Establishment of Schistosoma japonicum calpain-specific mouse T cell hybridomas and identification of a T cell epitope that stimulates IFNgamma production.

Calpain is a calcium-dependent cystein protease, and the homologues of schistosome are known as one of vaccine candidate molecules against schistosomiasis. Here, we established two IL-2 producing T cell hybridoma cell lines specific for Schistosoma japonicum calpain, to identify T cell epitope(s) on the molecule. Overlapping 15mer oligopeptides of calpain were synthesized and tested for their stimulatory abilities to the hybridomas. As a result, epitopes recognized by the two hybridoma lines were the same: EQLKIYAQRC. Spleen cells from calpain multiple antigenic peptide (MAP)-immunized BALB/c mice produced IFNgamma upon stimulation with MAP or soluble worm antigen preparation (SWAP). The identification of the T cell epitope to stimulate Th1 response will contribute to the proper design of synthetic vaccines, evaluation of their protective potentials and elucidation of protective mechanisms in murine experimental schistosomiasis.