Human resistance to Schistosoma mansoni is associated with IgG reactivity to a 37-kDa larval surface antigen

The aim of this work was to determine whether human resistance to Schistosoma mansoni was associated with increased antibody reactivity to certain larval surface Ag. To this end, young residents of a hyperendemic area were selected for their low or high susceptibility to reinfection after parasitologic cure, and the reactivity of their sera to individual larval surface Ag was determined at different times before and after treatment. The data showed that six Ag: 202, 165, 90 to 92, 85, 72, and 37 kDa are the principal targets on the larva of IgG in the sera of resistant subjects. The comparative study, by immunoblotting and ELISA on purified Ag, of the sera from high and low susceptibility subjects indicates that IgG reactivity toward the 37-kDa Ag may be associated with resistance. This work and ongoing vaccination trials carried out in mice suggest that the 37-kDa Ag may have vaccinating potentials.