U.S. Scientist Admits Mix-Up in AIDS Virus Specimen : Health: Dr. Gallo says his sample may have been contaminated. Issue goes to heart of dispute over who gets credit for finding cause of disease.

A top government scientist credited with co-discovery of the AIDS virus conceded Thursday that the virus he identified in 1984 appears to have been a contaminant from a separate AIDS virus specimen that already had been identified by French scientists.

The acknowledgement by Dr. Robert Gallo of the mix-up helps answer nagging questions about the striking similarity between the initial U.S. and French virus samples--an issue in a convoluted controversy over who deserves credit for unearthing the cause of AIDS.

“The similarity . . . now seems to be explained,” Gallo wrote in a letter published Thursday in the British scientific journal Nature. “. . . It is now time for this period of controversy to come to an end and for us all to focus our efforts on ending the pandemic.”

The controversy over credit has no bearing on current efforts to find ways of preventing and treating AIDS. But it could influence the choice of a winner of the Nobel Prize that some believe may one day go to the discoverer of the disease’s cause.

It could also affect the distribution of royalties from the lucrative patent on the AIDS virus test Gallo developed from early AIDS virus specimens. The U.S. and French scientists agreed in 1987 to share credit for the discovery and split the royalties evenly.

At a press conference in Paris on Thursday, French virologist Luc Montagnier reportedly said Gallo’s concession would not undermine the 1987 agreement. But he said it might eventually call into question the fairness of the current 50-50 royalty split.

After wire service reports stated that Montagnier had suggested that Gallo at one time had lied about his role in identifying the virus, Gallo reportedly countered by calling Montagnier’s statements “bizarre” and “outrageous.”

“Horse manure,” Gallo said, according to the Associated Press, in response to the suggestion that Montagnier was now the undisputed discoverer of the virus. “It’s become obvious wicked politics.”

The controversy stems from the early 1980s when Gallo, head of the U.S. National Cancer Institute’s laboratory of tumor cell biology, and Montagnier of the Institute Pasteur in Paris began analyzing the blood of AIDS patients for a possible cause of the disease.

In 1984, both men claimed for the first time to have identified and isolated strains of the virus, now known as the human immunodeficiency virus. But on close scrutiny, the French and U.S. strains proved virtually identical, though ostensibly from different patients.

That finding--which was surprising, in light of the wide variability of AIDS virus strains in their genetic makeup--prompted allegations that Gallo had used, either accidentally or on purpose, a specimen sent to him by the French in 1983. The French sued the U.S. government in 1985, saying they deserved to own the patent on the AIDS test Gallo had developed.

Gallo has consistently denied any wrongdoing.

The lawsuit was settled out of court in 1987. Last fall, the U.S. National Institutes of Health partially exonerated Gallo, concluding that he had no motive to misappropriate the French specimen since he had already isolated specimens of his own.

On Thursday, Gallo appeared to accept an explanation of the mix-up offered earlier this month by the French, who said lab records suggest they had accidentally sent a contaminated specimen to Gallo, with whom they were collaborating in 1983.

The contaminant then contaminated one of Gallo’s own specimens, the scientists say.

Because the contaminant was an especially virulent strain of the virus, it appears to have overwhelmed both the French and the U.S. specimens. When the two labs analyzed those samples, they were identifying the contaminant strain from the French lab.

“(The contaminant strain) seems to grow extremely well in cell culture, and reports from other laboratories show that (that strain) frequently contaminates cultures of viruses from people with AIDS,” Gallo wrote.