IFNG and tuberculosis: Currently available assays for the diagnosis of LTBI include the tuberculin skin test (TST) and the interferon-gamma (IFN-γ) release assays (IGRAs) T-SPOT.TB (Oxford Immunotec, Oxford, UK) and QuantiFERON-TB Gold In Tube (QFT-GIT; Cellestis, Carnegie, Victoria, Australia).