PRODUCTION OF VACCINES AGAINST GASTROINTESTINAL NEMATODES OF LIVESTOCK

Three international collaborations involving Australian research scien tists are currently developing vaccines against Haemonchus, Trichostro ngylus and Ostertagia parasites using recombinant DNA technology. The variety of protective antigens identified can be classified as 'conven tional' (stimulate naturally acquired immunity) or 'novel'/'covert'/'c oncealed' (protective once immunity is induced by vaccination). To dat e, the most gratifying progress has resulted in 60-90% protection agai nst Haemonchus and other blood-sucking parasites (e.g. ticks) using no vel antigens, where high titres of serum antibody ingested by feeding worms leads to their demise. A great deal of research effort is unrave lling the complexity of naturally acquired immunity so that convention al antigens, which may be the principal means of removing 'mucosal-bro wsing' parasites, may be formulated and delivered to achieve optimal e fficacy. This work reveals that to remove early stages of parasites be fore they take up residence, deliberate induction of hypersensitivity responses akin to asthma, may be a desirable goal for vaccines and tha t the two models have much in common.