Immune response of Clun Forest sheep to vaccination with membrane glycoproteins from Haemonchus contortus.

Clun Forest lambs were injected with a fraction containing integral membrane glycoproteins derived from the intestinal microvilli of Haemonchus contortus in two equal doses of 0.5, 5, 50 or 500 micrograms protein and then challenged with 10,000 infective larvae. The time-course of serum specific antibody responses were determined. Compared to the adjuvant control group, the animals injected with 1000 micrograms protein were better than 84% protected and those injected with 100 micrograms, better than 95% protected by all criteria. For these two groups parasite egg output was reduced 99% on average over the patent period. Two of the animals injected with 10 micrograms protein were partially protected, with 86% reduction in egg output. Two animals in the group injected with 1 microgram protein also showed partial protection. Antibody level correlated with protection.