Scientists in the UK have found a way of reversing the early symptoms of prion diseases.

These diseases such as the human form of mad cow disease, variant Creutzfeldt-Jakob disease, or vCJD, and the disease in cattle called bovine spongiform encephalopathy, are more often than not fatal.

The researchers at University College, London, believe they have found a way to treat the disease in humans as long as it is detected before it has done harm to a large number of brain cells.

The scientists from the Medical Research Council (MRC) of the college, infected mice with abnormal prions and found they began to develop the disease but when the mice stopped producing their own prions, the symptoms cleared up.

The mice had been genetically altered to generate an enzyme in their bodies at around nine weeks of age, which effectively removed the gene that makes prions.

The mice which continued to produce normal prions became increasingly ill and died.

This says lead researcher Giovanna Malucci suggests that blocking the body's ability to make its own natural, healthy prions can reverse the early symptoms of the disease.

Prions or rogue proteins, affect the brain cells by changing their shape, creating holes and turning them "spongy".

Malucci and her team were able to stop this chain reaction by genetically switching off production of normal prion proteins.

It appears that if there is no natural prion protein present in the brain, the conversion process to the rogue form cannot take place and damage to brain cells will be prevented.

Malucci and her team believe the results could be useful in developing a treatment for vCJD or other prion diseases if the disease is detected in the early stages.

Dr. Mallucci hopes that the findings will eventually benefit people showing the first symptoms of vCJD, or other prion diseases such as "classic" CJD, the cause of which is unknown.

However Malucci says more needs to be found out about the exact role of prions in the system and the MRC unit has already taken a first step by identifying drugs that bind to normal prions.

Since vCJD - the human form of BSE - emerged in 1990, there have been 158 confirmed or suspected cases of death caused by the disease; another seven people believed to have the disease are still alive.

The study is published in the journal Neuron.