More recently, however, the hopes of these patients have suffered an extraordinary battering. In a scientific reversal as dramatic and strange as any in recent memory, the finding has been officially discredited; a string of subsequent studies failed to confirm it, and most scientists have attributed the initial results to laboratory contamination. In late December, the original paper, published in the journal Science, and one other study that appeared to support it were retracted within days of each other.

As the published evidence for the hypothesis fell apart, a legal melodrama erupted, dismaying and demoralizing patients and many members of the scientific community. Dr. Mikovits was even briefly jailed in California on charges of theft made by the institute.

“I’m stunned that it’s come to this point,” said Fred Friedberg, a professor at Stony Brook University Medical Center and president of the International Association for C.F.S./M.E., a scientific organization. “This is a really sad unraveling of something that was perhaps going to generate a whole new direction in this illness.”

Despite the controversy, Dr. Mikovits is now supervising some lab work as part of a large government-sponsored study being spearheaded by Dr. Ian Lipkin, a leading Columbia University virologist. The study was established before the two retractions to examine the possible link between chronic fatigue syndrome and mouse retroviruses. Dr. Mikovits still hopes to replicate her original results, and many patients continue to believe fervently in her hypothesis; study results are expected early this year.

She did not respond to requests for comment.

An estimated one million people in the United States suffer from chronic fatigue syndrome, which is characterized by profound exhaustion, a prolonged loss of energy following minimal exertion, swollen lymph nodes, sore throat, cognitive dysfunction and other symptoms. Experts now generally believe that one or more infectious agents, or perhaps exposure to toxins, set off a persistent, hyperactive immune response — the likely cause of many of the symptoms.