Immunogenicity of synthetic peptides from the Sm31 antigen (cathepsin B) of the Schistosoma mansoni adult worms

The chemical synthesis of peptides may simplify the production of molecules for diagnosis of Schistosoma mansoni. Seventeen polymeric, 20-amino acids long, peptides comprising the entire Sm31 molecule of the adult worm, were synthesized under the t-boc strategy and their immunogenicity was evaluated. Of these, 10 peptides were immunogenic in rabbits. The peptides containing the sequence Gly74-Ser93 (peptide IMT-172) and the sequence Val154-Ala173 (peptide IMT-180) were responsible for the recognition of the Sm31 molecule by Western blot. This was confirmed by the specific inhibition of recognition of each molecule with the homologous peptide. Additionally, antibodies against these peptides strongly fixed to the adult worm gut. The present results, together with the strong immunogenicity shown for the adult worm 31 kDa antigen, establish the basis for the development of an immunodiagnostic method using synthetic peptides.