title: Immunological similarity between Schistosoma and bovine cathepsin D.
abstract: IgG antibodies from sera of rabbits immunized with a mixture of three synthetic peptides of highly conserved surface-exposed sequences between Schistosoma japonicum and S. mansoni cathepsin D, and a rabbit anti-bovine cathepsin D serum strongly recognized a 45 kDa molecule on immunoblots of adult S. mansoni worm saline extracts (AWSE). This recognition was abolished by immunoadsorption with two of the three selected peptides. The anti-peptide antibodies fixed onto Protein A-Sepharose specifically immunoprecipitated a S. mansoni AWSE component that was able to degrade bovine hemoglobin at pH 3.8. This reaction was inhibited by 7 microM pepstatin A, a classical aspartyl protease inhibitor, suggesting that the parasite cathepsin D was immunoprecipitated. The anti-peptide antibodies also recognized on a dot-blot assay a purified, commercially obtained bovine cathepsin D preparation but not the purified human counterpart. On the other hand, the anti-bovine cathepsin D serum recognized the two above-mentioned schistosome peptides. In addition, S. mansoni-infected patient sera recognized on immunoblots the bovine but not the human cathepsin D. These results, together with a comparative analysis of the selected peptide sequence regions between the schistosome and the two mammal enzymes, allowed us to pinpoint to one amino acid the cross-reactivity between parasite and bovine cathepsin D and the lack of it with human cathepsin D. This difference might be of relevance for immunodiagnosis.
authors.affiliation: Laboratorio de Inmunoparasitologia, Centro de Microbiologia y Biologia Celular, I.V.I.C., Apdo. 21827 Caracas 1020 A, Venezuela.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Valdivieso
authors.forename: Henry
authors.initials: H
authors.lastname: Bermudez
authors.forename: Johan
authors.initials: J
authors.lastname: Hoebeke
authors.forename: Oscar
authors.initials: O
authors.lastname: Noya
authors.forename: Italo M
authors.initials: IM
authors.lastname: Cesari
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D000909:Antibodies, Helminth / Q000276:immunology; D015153:Blotting, Western; D002402:Cathepsin D / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism; D002417:Cattle; D002846:Chromatography, Affinity; D006224:Cricetinae; D003429:Cross Reactions; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D008297:Male; D011233:Precipitin Tests; D011817:Rabbits; D012549:Schistosoma japonicum / Q000201:enzymology* / Q000276:immunology; D012550:Schistosoma mansoni / Q000201:enzymology* / Q000276:immunology / Q000648:ultrastructure
chemical_list: D000909:Antibodies, Helminth; D007106:Immune Sera; D002402:Cathepsin D