Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Virulence of TB strain in Leicester outbreak caused by ‘unusual’ mechanism

04.10.2006
Scientists have identified a mechanism that contributes to the virulence of a particular strain of tuberculosis, making it appear more likely to lead to disease than other strains. In 2001, this strain, known as CH, was responsible for a major school outbreak of TB in Leicester thought to have infected at least 254 pupils.

In general, most people infected with Mycobacterium tuberculosis, the bacterium that causes TB, will not show any symptoms. It is thought that one third of all people carry the bacteria, yet less than one in ten will develop TB. However, almost a quarter of the people infected with the CH strain required treatment for the disease. Left untreated, TB can prove fatal.

Now, a team jointly led by Dr Robert Wilkinson at the Wellcome Trust Centre for Clinical Tropical Medicine, Imperial College London, and Professor Mike Barer at the University of Leicester, has identified a segment of the CH genome which, when absent, modifies the immune system’s response to the strain and make it more likely to lead to disease. The findings of their research are published today in Proceedings of the National Academy Sciences of the USA. The research was funded by the Wellcome Trust and the Medical Research Council.

“Whilst this particular strain of TB does not appear more infectious than others, it appeared more likely to cause primary disease and endanger the health of an infected person,” says Dr Wilkinson. “The CH strain has evolved a mechanism to avoid the early immune response and thus give it an advantage in the early struggle against the immune system. Interestingly the genetic basis for this appears to be the loss, rather than gain, of a gene, which is unusual.”

The missing segment is thought to be have been deleted during a rare rearrangement within the CH genome.

“TB and other mycobacteria appear to be remarkably careless about preserving their genomes and appear to have evolved by a succession of ‘accidents’ in which several genes have been lost at a time,” explains Professor Barer. “We don't really understand how the losses occur, but it is likely that, for one reason or another, loops form in the DNA and the genes in the loops are lost.

“Unlike many other bacteria, the TB group cannot pick up DNA from its relatives so it cannot get lost genes back again. The ultimate example of this is the leprosy bacillus. This has lost so many genes that it can now only grow in the tissues of humans, nine-banded armadillos and immunocompromised mice.”

Despite the increased likelihood that the CH strain of tuberculosis will develop to the disease stage, Dr Wilkinson is keen to stress that it is still possible to treat the strain.

“Although this strain appears more likely to lead to disease than others, it is responsive to the antibiotics prescribed for TB infection,” says Dr Wilkinson.

Professor Barer comments: “Our studies on the TB outbreak strain seem to have uncovered a deeper truth about how the bacterium may evolve and adapt to persist in different human populations.”

According to the Health Protection Agency, the incidence of TB in the UK is increasing, but it still remains quite rare, with less than 7000 new cases a year. Cases in the UK are predominantly confined to the major cities and about 40% of all cases are in London. However, globally TB is a major problem: an estimated one third of the world's population – nearly two billion people – are infected. Ten million people a year develop the active disease worldwide, which kills three million each year.

Alex Jelley | alfa
Further information:
http://www.imperial.ac.uk

More articles from Health and Medicine:

nachricht Millions through license revenues
27.04.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht New High-Performance Center Translational Medical Engineering
26.04.2017 | Fraunhofer ITEM

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>