Sound the trumpets! The long-awaited day is finally here – chronic fatigue syndrome is being taken seriously by the medical community!
On Monday afternoon, August 23, 2010 in their early online edition, the Proceedings of the National Academy of Sciences (PNAS) published the much-anticipated research article "Detection of MLV-related virus gene sequences in blood of patients with Chronic Fatigue Syndrome and healthy controls" (in PDF format).
This study – a collaboration between the Food and Drug Administration (FDA), the National Institutes of Health (NIH) and Dr. Anthony Komaroff of Harvard Medical School – found murine leukemia virus (MLV)-related gene sequences in blood samples collected from patients diagnosed with chronic fatigue syndrome and a few healthy blood donors.
The FDA/NIH study looked at blood samples from 37 CFS patients and 44 healthy controls. The CFS samples used were preserved from another study done in the mid-1990s using clearly defined CFS patients. The researchers found evidence of gene sequences for MLV-related virus in 32 of 37 CFS patients (86.5 percent) and three of 44 health controls (6.8 percent).
Comparing FDA/NIH and WPI Studies
The Whittemore Peterson Institute (WPI) study, published October 23, 2009 in Science, found the XMRV retrovirus in 67 percent of CFS patients and 3.7 percent of healthy controls. (After further testing, the WPI reportedly found XMRV in 95% of their XMRV samples.) XMRV stands for xenotropic murine leukemia virus-related virus. The FDA/NIH study did not find XMRV in their samples, however, they did find MLVs that were closely related to polytropic murine leukemia viruses. You're probably wondering what the difference is – I know I was.
In yesterday's telebriefing for reporters, Dr. Harvey Alter from the NIH and Dr. Shyh-Ching Lo from the FDA explained that xenotropic and polytropic murine leukemia viruses were from the same family of viruses. Murine means mouse and murine leukemia viruses are a group of viruses found in mice that can cause leukemia and other types of cancer in mice. Polytropic viruses can infect both mouse and human cells, but when a virus becomes xenotropic, it can no longer infect mouse cells but only infects human cells. So xenotropic and polytropic murine leukemia viruses are slightly different but very closely related. Dr. Alter said he feels that murine leukemia virus-related virus is a better term to use because it encompasses XMRV as well as the other related viruses.
The FDA/NIH study authors stated, "Although we find evidence of a broader group of MLV-related viruses, rather than just XMRV, in patients with CFS and healthy blood donors, our results clearly support the central argument by Lombardi et al. [the WPI study] that MLV-related viruses are associated with CFS and are present in some blood donors." (emphasis mine) In fact, in the telebriefing, Dr. Alter revealed that the “WPI has found that their viruses were more diverse than originally published.”
What Does This Mean for ME/CFS Patients?
Dr. Alter stressed that while this study showed a “dramatic association” between MLV-related viruses and chronic fatigue syndrome, it did not establish whether or not MLV-related viruses may be the cause of CFS. It is not known whether MLV-related viruses directly cause CFS, reflect an underlying immune system disorder or alter the immune system, allowing other opportune viruses to take hold.
In addition to these cause or effect questions, the discovery of the MLV-related virus in CFS patients brings with it other questions yet to be answered:
- Do all accurately diagnosed CFS patients have MLV-related viruses or is it found only in a subset of those patients?
- Why do some apparently healthy people have MLV-related virus in their blood but show no symptoms of CFS?
- How is the MLV-related virus transmitted? Is it a bloodborne pathogen like HIV?
MLC-Related Viruses and the Blood Supply
How the MLV-related virus is transmitted is perhaps the most serious question. If it is indeed a bloodborne pathogen, the world's blood supply could be at risk. During yesterday's telebriefing, Dr. Alter indicated that they were already in the process of doing studies to determine if there is a transfer of the virus from donor to recipient.
Following WPI's discovery of XMRV in CFS patients last October, Australia, Canada and New Zealand banned CFS patients from giving blood. Then after news of the FDA/NIH's positive study was leaked in June of this year, the American Association of Blood Banks issued a bulletin to its members urging them to “actively discourage potential donors who have been diagnosed by a physician with CFS from donating blood or blood components.”
In addition to research on how MLVs are transmitted, other studies include:
- The National Heart Lung and Blood Institute has undertaken studies to develop a standardized test sensitive enough to accurately identify MLVs in the blood.
- A working group of governmental agencies has been formed for the task of examining the nation's blood supply for MLVs.
- More and larger studies will be needed to discover MLV's prevalence in the CFS population and its relationship to the immune system.
- Possible treatment options will need to be developed and tested (i.e., anti-retrovirals).
The authors of a commentary about the FDA/NIH study which was also published in PNAS yesterday, suggest that interventional studies using anti-retrovirals would now be appropriate. They point to the fact that the Helicobacter pylori hypothesis of peptic ulcer disease was only accepted after it was shown that eradicating the H. pylori bacteria with antibiotics cured peptic ulcer. Since three anti-retroviral drugs used against HIV have already been found to inhibit XMRV in the lab, it seems reasonable to think that might be a good place to start.
I can't even put into words how excited I am about this news! After nearly three decades of being treated like the red-headed stepchild, ME/CFS is finally getting the attention it deserves. Some of the biggest players in the medical world are coming together in an effort to identify the cause of this debilitating illness and hopefully find an effective treatment for it. As Martha Stewart would say, “It's a good thing.”
For additional information:
- Reporter Mindy Kitei has written an exceptionally good article about the FDA/NIH study, complete with interesting background information, on her blog, CFS Central: The FDA/NIH/Harvard “XMRV” Study: The Same Thing Only Different
- Questions and Answers from the FDA site: Murine Leukemia Virus Gene Sequence Study
- If you would like to listen to a recording of the August 23, 2010 telebriefing for reporters by the scientists involved in the study, call 1-866-373-4990 and enter passcode 5711. The complete briefing and Q & A period lasts for 40 minutes.
Lo, Shyh-Ching, et al. Detection of MLV-related virus gene sequences in blood of patients with Chronic Fatigue Syndrome and healthy controls. PNAS Early Edition. August 23, 2010.
Courgnaud, Valerie, et al. Mouse retroviruses and chronic fatigue syndrome: Does X (or P) mark the spot? PNAS Early Edition, August 23, 2010.
Published On: August 24, 2010