In contrast, currently available commercial IGRAs such as T-SPOT.TB (Oxford Immunotec), an enzyme-linked immunosorbent spot (ELISpot)-based assay quantifying IFN-γ spot-forming cells, and Quantiferon®-TB Gold Plus (Qiagen), an enzyme-linked immunosorbent assay (ELISA)-based method measuring the IFN-γ concentration in the serum of blood stimulated with Mtb antigens, show improved sensitivity and specificity in latent TB infection, particularly in BCG-vaccinated individuals [3,7,8,9]. Here, IFNG is linked to tuberculosis.