Evaluation of the integral membrane proteins of juvenile fasciola gigantica for control of ovine fascioliasis

Abstract

Phase separation of Fasciola gigantica metacercarial homogenate was carried out using non-ionic detergent Triton X-114. The protein composition of the homogenate (FgWh), detergent phase (FgTx) and the aqueous phase (FgAq) were analyzed using Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDSPAGE) and gel were stained for proteins by coomassie blue. More than 21 proteins were demonstrated in the homogenate distributed between 10-200 kDa molecular weight range. Distributed within the same range, were more than 16 proteins in the detergent phase. the aqueous phase contained more than 19 proteins. Two proteins of about 58 and 75 kDa in the homogenate, separated strongly in the detergent phase. Sheep were immunized 3 times in 4 weeks with the homogenate (FgWh), detergent phase (FgTx) and aqueous phase (FgAq). They were then challenged with 150 metacercariae of Fasciola gigantica. Immunization induced high antibody responses to several antigens in the homogenate and the phase fractions in contrast to the response observed in t~e. control animals after challenge. The control group mounted antibodies to 12 protein in both FgWh and FgTx and 7 in FgAq 2 weeks after infection. Throughout the study, the progress of fluke infection was monitored by measuring the extent of liver damage by ana lysing serum glutamate dehydrogenase and gamma glutamyl transferase. Faecal egg counts and packed cell volume were used to asses patency and development of anaemia respectively. Sheep immunized with FgTx had low serum liver enzyme activity, delayed patency, lower mean faecal egg counts and reduced tendency towards developing anaemia compared with FgWh, FgAq and the control group. This was complementary to the lower fluke burden in this group relative to the controls giving a reduction percentage of 87% as compared to the controls. The result suggest that the detergent phase has one or more protein components that significantly reduce the effects of Fasciola gigantica infection in sheep.