The authors of a controversial paper published in Science that linked chronic fatigue syndrome to a mouse retrovirus have partially retracted their findings, admitting that some of their samples were contaminated. At the same time new research casts further doubt on the original findings.

However, the study’s authors, led by Vincent Lombardi at the Whittemore Peterson Institute in Reno, Nevada, say that their research (Science 2009;326:585, doi:10.1126/science.1179052) didn’t rely solely on the data they are retracting.

The paper created much interest when it was published in 2009. It seemed to show that 67% of a group of patients with chronic fatigue syndrome but only 3.7% of healthy controls showed signs of infection with xenotropic murine leukaemia virus related virus (XMRV).

The study was welcomed by patients’ groups, who saw it as a validation of the clinical basis for the syndrome and as an area for researching a cure. Antiretroviral drugs were proposed as a potential …