IMMUNIZATION OF GUINEA-PIGS AGAINST DICTYOCAULUS-VIVIPARUS USING ADULT ES PRODUCTS ENRICHED FOR ACETYLCHOLINESTERASES

The adult ES products of Dictyocaulus viviparus are a source of protec tive antigens against challenge in the guinea pig laboratory model. Hi gh levels of acetylcholinesterase (AChE) activity are present in these products and these enzymes are immunogenic in infected cattle. Here, the potential role of these enzymes in protective immunity was investi gated using a fraction enriched for AChE to immunise guinea pigs. The antibody response stimulated by immunisation with AChE-enriched ES pro ducts and the worm burdens obtained following challenge with infective larvae were compared with those in animals immunised with whole ES pr oducts and challenge controls. The AChE-enriched preparation stimulate d high levels of enzyme-specific antibody in immunised animals, which was not the case for those which received unfractionated ES products. Worm burdens of guinea pigs which received the AChE-enriched fraction were significantly lower than those obtained in adjuvant controls. The animals which received the unfractionated ES products were not signif icantly protected against challenge. These results suggest that AChEs may be potential candidates for incorporation in a sub-unit vaccine ag ainst D. viviparus.