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health world

New study on potential link between XMRV and chronic fatigue syndrome finds, again, nothing

May 06, 2011|By Trine Tsouderos, Chicago Tribune / For the Booster Shots blog
  • Researchers have looked, and failed to find, evidence supporting a possible link between XMRV and chronic fatigue syndrome.
Researchers have looked, and failed to find, evidence supporting a possible… (Mark Boster / Los Angeles…)

* This post has been corrected. See note at bottom for details.

The news this week was not good for those banking on a link between the retrovirus XMRV and chronic fatigue syndrome.

A much-awaited study — arguably the most comprehensive search for evidence of XMRV in the blood of chronic fatigue syndrome patients to date — was published Wednesday in the Journal of Virology. That study, which examined the blood of 100 patients and 200 healthy peers, found no evidence of the retrovirus in anybody’s blood.

The team, led by Dr. Ila R. Singh of the University of Utah, also found no evidence of XMRV in the blood of 14 chronic fatigue syndrome patients identified as XMRV-positive by the Nevada institute involved in originally reporting a link between the retrovirus and the illness.

"Given the results, “we feel that XMRV is not associated with CFS," wrote Singh’s team in the paper.

The paper is a blow to the Whittemore Peterson Institute for Neuro-Immune Disease of Reno, Nev., and to its fans who passionately believe XMRV is linked to chronic fatigue syndrome and many other mysterious conditions, such as autism and Gulf War syndrome.

The Singh study is the latest in a long line of studies published by independent teams in the U.S., Europe and China that have failed to find evidence of XMRV in the blood of chronic fatigue syndrome patients and healthy people.

A consensus is forming that the original finding linking the retrovirus and the illness was actually the result of lab contamination, a frustrating problem known to virologists the world over.

The Whittemore Peterson Institute's lead researcher, Judy Mikovits, has fiercely defended her work, denied that contamination explains her results and criticized the negative studies, arguing that flaws in their design explain their failure to find evidence of the retrovirus.

But in an interview Friday, Singh said the new study was designed to be as “perfect a replication as you can make." Patients were carefully screened and selected. Blood samples were taken in the same three-week period and handled the same way. Samples were blinded, so researchers had no idea which came from chronic fatigue syndrome patients and which came from healthy controls. Scientists used extreme measures to avoid contamination and to detect it if it happened.

The study used polymerase chain reaction, or PCR, to look for genetic sequences unique to XMRV in the blood samples. Researchers found none. They searched for evidence of antibodies to XMRV in the blood samples. They found none. They tried to grow XMRV from blood samples in cells hospitable to the retrovirus. No virus grew from the samples.

 “It is an extremely strong study,” said Vincent Racaniello, a virologist at Columbia University whose Virology Blog has become a hub of microbiology news on the Internet. “Here the results are overwhelmingly convincing that XMRV is not there. …This study trumps Mikovits' because it is more convincing in its methodology.”

This is a case study “of science at its best,” Racaniello said.

“There is an initial finding, others try to replicate it but fail,” he said. “So along comes another independent scientist, with no interest except to get the story straight. That scientist carefully plans all the right experiments, and even gets blood from some of the original patients, and finds nothing. It is done in a way that all scientists can completely believe.”

Neither Mikovits nor WPI answered a request for a response to Singh’s study.

Singh said her work on prostate cancer and XMRV will continue.

In some online patient forums, the role of XMRV has become a wedge dividing patients. Some dismissed Singh’s study as part of an elaborate conspiracy against patients.

On ME/CFS Forums, one poster wrote, “It is clear that this is an orchestrated attack on the WPI science. I think we should breathe deeply and take this with a grain of salt. … We cannot let them bury us.”

But others wrote about accepting the results and hoping that researchers’ interest in their disease doesn’t die with the XMRV hypothesis. On the Phoenix Rising forum, one poster wrote, “if xmrv doesnt pan out, i hope they keep looking and dont start recommending bloody exercise again.”

ttsouderos@chicagotribune.com 

For the record: Because of editing changes, an earlier version of this post used "chronic fatigue" instead of "chronic fatigue syndrome."

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