Gold nanoprobe assay for the identification of mycobacteria of the Mycobacterium tuberculosis complex

Members of the Mycobacterium tuberculosis complex (MTC) are causative agents of human and animal tuberculosis. This complex encompasses several phylogenetically related species, including M. tuberculosis, the main aetiological agent of human tuberculosis, and Mycobacterium bovis, the causative agent of bovine tuberculosis, a relevant worldwide zoonosis. Clear epidemiological evaluation of appropriate and effective treatment requires unambiguous differentiation between MTC members. Routine diagnosis has been increasingly relying on the molecular identification of MTC members. In the present study, we report the use of a gold nanoparticle-based approach for the sensitive, specific and fast identification of MTC and for the differentiation of M. bovis and M. tuberculosis using the gyrB locus as target. This gold nanoprobe strategy relies on the colorimetric differentiation of specific DNA sequences based on differential aggregation profiles in the presence or absence of specific target hybridization. Three nanoprobes were designed and successfully used for the specific identification of members of MTC, M. bovis and M. tuberculosis.