title: Validation of a competitive enzyme-linked immunosorbent assay for detection of Babesia bigemina antibodies in cattle.
abstract: A competitive enzyme-linked immunosorbent assay (cELISA) based on a broadly conserved, species-specific, B-cell epitope within the C terminus of Babesia bigemina rhoptry-associated protein 1a was validated for international use. Receiver operating characteristic analysis revealed 16% inhibition as the threshold for a negative result, with an associated specificity of 98.3% and sensitivity of 94.7%. Increasing the threshold to 21% increased the specificity to 100% but modestly decreased the sensitivity to 87.2%. By using 21% inhibition, the positive predictive values ranged from 90.7% (10% prevalence) to 100% (95% prevalence) and the negative predictive values ranged from 97.0% (10% prevalence) to 48.2% (95% prevalence). The assay was able to detect serum antibody as early as 7 days after intravenous inoculation. The cELISA was distributed to five different laboratories along with a reference set of 100 defined bovine serum samples, including known positive, known negative, and field samples. The pairwise concordance among the five laboratories ranged from 100% to 97%, and all kappa values were above 0.8, indicating a high degree of reliability. Overall, the cELISA appears to have the attributes necessary for international application.
authors.affiliation: Animal Disease Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, Washington 99164-6630, USA. wgoff@vetmed.wsu.edu
authors.forename: Will L
authors.initials: WL
authors.lastname: Goff
authors.forename: Wendell C
authors.initials: WC
authors.lastname: Johnson
authors.forename: John B
authors.initials: JB
authors.lastname: Molloy
authors.forename: Wayne K
authors.initials: WK
authors.lastname: Jorgensen
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Waldron
authors.forename: Julio V
authors.initials: JV
authors.lastname: Figueroa
authors.forename: Olivier
authors.initials: O
authors.lastname: Matthee
authors.forename: D Scott
authors.initials: DS
authors.lastname: Adams
authors.forename: Travis C
authors.initials: TC
authors.lastname: McGuire
authors.forename: Ignacio
authors.initials: I
authors.lastname: Pino
authors.forename: Juan
authors.initials: J
authors.lastname: Mosqueda
authors.forename: Guy H
authors.initials: GH
authors.lastname: Palmer
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Suarez
authors.forename: Donald P
authors.initials: DP
authors.lastname: Knowles
authors.forename: Terry F
authors.initials: TF
authors.lastname: McElwain
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D001403:Babesia / Q000276:immunology*; D001404:Babesiosis / Q000175:diagnosis / Q000662:veterinary*; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis* / Q000469:parasitology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D011237:Predictive Value of Tests; D015800:Protozoan Proteins / Q000276:immunology; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D000913:Antibodies, Protozoan; D015800:Protozoan Proteins; C097551:rhoptry-associated protein-1, Babesia