Application of an immunomagnetic bead ELISA based on IgY for detection of circulating antigen in urine of mice infected with Schistosoma japonicum.

Schistosomiasis is an important zoonosis and some livestock especially bovine and swine play a crucial role on the disease transmission in endemic areas. The gold standard for animal Schistosoma japonicum infection is fecal examination although indirect agglutination assay (IHA) is so far mostly used in field survey and laboratory examination. Lack of sensitivity, poor practicality and high false positivity limit the use of those methods for routine veterinary detection as well as human diagnosis. A novel immunomagnetic bead ELISA based on IgY (egg yolk immunoglobulin) was developed for detection of circulating schistosomal antigen (CSA) in sera of hosts infected with S. japonicum. To assess the application of this method for diagnosis of domestic animal schistosomiasis with urine sample, the immunomagnetic bead ELISA based on IgY (IgY-IMB-ELISA) was employed in the present study to detect CSA in urine of murine schistosomiasis with either light (10 S. japonicum cercariae infection per mouse) or heavy infection (30 S. japonicum cercariae infection per mouse). The results showed that the CSA levels in urine of heavily and lightly infected mice reached a peak in 8 and 10 weeks after infection, respectively, remaining at a constant plateau in both groups by the end of the experiment (14 weeks after infection). The CSA level in urine of heavily infected mice was much higher than that of lightly infected mice from 8 to 14 weeks after infection. The effect of praziquantel treatment on the CSA level in urine of heavily infected mice was also investigated. It was found that the CSA level in urine of heavily infected mice with treatment was much lower than that of untreated mice at 4 weeks post-treatment, although still higher than that of control mice, and then gradually descended to the background level by 8 weeks after treatment. Our findings suggested that the IgY-IMB-ELISA may be an efficient and practical tool in non-invasive diagnosis of schistosome infection based on antigen detection, and evaluation of the efficacy of chemotherapy as well.