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ARS Home » Pacific West Area » Pullman, Washington » Animal Disease Research » Research » Publications at this Location » Publication #197498

Title: Validation of a Competitive Enzyme-Linked Immunosorbent Assay for Detection of Antibodies against Babesia bovis

item Goff, Willard
item MOLLOY, J
item Johnson, Wendell
item Suarez, Carlos
item PINO, I
item RHALEM, A
item SAHIBI, H
item CECI, L
item ADAMS, D
item Knowles Jr, Donald

Submitted to: Clinical and Vaccine Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2006
Publication Date: 11/6/2006
Citation: Goff, W.L., Molloy, J.B., Johnson, W.C., Suarez, C.E., Pino, I., Rhalem, A., Sahibi, H., Ceci, L., Carelli, G., Adams, D.S., Mcguire, T.C., Knowles Jr, D.P., Mcelwain, T.F. 2006. Validation of a Competitive Enzyme-Linked Immunosorbent Assay for Detection of Antibodies against Babesia bovis. Clinical and Vaccine Immunology. 13(11):1212-1216.

Interpretive Summary: Tick-borne diseases (TBD) of livestock are economically important throughout the world. Babesia bovis is one of three important parasites causing the TBD babesiosis in cattle. It is often misdiagnosed in many areas due to the lack of a good assay that can differentiate this parasite infection from other similar parasites. Since the pathology and treatments associated with each parasite differ, accurate diagnosis is important. In addition, the assay should be formatted so that a large number of samples can be evaluated efficiently thus serving as a tool for use in regional diagnostic laboratories. We described an improved assay for detecting Babesia bovis infections in cattle recently and now have validated its use and determined its reliability in laboratories in different countries. The assay has the characteristics necessary and meets the regulatory stringency for use as an international standard.

Technical Abstract: A previously developed competitive ELISA (cELISA) based on a species-specific, broadly conserved, and tandemly repeated B-cell epitope within the C-terminus of the rhoptry-associated protein-1 of Babesia bovis was refined and validated for use internationally. Receiver Operator Characteristic (ROC) analysis revealed an assay with a specificity and positive predictive value of 100% and sensitivity of 91.1% with varying negative predictive values depending on the disease prevalence in the area where applied. The cELISA was distributed to 4 different laboratories along with a reference set of 100 defined bovine sera, including known positive, known negative and field samples. Pairwise concordance among the 4 laboratories ranged from 94% to 88% and analysis of variance of the resulting optical densities and a test of homogeneity indicated that there was no significant difference among the laboratories. When applied to field samples along with PCR, discordant samples were obtained in 19% of the samples suggesting that early infections can be detected by PCR prior to seroconversion and/or that the cELISA titer may wane over time in a persistently infected animal if not re-exposed. Overall, the cELISA has the attributes necessary for international application.