ABSTRACT
There is an increasing awareness of fasciolosis as an important human and veterinary disease. In order to study the humoral inmune response of bovines, 5-month old calves were experimentally inmunized using 1000 ç irradiated metacercariae per animal, and challenged six weeks later with 500 normal ones per calf. Profiles of antibody responses of non inmunized animals following challenge, measured by ELISA, using both excretion/secretion ans somatic antigens, showed a sharp increase in antibody titres in the first 3 weeks post-infection which were maintained throughout the infection. Animals which instead were inmunized with inactivated parasites had similar antibody responses, but the antibody titres were higher. No booster effect was observed when these inmunized animals were challenger. Result of western blot analysis are consistent with these observations: antibodies against high molecular weight parasite-specific bands, ranging from 72,5 to 40 KD, appeared in week 2 PI in inmunized animals, and were mantained throughout infection, importanfly, inmunization resulted in a 84,2 percent reduction in parasite burden, indicating that high circulating antibody titres against these antigens probably are involved in a protective response. The results presented here indicate that, irradiated metacercariae of fasciola hepatica can be used as useful tool to generate a normal antigenic stimulus for the development of circulation antibodies, and toidentify antigens invloved in triggering a protective inmune response