Controversial link. A previous study of chronic fatigue syndrome pointed to a retrovirus found in cancerous prostate cells (magnified in inset).
Credit: ROBERT SCHLABERG AND HARSH THAKER
Posted on 01/11/2010 12:37:17 PM PST by neverdem
Controversial link. A previous study of chronic fatigue syndrome pointed to a retrovirus found in cancerous prostate cells (magnified in inset).
Credit: ROBERT SCHLABERG AND HARSH THAKER
Here we go again. Late last year, scientists seemed to be homing in on the cause of chronic fatigue syndrome (CFS)—excessive tiredness and other symptoms that have no known biological cause--by finding a supposed viral link. But a new paper challenges that link, a development that may plunge the field back into the same confusion and acrimony that has characterized it for years.
Many CFS patients report that their symptoms began after an acute viral infection. Yet scientists have been unable to pin CFS on common viruses such as the Epstein-Barr virus. As a result, patients have faced skepticism for years that CFS might not be a real disease, or that it is perhaps a psychiatric disorder.
A team of American researchers thought it finally struck pay dirt last October when it reported in Science that it found DNA traces of a virus in the blood cells of two-thirds of 101 patients with CFS, compared with 4% of 218 healthy controls. XMRV is a rodent retrovirus also implicated in an aggressive prostate cancer, though why it might cause or be associated with CFS remains unclear.
Other scientists were dubious about the XMRV connection. They criticized the Americans for not explaining enough about the demographics of their patients and the procedures to control for contamination. Several virologists around the world practically sprinted to their labs to redo the experiments, and the discovery that a clinic associated with the Science paper was selling a $650 diagnostic test for XMRV made the issue more pressing. A British team already exploring the XMRV-prostate cancer link won the race, submitting a paper to debunk the claim on 1 December.
The team, led by Myra McClure, a professor of retrovirology at Imperial College London, examined DNA from the blood of 186 CFS patients ranging in age from 19 to 70, with an average age of 40. Most were markedly unwell. McClure's team used a PCR machine--which copies and amplifies scraps of DNA--to search for two viral sequences, one from XMRV and the other from a closely related virus. They discovered nothing. At a press conference discussing the results, published in PLoS ONE, McClure was blunt and confident: "If there was one copy of the virus in those samples, we would have detected it."
This null result prompts the question of what--if anything--was wrong with the original paper. In their own paper, the PLoS ONE authors seem to suggest that contamination was at fault, stating that they were careful to work in labs that had never handled XMRV and in PCR machines that analyze no mouse tissues. But McClure says her group merely wanted to make that explicit, not accuse anyone.
Regardless, the American team followed the same procedures, says Vincent Lombardi, a biochemist at the Whittemore Peterson Institute for Neuro-Immune Disease in Reno, Nevada, and co-author of the Science paper. He also expressed bewilderment that the McClure group didn't search its CFS samples for the same DNA sequence as his team had, raising the possibility that that's why the two groups came up with different results. McClure and colleagues, however, looked for not only an XMRV sequence but also a sequence in a closely related virus, MLV. That MLV sequence, highly conserved among viruses of its class, would presumably have been found if XMRV was present, they said.
One distinct possibility, says John Coffin, a microbiologist at Tufts University in Medford, Massachusetts, who studies retroviruses, is that both papers are right. He called the PLoS ONE paper too "preliminary" to settle the debate and said XMRV could show more genetic variety, and thus be harder to detect, than anyone assumed. It's also possible that distinct strains of XMRV appear in different parts of the world, like the retroviruses HIV and HTLV (a leukemia virus).
Coffin says one more possibility, raised by many different scientists, is that CFS is actually a suite of diseases that presents the same symptoms and so might have many causes. Lombardi seconds this point. "It's naïve to think that everyone with chronic fatigue has the same etiology. There's probably going to be a subset of people with CFS that have XMRV, and it will probably end up being classified as XMRV-related CFS."
All of this leaves doctors and patients in a muddle. There's no doubt they're hungry for information. Out of curiosity, Lombardi did a Google search on "XMRV" the day before the Science paper hit and found about 22,500 hits. Three months later, there are 400,000 hits.
But some scientists, including Coffin and McClure, fear that Lombardi's clinic took advantage of that hunger by offering the $650 diagnostic test, 300 of which have been administered so far. Lombardi's group never claimed XMRV caused CFS, so it's not clear what a patient could do with a positive result. Lombardi argues that patients can avoid infecting other people with XMRV and have their diagnoses validated, if nothing else. His test results also bolster the science in the original paper--he says 36% of tests have detected XMRV, including a few from the United Kingdom.
To resolve the dispute, both sides say they are willing to work with the other and possibly test each other's samples. In the meantime, more papers exploring the link are slated to appear in the next few months, and each side says it knows of work supporting its hypothesis. Meanwhile, the field will continue to churn. As McClure told Science, "We take no pleasure in finding colleagues wrong or dashing the hopes of patients, but it's imperative the truth gets out."
That's how science is supposed to work out contentious subjects, not by consensus.
