Molecular Characterization and Diagnostic Value of Taenia solium Low-Molecular-Weight Antigen Genes

Neurocysticercosis (NCC) caused by infection with the larvae of Taenia solium is an important cause of neurological disease worldwide. In order to establish an enzyme-linked immunosorbent assay (ELISA) for this infection using recombinant proteins, we carried out molecular cloning and identified four candidates as diagnostic antigens (designated Ag1, Ag1V1, Ag2, and Ag2V1). Except for Ag2V1, these clones could encode a 7-kDa polypeptide, and Ag2V1 could encode a 10-kDa polypeptide. All of the clones were very similar. Except for Ag2V1, recombinant proteins were successfully expressed using an Escherichia coli expression system. Immunoblot analysis of NCC patient sera detected recombinant proteins, but because reactivity to recombinant Ag1 was too weak, Ag1 was not suitable as an immunodiagnostic antigen. So, Ag1V1 and Ag2 were chosen as ELISA antigens, and the Ag1V1/Ag2 chimeric protein was expressed. Of 49 serum samples from NCC patients confirmed to be seropositive by immunoblot analysis, 44 (89.7%) were positive by ELISA. No assays of serum samples from patients with other parasitic infections recognized the Ag1V1/Ag2 chimeric protein. The Ag1V1/Ag2 chimeric protein obtained in this study had a high value for differential immunodiagnosis.

脑囊尾蚴病（Neurocysticercosis, NCC）是由猪带绦虫（Taenia solium）幼虫感染引发的神经系统疾病，在全球范围内属于重要的致病病因。为构建基于重组蛋白（recombinant proteins）的该感染的酶联免疫吸附试验（enzyme-linked immunosorbent assay, ELISA）检测方法，本研究开展了分子克隆（molecular cloning）工作，筛选得到4种候选诊断抗原（diagnostic antigens），分别命名为Ag1、Ag1V1、Ag2及Ag2V1。除Ag2V1外，其余克隆均可编码一条7 kDa的多肽（polypeptide），而Ag2V1可编码一条10 kDa的多肽；所有克隆的序列相似性均较高。除Ag2V1外，其余重组蛋白均通过大肠杆菌（Escherichia coli）表达系统成功获得表达。对脑囊尾蚴病患者血清的免疫印迹（immunoblot）分析可检测到重组蛋白，但由于重组Ag1的反应性过弱，其不适用于免疫诊断抗原。因此，本研究选取Ag1V1与Ag2作为ELISA检测抗原，并成功表达了Ag1V1/Ag2嵌合蛋白（chimeric protein）。在经免疫印迹分析确认血清学阳性的49份脑囊尾蚴病患者血清样本中，44份（89.7%）在该ELISA检测中呈阳性。针对其他寄生虫感染患者的血清样本开展的所有检测均未识别出该Ag1V1/Ag2嵌合蛋白。本研究获得的Ag1V1/Ag2嵌合蛋白在鉴别免疫诊断（differential immunodiagnosis）中具备较高应用价值。