Immunization against schistosome infection in rhesus monkeys with living worms by intraperitoneal injection

Abstract

Immunization was performed against Schistosoma mansoni or S. japonicum infection in rhesus monkeys either with living schistosomula and young adult worms or with only schistosomula by intra-peritoneal injection. Each monkey was immunized four or more times and subsequently challenged. A significant degree of resistance against the challenge was produced. The injected worms lived in the peritoneal cavity for a short period, then died and disintegrated therein, thus obviating their inhabiting the circulatory system. The functional antigens were evidently derived from the metabolic products of the immunizing living schistosomes in the peritoneal cavity.The results of the present experiment indicate that the main immune mechanism induced by the intraperitoneal injection of living schistosomula and young adult worms is that which inhibits the development of the late stage of schistosomula and the early stage of adults which have originated from the challenge infection. This immune mechanism may be induced by the functional antigens either from both the schistosomula and adult worms or from the schistosomula alone.