Detection of IgG in sera of patients with schistosomiasis japonica by developing magnetic affinity enzyme-linked immunoassay based on recombinant 14-3-3 protein

BACKGROUND: Low intensity of Schistosoma infection is the current status in China after long time treatment with praziquantel, therefore more sensitive diagnostic methods are required now. In this study, a magnetic affinity enzyme-linked immunoassay (MEIA) based on the signal transduction protein 14-3-3 of Schistosoma japonicum (Sj14-3-3), was developed for detecting schistosomiasis. METHODS: Sera of infected BALB/c mice were collected and analyzed with MEIA and ELISA. Both MEIA and ELISA based on Sj14-3-3 were further used to detect serum IgG in patients. Sera from 58 schistosomiasis-related patients with low-intensity infection, and 30 non-endemic negative controls, were collected to assess the assay. Six sera from paragonimiasis patients were used to analysis cross-reactions. RESULTS: Compared with ELISA, MEIA has a higher ratio of the mean positive value to the mean negative value (P/N) at the same dilution ratio in infected mice (3.71 vs 2.45). Similar results were observed in humans, higher P/N of MEIA compared to ELISA (3.57 vs 2.68). There was no cross-reaction with the sera of paragonimiasis patients detected by both MEIA and ELISA. CONCLUSIONS: Our studies suggested that MEIA based on recombinant Sj14-3-3 protein (rSj14-3-3) had the potential for the diagnosis of schistosomiasis.