controversial link. An earlier study of chronic fatigue syndrome pointed a retrovirus found in cancerous prostate cells (magnified inset).
ROBERT SCHLABERG Thaker AND HARSH
Here we go there again. Last year, scientists seem to be homing on the cause of chronic fatigue syndrome (CFS) -excessive fatigue and other symptoms that have no known biological cause - finding a supposed viral link. But a new paper challenges this link, a development that could plunge the new field in the same confusion and acrimony that has characterized it for years.
Many CFS patients report that their symptoms began after an acute viral infection. However, scientists were able to identify CSA common viruses such as Epstein-Barr virus. As a result, patients have faced skepticism for years that the CSA may not be a real disease, or it may be a psychiatric disorder.
A team of US researchers thought he finally hit pay dirt last October when he reported in science found that DNA traces of a virus in blood cells of two thirds of 101 CFS patients compared to 4% of 218 healthy controls. XMRV is a retrovirus also involved rodent in aggressive prostate cancer, although why it could cause or be associated with CFS remains unclear.
Other scientists have expressed doubts about the XMRV connection. They criticized the Americans for not explaining enough about the demographics of their patients and infection control procedures. Many virologists around the world practically sprinted to their laboratories to repeat experiments, and the discovery that a clinic associated with the Science paper was the sale of a diagnostic test for XMRV $ 650 because of the most pressing issue. A British team is already exploring the XMRV in prostate cancer link won the race, report to demystify the application on 1 December.
The team, led by Myra McClure, professor of Retrovirology at Imperial College London, examined the DNA of 186 patients with blood CFS aged 19 to 70, with an average age of 40. most were clearly sick. McClure's team used a PCR machines - which copies and amplifies the DNA remains - to search two viral sequences, one of XMRV and the other from a closely related virus. They found nothing. At a press conference to discuss the findings, published in PLoS ONE , McClure was blunt and confident: "If there was a copy of the virus in these samples, we found it."
This null result prompts the question of what - if anything - was wrong with the original article. In their own paper, PLoS ONE authors seem to suggest that the contamination was at fault, stating that they were careful to work in laboratories that had never treated XMRV and the PCR machines that analyze any mouse tissues. But McClure said his group simply wanted to make this explicit, not accuse anyone.
Regardless, the US team has followed the same procedures, said Vincent Lombardi, a biochemist at the Whittemore Peterson Institute for Neuro-Immune Disease in Reno, Nevada, and co-author of science paper. He also expressed confusion as McClure group did not seek his samples CWS for the same sequence of DNA that his team, raising the possibility that this is why the two groups came up with different results. McClure and his colleagues, however, sought not only an XMRV sequence but also a sequence in a closely related virus, MLV. This MLV sequence, highly conserved among his class of virus would likely have been found if XMRV was present, they said.
a distinct possibility, says John Coffin, a microbiologist at Tufts University in Medford, Massachusetts, who studies retroviruses is that the two documents are right. He called PLoS ONE paper too "preliminary" to settle the debate and said XMRV could show the most genetic variety, and therefore more difficult to detect than anyone assumed. It is also possible that different strains of XMRV appear in different parts of the world, such as HIV and HTLV retroviruses (a leukemia virus).
Coffin said another possibility, raised by many scientists is that CFS is actually a suite of diseases that have the same symptoms and so can have many causes. Lombardi seconds that. "It is naive to think that everyone with chronic fatigue has the same etiology. It will probably be a subset of people with CFS who have XMRV, and it will probably end up being classified as CFS linked XMRV. "
All this leaves doctors and patients in a muddle. It no doubt they are hungry for information. out of curiosity, Lombardi has done a Google search on "XMRV" the eve of Science hit paper and found about 22,500 hits. Three months later there are 400,000 hits.
But some scientists, including Coffin and McClure, fear that the Lombardi clinic benefited from hunger by offering $ 650 diagnostic test, 300 were administered up now. the group of Lombardi never claimed XMRV cause CFS, so it is not known what the patient could do with a positive result. Lombardi says patients can avoid infecting other people with XMRV and their diagnoses validated, if nothing else. His test results also strengthen science in the original document - it says 36% of tests detected XMRV, including some of the UK
To resolve the dispute, both sides say they are willing to work. and optionally with the other test samples of each. Meanwhile, more documents exploring the link are scheduled to appear in the coming months, and each side says he knows of work supporting his hypothesis. Meanwhile, the area will continue to multiply. As McClure said Science "We do not take pleasure in finding colleagues wrong or dashing the hopes of patients, but it is imperative that the truth comes out."
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