Paragonimiasis is a foodborne trematode infection that affects 23 million people, mainly in Asia. Lung fluke infections lead frequently to chronic cough with fever and hemoptysis, and are often confused with lung cancer or tuberculosis. Paragonimiasis can be efficiently treated with praziquantel, but diagnosis is often delayed, and patients are frequently treated for other conditions. To improve diagnosis, we selected five Paragonimus kellicotti proteins based on transcriptional abundance, recognition by patient sera, and conservation among trematodes and expressed them as His-fusion proteins in Escherichia coli. Sequences for these proteins have 76–99% identity with amino acid sequences for orthologs in the genomes of Paragonimus westermani, Paragonimus heterotremus, and Paragonimus miyazakii. Immunohistology studies showed that antibodies raised to four recombinant proteins bound to the tegument of adult P. kellicotti worms, at the parasite host interface. Only a known egg antigen was absent from the tegument but present in developing and mature eggs. We evaluated the diagnostic potential of these antigens by Western blot with sera from patients with paragonimiasis (from MO and the Philippines), fascioliasis, and schistosomiasis, and with sera from healthy North American controls. Two recombinant proteins (a cysteine protease and a myoglobin) showed the highest sensitivity and specificity as diagnostic antigens, and they detected antibodies in sera from paragonimiasis patients with early or mature infections. In contrast, antibodies to egg yolk ferritin appeared to be specific marker for patients with adult fluke infections that produce eggs. Our study has identified and localized antigens that are promising for serodiagnosis of human paragonimiasis.

肺吸虫病是一种食源性吸虫性感染，主要在亚洲影响2300万人。肺吸虫感染经常导致慢性咳嗽伴发烧和咯血，并常常与肺癌或结核病相混淆。吡喹酮可以有效地治疗肺吸虫病，但是诊断通常会延迟，并且经常需要针对其他疾病进行治疗。为了改善诊断，我们基于转录丰度，患者血清的识别以及吸虫的保守性选择了五种Paragonimus kellicotti蛋白，并在大肠杆菌中将其表达为His-fusion蛋白。这些蛋白质的序列与欧洲百里香（Paragonimus westermani）基因组中直向同源物的氨基酸序列具有76–99％的一致性，Paragonimus heterotremus和Paragonimus miyazakii。免疫组织学研究表明，针对四种重组蛋白的抗体结合了成年P. kellicotti的外皮蠕虫，在寄生主机接口。皮中仅不存在已知的卵抗原，但存在于发育中和成熟的卵中。我们通过Western blot，用肺吸虫病（来自密苏里州和菲律宾），筋膜炎和血吸虫病患者的血清，以及健康北美对照患者的血清，通过Western blot评估了这些抗原的诊断潜力。两种重组蛋白（半胱氨酸蛋白酶和肌红蛋白）作为诊断抗原显示出最高的敏感性和特异性，并且它们在患有早期或成熟感染的肺吸虫病患者的血清中检测到抗体。相反，针对蛋黄铁蛋白的抗体似乎是成年吸虫成虫的患者的特异性标记。我们的研究已经鉴定并定位了对人类肺吸虫病进行血清诊断的抗原。