The African buffalo (Syncerus caffer) is an economically and ecologically important wildlife species in South Africa; it is also a primary wildlife maintenance host of Mycobacterium bovis. Accurate and early detection of M. bovis infection in buffaloes is important for controlling transmission. Assays that detect cell-mediated immune responses to M. bovis in buffaloes have been developed although these often display suboptimal sensitivity or specificity. Therefore, the aim of this study was to evaluate the newly available Mabtech bovine interferon-gamma (IFN-γ) ELISA^PRO kit and optimize its use for detection of buffalo IFN-γ in whole blood samples stimulated with the QuantiFERON® TB Gold Plus antigens. Additionally, the test performance of the Mabtech IFN-γ release assay (IGRA) was compared to the currently used Cattletype® IGRA by determining buffalo-specific cut-off values for the two IGRAs and using gold standard-positive (M. bovis culture-confirmed) and M. bovis-unexposed negative cohorts. Validation of the Mabtech ELISA revealed negligible matrix interference and a linear and parallel response for recombinant bovine and native buffalo IFN-γ in the range 1.95–250 pg/mL. Intra- and inter-assay reproducibility produced coefficients of variation <5.5 % and <6.1 %, respectively, with a limit of detection at 3.2 pg/mL. Using receiver operator characteristic curve analyses, buffalo-specific cut-off values were calculated as 8 pg/mL for the Mabtech IGRA and 5 % (signal to positive control ratio) for the Cattletype® IGRA. The sensitivities were 89 % and 83 % for the Mabtech and Cattletype IGRAs with specificities of 94 % and 97 %, respectively. Although the species-specific cut-off values require further evaluation in a relevant test group, the results suggest that the Mabtech IGRA is a promising, sensitive and specific diagnostic tool for M. bovis detection in African buffaloes.

非洲水牛（Syncerus caffer）是南非的一种在经济和生态上重要的野生动植物。它也是牛分枝杆菌的主要野生动植物维护宿主。准确和早期发现水牛中的牛分枝杆菌感染对于控制传播很重要。已经开发出检测水牛中牛分枝杆菌的细胞介导的免疫反应的检测方法，尽管这些检测通常表现出次优的敏感性或特异性。因此，本研究的目的是评估最新可用的Mabtech牛干扰素-γ（IFN-γ）ELISA ^PRO试剂盒并优化其用于检测用QuantiFERON®TB Gold Plus抗原刺激的全血样品中的水牛IFN-γ。此外，通过确定两个IGRA的水牛特异性截止值，并使用金标准阳性（牛分枝杆菌培养物- ），将MabtechIFN-γ释放试验（IGRA）的测试性能与当前使用的Cattletype®IGRA进行了比较。确认）和M. bovis-未暴露的阴性人群。Mabtech ELISA的验证显示，重组牛和天然水牛IFN-γ的基质干扰和线性和平行响应均可以忽略不计，范围为1.95–250 pg / mL。批内和批间可重复性的变异系数分别<5.5％和<6.1％，检出限为3.2 pg / mL。使用接收器操作员特征曲线分析，对于Mabtech IGRA，水牛特定的临界值计算为8 pg / mL，对于Cattletype®IGRA，水牛特定的临界值计算为5％（信号与阳性对照的比率）。Mabtech和Cattletype IGRA的敏感性分别为89％和83％，特异性分别为94％和97％。尽管特定物种的临界值需要在相关测试组中进行进一步评估，但结果表明，Mabtech IGRA是有前途的，在非洲水牛中检测牛分枝杆菌。