Saposin-like Proteins, a Multigene Family of Schistosoma Species, are Biomarkers for the Immunodiagnosis of Schistosomiasis Japonica

J Infect Dis. 2016 Oct 15;214(8):1225-34. doi: 10.1093/infdis/jiw188. Epub 2016 May 10.


Background: One major obstacle to schistosomiasis prevention and control is the lack of accurate and sensitive diagnostic approaches, which are essential for planning, targeting, and evaluating disease control efforts.

Methods: Based on bioinformatics analysis, we identified a multigene family of saposin-like protein (SAPLP) in the schistosome genomes. Schistosoma japonicum SAPLPs (SjSAPLPs), including recently reported promising biomarker SjSP-13, were systematically and comparatively assessed as immunodiagnostic antigens for schistosomiasis japonica.

Results: Two novel antigens (SjSAPLP4 and SjSAPLP5) could specifically react to serum samples from both S. japonicum-infected laboratory animals and patients. The sensitivities of SjSAPLP4, SjSAPLP5, and SjSP-13 for immunodiagnosis were 98% (95% confidence interval, 88.0%-99.9%), 96% (85.1%-99.3%), and 88% (75.0%-95.0%), respectively, and 100% (91.1%-100%) specificity was observed for the 3 antigens with enzyme-linked immunosorbent assay; there was no cross-reaction with clonorchiosis (0 of 19 patients), echinococcosis (0 of 20 patients), or trichinellosis (0 of 18 patients) for the 3 antigens. Antibodies to the 3 antigens could be detected in the serum samples of rabbits infected with 1000 cercariae as early as 3-4 weeks after infection.

Conclusions: These results suggest that SjSAPLP4 and SjSAPLP5 could serve as novel biomarkers for the immunodiagnosis of schistosomiasis japonica, which will further improve diagnostic sensitivity and specificity.

Keywords: Schistosoma japonicum; biomarkers; immunodiagnosis; saposin-like proteins; schistosomiasis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Helminth / immunology
  • Antigens, Helminth / immunology
  • Biomarkers / blood*
  • Female
  • Humans
  • Immunologic Tests / methods
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Multigene Family / genetics*
  • Multigene Family / immunology
  • Rabbits
  • Saposins / blood*
  • Saposins / immunology*
  • Schistosoma japonicum / genetics
  • Schistosomiasis japonica / blood
  • Schistosomiasis japonica / diagnosis*
  • Schistosomiasis japonica / immunology*
  • Schistosomiasis japonica / parasitology
  • Sensitivity and Specificity


  • Antibodies, Helminth
  • Antigens, Helminth
  • Biomarkers
  • Saposins