Dr James Ironside, of the CJD Surveillance Unit in Edinburgh, said that the results of the research - in which three macaque monkeys became ill after the BSE agent was injected into their brains - "strengthens the hypothesis" that there is a direct link between exposure to material infected with bovine spongiform encephalopathy (BSE) and the fatal brain disorder CJD.
The possibility of a link was first raised officially by Dr Ironside and his colleagues at the unit last March, after they identified an unusual variant of CJD which had affected 11 people under 42 in the past two years. The more common form of the disease usually affects people over 60. According to the French researchers, three years after the injection all three monkeys began to behave unusually, showing anxiety, nervousness and depression - the same symptoms as were identified in the 11 British CJD cases.
Macaques are the closest relative to man that BSE has been passed to experimentally, although the disease has previously been passed to other monkeys. The French researchers said the experiment is "the first experimental evidence supporting a link between BSE and the new form of CJD in man".
Dr Ironside said that his examination of the monkeys' brains showed a number of changes which matched those in humans with the new CJD variant. "It is not absolutely identical. But it's interesting, and potentially important." He added, however, that the research "doesn't prove the link".
His comment was echoed by the French scientists, who took the unusual step of holding a press conference about their work yesterday, breaking the embargo on the publication of their paper, due in a fortnight in the science journal Nature.
Nature called their decision "highly regrettable" but said it would not postpone publication. The scientists' decision to announce their results early may have been precipitated by the revelation yesterday that British companies had sold French farmers thousands of tons of animal feed that may have been contaminated with BSE after its sale was banned in Britain in 1988.
Dr Ironside said that further research was required before a definite link can be demonstrated between the new CJD variant and BSE. But this may take up to 18 months to emerge through experiments now being carried out in Britain.
Meanwhile, hopes of avoiding a bitter and damaging confrontation over beef at the European Union summit in Florence next week appeared to be fading, write Sarah Helm and John Lichfield.
A revised British five-point plan to solve the dispute will be discussed by EU veterinary experts in Brussels today, but officials said there was little chance of agreement on the detailed and virtually binding framework demanded by Britain for the gradual lifting of the ban on beef exports from the United Kingdom.
The only hope of an agreement before Florence was a vague statement of intent, which could leave much of the ban in place for many months, even years.
The Government long ago abandoned hopes of achieving a specific timetable for lifting the ban in time for next Friday and Saturday's summit. Yesterday, officials conceded that even hopes of securing a general framework for a phased lifting were now fading. As long as "elements of a deal are there at Florence", the deal itself could be concluded later, a British source said.Reuse content