Chronic fatigue syndrome, 'not caused by the XMRV virus'. Or is it?
December 21, 2010
XMRV is in the headlines again. This time the media have picked up on a new batch of research published in the journal Retrovirology. In the latest work, the team, from London and the University of Oxford, used DNA sequencing methods to study XMRV. They say their evidence shows the virus found in patient samples arose from laboratory contamination."Our conclusion is quite simple: XMRV is not the cause of chronic fatigue syndrome," says Professor Greg Towers, a Wellcome Trust Senior Research Fellow at University College London (UCL). "All our evidence shows that the sequences from the virus genome in cell culture have contaminated human chronic fatigue syndrome and prostate cancer samples.
The WPI, who conducted the initial XMRV research (published in Science) quickly put out a statement saying that the new research does not prove there is no link between CFS and XMRV: "The coauthors stand by the conclusions of Lombardi et al. Nothing that has been published to date refutes our data." Judy A. Mikovits.
The Lombardi et al. and Lo et al. studies were done using four different methods of detection. They were not simply PCR experiments, as were the studies by McClure et al. and others who have recently reported their difficulties with contamination. Experienced researchers such as Mikovits, Lombardi, Lo and their collaborators understand the limitations of PCR technology, especially the possibility of sample contamination. As a result, we and Lo et al. conducted rigorous studies to prevent and rule out any possibility that the results reported were from contamination.
In addition to the use of PCR methodology, the Lombardi team used two other scientific techniques to determine whether, in fact, we had found new retroviruses in human blood samples. We identified a human antibody response to a gamma retroviral infection and we demonstrated that live gamma retrovirus isolated from human blood could infect human cells in culture. These scientific findings cannot be explained by contamination with mouse cells, mouse DNA or XMRV-related virus-contaminated human tumor cells. No mouse cell lines and none of the human cell lines reported today by Hue et al. to contain XMRV were ever cultured in the WPI lab where our PCR experiments were performed. Humans cannot make antibodies to viruses related to murine leukemia viruses unless they have been exposed to virus proteins. Therefore, recent publications regarding PCR contamination do not change the conclusions of the Lombardi et al. and Lo et al. studies that concluded that patients with ME/CFS are infected with human gammaretroviruses. We have never claimed that CFS was caused by XMRV,only that CFS patients possess antibodies to XMRV related proteins and harbor infectious XMRV, which integrates into human chromosomes and thus is a human infection of as yet unknown pathogenic potential.
The WPI, who conducted the initial XMRV research (published in Science) quickly put out a statement saying that the new research does not prove there is no link between CFS and XMRV: "The coauthors stand by the conclusions of Lombardi et al. Nothing that has been published to date refutes our data." Judy A. Mikovits.
The Lombardi et al. and Lo et al. studies were done using four different methods of detection. They were not simply PCR experiments, as were the studies by McClure et al. and others who have recently reported their difficulties with contamination. Experienced researchers such as Mikovits, Lombardi, Lo and their collaborators understand the limitations of PCR technology, especially the possibility of sample contamination. As a result, we and Lo et al. conducted rigorous studies to prevent and rule out any possibility that the results reported were from contamination.
In addition to the use of PCR methodology, the Lombardi team used two other scientific techniques to determine whether, in fact, we had found new retroviruses in human blood samples. We identified a human antibody response to a gamma retroviral infection and we demonstrated that live gamma retrovirus isolated from human blood could infect human cells in culture. These scientific findings cannot be explained by contamination with mouse cells, mouse DNA or XMRV-related virus-contaminated human tumor cells. No mouse cell lines and none of the human cell lines reported today by Hue et al. to contain XMRV were ever cultured in the WPI lab where our PCR experiments were performed. Humans cannot make antibodies to viruses related to murine leukemia viruses unless they have been exposed to virus proteins. Therefore, recent publications regarding PCR contamination do not change the conclusions of the Lombardi et al. and Lo et al. studies that concluded that patients with ME/CFS are infected with human gammaretroviruses. We have never claimed that CFS was caused by XMRV,only that CFS patients possess antibodies to XMRV related proteins and harbor infectious XMRV, which integrates into human chromosomes and thus is a human infection of as yet unknown pathogenic potential.
Posted by Craig.
