title: Immunocapture of circulating Schistosoma mansoni cathepsin B antigen (Sm31) by anti-Sm31 polyclonal antibodies.
abstract: Adult Schistosoma mansoni parasites have the capacity to degrade ingested host hemoglobin and other host plasma proteins by using a series of gut proteolytic enzymes, including cathepsin B; this enzyme is released to the host intravascular environment during regurgitations of adult worms. Cathepsin B becomes thus a circulating parasite component that has been shown to be specifically recognized as the Sm31 antigen by antibodies present in most S. mansoni infected patients. Taking advantage of this immunological property, we attempted here to immunocapture Sm31 from sera of infected patients using specific polyclonal rabbit antibodies raised against a highly enriched preparation of Sm31 and detect its intrinsic proteolytic activity using a previously described solid-phase procedure called Cysteine Protease Immuno Assay (CPIA). To produce highly specific anti-Sm31/cathepsin B antibodies, cathepsin B (Sm31 or SmCB) was enriched more than 3000-folds from an adult worm preparation using a series of conventional biochemical steps including ion exchange and affinity chromatography. Anti-cathepsin B antibodies were generated by immunizing rabbits with the enriched cathepsin B fraction; these antibodies recognized a band of Mr.~31 kDa in Western-blot (WB) analysis of this fraction and were able to capture, in a modified CPIA procedure, Sm31/SmCB present in sera from infected Venezuelan patients living in low endemic areas for schistosomiasis. CPIA showed 100% sensitivity and 100% specificity; representing a new diagnostic tool to detect circulating Sm31 antigen in actual infections.
authors.affiliation: Unidad de Trematodiasis, Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela.
authors.forename: Amelia Y
authors.initials: AY
authors.lastname: González
authors.affiliation: Unidad de Trematodiasis, Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela. Electronic address: guidennsayleth@gmail.com.
authors.forename: Guidenn S
authors.initials: GS
authors.lastname: Sulbarán
authors.affiliation: Unidad de Trematodiasis, Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela.
authors.forename: Diana E
authors.initials: DE
authors.lastname: Ballen
authors.affiliation: Unidad de Trematodiasis, Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela.
authors.forename: Italo M
authors.initials: IM
authors.lastname: Cesari
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000276:immunology*; D000947:Antigens, Helminth / Q000276:immunology*; D003546:Cysteine Endopeptidases / Q000276:immunology*; D015801:Helminth Proteins / Q000276:immunology*; D006801:Humans; D011817:Rabbits; D012550:Schistosoma mansoni / Q000276:immunology* / Q000302:isolation & purification; D012555:Schistosomiasis mansoni / Q000175:diagnosis / Q000469:parasitology*; D012680:Sensitivity and Specificity
chemical_list: D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D015801:Helminth Proteins; D003546:Cysteine Endopeptidases; C059747:Sm31 protein, Schistosoma mansoni
keywords: Schistosoma mansoni; Sm31/SmCB; cathepsin B; circulating antigen; immunodiagnosis