Bernitz Netanya, Clarke Charlene, Roos Eduard O, Goosen Wynand J, Cooper David, van Helden Paul D, Parsons Sven D C, Miller Michele A
DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 241, Cape Town 8000, South Africa.
Ezemvelo KwaZulu-Natal Wildlife, PO Box 25, Mtubatuba, 3935, South Africa.
Vet Immunol Immunopathol. 2018 Feb;196:48-52. doi: 10.1016/j.vetimm.2017.12.010. Epub 2017 Dec 22.
African buffaloes (Syncerus caffer) are wildlife maintenance hosts of Mycobacterium bovis, the cause of bovine tuberculosis. Consequently, M. bovis infected buffaloes pose a transmission risk for cattle and other wildlife species. Previously, a modification to the Qiagen QuantiFERON-TB Gold (QFT) system, using QFT tubes and an in-house bovine interferon-gamma (IFN-γ) ELISA, was evaluated for the detection of M. bovis infection in buffaloes. Subsequently, Qiagen has developed a commercially available cattletype IFN-gamma ELISA for the detection of antigen-specific IFN-γ release in ruminants. The aim of this study was to investigate the use of QFT tubes and the cattletype IFN-gamma ELISA, in a cattletype IFN-γ release assay (IGRA), to detect M. bovis infection in African buffaloes. The test agreements between the cattletype IGRA, single comparative intradermal skin test (SCITT) and Bovigam 1G IGRA in two M. bovis-exposed buffalo populations (n = 134 and n = 92) were calculated and κ coefficients ranged from 0.65 (95% CI 0.48-0.82) to 0.86 (95% CI 0.72-0.99). Increasing the QFT incubation time in one M. bovis-exposed buffalo cohort (n = 92), from 20 to 40 h, had no effect on the cattletype IGRA test results. Inter-assay and intra-assay reproducibility determination for the cattletype IGRA produced coefficient of variations (CV) <9.1% and <1.7%, respectively. A total of 21/21 known M. bovis-unexposed buffaloes tested negative in the cattletype IGRA. Moreover, the cattletype IGRA test result values were significantly greater for 13 M. bovis culture-positive buffaloes compared with 14 M. bovis-exposed culture-negative (P < .01) and 21 M. bovis-unexposed (P < .001) buffaloes, respectively. These findings suggest that the combination of QFT tubes and the cattletype IFN-gamma ELISA is a promising new diagnostic assay for the detection of M. bovis infection in African buffaloes. However, further research is needed to evaluate the sensitivity and specificity of the assay in larger African buffalo populations.
非洲水牛（非洲水牛属）是牛分枝杆菌的野生动物维持宿主，牛分枝杆菌是牛结核病的病原体。因此，感染牛分枝杆菌的水牛对牛和其他野生动物物种构成传播风险。此前，对Qiagen公司的结核菌素金标定量检测（QFT）系统进行了改进，使用QFT管和内部牛干扰素-γ（IFN-γ）酶联免疫吸附测定（ELISA），以检测水牛中的牛分枝杆菌感染。随后，Qiagen公司开发了一种可商购的牛型IFN-γ ELISA，用于检测反刍动物中抗原特异性IFN-γ的释放。本研究的目的是调查在牛型IFN-γ释放测定（IGRA）中使用QFT管和牛型IFN-γ ELISA来检测非洲水牛中的牛分枝杆菌感染情况。计算了在两个暴露于牛分枝杆菌的水牛群体（n = 134和n = 92）中，牛型IGRA、单次比较皮内试验（SCITT）和Bovigam 1G IGRA之间的检测一致性，κ系数范围为0.65（95%置信区间0.48 - 0.82）至0.86（95%置信区间0.72 - 0.99）。在一个暴露于牛分枝杆菌的水牛队列（n = 92）中将QFT孵育时间从20小时增加到40小时，对牛型IGRA检测结果没有影响。牛型IGRA的批间和批内重复性测定产生的变异系数（CV）分别<9.1%和<1.7%。总共21头已知未暴露于牛分枝杆菌的水牛在牛型IGRA检测中呈阴性。此外，与14头暴露于牛分枝杆菌但培养阴性（P < 0.01）和21头未暴露于牛分枝杆菌（P < 0.001）的水牛相比，13头牛分枝杆菌培养阳性的水牛的牛型IGRA检测结果值显著更高。这些发现表明，QFT管和牛型IFN-γ ELISA的组合是一种有前景的新诊断方法，可用于检测非洲水牛中的牛分枝杆菌感染。然而，需要进一步研究以评估该检测方法在更大规模非洲水牛群体中的敏感性和特异性。
