Research finds ‘hidden’ germ

RESEARCHERS who cracked the secret of humanity’s genetic code have discovered a type of bacteria which has learned to hide among the body’s own cells.

Scientists at the Wellcome Trust Sanger Centre in Hinxton have been looking at the secrets of the tiny Tropheryma whipplei bacterium, which has proved to be a master of disguise.

Working with colleagues in the UK, USA and Germany, they say it carries a series of DNA sequences and can change its outer coating to avoid detection by the body’s immune system.

Amazingly it can also cloak itself in membranes stripped from surrounding cells to further improve its disguise.

Once hidden in the host’s body it settles down to multiply, occasionally breaking out to cause disease.

The researchers hope closer examination of Tropheryma whipplei will help explain how other pathogens survive and spread.

Dr Stephen Bentley, who led the team at The Wellcome Trust Sanger Institute, said, “This really is a wolf in sheep’s clothing.

“Within this amazingly small genome, it has packed a sophisticated array of tools to escape our defence mechanisms. It’s an incredibly adept operator which can tell us a great deal about bacteria and their evolution.”

Even with its genome sequence plotted and a prediction of all the proteins it can make, the bacterium remains a mystery.

The organism lives in the lining of the gut but it is not known how it is spread or even how many cases of disease it causes.

Whipple’s disease is marked by weight loss, diarrhoea and abdominal pain. Advanced cases may die from heart disease or neurological disease up to 20 years later.

Treatment once diagnosed is usually very effective, although relapses years later are quite common.

Bizarrely, men are eight times more likely to be infected than women.

Published on 22 February 2003