In vivo and In vitro Studies Demonstrating the Presence and Turnover of Host Substances on the Tegument of Mesocestoides corti (Cestoda) Tetrathyridia

In vivo xenogenic transfer and in vitro indirect immunofluorescence (IIF) experiments demonstrated the presence of host substances on the tegument of Mesocestoides corti tetrathyridia from rats and mice. Serum from mice infected with larvae from rats contained antibodies against rat serum and erythrocytes. These animals harbored significantly fewer worms in their peritoneal cavities and livers than did mice infected with worms from mice. Prior immunization with rat antigens specifically diminished larval populations in mice receiving parasites from rats, but did not affect populations in mice receiving worms from mice. Immunization with Freund's complete adjuvant did not affect larvae from either rats or mice transplanted into mice. Experiments with IIF using antisera against rat and mouse antigens allowed the detection of host substances on the larval tegument. Living larvae redistributed and shed fluorescein-labelled particles from their tegument. This shedding was inhibited at 4 C. In vivo xenogenic transfer experiments showed that tetrathyridia were capable of losing substances from donor hosts and acquiring substances from recipient hosts. In vitro maintenance of larvae in media containing xenogenic host serum demonstrated that this loss and acquisition occurred whether normal or M. corti-infected host serum was added to the media. The acquisition of host substances by this parasite appears not to be caused exclusively by the binding of anti-M. corti antibodies.