Development of an immunodiagnosis method using recombinant PsCP for detection of Paragonimus skrjabini infection in human.

Paragonimiasis skrjabini is a kind of zoonosis and prevalent in 16 provinces in China, such as Chongqing, Fujian, Sichuan, and Yunnan. However, sensitive and efficient diagnostic methods for the infection are limited. In order to provide a more convenient and simple method for serologic diagnosis, the recombinant P. skrjabini cysteine protease (PsCP) was expressed, purified, and then used to develop an indirect enzyme-linked immunosorbent assay (ELISA) for detecting anti-PsCP antibodies in human. Given the positive/negative cutoff value as 0.606, the maximum dilution of human sera in which anti-PsCP antibodies could be detected was 1:12,800. In addition, the coefficients of variation (CVs) of inter-assay and intra-assay experiments were both below 10 %. Furthermore, the sensitivity of the PsCP-based ELISA was 95.5 %, and the indirect ELISA displays no cross-reactivity with human antisera against Echinococcus granulosus, Taenia solium, Schistosoma japonicum, and Trichinella spiralis, either. In conclusion, recombinant PsCP was readily produced and used to establish a simple PsCP-based ELISA that provided a highly specific and sensitive method for analysis of clinical samples. Besides, the method can also probably be used to diagnose P. skrjabini infection in animals.