Potential cross-reactivity of monoclonal antibodies against clinically relevant mycobacteria

Abstract

Tuberculosis is a disease caused by the Mycobacterium tuberculosis complex (MTb). In 2011, global mortality due to tuberculosis was 1·4 million individuals. The only available vaccine is the attenuated M. bovis [bacillus Calmette-Guérin (BCG)] strain, which confers variable protection against pulmonary tuberculosis. Some widely distributed non-tuberculous mycobacteria (NTM), such as M. avium and M. arupense, are also potential pathogens for humans. This work aimed to produce and characterize monoclonal antibodies against the M. bovis BCG Mexico strain of the MTb, M. avium subs. hominissuis and the M. arupense strain from NTM. Hybridomas were produced from splenocytes of BALB/c female mice immunized with radiation-inactivated mycobacteria, and the immunoglobulin (Ig)G2a antibody-producing clones with the highest antigenic recognition were selected. The selected clones, Mbv 2A10 for M. bovis BCG Mexico, Mav 3H1 for M. avium and Mar 2D10 for M. arupense, were used in further studies. Enzyme-linked immunosorbent assay (ELISA) and immune proteomics analyses characterized the clones as having the highest cross-reactivity with mycobacteria. Using mass spectrometry, a number of proteins recognized by the monoclonal antibody (mAb) clones were identified. These proteins had roles in metabolic processes, hypoxia, cell cycle and dormancy. In addition, a Clustal W and Immune Epitope Database (IEDB) in-silico analysis was performed in protein sequences that result in the conserved regions within probability epitopes that could be recognized for Mbv2A10 and Mav3H1 clones.