Keeratijarut Angsana, Lohnoo Tassanee, Yingyong Wanta, Sriwanichrak Kanchana, Krajaejun Theerapong
Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Bangkok, Thailand.
Southeast Asian J Trop Med Public Health. 2013 Jul 4;44(4):672-80.
Human pythiosis is a life-threatening infectious disease caused by the oomycete Pythium insidiosum. Diagnosis of pythiosis relies on culture identification, serodiagnosis, and molecular-based assay. Preparation of a serodiagnostic test requires culture filtrate antigen (CFA) extracted from the live pathogen. A 74-kDa immunoreactive protein of P. insidiosum, is encoded by the exo-1,3-beta-glucanase gene (PinsEXO1). PinsEXO1 protein is recognized by sera from pythiosis patients but not by sera from uninfected patients; therefore, this protein could be used to detect anti-P. insidiosum antibodies. In this study we aimed to: identify, synthesize, and evaluate an antigenic determinant (epitope) of PinsEXO1 to be used to serodiagnose pythiosis based on peptide ELISA, and to compare the diagnostic performance of that test with the current CFA-based ELISA. Two antigenic determinants of PinsEXO1 (Peptide-A and -B) were predicted using the PREDITOP program. The sera from 34 pythiosis patients and 92 control subjects were evaluated. Peptide-A, Peptide-B, and CFA-based ELISAs all had a specificity of 100%. Peptide-B ELISA had a sensitivity of 91% and an accuracy of 98% and both Peptide-A and CFA-based ELISAs had a sensitivity of 100% and an accuracy of 100%. Peptide-A is a more efficient epitope than Peptide-B, and can be used as an alternative antigen to develop a serodiagnostic assay for pythiosis.
人类腐皮病是一种由卵菌纲的隐匿腐霉引起的危及生命的传染病。腐皮病的诊断依赖于培养鉴定、血清学诊断和基于分子的检测方法。血清学诊断测试的准备需要从活病原体中提取培养滤液抗原（CFA）。隐匿腐霉的一种74 kDa免疫反应蛋白由外切-1,3-β-葡聚糖酶基因（PinsEXO1）编码。PinsEXO1蛋白能被腐皮病患者的血清识别，但不能被未感染患者的血清识别；因此，这种蛋白可用于检测抗隐匿腐霉抗体。在本研究中，我们旨在：鉴定、合成并评估PinsEXO1的一个抗原决定簇（表位），以便基于肽酶联免疫吸附测定（ELISA）对腐皮病进行血清学诊断，并将该测试的诊断性能与当前基于CFA的ELISA进行比较。使用PREDITOP程序预测了PinsEXO1的两个抗原决定簇（肽A和肽B）。对34例腐皮病患者和92例对照受试者的血清进行了评估。基于肽A、肽B和CFA的ELISA特异性均为100%。基于肽B的ELISA灵敏度为91%，准确率为98%，基于肽A和CFA的ELISA灵敏度均为100%，准确率均为100%。肽A是比肽B更有效的表位，可作为替代抗原用于开发腐皮病的血清学诊断检测方法。
