Molecule can be used to detect TB in cells

A new method using a small molecule has been developed to detect tuberculosis inside cells.

Methods for detecting TB have not changed dramatically over the last century. They still rely on staining tissue sections and conducting chest x-rays, according to

In a recent issue of the journal Nature Chemical Biology, a team of scientists from the Oxford University Department of Chemistry led by Ben Davis described a new method by which they can identify TB.

"We designed and created a fluorescent sugar that we discovered is a substrate for an enzyme, Ag85, found on the surface of TB bacteria," Davis said, according to "The sugar is a variant of one that TB uses but is not used at all in mammalian biology. The Ag85 enzyme takes this and attaches a greasy lipid tail - this greasy product then becomes buried on the greasy surface of TB. The result is that the cell surface of the bug is fluorescently 'painted.'”

The TB is selectively labeled, even when it lies inside mammalian macrophages, where it is normally found dormant in infected hosts. It is extremely selective. Other parasites are not labeled, and other sugars do not work.

"We've been able to use this here to map out aspects of TB cell biology but the implications for diagnosing and monitoring TB as a disease are clearly much broader," Davis said, reports.