The isolation of Fasciola gigantica-specific antigens and their use in the serodiagnosis of fasciolosis in sheep by the detection of circulating antigens.

The 17kDa and 69kDa polypeptide antigens which are specific to Fasciola gigantica were excised from polyacrylamide gels and used for the immunization of rabbits to raise monospecific antisera against these polypeptides. These sera were labelled with horseradish peroxidase and used for the detection of circulating 17 kDa and 69 kDa antigens by a direct enzyme-linked immunosorbent assay in the sera of sheep that were experimentally or naturally infected with F. gigantica. The 17 kDa antigen was detected in the sera of infected sheep as early as 1 week after infection and, following chemotherapy with oxyclozanide, negative seroconversion occurred 2 weeks later. The 69 kDa antigen was detectable as from the fourth week of infection and its detection ceased 3 weeks after chemotherapy. The serodiagnosis of F. gigantica, based on the detection of the 17 kDa antigen in sheep sera, was more specific and sensitive than that based on the detection of the 69 kDa antigen.