A fluorescent tagging technique can allow the M. tuberculosis bacteria to be studied during infection of human cells with tuberculosis. These findings, reported in Nature Chemical Biology, could enhance further research on and treatment of this deadly pathogen.

Treating and preventing tuberculosis remains a significant medical challenge, particularly in developing nations. The lack of high-quality tuberculosis-specific probes for use in diagnosis and to monitor response to treatment has particularly hindered advances.

M. tuberculosis, the causative agent of tuberculosis, inserts a particular sugar residue — trehalose — into its cell wall during normal growth. This process is controlled by one of three enzymes, named Ag85A, Ag85B, and Ag85C.

Benjamin Davis, Clifton Barry and colleagues now show that, by studying the flexibility of the active site of these three enzymes, they can insert derivatives of trehalose containing fluorescent dyes into the M. tuberculosis cell wall. These dyes allow the detection of the bacteria within infected human cells enabling diagnosis of infection. The team hopes that it will lead to further research on the pathogen.