Protection against Fasciola hepatica in rats with adult fluke antigen in Freund's adjuvant: influence of antigen batch, antigen dose and number of sensitising injections.

Protection of rats against Fasciola hepatica infection induced by intraperitoneal injection of adult fluke antigen in Freund's adjuvant was dependent on the batch of antigen. Relatively modest protection of 41 per cent and 55 per cent provided by some batches at one dose could be improved to 65 to 84 per cent and 86 per cent respectively by increasing the amount of antigen used for sensitisation. Protection was found to require at least two sensitising injections. Subcutaneous sensitisation with adult fluke antigen in Freund's adjuvant did not protect, whereas when this was given in conjunction with intraperitoneal injections of saline in Freund's adjuvant protection was achieved.