Claims that the world's first Aids case was a sailor from Manchester who died in 1959 were wrong, two of the scientists who did the original research have admitted.
The scientists say the mistake arose because tissue samples from the patient probably became contaminated with a modern strain of HIV. Doubts over the validity of the claim were first revealed in the Independent last year.
Subsequent tests show that David Carr, a 25-year-old who died of a mysterious illness in Manchester Royal Infirmary, was not infected with the virus.
In a letter published in tomorrow's issue of the Lancet, two of the scientists, Andrew Bailey and Gerald Corbitt admit "we can find no evidence . . . to suggest that the 1959 Manchester patient carried [HIV]."
It was another letter signed by Dr George Williams, a pathologist at Manchester University, Mr Corbitt and Mr Bailey, published in the Lancet in 1990 which brought worldwide attention and acclaim. It challenged the accepted view that Aids, reported first in 1981, was a newly emerging disease.
Dr Williams, who had carried out the post-mortem examination on Mr Carr in 1959, retrieved samples of Mr Carr's tissue which had been in storage for more than 30 years, for detailed analysis by colleagues at the university. Dr Williams had remembered the case because it was so unusual; Mr Carr had suffered from infections common in Aids patients.
In 1994, however, leading American Aids scientists questioned the validity of the research carried out by the team. They had studied the genetic make-up of the Carr virus and were astonished to find that it was identical to HIV strains circulating in the 1980s. HIV mutates very rapidly and experts expected the Carr virus to be very different from modern strains.
The American team performed more tests and later suggested that tissue samples from Carr used in the original research may have been mixed up with those of another man who died in the 1980s. This has always been strenuously denied by the Manchester scientists.
In their most recent Lancet letter, Mr Bailey and Mr Corbitt said that experiments by an independent team which would have settled this matter were inconclusive.