Virus Tied To Chronic Fatigue Syndrome Scientists have identified a virus lurking in 68 of 101 patients diagnosed with chronic fatigue syndrome. Whether the virus — known as XMRV — causes the syndrome is unclear. Molecular biologist John Coffin describes how the findings fit with what scientists know about XMRV.
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Virus Tied To Chronic Fatigue Syndrome

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Virus Tied To Chronic Fatigue Syndrome

Virus Tied To Chronic Fatigue Syndrome

Virus Tied To Chronic Fatigue Syndrome

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Scientists have identified a virus lurking in 68 of 101 patients diagnosed with chronic fatigue syndrome. Whether the virus — known as XMRV — causes the syndrome is unclear. Molecular biologist John Coffin describes how the findings fit with what scientists know about XMRV.


You're listening to SCIENCE FRIDAY from NPR News. I am Ira Flatow.

Up next, the latest on a mysterious illness called chronic fatigue syndrome. Researchers have been studying people who have been diagnosed with it, trying to figure out what might be causing their symptoms, which range from joint pain, debilitating fatigue and inflammation.

A team of researches reports that - the team report that they hit - they've hit on something. Out of 101 people diagnosed with chronic fatigue, 67 percent of them had a specific virus in their blood: a virus called XMRV. And just four percent, or so, of healthy volunteers had the virus in their blood. Scientists have known about the virus for a while. It's been implicated in other diseases.

Joining me now to talk more about this work, published in the journal Science, is John Coffin, professor of molecular biology and microbiology at Tufts University in Boston.

Welcome to SCIENCE FRIDAY, Dr. Coffin.

Dr. JOHN COFFIN (Professor of molecular biology and microbiology, Tufts University, Boston): Good afternoon, Ira. Thank you.

FLATOW: So, this is a pretty good indication, a pretty good connection?

Dr. COFFIN: For a first report, it's very good, in fact. There's still a lot of work to be done, to firmly establish a causal relationship between the virus and the disease. But it's a very, very interesting first step.

FLATOW: Well, this would also vindicate a lot of people who have chronic fatigue syndrome who have, you know, been abused by people who think it's all in your head, you've got something else, it's just a syndrome, there's no real cause to it. Things like that.

Dr. COFFIN: I would imagine that's the case, yes.

FLATOW: Mm-hmm. And so how did you go about - what was your motivation for looking for this viral connection?

Dr. COFFIN: I have to make one thing very clear right here. The work we're discussing was not mine. It was done by other groups. I'm a very interested observer and chronicler of their work. And I had worked on this virus many years ago when we thought it was just a mouse virus.

The people that did work on it, my understanding is that their motivation was based on a correlation that had been previously reported - this virus in a certain specific mutation in individuals with prostate cancer in a gene called RNA cell(ph).

FLATOW: Mm-hmm. How many more people would need to be studied, do you think? Do you need a much larger study to make a better, more symmetrical...

Dr. COFFIN: Well, we certainly need much a larger study - that's absolutely called for. We don't know very much about the association, except for the 101 people you just mentioned. And my understanding is there's over a million people diagnosed with chronic fatigue syndrome, or suspected to have chronic fatigue syndrome in the United States alone. It's...

FLATOW: Is it...

Dr. COFFIN: ...possible there are multiple diseases that have very similar symptoms. And there's all kinds of things that are possible here that we just haven't sorted out yet.

FLATOW: Yeah. Is it possible that the virus is a red herring, in a way? And I mean, by that, that people with chronic fatigue may have some other problem that leaves them susceptible to getting this virus.

Dr. COFFIN: Oh, that's entirely possible. And this all needs to be sorted out. And I think it will be sorted out very quickly, probably within the next few months.

FLATOW: Where do you find the virus in the body?

Dr. COFFIN: The virus, so far, has been found in white blood cells, principally. And it's been possible, by the groups who are doing this, to actually isolate and grow virus from those cells, and to grow it in new cells of the same type from healthy donors.

FLATOW: Mm-hmm.

Dr. COFFIN: So we don't know - it's been isolated from those cells because those are, in a sense, the easiest cells to look at. You can just take some blood and then get them out of it. We don't know what other cells it is and isn't in, in infected individuals at this point.

FLATOW: And the virus has been implicated in other diseases?

Dr. COFFIN: There's an implication with - of prostate cancer. There was a paper that appeared about a month, or so, ago, providing a somewhat less striking -about a 25 percent incidence of the virus in cases of prostate cancer.

FLATOW: Mm-hmm. Do we know where it comes from?

