CJD diagnostic test 'ready in a year'

Variant CJD is notoriously hard to diagnose

By BBC News Online's Ivan Noble

Researchers in Israel claim to have developed a simple diagnostic test for variant Creutzfeldt Jakob disease (vCJD), the human form of BSE.

We were able to detect all the positives as positives and all the negatives as negatives

Ruth Gabizon
Hadassah Medical Organisation

They say their method can reliably distinguish between urine samples from healthy humans and samples preserved from people who died of vCJD.

They are working on making the test generally available and say it could be ready in a year.

British specialists say the work is interesting, but raise questions about its accuracy.

Diagnostic difficulty

Variant CJD - a fatal degenerative disease affecting the brain - is hard to distinguish from other degenerative diseases like Alzheimer's.

Doctors often cannot be sure that a person has vCJD until after a post mortem examination.

So a urine test would make diagnosis much simpler and might even be used to work out how far and how quickly the disease has spread through the general population.

Ruth Gabizon, who leads the team at the Hadassah Medical Organisation in Israel, says that the procedure was developed using urine from humans, hamsters and cattle.

Family of diseases

vCJD in humans, BSE in cows and scrapie in hamsters are believed to be related forms of the same disease, known as transmissible spongiform encephalopathies.

"We had urine samples from all the cases of CJD in Israel in the last year," she told BBC News Online.

The team compared these samples with urine from non-infected people, and carried out the same procedure on urine from British BSE-infected cattle and scrapie-infected hamsters.

"We were able to detect all the positives as positives and all the negatives as negatives," Ruth Gabizon, adding that in some cases the team could detect scrapie infection in hamsters which had not yet shown any symptoms.

Controversial findings

The debate about the test arises from the difficulty in detecting CJD.

Ruth Gabizon says that there is only one substance which all scientists agree is evidence of CJD infection.

This substance is known as PrPSc and forms part of the prion or rogue protein believed to cause the disease.

The Israeli team's test detects a related substance which they call UPrPSc.

They say that they are confident that the two are linked because the test produced reliable results. But researchers from Britain's MRC Prion Research unit - who are world leaders in the field - are more cautious.

They do not believe that there have been sufficient controls to show that the Israeli team really are detecting prions. The question is whether prions really do move from the brain to urine.

If prions move into urine, the British team think it is likely that the rogue proteins would accumulate in the kidneys, where they would be found by doctors conducting post mortems. But Ruth Gabizon disagrees.

The Israeli research is published in the Journal of Biological Chemistry.