Researchers in Switzerland have developed an antibody which recognises prions - the infectious particles of protein which spread diseases like v-CJD and BSE.
The scientists, at Prionics AG based at the University of Switzerland, say the breakthrough could lead to a test being developed which could detect the early stages of CJD and BSE in the future.
In a report in the science journal Nature, Bruno Oesch described how he and his colleagues isolated the antibody, 15B3 which can distinguish between good and bad brain prions. "The new antibodies will potentially be able to detect prion production in blood which will be useful in detecting the early stages of BSE in cattle and v-CJD in humans," he said.
"It will also be a tool for screening donated blood and prevent large batches of products having to be recalled."
In England, the Committee of Scientific Experts, set up to advise the Government on BSE and v-CJD, said yesterday that it will recommend that all blood supplies should be tested to prevent the possibility of infection.
But it pointed out that there was no evidence that the disease has ever been transferred in this way.
Speaking on BBC Radio 4's The World Tonight, Professor Jeffrey Almand said: "There is the possibility, therefore we don't want to take any risks. We are not recommending immediate measures as of tomorrow morning we are simply suggesting that it might be in the longer term advisable to consider ways in which blood can be treated to reduce any possible risk there might be."
Blood supplies are already tested for certain diseases, including HIV and hepatitis, but the only test that exists for BSE and v-CJD involves examining the brain tissue from victims. It is not very effective and can only be carried out once an animal or person has died.
Professor Richard Lacey, the first person to warn that BSE could spread to people, welcomed the new development but warned it may have come too late.
"This is the bare bones for a test which identifies which cattle will get ill and which people might be incubating the disease," he said.
"It is a step forward but it is still not known how much abnormal prion production is needed to cause the disease. Therefore to validate the test, it needs to be looked at prospectively for some years to see whether findings correlate with events. With cattle this could be five or six years, with humans it could be decades."Reuse content