A new exciting method for tuberculosis diagnosis as explained by Hexin Xie et al, published in Nature Chemical biology PUBLISHED ONLINE: 2 SEPTEMBER 2012 | DOI: 10.1038/NCHEM.1435
Abstract:
Early diagnosis of tuberculosis can dramatically reduce both its transmission and the associated death rate. The extremely
slow growth rate of the causative pathogen, Mycobacterium tuberculosis (Mtb), however, makes this challenging at the
point of care, particularly in resource-limited settings. Here we report the use of BlaC (an enzyme naturally
expressed/secreted by tubercle bacilli) as a marker and the design of BlaC-specific fluorogenic substrates as probes for
Mtb detection. These probes showed an enhancement by 100–200 times in fluorescence emission on BlaC activation and a
greater than 1,000-fold selectivity for BlaC over TEM-1 b-lactamase, an important factor in reducing false-positive
diagnoses. Insight into the BlaC specificity was revealed by successful co-crystallization of the probe/enzyme mutant
complex. A refined green fluorescent probe (CDG-OMe) enabled the successful detection of live pathogen in less than ten
minutes, even in unprocessed human sputum. This system offers the opportunity for the rapid, accurate detection of very
low numbers of Mtb for the clinical diagnosis of tuberculosis in sputum and other specimens.
Abstract:
Early diagnosis of tuberculosis can dramatically reduce both its transmission and the associated death rate. The extremely
slow growth rate of the causative pathogen, Mycobacterium tuberculosis (Mtb), however, makes this challenging at the
point of care, particularly in resource-limited settings. Here we report the use of BlaC (an enzyme naturally
expressed/secreted by tubercle bacilli) as a marker and the design of BlaC-specific fluorogenic substrates as probes for
Mtb detection. These probes showed an enhancement by 100–200 times in fluorescence emission on BlaC activation and a
greater than 1,000-fold selectivity for BlaC over TEM-1 b-lactamase, an important factor in reducing false-positive
diagnoses. Insight into the BlaC specificity was revealed by successful co-crystallization of the probe/enzyme mutant
complex. A refined green fluorescent probe (CDG-OMe) enabled the successful detection of live pathogen in less than ten
minutes, even in unprocessed human sputum. This system offers the opportunity for the rapid, accurate detection of very
low numbers of Mtb for the clinical diagnosis of tuberculosis in sputum and other specimens.
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