ATTEMPTS TO IMMUNIZE RATS AGAINST INFECTION WITH FASCIOLA-HEPATICA USING INVITRO CULTURE ANTIGENS FROM NEWLY EXCYSTED METACERCARIAE

Immunization of rats against F. hepatica was attempted using the culture products obtained from the in vitro cultivation of newly excysted metacercariae. Three culture regimes were chosen: medium NCTC 135 for 48 h; NCTC 135 + 20% fetal calf serum (FCS) for 47 h; NCTC 135 + 20% FCS for 14 days. The used culture medium from each of these regimes was concentrated, mixed with adjuvant and injected s.c. into rats. Similarly treated unused culture media was used in control rats. The rats were challenged with an oral dose of 20 F. hepatica metacercariae 35 days later and autopsied 96 days after the start of the experiment. The bile duct fluke burdens in those rats which had received the culture antigens did not differ significantly from those in the control groups.