Comparison of two competitive enzyme-linked immunosorbent assays for Anaplasma marginale in cattle

Abstract

Bovine anaplasmosis, caused by Anaplasma marginale, is the most prevalent tick-transmitted disease of cattle worldwide and a major obstacle to profitable production in the U.S. Several serological assays such as complement fixation (CF), card agglutination, and competitive enzyme-linked immunosorbent assay (cELISA) have been used in the detection of anaplasmosis carriers. The CF and card agglutination tests are not considered reliable due to low diagnostic sensitivities (<2 0% and 67%, respectively). Commercially available major surface protein-5 (MSP-5) epitope-based cELISA is more reliable with high sensitivity (99%) and specificity (89%). Recently, maltose binding protein included as fusion protein in the recombinant MSP-5 used in the commercially available cELISA was identified as the source of some false-positive results. A new cELISA test was developed to improve diagnostic specificity by reducing false positive reactions due to maltose binding protein antibodies and other non-specific antibodies in bovine sera. The objective of this study was to compare results generated using the current and new cELISA tests and real-time RT-PCR to provide veterinarians with up to date information regarding the most appropriate test to use for anaplasmosis diagnosis.