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
Study suggests possible new target for treating and preventing Alzheimer's
02.12.2016 | Oregon Health & Science University
The first analysis of Ewing's sarcoma methyloma opens doors to new treatments
01.12.2016 | IDIBELL-Bellvitge Biomedical Research Institute
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
05.12.2016 | Power and Electrical Engineering
05.12.2016 | Materials Sciences
05.12.2016 | Power and Electrical Engineering