Studies on the serology of schistosomiasis. II. The in vitro activity of cercariae of Schistosoma mansoni in sera of normal and antigen-injected animals

Abstract

1. 1. The in vitro activity of cercariae of Schistosoma mansoni was tested in the sera of the cat, cow, chicken, dog, goat, guinea pig, hamster, horse, man, monkey, mouse, pig, pigeon, rabbit, rat, sheep, squirrel, and steer. Except for human, squirrel and steer all species were injected with a homogenate of cercariae of S. mansoni and the sera tested for the presence of a pericercarial membrane (CHR of Vogel and Minning, 1949a). 2. 2. The stored normal serum of rat, guinea pig, chicken, dog, steer, pig, sheep, and goat was cercaricidal. The sera of all other species tested inactivated cercariae. The sera of cow and horse agglutinated cercariae. After heating normal sera at 56 °C for 30 minutes the cercaricidal and inactivating properties of normal sera were lost and eight additional species agglutinated cercariae. 3. 3. Agglutination of cercariae was seen in all but rat sera during the course of injection of antigen. In some sera, the CHR prevented the agglutination of cercariae. 4. 4. The normal sera of all animals tested were negative for pericercarial membrane formation, (CHR of Vogel and Minning, 1949b). During the course of six intravenous injections of a cercariae antigen all species became positive for CHR. The appearance of the CHR after the start of antigen injections varied considerably from species to species. 5. 5. No correlation could be made between the in vitro response of serum of naturally resistant hosts, hosts with a high degree of resistance and susceptible hosts against cercariae of S. mansoni and the ability of these hosts to form antibodies after injection with a cercarial antigen. The sera of naturally resistant hosts and hosts with a high degree of resistance for S. mansoni were more cercaricidal than the sera of hosts susceptible to infection with S. mansoni.