Mapping of linear B-cell epitopes on the 14-kDa fatty-acid binding protein of Chinese Schistosoma japonicum.

The 14-kDa fatty-acid binding protein (FABP) of schistosomes is of recognised importance as a potential vaccine and/or drug target against schistosomiasis, but little is known of its antigenicity. In this study, we have identified and compared linear B-cell epitopes present on the FABP of Chinese strain Schistosoma japonicum, using sera obtained from experimentally infected mice, or from mice immunised with the functionally active recombinant antigen (rSjFABP). Sera from three strains of mice, CBA, C57BL/6 and BALB/c, representing different genetic backgrounds, were reacted with a series of overlapping peptides in epitope-scanning studies. Sera from experimentally infected mice reacted predominantly with peptides 9-12, encoding amino acids 91-132, in the C-terminal region of the molecule. This was in contrast to sera from mice immunised with rSjFABP, which reacted predominantly with peptides 4-9, encoding amino acids 41-101, in the central portion of the molecule. The results presented here describing the epitope mapping of this molecule may prove important in research aimed at further defining immune responses to schistosomal antigens. They indicate that epitopes recognised during vaccination with functionally active rSjFABP, at least in the murine model, differ from those recognised during natural infection.