title: Aspartyl proteases from the intestinal brush border of Haemonchus contortus as protective antigens for sheep.
abstract: A novel pepsin-like aspartyl protease was identified as a component of Haemonchus galactose-containing glycoprotein (H-gal-GP), which is an integral membrane glycoprotein complex located on the intestinal cells of Haemonchus contortus, and a highly protective antigen for sheep. This molecule, designated HcPEP2, showed 50% sequence identity with a previously described aspartyl protease from H-gal-GP known as HcPEP1. Fractions of H-gal-GP, either containing both HcPEP1 and 2 or other lower molecular weight components of the complex, were evaluated as protective antigens in immunization - challenge trials in sheep. When separated from the rest of the complex by gel filtration in 8 m urea, the HcPEP1 and 2 fraction significantly reduced H. contortus egg counts by 48% and worm numbers by 36%, but the lower molecular weight components were not significantly protective. However, the HcPEP1 and 2 fraction did not protect if electro-eluted from SDS-dissociated H-gal-GP, nor did bacterially expressed recombinant HcPEP1, suggesting that conformational epitopes are important for inducing immunity.
authors.affiliation: Moredun Research Institute, Penicuik, Midlothian, UK.
authors.forename: W D
authors.initials: WD
authors.lastname: Smith
authors.forename: P J
authors.initials: PJ
authors.lastname: Skuce
authors.forename: G F J
authors.initials: GF
authors.lastname: Newlands
authors.forename: S K
authors.initials: SK
authors.lastname: Smith
authors.forename: D
authors.initials: D
authors.lastname: Pettit
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000947:Antigens, Helminth / Q000235:genetics / Q000302:isolation & purification; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D018509:DNA, Helminth / Q000235:genetics; D010450:Endopeptidases / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D000939:Epitopes / Q000235:genetics / Q000302:isolation & purification; D006188:Haemonchiasis / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D006189:Haemonchus / Q000201:enzymology* / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D015801:Helminth Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D007422:Intestines / Q000201:enzymology / Q000276:immunology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D008871:Microvilli / Q000201:enzymology / Q000276:immunology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology* / Q000517:prevention & control
chemical_list: D000947:Antigens, Helminth; D018509:DNA, Helminth; D000939:Epitopes; D015801:Helminth Proteins; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C119206:galactose-containing glycoprotein, Haemonchus contortus