A trial to produce an anti-schistosomal vaccine using heterophyid antigens.

Heterophyid metacercariae, crude and partially purified heterophyid antigens were given prior to S. mansoni infections in an attempt to produce a potent antischistosomal vaccine. Three main groups of albino mice were used. Each group after receiving the appropriate heterophyid antigen prior to S. mansoni infection was studied parasitologically as regards worm load and tissue egg count and histopathologically as regards granulomata number, size and cellular constituents as well as immunologically by the indirect immunofluorescent test. The results showed a reduction in worm burden recoveries and egg load resulting in lesser number of granulomata and diminution in size of granulomata as well as acceleration in their reaction together with inhibition of fluorescence. These results were more obvious in the group infected one month post heterophyid infection, as well as in mice immunized with the highest dose of crude heterophyid antigen (200 micrograms protein). However, a low dose of 50 micrograms of partially purified fractionated antigen gave the most evident results.