`Mad cow' link to humans confirmed

Humans can catch "mad cow disease" from infected cattle, according to test-tube experiments - but not easily. New work by a team of British scientists at the Institute for Animal Health in Newbury, Berkshire, has for the first time shown that cell proteins taken from cows infected with bovine spongiform encepalopathy (BSE), or from sheep infected with the equivalent disease, scrapie, can turn normal human cell proteins into the diseased form found in the fatal brain disorder Creutzfeldt-Jakob Disease (CJD).

The work backs up the fears of scientific advisors to the Government, who last year decided that a number of young people with a "new variant" of CJD probably caught it from exposure to BSE. So far 19 Britons have been diagnosed with the "new variant".

These brain diseases are thought to be caused by a cell protein called PrP "flipping" irreversibly from its normal shape to an insoluble, infectious one. A chain reaction follows, until all the PrP is "flipped", leaving spongy holes in the brain.

The experiment, reported today in the science journal Nature, took extracts of purified PrP from the brains of BSE-infected cows, scrapie-infected sheep and people who had died of "new variant" CJD.

Each was mixed in a test tube with normal human PrP - which subsequently turned into the "flipped" form.