Immunoprophylaxis against Fasciola hepatica in rabbits using a recombinantFh15 fatty acid-binding protein

Previous studies of ours have demonstrated that a recombinant protein (Fh15 ) related to fatty acid-binding proteins did not induce significant protect ion in rabbits challenged 2 or 4 wk postimmunization over nonimmunized cont rols. In the current study, rabbits were immunized with Fh15 and challenged with Fasciola hepatica metacercariae 12 and 20 wk later. In the current st udy in which longer lag periods for challenge infection after the second im munization were used, worm burden reductions compared to adjuvant controls were a significant 43% and 76%, respectively. Importantly, rabbits immunize d with Fh15 had significant numbers of immature flukes, 66% in the 12-wk pe riod and 84% in the 20-wk lag period as compared to controls. In addition, liver lesions were clearly diminished in the Vaccinated rabbits. Enzyme-lin ked immunosorbent assay absorbance values showed that immunized rabbits dev eloped high antibody levels to Fh15 from 8 wk after the first immunization and did not increase after challenge. These results suggest that a recombin ant F. hepatica molecule related to fatty acid-binding proteins induces pro tective (worm burden reductions), anti-fecundity (immature flukes), and ant i-pathology (less liver lesions) effects in rabbits and may serve as a mode l for the immunoprophylaxis of fascioliasis.