title: Antibodies to the CP24 protein of Brucella melitensis lack diagnostic usefulness in ovine brucellosis.
abstract: The potential diagnostic usefulness of antibodies to the ribosome recycling factor of Brucella melitensis (CP24) was assessed in sheep by an indirect ELISA with purified recombinant CP24. Sera from uninfected animals from the UK (n=44) and from local flocks (n=42), from sheep naturally infected with B. melitensis (n=12) or B. ovis (n=12), and from lambs (n=7) or pregnant ewes (n=6) vaccinated with B. melitensis Rev-1, were assayed. High specific optical densities (OD(with antigen) - OD(without antigen)) were obtained with both the groups of normal sera, which resulted in high cut-off values (1.414 and 1.267, respectively). Only two infected sheep yielded specific OD higher than these cut-off values. No significant difference was found between mean specific OD from B. melitensis- or B. ovis-infected sheep (0.574 and 0.472, respectively), those from vaccinated animals (0.396 and 0.400 for pregnant ewes and lambs, respectively), and those from Brucella-free animals. An inhibition ELISA with soluble CP24 confirmed the specificity of the antibodies detected in normal sera by the indirect ELISA; these antibodies belonged to the IgG class as revealed by the use of a specific conjugate. Sera from infected sheep were all positive for antibodies against lipopolysaccharides and lumazine synthase from Brucella. These results show that anti-CP24 antibodies have no diagnostic role in ovine brucellosis.
authors.affiliation: Instituto de Estudios de la Inmunidad Humoral (IDEHU), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires (UBA), Junín 956, 1113, Buenos Aires, Argentina.
authors.forename: M Victoria
authors.initials: MV
authors.lastname: Delpino
authors.forename: Juliana
authors.initials: J
authors.lastname: Cassataro
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Fossati
authors.forename: Pablo C
authors.initials: PC
authors.lastname: Baldi
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001426:Bacterial Proteins / Q000276:immunology*; D001428:Bacterial Vaccines / Q000276:immunology; D017347:Brucella melitensis / Q000276:immunology* / Q000302:isolation & purification; D002006:Brucellosis / Q000175:diagnosis / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary*; D005260:Female; D008297:Male; D011247:Pregnancy; D011994:Recombinant Proteins; D012756:Sheep; D012757:Sheep Diseases / Q000175:diagnosis / Q000276:immunology / Q000382:microbiology*
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; C102461:CP24 protein, Brucella melitensis; D011994:Recombinant Proteins; C471349:Rev.1 vaccine, Brucella melitensis