Researchers 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 that was 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 fewer 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 that, when absent, modifies the immune system's response to the strain and makes it more likely to lead to disease. The findings of the research were 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.

Image: Robert Wilkinson (right) and colleague.

See also

• Press release (full details)