Purification and characterization of surface-associated proteins from adult Haemonchus contortus

Extrinsic radioiodination experiments have shown that male and female adults of Haemonchus contortus (BPL strain) express a stage-specific set of surface-associated proteins with apparent molecular mass values of 30, 58, 81, and 143 kDa. A quantitatively different pattern of iodinated surface proteins is expressed by adults of the PPR strain of H. contortus, whereas the pattern of iodinated proteins expressed by Haemonchus similis is qualitatively distinct (38, 68, and 121 kDa). The 58-, 81-, and 143-kDa proteins of the BPL strain are glycosylated, whereas the 30-kDa protein is not. The binding of wheat germ agglutinin to the surface glycoproteins was inhibited by the trimer of N-acetylglucosamine (N,N,N-triacetylchitotroise) but not by the monosaccharide, indicating the presence of chitin-like homopolymers. The carbohydrate portion of the 58-kDa protein is N-linked and accounts for 30% of its apparent mass. Under nonreducing conditions, the 58-kDa glycoprotein forms a high molecular mass polymer that is unable to penetrate a 10% acrylamide gel. The 143- and 81-kDa surface glycoproteins were not hydrolyzed by either N- or O-glycanase, indicating unusual modifications to the saccharide-linkage and rendering it resistant to glycosidase digestion. The 30-, 58-, and 143-kDa purified surface proteins produced distinct peptide maps with Staphylococcus aureus V8 protease.