Validation and field evaluation of a competitive enzyme-linked immunosorbent assay for the diagnosis of Babesia bovis infections in Argentina

DOMINGUEZ M; ECHAIDE I; TORIONI DE ECHAIDE S ; WILKOWSKY S; ZABAL O; MOSQUEDA J; SCHNITTGER L; FLORIN-CHRISTENSEN M

CLINICAL AND VACCINE IMMUNOLOGY

AMER SOC MICROBIOLOGY

Lugar: Washington; Año: 2012 p. 924 - 928

1556-6811

Infections by Babesia bovis limit cattle production and cause important economic losses intropical and subtropical areas around the world. Monitoring of calf sera can be used todetect unprotected cattle herds, and decide on strategic control measures, as well as forepidemiological studies. The Merozoite Surface Antigen-2c (MSA-2c) is animmunodominant surface protein expressed in B. bovis merozoites and sporozoites,containing B-cell epitopes that are conserved among geographic isolates. A monoclonalantibody against recombinant MSA-2c (rMSA-2c) was previously shown to inhibit thebinding of anti-B. bovis antibodies to a parasite B-cell epitope, in a competitive enzymelinked immunosorbent assay (cELISA) format. In the work at hand, the parameters of thiscELISA were re-evaluated and adjusted when necessary, and a cut-off value wasdetermined by Receiver Operating Characteristic (ROC) curve analysis of a total of 357bovine sera of known reactivity as assessed by indirect immunofluorescence assay (IFAT).The established rMSA-2c-cELISA demonstrated a specificity of 98% and a sensitivity of96.2%. An additional set of 303 field bovine sera from tick-endemic and tick-free regionsof Argentina was tested both by rMSA-2c-cELISA and IFAT, and results were shown to bein very good agreement (Kappa index of 0.8325). The performance shown by rMSA-2ccELISA in the detection of B. bovis-specific antibodies, its suitability for standardizationand large-scale production, as well as the possibility of its application in most veterinarydiagnostic laboratories make this assay a powerful tool for the surveillance of herdimmunity as a strategic measure for the control of bovine babesiosis.