Authors

Discussion

Haemonchus contortus is a highly pathogenic, blood feeding gastrointestinal nematode of small ruminants. Proteins isolated from the gut membrane of H. contortus adult worms provide protection to lambs from ten weeks of age, which is highly desirable. A native, gut membrane protein vaccine, Barbervax, is now available in Australia, providing reductions in worm burdens of 70-95%. While highly effective, a vaccine incorporating recombinant forms of the proteins would help widen commercial production. Previous attempts to vaccinate with recombinant H. contortus proteins expressed in bacteria or yeast have failed to protect against infection. The aims of this project are to identify correlates of immunity to the H. contortus gut antigen vaccine. To achieve this, the antibody responses in groups of lambs were compared following vaccination with 1) Barbervax vaccine 2) recombinant vaccine using C. elegans-expressed proteins and 3) challenge control group. Data shows that the best protected sheep are vaccinated with Barbervax. Early recognition of antigens H11 and H-gal-GP and high antibody titres are detected in sheep showing greatest reductions in egg count. Antibody isotype responses and glycan recognition are being investigated. Understanding the immune mechanism by which the successful Barbervax vaccine provides protection should help in development of a future recombinant vaccine against H. contortus