Performance comparison and evaluation of interferon-gamma assay kit for bovine tuberculosis diagnosis

In Korea, bovine tuberculosis (bTB) is a representative zoonotic disease that causes considerable economic loss. In determining the positive bTB, the ELISA method for examining the amount of interferon- gamma (IFN-γ) is included in Koreas diagnostic standard method. Recently, commercially available BIONOTE TB-Feron ELISA Plus (TB-Feron Plus) that detects IFN-γ has been introduced. However, since the scientific basis for the performance is limited, we evaluated performance by comparing it with the results of another IFN-γ ELISA assay kit (BOVIGAM Ⓡ ) certified by Office International des Epizooties.\nIn our research, 42 positive blood samples preliminarily tested with a tuberculin skin test and/or BOVIGAM Ⓡ and 54 negative blood samples collected from three bTB free farms were subjected to IFN-γ assay using the TB-Feron Plus and the BOVIGAM Ⓡ , respectively. The result shows that the sensitivity, specificity and accuracy were 81.0% (34/42), 100% (54/54), 91.7% (88/96) in TB-Feron Plus kit and 78.6% (33/42), 100% (54/54), 90.6% (87/96) in BOVIGAM Ⓡ kit, respectively. Moreover, the overall accordance percentage of the two kits was 99.0% (95/96) and there was almost perfect agreement between two assays (Kappa=0.977, P＜0.0001). Furthermore, additional studies confirmed that elevated lymphocyte numbers in blood did not interfere with the results of the TB-Feron Plus kit. And, delayed time from sampling to culture decreased the optical density (OD) value. Therefore, we concluded that the TBFeron Plus kit was not inferior to BOVIGAM Ⓡ in performance. High lymphocyte numbers in blood did not impact on TB-Feron Plus results, while delayed time before culture interfered with OD value.