Dr. COFFIN: Well, it almost has to come from mice. It's very, very closely related to what's called an endogenous virus of mice. An endogenous virus is a retrovirus that's inherited in the DNA, in the germ line of its host. And we have been studying - this is a virus we have been studying for over 25 years now, in mice - never thinking that it might, in fact, also be in humans.

FLATOW: Hmm. 1-800-989-8255 is our number. Also you can tweet us, @scifri.

In the 101 patients, or in the total study of all the patients, were they split equally among different ages or did you find that the virus was in older or younger people or certain people of certain age?

Dr. COFFIN: I don't believe - again, it wasn't my study.

FLATOW: Mm-hmm.

Dr. COFFIN: My understanding is there wasn't any obvious connection of that sort. But I don't know that for sure, I have to admit.

FLATOW: Is there any way to get rid of this virus once it's in your bloodstream?

Dr. COFFIN: Probably not. A retrovirus like - HIV is also a retrovirus and there's no way to get rid of HIV that we know of, despite the fact that we have tried very, very hard over many years to do so. HIV infection can be suppressed and people can be relieved of the symptoms of the disease for very long periods of time, but nobody, as far as we know, has ever really been proven to be cured of the infection. And I suspect the same thing will prove to be true with this virus as well.

FLATOW: Mm-hmm. You write in an article, or I'm going to quote from an article from Science Express, that another notable feature of XMRV is that the frequency of infection in non-disease controls is remarkably high, about four percent...

Dr. COFFIN: Right.

FLATOW: both normal individuals from the same geographic region as infected patients. It would mean that, perhaps, it says, 10 million people in the U.S. and hundreds of millions worldwide are infected with this virus.

Dr. COFFIN: That's the implication. That's, again, a very initial study on just a few people and one needs to give a much larger sample and some real demographics and so on to establish those numbers. But that's certainly what that would imply as we look at the numbers if we take those numbers at face value right now...

FLATOW: Mm-hmm.

Dr. COFFIN: ...that would be about 10 times the number of people in the United States who are infected with HIV, for example.

FLATOW: Mm-hmm. Mm-hmm. Are you being inundated with people or do you feel that people are going to want to be tested now?

Dr. COFFIN: I've gotten a few emails. There are no - I should make it very clear that there are no clinically approved diagnostic tests based on this at present, and it will be some time before such tests are available. Any tests that are being done now are being done purely with research tools, most of which were originally developed to study the mouse virus, as I was talking about.

FLATOW: Mm-hmm. And we don't know how the virus is spread?

Dr. COFFIN: We have no idea how the virus is spread right now.

FLATOW: And - but we know that it's in mice.

Dr. COFFIN: It is in mice. All mice carry some virus like it in their DNA. And some, at least in laboratory mice, some express it as infectious virus. How -and it almost certainly, as I said, came from mice originally. How it got from mice to humans, again, we have no idea yet.

FLATOW: Let me get a phone call or two in here. Let's go to Bobby(ph) in San Francisco. Hi, Bobby.

BOBBY (Caller): Hi. Really enjoy your program, Ira.

FLATOW: Thank you.

BOBBY: I've had chronic fatigue syndrome now since my 40s. I'm 72. And I wonder if the individual you're talking to has heard of the work of Dr. Nancy Klimas, K-L-I-M-A-S, or the recent studies which found over 350 genetic expression anomalies in chronic fatigue patient syndromes? Oh, pardon me if I'm confused a little bit there.


Dr. COFFIN: I haven't heard of that work specifically, no. It certainly wouldn't surprise me to hear that there's a lot of differences in gene expression in patients - such patients.

FLATOW: The fact that this is - this is a retrovirus, what does that say to you?

Dr. COFFIN: The fact that it's a retrovirus means it's a virus that replicates in a very specific way by converting its genome RNA to DNA, causing that DNA to be integrated in - with the cellular genome to become essentially normal cellular gene. And then that gene directs the production of more virus.

There are many different types of retroviruses. HIV is one. There's a virus called human T-cell leukemia virus which is responsible for some cases of leukemia and lymphoma in human. And then there's a very large number of other viruses in this general group.

FLATOW: Can you explain the nomenclature XMRV to describe this?

Dr. COFFIN: X comes from xenotropic. It's a slightly confusing designation. What it means is that the virus is found as an endogenous virus, meaning it's in the germline of its host, in this case, mice. But it can't - but if you take the virus out of the germline and make - take the DNA out and make virus out of it, that virus will not infect mice. And therefore - but it will infect humans and many other species of animals, but not mice. And the reason for that is that mice - after the virus got into the germline of mice, after - which is probably around a million years ago or so - the mice became resistant to it by accumulating a mutation which made them no longer able to be infected by that virus.

