Host-Parasite Relationships in Echinococcosis

Abstract

Summary A standardized indirect hemagglutination test with block titration of the antigen was used to study some of the properties of the antigen present in hydatid cyst fluid and in fractions prepared from cyst fluids. The animal host or organ source of fertile cyst fluids is, with two unexplainable exceptions, without effect on the test. The antigen in hydatid cyst fluid is not produced solely by the scolices. Fluid from Taenia hydatigena cysticerci is also antigenic; this antigen is, therefore, group specific. T. hydatigena fluid also cross-reacts with hydatid antisera on agar-gel diffusion plates. Saline extracts of scolices were non-antigenic, and evidence is presented that non-antigenic protein extracted from scolices blocks antigen adsorption sites on tanned erythrocytes. Electrophoretic, infrared spectrophotometric and serological examinations of cyst fluid fractions indicate that the antigen, at least as derived from T. hydatigena cysts, is a globulinoid protein or a substance which separates with it. The antigen from HCF is stable at -20°C for at least 5 months and at 70°C for 25 minutes. It is completely inactivated at 100°C for 5 minutes. The antigen in HCF is adsorbed on Seitz filter pads and apparently can be eluted from pads with HCl.