A dominant B‐cell epitope on the 22 kDa tegumental membrane‐associated antigen of Schistosoma japonicum maps to an EF‐hand calcium binding domain

The 22 kDA tegumental surface membrane‐associated antigen of schistosomes is of recognized importance in immunity to schistosomiasis. Here, we have defined linear B‐cell epitopes on the recently cloned and expressed recombinant Schistosoma japonicum 22 kDa antigen (reSj22), using mice immunized with this molecule. Sera from three strains of mice, CBA, C57BL/6 and BALB/c, representing different genetic backgrounds, were reacted with a series of overlapping synthetic peptides in epitope‐scanning studies. The predicted hydrophilic N‐terminal domain was found to be highly immunogenic, containing several sequences that were strongly recognized by all strains of mice. The most dominant epitope identified, corresponding to peptide 6, was located in a region previously identified as an EF‐hand calcium binding domain. In contrast, the more hydrophobic C‐terminal region of the molecule was poorly recognized, with the exception of a single peptide encoding residues 121–140 that was recognized by CBA and C57BL/6 but not BALB/c mice, suggesting that the latter epitope was genetically restricted between the strains. The data presented here describing the epitope mapping of this molecule may prove important in research aimed at further defining immune responses to schistosomal antigens.