Demonstration of juvenile-specific antigens of Fasciola hepatica.

A hyperimmune serum was raised in rabbits against soluble antigens of Fasciola hepatica metacercariae. This was subsequently absorbed with antigens from adult flukes and examined by immunoelectrophoresis (IEP) and by an indirect fluorescent antibody test (IFAT). When the absorbed antiserum was tested with F. hepatica metacercarial homogenate and adult homogenates by IEP, three distinct arcs appeared against the metacercarial homogenate and none against the adult homogenate. When tested by IFAT against a developmental series of flukes obtained from mice, the absorbed antiserum was positive on surfaces of whole flukes up to 4 days postinfection (PI) and on the tegument of sectioned flukes up to 7 days PI. Thus juvenile-specific antigens were demonstrated in the tegument of young (up to 7 days in mice) F. hepatica.