Research on chronic fatigue syndrome (CFS) has been done by the Food and Drug Administration (FDA) and the National Institutes of Health (NIH). This research is said to have found the retrovirus XMRV in the blood of subjects with CFS and in the blood of healthy subjects.
However their paper has not yet been published. John Burklow of the NIH says the FDA-NIH paper is being held back by its authors to conduct further tests.
Other research on chronic fatigue syndrome and XMRV was headed by William Switzer of the Centers for Disease Control and Prevention. Their research found no sign of XMRV in any of their samples from subjects with chronic fatigue syndrome or subjects who were healthy. This paper has just been published.
"Annette Whittemore, president of the Whittemore Peterson Institute, whose investigators were part of the team that published in Science, says now that the Switzer paper is out it’s important that the FDA-NIH team’s paper be published immediately. 'Let the science speak for itself,' she says."
http://blogs.wsj.com/health/2010/07/01/cdc-teams-xmrv-chronic-fatigue-syndrome-paper-is-out/