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Saturday, 2 February, 2002, 00:08 GMT
E. coli could provide Alzheimer's clue
E. coli
E. coli produces the fibres found in Alzheimer's disease
E. coli, the bacteria which can cause severe food poisoning, may provide scientists searching for a way to treat Alzheimer's disease with vital clues.

A team from the Washington University School of Medicine has discovered that the bug produces fibres similar to those thought to cause Alzheimer's.

These amyloid fibres accumulate in the brains of people with the condition, forming plaques.

The version produced by certain strains of E. coli are known as curli.

They form a meshwork around the bacteria, joining them together in clusters or communities known as biofilms. Bacteria in biofilms are more resistant to antibiotics and to the body's immune defences.

It is the first time that amyloid has been found in bacteria. Previously, it was thought to be made only by cells of higher organisms. Even then, its presence was regarded as a mistake, a biological error.

Researcher Dr Scott Hultgren said that the discovery showed that amyloid fibres were sometimes produced intentionally.

He said: "This finding gives us a powerful genetic system to study the molecular details of amyloid formation and may allow us to begin designing drugs that will block the formation of amyloid or treat or prevent human amyloid diseases."

Bacterial infection


This will potentially allow research to move forwards more quickly

Dr Richard Harvey
The finding also raises the important question of whether bacterial infections play some role in amyloid diseases, including Alzheimer's disease.

The researchers think it possible that the amyloid fibres produced by bacteria may form part of the plaques found in the brain. Alternatively the presence of bacterial infection may in some way trigger the formation of plaques from amyloid material already being produced by the body.

Dr Richard Harvey, director of research for the UK Alzheimer's Society, said: "The most useful and important outcome from this research is that we may now have a non-animal system for studying amyloid production. This will potentially allow research to move forwards more quickly.

"Having a new system to investigate amyloid may help scientists to learn how to alter the system to prevent the amyloid being produced.

"This might lead to better treatments for antibiotic resistant infections, and some of what is learned my lead to new treatments for Alzheimer's disease."

Professor John Mayer, of the UK Alzheimer's Research Trust, stressed there was no hard evidence to back up the researchers' theory that bacterial infection in some way contributed to the formation of plaques.

He told BBC News Online: "The fibres in human amyloid are made from small fragments of the Alzheimer precursor protein whereas the bacterial amyloid appears to be made from two intact proteins.

"The formation of the extracellular material may therefore be by different molecular pathways."

The research is published in the journal Science.

See also:

12 Jan 02 | Health
E.coli used to reduce infection
23 Dec 01 | Health
Vitamin E could halt Alzheimer's
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