CHARACTERIZATION AND LOCALIZATION OF SCHISTOSOMA-MANSONI CALRETICULINSM58

Recombinant Schistosoma mansoni calreticulin (SmCaR) was expressed in Escherichia coli, using the glutathione S-transferase fusion protein, and its Ca2+-binding capacity was determined. Results obtained by a Ca -45(2+) overlay technique showed that Ca2+-binding site(s) were presen t in the recombinant CaR indicating that proper folding of the protein was obtained using this system. An antiserum raised against the recom binant SmCaR showed that the native protein (Sm58) was expressed in al l stages of the life-cycle from cercariae to the adult worm and in the egg. However, SmCaR seems to be a developmentally regulated protein w hose expression can be used to study the post-transformational differe ntiation of the schistosomulum. Localization of SmCaR demonstrated tha t the majority of SmCaR was expressed in the epithelia of the digestiv e duct and in the genital organs. These results suggest that SmCaR, by regulating the Ca2+ concentration, may play an important role during cell proliferation. Finally the presence of SmCaR in miracidia and in the genital organs suggests that the antibody response directed agains t this protein could interfere in egg production.