I would craft a reply to this article, but I am just too tired...
I wonder if there is more than one viral cause, and that is why the same virus won’t show up in all the patients.
After all, we call it “cancer”, no matter what the form or the cause is.
It will be amazing to watch this research develop over the next ten or twenty years.
I am so tired of hearing about Chronic Fatigue Syndrome.
“Here’s a thought. Perhaps what we have here is a bunch of lazy people”
Ignorant statement. You obviously have never had your life robbed by chronic fatigue that no Dr. can figure out or really cares to bother to find out. 15 years later, I finally found a Dr. who is finding the cause and treating me. My ‘regular’ Dr. has done nothing but criticize him, however she didn’t do anything for me but put me on a lot of prescriptions. Thanksfully I have a husband who is supportive and a Saint. I hope you never have to deal with this.
“I am so tired of hearing about Chronic Fatigue Syndrome.”
Me too. I just can’t get too worked up over it...
That reminds me of a sketch on the old Tracey Ullman show. She had some recurring characters on her show; a gay couple. One time one of them refused to get out of bed. When asked why his answer was
"I have Chronic Fatigue Syndrome. And there is no one who can prove I don't!"
So are they going back to its original name-hypochondria?
“CFS is actually a suite of diseases that presents the same symptoms and so might have many causes”
FWIW, I was completly run down and almost unable to function in December. They were thinking CFS.
Doc decided I might have a deep-seated sinus (bacterial) infection and put me on two stout anti-biotics (one was the kind used for anthrax, highest dosage without going in the hospital) for 21 days, plus two shots the first day.
He was clearly correct, as I started feeling better about 4 days in and like a new man at 10. (And yes, I finished all 21 days.)
CFS features immune-inflammatory dysfunction. The immune system is revved up in the resting state but primaily for unhelpful responses (e.g. misdirected inflammation). Actual anti-viral responses are often blunted.
So many viruses show up in these patients including reactivation of latent viral infections (e.g. herpes).
It is useful to distinguish environmental risk factors which may cause CFS from the multitude of effects associated that can arise with the condition.
I knew a woman with CFS. She could cure it by leaving her husband and going back to Louisiana where her family lived. While she was there, she was fine. She eventually left her husband and was cured.
Maybe he was making her sick. Maybe it was in her head. Maybe it was Depression. Maybe she just slept too much. Maybe she was paid to sleep too much. But she was always asleep when we stopped by.
Every person I have ever known with CFS got paid to have it.
Frankly, I view any retrovirus as suspect. When AIDS first arose, it was just coincidentally found to be a retrovirus, which had only just been invented. I think they should have looked a lot deeper rather than jumping to a conclusion of a radically different nature.
For example, it has been shown many times that HIV is orders of magnitude less communicable than standard sexually transmitted diseases. If it can’t be easily spread, then casting AIDS as a sexually transmitted disease resulting from the HIV virus is completely wrong.
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I’m going to go with suite of diseases that presents the same symptoms and may have many causes.
I had fatigue for about six months (in my twenties)which could not be diagnosed for a specific cause. Eventually it just went away. Pretty tough symptom for someone with a type A work ethic. I had a week of fatigue after a recent cold.
I don’t follow your last statement........can you explain further?
Since HIV doesn’t cause AIDS, maybe you should inject it into yourself to prove your claim to the world.
Looking for a single cause is never going to bear fruit; fatigue is a symptom, not a disease.
The concept of a retrovirus was invented around the same time that AIDS was discovered. At the time of the “AIDS” epidemic, there had been no significant discovery any where else where a retrovirus had been identified as a cuase of a disease.
Along comes “AIDS,” the discovery of which was based on a small sample of diseased homosexual men who shared many risk factors such as unprotected anal sex and the use of drugs, especially “popper” pills of amyl nitrate. Rather than make the simple diagnosis that the individuals suffered a multitude of opportunistic infections, eager beaver researches wanted to discover a new disease and earn a Nobel Prize along the way.
What happened was that AIDS was discovered to be caused by a retrovirus, HIV. So this is the situation: a brand new “disease” is discovered and, by the most amazing of chances, it happens to be caused by a retrovirus even though there had been no previously known example of a retrovirus-caused disease. There haven’t been many since, though I don’t have the number. I was immediately suspicious that these researchers claimed that CFS, which has been notoriously difficult to explain, was, all of a sudden, determined to be caused by a retrovirus.
There are many issues I have with the HIV-AIDS hypothesis. However, the most glaring thing about HIV is that it is virtually impossible to be transmitted through sexual contact or shared needles. The alleged infection rate of HIV are magnitudes less than syphilis, chlamydia, and gonorrhea. In other words, HIV, which is supposed to be the “cause” of AIDS, can’t be transmitted it via sex or shared blood!
A good book on this, and many other problems with the HIV-AIDS hypothesis, is: The Origin, Persistence and Failings of HIV/AIDS Theory by Henry Bauer. Despite being an academic text, it is mostly quite well-written and easy for the non-academic to read except for a few spots. To me, it is one of the most important books that I have read in the past decade.
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