Cross Protection in Infections Due to Schistosoma mansoni Using Tegument Antigens of Fasciola hepatica

Immunity to infection due to Schistosoma mansoni was induced in CBAI J mice by us-ing a tegument antigen from Fasciola hepatica worms. Multiple immunizations resulted in up to 830/0 higher worm-burden reductions than did single immunizations. Th.e vac-cine also had an adverse effect on the fecundity of female schistosome worms, whIch re-sulted in a lower number of eggs per worm pair recovered from the livers of infected mice. Mice immunized once with tegument antigens of F. hepatica survived lethal doses of S. mansoni cercariae for longer periods than did control mice. These results-lowered worm-burden recoveries, lower egg burdens per worm pairs resulting in lesser numbers of granulomatous lesions, and longer survival times- in immunized mice sug~est that protection against infection due to S. mansoni is possible using soluble antIgens as vaccines. We have previously demonstrated that mice and hamsters inoculated with subcellular fractions of Fasciola hepatica worms acquired resistance to challenge infection with Schistosoma mansoni cer