NIH/FDA Study Confirms: XMRV Tied to Chronic Fatigue Syndrome
Monday August 23, 2010
BREAKING NEWS: The much-anticipated FDA/NIH study on XMRV and chronic fatigue syndrome (ME/CFS) is out, and it not only confirms the original findings tying the retrovirus to a large number of cases, it identified a host of infectious agents in the same family, called MLV-related viruses. However, it also identified a more diverse selection of viruses than the original study, published last year in the journal Science.
News of this studies findings leaked out early this summer, but then the paper was held for publication because a similar study from the CDC had conflicting results. The CDC study came out a short time later. It found no evidence of XMRV in ME/CFS or in healthy controls, leading many to conclude that its detection methods were inadequate.
FDA and NIH researchers found evidence of XMRV in 32 out of 37 blood samples collected in the 1990s from people with ME/CFS, which comes out to 86.5 percent. In the control group, they found the retrovirus in 3 of 44 participants, or 6.8 percent. In fresh blood samples from 8 ME/CFS patients, they found XMRV in 7.
In the original research linked XMRV to ME/CFS, Whittemore Peterson Institute researchers found only one type of virus. This new paper, however, says researchers identified a diverse group of related viruses.
What Does MLV-Related Mean?
MLV means "murine-leukemia virus," which is one of the 3 identified human retroviruses. The M in XMRV stands for the same thing, and the R stands for "related." MLV-related viruses all belong to the same family of retroviruses. This new finding of a diverse virus population is more consistent with what we know of retroviruses -- that they tend to mutate frequently, which makes them harder to eradicate.
As research moves forward, expect to see a lot of drug makers testing their HIV drugs against XMRV and other MLV-related viruses. The drug trials we've seen so far have had positive results, which is good news. However, these anti-retroviral drugs can be extremely hard to tolerate, and people with ME/CFS are often less able to tolerate drugs than other people.
Don't expect doctors to start doling out these drugs, though. This study helps prove that this virus is in a lot of sick people, but we still don't know if it's what's making them sick. It's possible that it's a harmless virus that takes advantage of an immune system already weakened by something else. The next step for researchers is to determine what, if any, impact these viruses have on the human body.