Biochemical and Molecular Characterization of Some Biologically Important Fasciola hepatica Proteins

Abstract

Fascioliasis, caused by trematodes of the genus Fasciola, is one of the most important diseases of farmed ruminants, beside its high prevalence in human in temperate and tropical zones. The appearance of Fasciola hepatica populations that are resistant to common flukicidal drugs means that new methods of treatment will soon be required. The future prospect of anti-liver fluke vaccines requires identification of prime fluke targets for which new vaccine can be developed.

In the present study, F. hepatica whole worm homogenate (Fhwwh) specific antigens were first identified by SDS-PAGE then fractionated by model 491-prep cell fraction (BIO-RAD). The Fhwwh and the separated fractions were used in enzyme linked immunoelectrotransfer blot (EITB) to identify the antigen(s), which induce antibody formation in human fascioliasis. The pattern of antigens recognized by normal human sera, and that recognized by sera from infected subjects were also compared. The main antigenic polypeptides recognized were within 25-29 kDa and 12-14 kDa. The antigen(s) of 25-29 kDa was one of the most prominently recognized by all of the infected subjects followed by 12 kDa antigen.

To further characterize and evaluate these low M, antigens, experiments were made to isolate those polypeptides from several 491• prep cell fractions runs. The isolated fractions were used to induce lymphoproliferative responses of peripheral blood mononuclear cells (PBMC) of infected subjects. Results showed that the 25-29 kDa antigen(s) induced significant lymphoproliferative response of PBMC, followed by the 12 kDa antigen. The 25-29 kDa antigen(s) was thus considered as a target antigen(s). Further biochemical studies proved that this target antigen(s) is a glycoprotein. The isolated target antigen(s) was used in the generation of antibody probes to aid in the