Scientists who once linked chronic fatigue syndrome to a viral infection now say it's time to go back to the drawing board.

Researchers estimate that 42 out of 10,000 people have chronic fatigue syndrome, which manifests as persistent fatigue accompanied by headache, sore throat, muscle or joint pain, night sweats and memory loss. The disease is also sometimes referred to as myalgic encephalomyelitis.

In 2009, a paper published in the journal Science linked the disease to a mouse retrovirus called xenotropic murine leukemia virus-related virus, or XMRV, after finding traces of it in 68 chronic fatigue syndrome patients out of a 101-patient sample. A 2010 paper in the Proceedings of the National Academy of Sciences found traces of polytropic murine leukemia virus, or pMLV, in the blood of 32 patients from a 37-patient sample.

But other studies have since failed to find strong evidence linking either virus to chronic fatigue syndrome, casting doubt on the connection. Science would end up retracting the original paper in December 2011, citing both the failure of multiple laboratories -- including the authors' -- to replicate the results and "evidence of poor quality control." That same month, the authors of the PNAS paper said they were retracting their work as well.

But there was no large multicenter study to firmly refute the virus link -- until now.

Researchers from a broad spectrum of institutions -- the Centers for Disease Control and Prevention, Stanford University, Columbia University, the Food and Drug Administration and Tufts University, among others -- announced the results of a broad study of the possible viral connection on Tuesday with a paper in the journal mBio.

They examined blood samples from 147 people diagnosed with chronic fatigue syndrome and 146 healthy subjects and found no evidence of either XMRV or pMLV infection in either group.

"These results refute any correlation between these agents and disease," author Ian Lipkin of Columbia University said in a statement Tuesday.

Whittemore Peterson Institute researcher Judy Mikovits, the senior author of the 2009 Science paper that first raised the possibility of the XMRV connection, was also a co-author of this latest report, which nailed the coffin lid down on her original finding.

"Although I am disappointed that we found no association of XMRV/pMLV to CFS, the silver lining is that our 2009 Science report resulted in global awareness of this crippling disease and has sparked new interest in CFS research," Mikovits said in a statement.

SOURCE: Alter et al. "A Multicenter Blinded Analysis Indicates No Association between Chronic Fatigue Syndrome/Myalgic Encephalomyelitis and either Xenotropic Murine Leukemia Virus-Related Virus or Polytropic Murine Leukemia Virus." mBio 3: e00266-12, 18 September 2012.

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