Researchers find way to improve BSE testing

Claudio Soto led the team of researchers at Geneva-based Serono Keystone Archive

Scientists in Geneva have developed a method to replicate large amounts of the infectious agent blamed for mad cow disease. The method could open the way for improved testing and research into the disease.

Mad cow disease, or bovine spongiform encephalopathy (BSE), and a related disease in humans, variant-Creutzfeld-Jakob Disease (vCJD), are caused by prions. Prions are abnormally shaped proteins which prompt brain proteins to assume their shape.

The prions form sponge-like holes in the brain, eventually killing the animal or the person infected.

Scientists at the Serono Pharmaceutical Research Institute placed prions from infected hamster brains in contact with normal hamster brain proteins. Nearly all of the normal proteins were then converted to prions using an ultrasound technique.

The ultrasound vibrations broke up clusters of protein, bringing healthy ones into contact with new prions. The conversion, which takes years in the brain, was accomplished in hours in the laboratory.

“We wanted to mimic what happens during the disease”, said researcher, Claudio Soto. “We thought there must be a way to amplify the infectious agent.”

By raising the number of prions to detectable levels, the technique could lead to simple blood tests for detecting mad cow disease, said the Serono team. Current tests have trouble registering the small number of prions which may be in the bloodstream of those infected by the disease.

So far, the animals suspected of having the disease can only be tested after being killed. With humans, a brain biopsy has to be performed, usually after death.

A US expert on prion-related diseases has given a cautious welcome to the announcement. Randy Johnson, a consultant to the National Institutes of Health, pointed out that there is still no proof that prions can be found in the bloodstream and that even if they are, the Swiss researchers have not boosted prion levels enough to make a blood test effective.

Culturing prions may be useful for testing livestock, but this may not lead to a test for humans, he said. “This is a really tough problem, it’s not going to be solved easily.”

Cows and humans are believed to contract BSE and vCJD by eating meat from other animals infected with prions. About 100 people have died in Europe from mad cow related disease since 1995.

The outbreak has led to drastic measures in Europe with the killing of animals suspected of infection and a ban on the sale of certain cuts of meat.

The findings of the Geneva team are published in Thursday’s issue of the journal, Nature.

swissinfo with agencies