The soluble antigenic proteome of Schistosoma japonicum cercariae and schistosmula

Objective To screen and identify specific antigenic proteins of Schistosoma japonicum cercariae and schistosomula using immunproteomics approaches. Methods Soluble antigenic proteins of Schistosoma japonicun cercarie (SCAP) and 15 days lung-stage schistosomulum (SLAP) were separated by two-dimensional electrophoresis (2-DE). For each sample, three gels were run in parallel with one gel for silver stain and the other two gels for Western blot using Schistosoma japonicum infected rabbit sera and normal rabbit sera separately. The specific antigenic protein spots were determined on the membrane of Western blot. The matched antigenic protein spots on the sliver stained gels were subsequently analysed by MALDI-TOF/TOF-MS/MS respectively. Results 94 and 68 positive spots were visualised respectively on the membranes of 2-D Western blot of SCAP and SLAP, incubated with Schistosoma japonicum infected rabbit sera. There were 33 and 31 precisely matched protein spots on the corresponding sliver stained gels of SCAP and SLAP, separately. All SCAP protein spots were identified successfully with MALDI-TOF/TOF-MS/MS and NCBI database retrieval while 68.2％ (15/22) of SLAP were confirmed. 62.5％ of antigenic proteins of SCAP were protease and that of SLAP was 36.4％. Two antigenic proteins existed both in SCLP and SLAP. Conclusions 2-DE could efficiently separate proteins of SCAP and SLAP and 2-D Western blot could screen specific antigens very well, but the matching rate between positive spots on 2-D Western blot and protein spots on 2-DE silver stained gels were low, and low-abundant antigenic proteins were easily missed to be detected. The antigenic proteomes were significantly different between SCAP and SLAP. Key words: Schistosoma japonicum;  Antigen;  Proteome