(Press-News.org) A virus previously thought to be associated with chronic fatigue syndrome is not the cause of the disease, a detailed study has shown. The research shows that cell samples used in previous research were contaminated with the virus identified as XMRV and that XMRV is present in the mouse genome.
XMRV was first linked to chronic fatigue syndrome – also known as myalgic encephalomyelitis (ME) – in a study published in October 2009, where blood samples from chronic fatigue syndrome patients were found to have traces of the virus. XMRV had also been identified previously in samples from certain prostate cancer patients.
The new study, published in Retrovirology, identifies the source of XMRV in chronic fatigue syndrome samples as being cells or mouse DNA rather than infection by XMRV. The research does not rule out a virus cause of chronic fatigue syndrome - it is simply not this virus.
The research team developed improved methods to detect XMRV against the genetic noise of other sequences and make recommendations for future study of virus causes of human disease.
"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.
"It is vital to understand that we are not saying chronic fatigue syndrome does not have a virus cause – we cannot answer that yet – but we know it is not this virus causing it."
The team, from University College London, Wellcome Trust Sanger Institute and University of Oxford, showed clearly that the experimental design of previous studies would pick up sequences that resembled XMRV; however, in this improved study, they could prove that the signal was from contamination by a laboratory cell line or mouse DNA. The sequences from the contaminated cell line and chronic fatigue patient samples were extremely similar, contrary to the pattern of evolution expected during the infectious spread of a virus in a human population.
They also showed that the existing methods would indicate that one in fifty human cell lines they examined were infected with XMRV-related viruses: they showed that contamination of human tumour cells with XMRV-related viruses is common and that a principal prostate cancer line used is contaminated.
"When we compare viral genomes, we see signs of their history, of how far they have travelled in space or time," says Dr Stéphane Hué, Post Doctoral Researcher at UCL. "We would expect the samples from patients from around the world, collected at different times, to be more diverse than the samples from within a cell line in a lab, where they are grown under standard conditions. During infection and transmission in people, our immune system would push XMRV into new genetic variants.
"Viral infection is a battle between the virus and the host and XMRV does not have the scars of a virus that transmits between people."
Together the results demonstrate that XMRV does not cause chronic fatigue syndrome or prostate cancer in these cases. The team's methods suggest ways to ensure that virus contamination does not confound the search for a cause of disease in future work.
The authors propose that more rigorous methods are used to prevent contamination of cell and DNA samples. They also suggest that consistent and considered standards are needed for identifying viruses and other organisms as cause of a disease.
"Increasingly, we are using DNA-based methods to accelerate our understanding of the role of pathogens in disease," explains Professor Paul Kellam, Virus Genomics group leader from the Wellcome Trust Sanger Institute. "These will drive our understanding of infection, but we must ensure that we close the circle from identification to association and then causation.
The strongest lesson is that we must fully use robust guidelines and discriminatory methods to ascribe a cause to a disease."
INFORMATION:
The research paper can be found online at http://www.retrovirology.com/content/7/1/111.
New research shows virus previously linked to chronic fatigue syndrome is a lab contaminant
2010-12-21
ELSE PRESS RELEASES FROM THIS DATE:
Without intervention, Mariana crow to become extinct in 75 years
2010-12-21
Researchers from the University of Washington say the Mariana crow, a forest crow living on Rota Island in the western Pacific Ocean, will go extinct in 75 years.
The extinction could happen almost twice as soon as previously believed.
The crow's extinction can be prevented with a bird management program that focuses on helping fledgling birds reach their first birthday, said James Ha, UW research associate professor in psychology.
Ha examined survival rates in 97 Mariana crows – Corvus kubaryi – that had been tracked between 1990 and 2010 by researchers. He found ...
Finnish researchers find a compound that prevents the growth of prostate cancer cells
2010-12-21
Evidence pointing to the effects of monensin emerged in a project investigating the effects of nearly 5,000 drugs and micromolecules on the growth of prostate cancer cells. The project involved most of the drugs on the market today. Researchers found that small amounts of compounds – disulfiram (Antabus), thiram, tricostatin A, and monensin – can prevent the growth of prostate cancer cells without significant effects on the growth of the normal human prostate epithelial cells.
