Purification and partial immunochemical characterization of a low molecular mass, diagnostic Echinococcus granulosus immunogen for sheep hydatidosis.

A hydatid specific antigen of 8 kDa molecular mass was affinity-purified from crude hydatid cyst fluid. Some of the epitopes recognised by antibodies in the sera from sheep with hydatidosis were periodate-sensitive. The purified 8 kDa antigen was observed to be a thermo-stable glycoprotein in its immunochemical characteristics. By immunofluorescence on acetone-fixed protoscolices anti-8 kDa monospecific IgG antibodies indicated the existence of the 8 kDa molecule on the hooklets of protoscolices. The purified antigen was used in an enzyme-linked immunosorbent assay for the detection of specific antibodies in sera from sheep hydatiodosis. Eighteen (90%) of 20 sera from sheep hydatidosis had antibodies to purified 8 kDa antigen while none of the sera from other parasitic infections or uninfected animals had any detectable levels of antibodies to 8 kDa antigen. Thus, the data on localization and recognition of hydatid specific 8 kDa molecule suggested that this may be one of the major molecules for specific immunodiagnosis and for modulating the hydatid disease process in infected hosts.