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-purifi ed from crude hydatid cyst fluid. Some of the epitopes recognised by a ntibodies in the sera from sheep with hydatidosis were periodate-sensi tive. The purified 8 kDa antigen was observed to be a thermo-stable gl ycoprotein in its immunochemical characteristics. By immunofluorescenc e on acetone-fixed protoscolices anti-8 kDa monospecific IgG antibodie s indicated the existence of the 8 kDa molecule on the hooklets of pro toscolices. The purified antigen was used in an enzyme-linked immunoso rbent assay for the detection of specific antibodies in sera from shee p hydatidosis. Eighteen (90%) of 20 sera from sheep hydatidosis had an tibodies to purified 8 kDa antigen while none of the sera from other p arasitic infections or uninfected animals had any detectable levels of antibodies to 8 kDa antigen. Thus, the data on localization and recog nition of hydatid specific 8 kDa molecule suggested that this may be o ne of the major molecules for specific immunodiagnosis and for modulat ing the hydatid disease process in infected hosts.