In an attempt to investigate the specific antigenic substance of Fasciola hepatica, Ouchterlony tests and immunoelectrophoretic analyses were carried out. Crude Fasciola antigen was prepared and fractionated by Sephadex G-200 column to Antigen I, II and III according to protein content. Crude antigens of Paragonimus westermani, Clonorchis sinensis and Paramphistomum sp. were also prepared for control and absorption study. Antiserum was prepared by injecting 0.5 ml of crude Fasciola antigen with same amount of complete Freund's adjuvant in rabbits, 10 times at an interval of l week. The results obtained in this study were as follows: Crude Fasciola antigen reacted with antiserum with 9 precipitin bands by Ouchterlony test and with 11 bands by immunoelectrophoresis. Cross reaction was observed between Paragonimus, Clonorchis and Paramphistomum antigens and anti-Fasciola rabbit serum respectively. By Ouchterlony test, 3-4 cross reacting bands were found. Anti-Fasciola sera which were absorbed with respective Paragonimus, Clonorchis and Paramphistomum antigens, reacted with Fasciola crude antigen. Ouchterlony test gave 5-6 precipitin bands. Further reaction between Fasciola antigen and antiserum absorbed with the above 3 antigens concomitantly gave 5 precipitin bands by Ouchterlony test and 7 bands by immunoelectrophoretic analyses. Fractionated Fasciola antigens (Antigens I, II and III) reacted with anti-Fasciola rabbit serum in immunoelectrophoresis. Antigen I, II and III gave 2, 3 and 5 precipitin bands respectively. Anti-Fasciola rabbit serum which was absorbed with 3 trematodes antigens gave, by immunoelectrophoresis, 1 band with Antigen I, 2 bands with Antigen II and III of Fasciola hepatica. From the above results, it is concluded that Fasciola hepatica possessed the specific antigenic substance not cross-reacted with other trematodes.
