Use of a multiplex enzyme-linked immunosorbent assay to detect a subpopulation of Mycobacterium bovis–infected animals deemed negative or inconclusive by the single intradermal comparative tuberculin skin test

Abstract

Although the single intradermal comparative tuberculin skin test (SICTT) remains the most effective assay for detecting cattle infected with Mycobacterium bovis, not all infected animals are detected with the SICTT. This has made it difficult to control bovine tuberculosis using a single assay. Use of the gamma interferon assay in conjunction with the SICTT has improved the level of detection but some infected animals still go undetected. This could be in part attributable to both assays being reliant on a cell-mediated immune response. The present study was undertaken to determine if a multiplex assay can improve the level of detection of infected animals when used in combination with the SICTT. The Enferplex TB assay is a multi-antigen ELISA designed for the detection of antibody in animals at different stages of infection and disease. Sixty cattle that were confirmed by histopathology and/or culture to be infected with M. bovis and that were SICTT negative (43.3%) or difficult to evaluate (56.7% inconclusive) were used in the study. Fifty-three (88.3%) of the animals were positive in multiplex ELISA. The results show that the level of detection of M. bovis-infected animals can be improved by the combined use of the SICTT and the multiplex ELISA.