XMRV Can Cause Persistent Infection in Monkeys

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THE WALL STREET JOURNAL

Health Blog

WSJ's blog on hlath and the business of health

February 17, 2011,

XMRV: Study Shows Virus Can

Cause 'Persistent Infection' in

Monkeys

By Amy Dockser Marcus

The debate over what XMRV may do to humans

continues (http://on.wsj.com/eqlqix). But at least in

a small group of monkeys, one thing is clear,

according to a new study.

*The virus causes chronic, persistent infection,*

says Silverman of the Cleveland Clinic, a

co-author of the paper, which was published online

yesterday in the Journal of Virology

(http://bit.ly/gnxlqY).

Moreover, the new research suggests that in these

monkeys, at least, the virus can be difficult to detect

in blood, even though it's taken root in the body.

This is a tantalizing finding because it raises the

prospect that someone could be infected with XMRV

but show no clinical symptoms of disease until years,

possibly decades, later.

The study involved five macaque monkeys who were

infected intravenously with XMRV. Researchers were

studying the monkeys for a variety of reasons.

Abbott Labs — which helped fund the study and

whose scientists were among the researchers — is

one of a number of companies developing tests

(http://on.wsj.com/fkyz1y) that could potentially be

used to screen the blood supply for XMRV.

Abbott scientists have used the XMRV-positive

monkey blood in their test development process.

Researchers looking at what happens after XMRV

infection in people also needed an animal model and

monkeys are *about as close as we can get to what

happens in humans,* says Klein, a Cleveland

Clinic prostate-cancer surgeon who was also involved

in the study.

There has been concern about the possible risks

XMRV poses to blood supply since a paper published

in Science in 2009 reported finding the virus in 68%

of chronic-fatigue syndrome patients as well as 4%

of the healthy people studied.

The discovery raised the possibility that people who

show no apparent signs of ill health may be infected

with the virus. The Science paper has also generated

controversy over whether XMRV is tied to CFS or

causes the disease (http://on.wsj.com/bRG0YF).

The new monkey study illustrated some of the

challenges that continue to perplex scientists.

The animals showed signs of the virus in their blood

right after being infected, but very soon afterward,

those signs disappeared, making detection very

tough.

When monkeys were autopsied, however, organs

including the spleen, lungs, and prostate contained

XMRV-infected cells.

Klein, who specializes in prostate cancer, tells the

Health Blog that the study showed that the gland is

a *early target for XMRV,* which sets up a *genuine

chronic infection* within a week.

He adds that that this finding does not prove that

XMRV causes prostate cancer, but it does raise

important questions about the long-term

consequences of XMRV infection.

Additional primate studies are underway that will

explore other routes of infection, among other

issues.

*We know XMRV likes to live in the prostate,*

Klein says.

*Now we want to know what it is doing there.*