IFNG and infection: Two proteins from M. tuberculosis, ESAT-6 and CFP-10, stand out as suitable antigens that induce a strong IFN-γ-secreting CD4 T-cell-mediated immune response to infection [6,7] and are absent in M. bovis BCG and most NTM's, with the exceptions of M. szulgai, M. marinum, and M. kansasii.