Image: Wikimedia - Burrows Xenotropic murine leukemia virus-related virus (XMRV) was in the news a month ago as researchers provided new evidence that the virus could contribute to the development of prostate cancer. Now, scientists have linked XMRV to Chronic Fatigue Syndrome (CFS).
Knowing that patients with CFS can share an immune system defect with prostate cancer sufferers, the team looked for XMRV in blood samples from patients with CSF. In the study, which is published in the journal Science, XMRV was detected in blood samples from 67% of CFS patients and in only 4% of samples from healthy individuals. The infected blood samples not only contained viral DNA but were shown to produce viral proteins and infectious viral particles. Retroviral particles were also detected in patient samples using transmission electron microscopy. The virus, which is transmitted through body fluids and is not airborne, was found to be transmitted by both cell-to-cell and cell-free mechanisms. Secondary viral infections could be established in uninfected primary lymphocytes by exposure to activated PBMCs, B cells, T cells, or plasma derived from CFS patients.
The data demonstrate the first direct isolation of infectious XMRV from humans and raise the possibility that XMRV may be a contributing factor in CFS. Although the research provides a strong association between XMRV and CFS, it does not prove that XMRV causes CFS. If cause-and-effect is established, antiretroviral drugs could potentially be developed to treat CFS. Since the Science paper was submitted, the team have shown that 95% of plasma samples from CFS patients tested positive for XMRV antibodies. A clinically validated test to detect XMRV antibodies in plasma is currently under development, and the team plan to collect more data on the incidence of XMRV in the general population. The team are also investigating whether approved antiretroviral drugs are effective against XMRV and could benefit CFS patients.