Most of the antigens of Mycobacterium leprae and M. tuberculosis that have been identified are members of stress protein families, which are highly conserved throughout many diverse species. Of the M. leprae and M. tuberculosis antigens identified by monoclonal antibodies, all except the 18-kDa M. leprae antigen and the 19-kDa M. tuberculosis antigen are strongly cross-reactive between these two species and are coded within very similar genes [1,2].

1: Homologs of Mycobacterium leprae 18-kilodalton and Mycobacterium tuberculosis 19-kilodalton antigens in other mycobacteria. Booth RJ, Williams DL, Moudgil KD, Noonan LC, Grandison PM, McKee JJ, Prestidge RL, Watson JD; Infect Immun 1993;61:1509-1515. PMID:8454357

2: Cloning and characterization of the gene for the '19 kDa' antigen of Mycobacterium bovis. Collins ME, Patki A, Wall S, Nolan A, Goodger J, Woodward MJ, Dale JW; J Gen Microbiol 1990;136:1429-1436. PMID:2230723