IFNG and tuberculosis: Interferon‐gamma (IFN‐γ) release assay tests were originally developed on the principle of quantitatively evaluating IFN‐γ production by peripherally circulating antigen‐specific effector memory T‐cells upon in vitro stimulation, in order to aid the diagnosis of M. bovis TB (bTB) in cattle, where it has a reported sensitivity of 81.8%–100% and specificity of 88%–99% (Bezos et al., 2014; Schiller et al., 2009; Vordermeier et al., 2006; Wood & Jones, 2001).