Praziquantel treatment of individuals exposed to Schistosoma haematobium enhances serological recognition of defined parasite antigens

Background. Schistosomiasis is a major parasitic disease affecting 1200 million people in the developing world, and 400 million people are at risk for infection. This study aimed to identify and compare proteins recognized by serum samples from schistosome-exposed individuals before and after curative praziquantel treatment.

Methods. Proteins recognized by pooled serum samples from Schistosoma haematobium-exposed Zimbabweans were determined by 2-dimensional Western blotting and identified by mass spectrometry.

Results. Serum samples recognized 71 spots, which resolved to 26 different characterized proteins. Eleven of these proteins have not previously been shown to be immunogenic in natural human infection or in experimental models of schistosomiasis, making them novel antigens in the parasite. Pretreatment serum samples recognized 59 spots, which resolved to 21 different identified proteins. Posttreatment serum samples recognized an additional 12 spots, which resolved to 8 different identified proteins. Of these 8 proteins, 3 had putative isoforms recognized before treatment, and 5 (calreticulin, tropomyosin 1, tropomyosin 2, paramyosin, and triose phosphate isomerase) did not.

Conclusions. This study is the most comprehensive characterization of S. haematobium antigens to date and describes novel antigens in all schistosome species. Posttreatment results are consistent with praziquantel treatment inducing quantitative and qualitative changes in schistosome-specific antibody responses.