Friday, March 19, 1999 Published at 10:55 GMT
CJD's deadly switch revealed
Rogue proteins form fatal clumps in the brain
The breakthrough is a major step forward for the future development of new diagnostic tests and possibly even effective treatments of the fatal diseases.
"It opens up new research directions to understand CJD and BSE," said the research leader, Professor John Collinge, Director of the UK's Medical Research Council's Prion Unit.
In Britain, 39 people have died of CJD. But the incubation period may be as long as 30 years, meaning the final extent of the disease cannot yet be predicted. A blood test for CJD could reveal this.
Sharp rise in cases
The research breakthrough comes in the same week that a sharp rise in confirmed cases (nine) and referrals of CJD were announced for the last quarter of 1998.
Professor Collinge agreed the rise was worrying and that it was "too early to know what the figures mean". But he added that it was still entirely possible that there could be a CJD epidemic.
His new research has unmasked the mysterious mechanism by which normal prion proteins in the brain are transformed into a different, deadly form.
It is believed that the abnormal prion causes the normal protein to change shape to form a new rogue prion. A domino effect follows.
The altered proteins cannot dissolve as normal and build up in hard clumps or "plaques". This kills the cells they form in and is also a barrier to scientific analysis of the rogue protein's structure.
The protein clumps are the "holes" which characterise the prion brain diseases and cause the brain damage which is ultimately fatal.
"We now know that the conversion involves breaking a single bond in the molecule using conditions which exist normally within cells," explains Professor Collinge.
"This remarkable property of prion protein is unprecedented: no other protein has yet been shown to be able to exist in two such entirely unrelated shapes."
The team was convinced they had exposed the disease's secret when their altered protein formed clumps which were indistinguishable from the rogue form found in the brain of CJD and BSE victims.
The scientists believe the new information should make it possible to create antibodies which detect the rogue protein specifically. This would mean new diagnostic tests for prion disease in humans and animals.
Also, knowing how the switch from normal to rogue protein occurs could help researchers develop new drugs to treat and prevent prion disease.
The research is published in Science magazine and was funded by the Medical Research Council and the Wellcome Trust.