FLATOW: So - and so, it worked its way into the human population?

Dr. COFFIN: And somehow, it's worked its way into the human population.

FLATOW: Mm-hmm. So do we think it's much more prevalent than we might think otherwise?

Dr. COFFIN: Well, the estimated prevalence right now is that four percent number that we're discussing earlier. Whether there's more than that, what -how real that number is and so on...


Dr. COFFIN: ...we just have to find out a real - good studies have to be done to establish that.

FLATOW: All right, Dr. Coffin. I'll thank you for taking time to be with us.

Dr. COFFIN: You're very welcome.

FLATOW: Good luck to you. John Coffin, a professor of molecular biology and microbiology at Tufts University in Boston, and author of "A New Virus for Old Diseases?" That's in the Science Express paper.

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Virus Linked To Chronic Fatigue Syndrome

Virus Linked To Chronic Fatigue Syndrome

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Some scientists think this retrovirus might play a role in chronic fatigue syndrome. Whittemore Peterson Institute hide caption

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Whittemore Peterson Institute

Some scientists think this retrovirus might play a role in chronic fatigue syndrome.

Whittemore Peterson Institute

Scientists have uncovered a strong link between an unusual virus and chronic fatigue syndrome, which affects more than 1 million people in the United States.

Researchers found that two-thirds of people with chronic fatigue are infected with a retrovirus called XMRV, according to a new study in the journal Science Express. XMRV has also been found in the tumors of some prostate cancer patients.

Scientists say it's too soon to say whether XMRV actually causes chronic fatigue.

People with the syndrome feel tired even after a good night's sleep. Many also have debilitating pain in their muscles or joints, trouble concentrating and immune problems.

The new study compared blood samples from 101 chronic fatigue patients with samples from 218 healthy people. About 67 percent of the sick people had XMRV, compared with fewer than 4 percent of healthy people.

Understanding The Retrovirus

XMRV and other retroviruses are known to infect immune cells. XMRV has been found in some prostate tumors. It's also related to a retrovirus that causes cancer in animals.

The best-known retrovirus is HIV. But scientists say XMRV is simpler, and not a close relative.

In people, XMRV could explain "the entire spectrum of symptoms that have come to be known as chronic fatigue syndrome," says Judy Mikovits, one of the study's authors and research director of the Whittemore Peterson Institute at the University of Nevada, Reno.

But scientists have pointed to viruses as a cause of chronic fatigue before and been wrong.

"This is a very striking initial finding, but it is only an initial finding," says John Coffin, a molecular biologist from Tufts University who was not involved in the study. He co-authored a companion piece about the finding in Science Express.

Researchers have suspected for a long time that chronic fatigue might be caused by a virus.

One reason for that suspicion is that many people get the condition after a flu-like illness, says Mikovits. "They get very bad flu-like symptoms and essentially never recover," she says.

Most viruses don't survive long in the body. But retroviruses are one type that lingers. HIV, for example, is a retrovirus that infects people for a lifetime.

So when scientists found XMRV in people a couple of years ago, Mikovits thought there might be a connection to chronic fatigue, which also tends to last a lifetime.

She was in a position to find out. After many years at the National Institutes of Health, she'd come to the Whittemore Peterson Institute, a place founded to help people with chronic fatigue.

Mikovits worked with a team that began checking patients' blood for XMRV.

"We simply did a screen of the sickest of the sick of our patients because we figured that would be where we would find the most virus," she says. "And, lo and behold, there it was."

Tests also showed the virus was infectious and was provoking an immune response in people with chronic fatigue.

Isolating The Cause

The finding is "the best news ever" for people with chronic fatigue, says Annette Whittemore, one of the founders of the Whittemore Peterson Institute. "We've always known there was something out there. Now we see its face," she says.

Whittemore has an adult daughter who has had chronic fatigue since she was 12. She created the institute with Dr. Daniel Peterson, one of the first doctors to identify people with the condition that later became known as chronic fatigue syndrome.

Even though XMRV has not yet been shown to cause chronic fatigue syndrome, it has characteristics that make it a likely suspect, experts say.

For one thing, it's a retrovirus.

"Retroviruses in general give rise to infections that persist indefinitely," says Coffin. Most other viruses are eliminated from the body.

Coffin says he's concerned by the finding that nearly 4 percent of healthy people carried XMRV. That would mean 10 million people in the U.S. are infected.

Coffin says scientists need to find out whether the virus is causing health problems other than chronic fatigue in any of these people.

For people who have chronic fatigue, the XMRV finding could lead to the first treatments.

Antiviral drugs developed for people with HIV may also work against XMRV, Mikovits says. The institute plans to begin testing that idea soon.