A team of researchers announced that they have succeeded in delaying the onset of prion diseases, which include mad cow disease, by inoculating mice with normal prion proteins taken from other animals.

The results of the study, led by Suehiro Sakaguchi, an assistant professor at Nagasaki University, and Daisuke Ishibashi, a researcher at the Japan Science and Technology Agency, were presented Tuesday at a meeting of the Japanese Society for Virology in Yokohama.

While the method poses some safety concerns, the researchers believe that it paves the way to find a way to prevent prion-triggered diseases, including bovine spongiform encephalopathy, and its human form, variant Creutzfeldt-Jakob disease.

Prion diseases are caused when abnormal prion proteins in the body change the form of normal prion proteins.

Immunizing animals with abnormal prion proteins does not always cause antibodies to be created because abnormal prion proteins are different from normal ones only in shape.

However, the Japanese team found that mice created antibodies when they were injected with normal prion proteins from different mammals, such as cows, sheep and humans.

The researchers measured how long it took for a group of mice infected with the foreign prion proteins in the abdomen to develop symptoms.

Those injected with normal prion proteins taken from cows took 332 days to show symptoms, and those injected with proteins from sheep took 316 days, while the mice that were not injected with prion proteins developed symptoms in 293 days.

Sakaguchi said the researchers believe the antibodies destroy normal prion proteins as well as abnormal ones, but the study shows prion diseases can be prevented.