the other hand, the amount of antigens in the amastigote preparation immunoprecipitated by antibodies in 6 of 10 sera examined was higher than the amount of antigens in the epimastigote preparation immunoprecipitated by antibodies in the same sera. In two sera the amount was similar, and in the remainder more antigens in the epimastigote antigen preparation were immunoprecipitated. These results are of interest and may suggest clinical implications.
对源自克氏锥虫无鞭毛体或前鞭毛体阶段、经超声处理或甲醛固定制备的抗原，在免疫荧光抗体（IFA）试验和酶联免疫吸附测定（ELISA）中进行检测和比较，以检测感染人类血清中针对该寄生虫的抗体。结果显示，细胞培养的无鞭毛体衍生的抗原可用于两种试验中检测针对克氏锥虫的抗体。在IFA试验中，46.3%的血清对无鞭毛体抗原的效价更高，41.5%的血清对两个阶段抗原的效价相同，12.2%的血清对前鞭毛体抗原的效价更高。在ELISA中，43.9%的血清对无鞭毛体抗原的效价更高，43.9%的血清对两个阶段抗原的效价相同，12.2%的血清对前鞭毛体抗原的效价更高。然而，效价差异的幅度不足以表明无鞭毛体抗原具有更高的敏感性。使用两个阶段经甲醛固定或超声处理的生物体成功进行了ELISA。与先前报道的ELISA方法相比，使用甲醛固定的寄生虫具有新的优势。甲醛固定的抗原更容易制备，并且可以在4℃下长时间保存。通过使用125I标记的抗原确定抗原与ELISA中使用的塑料固相的结合，并比较每个阶段可被克氏锥虫抗体免疫沉淀的抗原，研究了无鞭毛体抗原效价更高的原因。无鞭毛体抗原与塑料固相结合的能力似乎略高于前鞭毛体抗原，尽管差异无统计学意义。另一方面，在检测的10份血清中的6份中，无鞭毛体制备物中被抗体免疫沉淀的抗原量高于相同血清中前鞭毛体制备物中被抗体免疫沉淀的抗原量。在两份血清中，量相似，其余血清中前鞭毛体抗原制备物中有更多抗原被免疫沉淀。这些结果令人感兴趣，可能具有临床意义。