Further studies revealed that monensin caused prostate cancer cell death by reducing the amount ...
Subsidies have no effect on Spanish cinema productivity
2010-12-21
Awards have an impact on Spanish movie productivity, since they increase internal and external distribution demand, but subsidies have no effect whatsoever on the productivity of the Spanish film industry. This is the conclusion of researchers at the University of Granada (UGR), who have studied the production of films in Spain.
"Awards increase the amount of films produced by increasing productivity. In other words film industry workers and companies are more productive and efficient. However, we did not detect that subsidies had any such effect on productivity", Henry ...
A possible cause -- and cure -- for genital cancer in horses?
2010-12-21
Horses are prone to develop genital cancer, especially as they grow older. Male horses are more commonly affected than mares but both sexes suffer from the condition, which is extremely difficult to treat and may result in the animals' death. Because of the similarity of the disease to human genital cancer it seemed possible that a similar agent might be responsible. Several human genital cancers, including cervical tumours, are known to be caused by a papillomavirus infection, so Brandt and her coworkers used genetic techniques to look for papillomavirus DNA in tissue ...
Study finds food in early life affects fertility
2010-12-21
The reproductive success of men and women is influenced by the food they receive at an early stage in life, according to new research by the University of Sheffield.
The research, which was published online this month (17 December 2010) in the journal Ecology, is the first study of its kind to show that early life food can have a serious influence on the life-long fertility of individuals.
The research team, led by Dr Ian Rickard from the Department of Animal and Plant Sciences at the University, used a combination of church record data on births in 18th century Finland ...
Muscle filaments make mechanical strain visible
2010-12-21
Plastics-based materials have been in use for decades. But manufacturers are facing a serious hurdle in their quest for new developments: Substantial influences of the microscopic material structure on mechanical material properties cannot be observed directly. The synthetic polymer molecules are simply too small for microscopic observation in mechanical experiments. A team of physicists led by professor Andreas Bausch of the Technische Universitaet Muenchen (TUM) has now developed a method that allows just these kinds of measurements. They present their results in Nature ...
When the zebra loses its stripes
2010-12-21
Milan, Italy, 20 December 2010 – The capacity to remember that a zebra has stripes, or that a giraffe is a four-legged mammal, is known as semantic memory. It allows us to assign meaning to words and to recall general knowledge and concepts that we have learned. The deterioration of these capacities is a defining feature of semantic dementia and can also occur in Alzheimer's disease. A group of French neurologists and neuropsychologists have now identified the elements of semantic memory which are the first to deteriorate and may have thus explained why a surprising phenomenon ...
Genome-wide hunt reveals links to abnormal rhythms behind sudden death, heart damage
2010-12-21
A study among almost 50,000 people worldwide has identified DNA sequence variations linked with the heart's electrical rhythm in several surprising regions among 22 locations across the human genome. The variants were found by an international consortium, including Johns Hopkins researchers, and reported Nov. 14 in the Nature Genetics advance online publication.
Among the notable discoveries were variations in two side-by-side genes that regulate electrically charged particles to produce signals that start contraction of the heart and register as pulsing waves seen on ...
Johns Hopkins faculty highly value involvement of nearby urban community for improving research
2010-12-21
A survey conducted by Johns Hopkins faculty found strong support among their peers for working more closely with the minority, inner-city community that surrounds the institution. Overall, 91 percent of faculty responders said closer ties make research more relevant to those it ultimately serves, and 87 percent said it improves the quality of research.
"This is a huge, stunning finding," says Nancy Kass, Sc.D., deputy director for public health at the Johns Hopkins Berman Institute of Bioethics. "Faculty are giving a ringing endorsement of how important working with ...
New software detects piping flaws
2010-12-21
New software developed by the U.S. Department of Energy's Savannah River National Laboratory (SRNL) and Northrop Grumman Shipbuilding (NGSB) may lead to a less expensive and less time consuming method to detect corrosion or other defects in a ship's pipes.
The copyrighted software, which is used to analyze digitized x-ray images to determine loss of wall thickness in pipes, was developed as the result of a six-month cooperative research and development agreement between SRNL and NGSB. SRNL has granted NGSB a license to commercialize and continue maturing the software ...