Professor John O’Leary, who did the tests for solicitors representing the families of autistic children, said his scientific findings “did not support the MMR/autism hypothesis”.

He also said he was “shocked” by the outcome of a Sunday Times investigation into the activities of Andrew Wakefield, the controversial doctor behind the anti-MMR panic. O’Leary, of Trinity College Dublin, had been seen as one of Wakefield’s closest scientific collaborators.

“This is very surprising,” said Professor Michael Langman, chairman of the government’s joint committee on vaccination and immunisation. “O’Leary’s work was supposed to uphold the hypothesis, although it was never reproducible by others.”

Wakefield had already suffered a blow last week when 10 of his former colleagues retracted clinical research that had suggested a possible link between the vaccine and autism. A Sunday Times investigation led The Lancet, which had published the research, to condemn it last month as “fatally flawed”.

O’Leary began research collaboration with Wakefield in 1999. They were co-authors of a paper that appeared two years ago in a scientific journal, Molecular Pathology, detailing their search for evidence of the measles virus in the gut of autistic children. In early 2000, O’Leary also set up a “campus company”, Unigenetics Ltd, to carry out scientific tests for Alexander Harris, a firm of solicitors representing parents seeking to sue three vaccine manufacturers over the alleged links with autism. Wakefield also carried out scientific work for some of the same cases through the same solicitors.

Wakefield was allocated £55,000 for his work by the Legal Services Commission in August 1996. According to the commission, O’Leary’s company was subsequently funded with up to £800,000 for its tests. He “could not confirm” this amount last week.

The tests involved using sophisticated DNA-amplification technology to hunt for fragments of the measles virus in the gut and blood of autistic children.

In a letter sent to The Sunday Times through his solicitors, O’Leary revealed: “The testing continued until late 2003 and reports were provided to Alexander Harris and to the UK court on our findings. These did not support the MMR/autism hypothesis.”

It is understood that the tests found no difference in blood taken from autistic children and those from healthy “controls”.

O’Leary added in his letter that he had consistently advised parents to use MMR.

Wakefield, who with two other doctors is under investigation by the General Medical Council over events at the Royal Free hospital, London, was unavailable for comment.

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