Virus bloodhound. study author Harvey Alter said he is confident in his conclusions.
NIH
There is a new twist in the ongoing battle to find out if a virus is linked to chronic fatigue syndrome (CFS). After reviewing held for 2 months, a study supporting a link between a mouse retrovirus and CFS was published today in the Proceedings of the National Academy of Sciences ( PNAS ). Many are still doubtful of the link, but they are impressed by the efforts made by the authors to ensure accuracy.
In the new study, conducted by the National Institutes of Health scientists (NIH), the US Food and Drug Administration (FDA) and the University of Harvard, the researchers scanned traces of a virus known as XMRV in samples of 37 CFS patients, collected by Harvard Medical School expert Anthony Komaroff CFS in the mid 190. They found evidence of the virus in 32 (87%) patients, but in only three healthy controls 44 (6.8%). It remains to see if the infection causes disease, or vice versa, said NIH virologist and co-author Harvey Alter-but he is "confident" that the results are correct.
XMRV-less succinctly known as murine name xenotropic virus related to leukemia virus was implicated for its potential involvement in prostate cancer, a link that is still intense debate. Then, in a document Science published last year, a team led by retrovirologist Judy Mikovits of the Whittemore Peterson Institute for Neuro-Immune Disease (WPI) in Reno, Nevada, found evidence of infection in 67% of CFS patients, against only 3.4% of healthy controls. Since then, four other papers failed to find the link, or any evidence of XMRV infection in humans at all. The last of the four, by researchers from the US Centers for Disease Control and Prevention (CDC), also took place for some time, at the request of researchers, while they tried to understand how government labs could come to these opposite conclusions. The CDC paper was finally published in July 1 Retrovirology .
The skeptics feared that XMRV Mikovits had found could be the result of contamination from mouse DNA in the laboratory. To remedy this, the first FDA-virologist author of the new Shyh-Ching Lo study and his colleagues tested each sample positive for murine mitochondrial DNA. They found none.
Although the document was waiting, also because of conflicts with other studies, the team ran additional controls that further strengthened the data, says Alter. "I felt that we needed to do more to prove our case," says Alter, in part because of a third additional examiner looked at the paper demand PNAS. For example, researchers took eight fresh patient samples and found that, 15 years later, they were still infected and the virus had evolved, "just as we expect from a retrovirus," says Alter. the wait was "well spent," he adds.
the data seem solid, admits Steve Monroe, director of the CDC Division of High-Consequence Pathogens and Pathology. "it is simply a good paper, "adds Reinhard Kurth, former director of the Robert Koch Institute in Germany, who helped test some samples of CDC and did not find the virus is. Alter-virologist widely respected and winner of the Albert Lasker Award for Clinical Medical researchers "clearly knows what he's doing. They did everything correctly," says Kurth, who nevertheless said he remains skeptical.
so too did virologist Robin Weiss of Imperial College London (ICL), who said he has seen too many examples of new human retrovirus projects that fell outside looking closer, including one he reported in arthritis and lupus patients in 1999 which proved to be a harmless rabbit virus. (in a review of 40 pages which he co-wrote in 08, Weiss called such incidents "virus of human rumor. ")" You can have a very good reputation and be very careful and always get it wrong, "says Weiss.
Part of the problem, say the skeptics, is that researchers do not replicate exactly the science paper [XMRVestunsoi-disantvirusmurinxénotropiquecequisignifiequ'ilnepeutplusentrerdanslescellulesdesourismaispeutinfecterdescellulesd'autresespèces(moyensmurins"desouris")Leschercheursdu PNAS paper say they found viral sequences that are more diversified and more closely resemble the so-called polytropic viruses, which is why they adopted the term MLV-related virus, the virus of murine leukemia. "Let's be clear :. This is another virus They confirm [Mikovits's] results," said Myra McClure retrovirologist ICL, a co-author of one of the four negative studies.
Yet " in the grand scheme of things, "viral sequence found in PNAS closely resembles those of XMRV, said Celia Witten, director of the Office of FDA cells, gene tissue therapies, who was not an author of the document itself but spoke on behalf of Lo. Witten added that the data "support" the Science paper. Mikovits-is "delighted" with the new paper says difference is important. in non unpublished results, his group found greater genetic diversity in the virus as well, she said.
Meanwhile, a working group coordinated by the National Heart, Lung , and Blood Institute (NHLBI) is coordinating an effort to answer the most baffling question: Why do some labs finding the virus in both patients and healthy people, and others are in no. At first, some thought that there could be geographical, because the first three negative studies were all of Europe, but that theory seems unlikely after the CDC paper, the patients were from Kansas and Georgia. Patient selection could play a role: Various studies have used different diagnostic criteria and recruitment. But even given this disorder, it is difficult to explain why four studies are not included a single infected patient.
The discordant results may also come from subtle differences in the handling of samples or perform tests that would have led the four laboratories miss the virus. But Monroe CDC said it is confident that the laboratory can identify the virus. As part of the NHLBI program, FDA researchers, CDC, WPI and other laboratories have all blindly tested a panel of samples, some of them "doped" with various amounts of virus; well done all. Also the exchange of samples and reagents is underway to understand where the differences came. "They should be able to clarify this point by Christmas," said Kurth.
Many of the key players in the controversial plan to attend a workshop organized by the NIH, on 7 and 8 September. Mikovits, who is on the scientific committee, said she saw the summaries of both presentations confirming its conclusions. "I think it will be fun," she said.
This article has been corrected. A wrongly earlier said that Monroe was a co-author of the CDC paper Retrovirology.
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