New WPI paper

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Given the results of the macaque monkeys where XMRV cleared the blood within a few weeks I am not sure that a blood test will ever be sufficient to identify all infected individuals. My guess is that a complete test for XMRV will likely require a set of protocols involving multiple body fluids / biopsies. A blood / urine test will probably be given first and if positive, the test would be considered positive. If negative, they would probably need additional tests.
 
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By the way, this would mean the even if the blood working group can develop an assay that can detect XMRV in the blood with 100% accuracy, it would be an insufficient test for detecting XMRV in infected individuals.

XMRV quickly clearing the blood may also explain why only 70-80% of CFS patients are XMRV positive in the blood tests. XMRV negative individuals with CFS may currently have the virus in tissue reservoirs but not in the blood.

Also, this may indicate that the 4-7% infection rate in the healthy population may be significantly underestimated, since there may be many more infected individuals that have cleared XMRV from their blood but not their other tissues, and show up negative on all the blood tests.
 

alex3619

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Hi SA2, it has been obvious since last year that the figure for XMRV prevalence in the general population would be higher. I am working on a figure of 10% prevalence, because that is roughly the number of patients who develop CFS after a major infection (EBV, bacterial, it doesn't matter much I don't think).

The issue of XMRV not showing up in the blood might be entirely about technique: it is much harder to find once there is no free XMRV, only XMRV bound in blood cells. The right technique might well overcome this, but I do have to say this idea has been discussed before, and I can't be sure you are not correct about needing a complicated test protocol: it is a distinct possibility.

Bye
Alex

Also, this may indicate that the 4-7% infection rate in the healthy population may be significantly underestimated, since there may be many more infected individuals that have cleared XMRV from their blood but not their other tissues, and show up negative on all the blood tests.
 

Rrrr

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HERE is the abstract

Distribution of Xenotropic Murine Leukemia Virus-Related Virus (XMRV) Infection in Chronic Fatigue Syndrome and Prostate Cancer.

Mikovits JA, Huang Y, Pfost MA, Lombardi VC, Bertolette DC, Hagen KS, Ruscetti FW.

Whittemore-Peterson Institute for Neuroimmune Diseases, University of Nevada, Reno NV, USA.
Abstract

In 2006, sequences described as xenotropic murine leukemia virus-related virus (XMRV) were discovered in prostate cancer patients. In October 2009, we published the first direct isolation of infectious XMRV from humans and the detection of infectious XMRV in patients with chronic fatigue syndrome. In that study, a combination of classic retroviral methods were used including: DNA polymerase chain reaction and reverse transcriptase polymerase chain reaction for gag and env, full length genomic sequencing, immunoblotting for viral protein expression in activated peripheral blood mononuclear cells, passage of infectious virus in both plasma and peripheral blood mononuclear cells to indicator cell lines, and detection of antibodies to XMRV in plasma. A combination of these methods has since allowed us to confirm infection by XMRV in 85% of the 101 patients that were originally studied. Since 2009, seven studies, predominantly using DNA polymerase chain reaction of blood products or tumor tissue, have reported failures to detect XMRV infection in patients with either prostate cancer or chronic fatigue syndrome. A review of the current literature on XMRV supports the importance of applying multiple independent techniques in order to determine the presence of this virus. Detection methods based upon the biological and molecular amplification of XMRV, which is usually present at low levels in unstimulated blood cells and plasma, are more sensitive than assays for the virus by DNA polymerase chain reaction of unstimulated peripheral blood mononuclear cells. When we examined patient blood samples that had originally tested negative by DNA polymerase chain reaction by more sensitive methods, we observed that they were infected with XMRV; thus, the DNA polymerase chain reaction tests provided false negative results. Therefore, we conclude that molecular analyses using DNA from unstimulated peripheral blood mononuclear cells or from whole blood are not yet sufficient as stand-alone assays for the identification of XMRV-infected individuals. Complementary methods are reviewed, that if rigorously followed, will likely show a more accurate snapshot of the actual distribution of XMRV infection in humans.
 

Andrew

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It's possible that the rhesus study scientists were not using the WPI method of testing blood, and that's why they thought the blood was 100 percent cleared.
 

aquariusgirl

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doesn't this suggest that it would be advisable to do the serology & the culture test if you're testing for xmrv, mulvs, or whatever we're calling it now?