Virus Linked to CFS but is history repeating itself?

Earlier this month, a relatively new retrovirus called XMRV was reported to be found in 68 percent of 101 chronic fatigue syndrome (CFS) blood samples, while the viral infection was detected in only 3.7 percent of 218 healthy controls. Scientists at the Whittemore Peterson Institute in Reno, NV, whose medical director is Daniel Peterson, M.D., worked in collaboration with the Cleveland Clinic and the National Cancer Institute to generate this discovery published in the journal Science.¹ Following the study, a press release from the Whittemore Peterson Institute stated the tests for XMRV were refined and now up to 95 percent of the CFS samples have evidence of the virus.

XMRV was originally discovered by researchers at the Cleveland Clinic in 2006 from prostate cancer tissue of men who had a specific genetic defect in their antiviral enzyme RNASE L.² This enzyme destroys viruses by degrading RNA, their genetic machinery. A similar defect associated with a portion of CFS patients prompted researchers to suspect that XMRV might be linked to this illness, which then led to the report in Science. The relationship between prostate cancer and the virus is unknown, and it turns out that the RNASE L enzyme defect did not correlate with the presence of XMRV in the CFS patients studied.

Aside from XMRV, there are two other known retroviruses, HIV which causes AIDS and HTLV which causes leukemia. This family of viruses operate by inserting their genetic RNA material into their hosts’ genetic DNA, causing permanent changes in the way the hosts’ cells operate. Retroviral infections are serious business that cause lifelong diseases affecting the immune and neurological systems, unlike the common flu bug that usually only makes you ill for a few days. While the prospect of a viral cause may validate the symptoms of CFS and possibly fibromyalgia (a small sample of patients have tested positive), the study findings need to be confirmed and many more questions need to be answered.

Keep in mind that close to 4 percent of the healthy subjects turned up positive for XMRV. Does this mean that the virus is benign or will these subjects start to develop symptoms of CFS after some unknown environmental trigger? The role this virus might be playing in CFS is completely unknown. Is this some sort of “passenger” virus that happens to infect people with a dysfunctional immune system? Whether XMRV is involved in the generation of CFS symptoms remains unclear, but researchers appear confident that the virus is not airborne.

Depending upon your perspective, the report of a retroviral link to CFS can be exciting or alarming news. However, the history of CFS is paved with a number of viral claims by well-intended scientists that later turned out not to be the cause of this condition.

After the first outbreak of fatiguing illnesses occurred in Incline Village, NV, where Dr. Peterson was practicing in 1984, there were others that occurred elsewhere in the United States. The initial name was post-viral fatigue syndrome because the symptoms seemed like they were caused by a virus, but no specific agent could be identified. Then researchers claimed the illness was caused by the Epstein-Barr virus (EBV), the bug that causes mono, because almost every patient had antibodies to EBV. As it turned out, so did everyone else in the general population over the age of 6. Then came human herpes virus 6 (HHV-6), followed by HHV-7, an enterovirus that infected the muscles, cytomegalovirus (CMV), and others that were later found not to be the cause of CFS.

While the patients for the current study all met the CFS diagnostic criteria, the authors state, “Samples were selected from several regions of the United States where outbreaks of CFS had been documented.” They go on to say that these are severely disabled patients with multiple immunological abnormalities and extremely low exercise capacities. It remains unknown how these CFS patients from the mid-1980s outbreaks compare to today’s population of CFS patients or those with fibromyalgia.

Given the number of viral reports that have been associated with CFS, it would be prudent to wait for an independent laboratory to confirm the initial study that appeared this month in Science. This does not in any way diminish the potential significance of the research findings by the Whittemore Peterson Institute, but until more information is known, there is really nothing else we can do but wait.

1. Lombardi VC, et al. Science 326:585-89, 2009.
2. Urisman A, et al. PloS Pathogens 2:211-25, 2006.