A MODEL SYSTEM FOR THE STUDY OF ANTIGEN SECRETION BY ADULT SCHISTOSOMA-MANSONI IN-VIVO

Schistosoma mansoni (6 weeks old) were surgically transferred from don or C57BI/6 mice to the hepatic portal veins of naive recipients of the same inbred strain. Between 70% and 100% of the parasites were alive 15 days later, and egg deposition was observed after transfer of worm pairs. The physiological status of the parasites was monitored by meas uring the levels of a schistosome gut antigen, circulating anodic anti gen (CAA), in the serum of the recipients. When only male worms were t ransferred, serum CAA levels increased slowly to a peak 9 days later, which was followed by a rapid decline. When worm pairs were transferre d, there was an early peak in serum CAA levels followed by a gradual d ecline, but these levels were always higher than those recorded after male-only transfer; in two mice the pattern was similar to that observ ed following receipt of male worms. More CAA and eggs were produced af ter transfer of paired versus separated worms. It was concluded that a lthough worm pairs can be successfully transferred, their physiologica l status may be sub-optimal. In contrast, male worms survive consisten tly well, and their transfer to a naive recipient provides a convenien t model with which to study the release of antigens by schistosomes in vivo.