Monoclonal antibodies selectively directed against the cell wall surface of Mycobacterium tuberculosis

In the last few years several monoclonal antibodies against Mycobacterium tuberculosis have been described, but their use as diagnostic tools has been limited. In this study we describe eight monoclonal antibodies against M. tuberculosis for diagnostic purposes. The monoclonal antibodies were selected after enzyme-linked immunosorbent assay screening with whole bacterial suspensions of mycobacteria and other bacterial species. Four monoclonal antibodies (BS100, BS101, BS102, and BS104) reacted with a whole bacterial suspension of M. tuberculosis but not with the other mycobacteria. When tested with a cytoplasmic fraction of mycobacteria the same monoclonal antibodies showed a broad cross-reactivity. Therefore the monoclonal antibodies showed not specific but selective binding to M. tuberculosis. The molecular size of the recognized antigens ranged from 12 to 71 kilodaltons as determined by the immunoblotting technique. The ability to differentiate M. tuberculosis from mycobacteria other than tuberculosis was investigated by enzyme-linked immunosorbent assay with 131 freshly cultured strains of M. tuberculosis from patients and 36 strains of mycobacteria other than tuberculosis. The monoclonal antibody BS104 could clearly distinguish between M. tuberculosis and other mycobacterial species.