A Family of Cross‐Reacting Proteins Secreted by Mycobacterium tuberculosis

Abstract

Cross-reactions between five proteins actively secreted by Mycobacterium tuberculosis were studied by crossed immunoelectrophoresis, SDS-PAGE with immunoblotting, and ELISA using polyclonal rabbit antisera and mouse monoclonal antibodies to the purified proteins. The monoclonal antibody HBT4 was demonstrated to react with the MPT51 protein. The 85A, 85B and 85C constituents of the M. tuberculosis and Mycobacterium bovis BCG antigen 85 complex cross-react extensively, each of the components containing component-specific as well as cross-reacting epitopes. These components also cross-reacted with MPT51 and MPT64. N-terminal sequence studies revealed striking homology at the amino acid level between 85A, 85B, 85C and MPT51. MPT64 showed less homology. In addition, striking homology was demonstrated between two different stretches within the 85B sequence and indicated between three stretches within the MPT64 molecule. Thus, a family of at least four secreted proteins with common structural features has been demonstrated in mycobacteria. MPT64 may also belong to this family.

Pulmonary Mononuclear Cell Responses to Antigens ofMycobacterium tuberculosisin Healthy Household Contacts of Patients with Active Tuberculosis and Healthy Controls from the Community

“…Ag 85co is a predominant product of live M. tuberculosis (19,27) and may be critical in the development of protective immunity in M. tuberculosis infection (28). Recently, it has been shown that vaccination with Ag 85co conferred protection against M. tuberculosis challenge in mice (29 -31) and guinea pigs (32,33).…”

The Novel Fibronectin-binding Motif and Key Residues of Mycobacteria

“…These proteins may play important roles not only in the establishment, progress, and continuation of the infection, but also in the host defense system since live mycobacteria can provoke protective immunity against tuberculosis, but killed organisms cannot (8). ␣-Antigen (Ag), 1 also known as Ag 85B (9), Ag 6 (10), and MPT59 (11), is one of the most dominant secretary proteins (12) and is a major stimulant of cellular and humoral immunity (11,(13)(14)(15). It is widely distributed among M. tuberculosis, Bacillus Calmette-Guérin (BCG) isolated from Mycobacterium bovis, and atypical mycobacteria (16).…”

New Simple and Rapid Test for Culture Confirmation of Mycobacterium tuberculosis Complex: a Multicenter Study

“…Several secreted mycobacterial proteins have been reported that showed some promise in diagnostic use (4,9,19). Among these secreted proteins, MPB64, which was first described as MPT64, has been found in unheated culture media of M. tuberculosis, M. bovis, and some but not all substrains of M. bovis BCG.…”