PROTECTION STUDIES WITH INTEGRAL MEMBRANE-FRACTIONS OF HAEMONCHUS-CONTORTUS

Techniques for targetting glycoproteins integral to the luminal membra ne of the intestinal cells of Haemonchus contortus were used to isolat e fractions of whole parasites with protective antigen potential. Shee p immunization trials with various candidate fractions revealed one wh ich selectively bound to lectins with specificity for N-acetylgalactos amine and which reduced mean challenge worm burdens by up to 72% and m ean faecal egg counts by up to 93%. The luminal surface of the intesti nes of the Haemonchus recovered from sheep immunized with this antigen were coated with host immunoglobulin, suggesting that the protective effect was due to antibodies interfering with the function of the gut. Further biochemical characterization of this fraction, which has been termed Haemonchus galactose-containing glycoprotein complex (H-gal-GP complex), showed that it could be distinguished from previously descr ibed protective antigens of this parasite and that it was only detecta ble in detergent extracts of the worms.