A candidate recombinant antigen for diagnosis of schistosomiasis japonica in domestic animals

Domestic animals infected with Schistosoma japonicum are a major source of infection and play an important role in transmission to humans. A key strategy for the elimination of schistosomiasis is to control the sources of infection. In the present study, we identified a candidate diagnostic antigen-encoding gene, SjMRP1, the putative multidrug resistance protein 1 gene, by screening a cDNA phage display library from 44-day-old S. japonicum worms using IgGs from goat, cattle, and buffalo infected with S. japonicum. We cloned and expressed the fragment of SjMRP1 and subsequently evaluated the diagnostic potential of the recombinant protein rSjMRP1. In the enzyme-linked immunosorbent assay of rSjMRP1 (rSjMRP1-ELISA), the sensitivity in goat, cattle, and buffalo was 95.6% (86/90), 100% (22/22), and 90% (81/90), respectively, and the specificity was 100% (30/30) in goat and cattle and 96.67% (29/30) in buffalo. These results were not significantly different from soluble egg antigen (SEA)-ELISA results. Notably, rSjMRP1-ELISA has no cross reaction with Haemonchus contortus, a most common nematode seen in goat and bovine in China, in 13 infected goats, and with Orientobilhazia turkestanica, which is genetically under Schistosoma, in 36 infected goats; whereas SEA-ELISA showed false positive rate of 15.38% and 83.33% in the two respective animal groups. The results obtained here suggest that rSjMRP1 may be used for diagnosis of S. japonicum infection of domestic animals.