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Why Didn't Singh Use the Same Assay As She Used in Her Prostate Study?

Discussion in 'XMRV Research and Replication Studies' started by Mya Symons, May 7, 2011.

  1. Mya Symons

    Mya Symons Mya Symons

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    Wyoming
    Regarding this question and answer from Mindy's Blog: CFS Central: In your prostate-cancer study, XMRV is present in malignant prostatic epithelium and is associated with prostate cancer, especially high-grade tumors, you found 4 percent of healthy controls with evidence of XMRV. If youre finding a background rate in controls in your prostate-cancer studies, why do you think you didnt find a background rate in CFS patients and controls?

    Singh: Not entirely sure, but there were different assays (e.g. immunohistochemistry) and different sample types (blood vs prostate tissue).

    This is probably obvious to someone else, but not to me. My question is: Why didn't Singh use the same assay she used in her prostate cancer study? Was it an assay that would only work for tissue samples and not for blood samples? Can someone answer this question for me please? Thank you.
  2. alex3619

    alex3619 Senior Member

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    Logan, Queensland, Australia
    Hi Mya, I haven't gone back and refreshed my memory of this so I could be wrong - the tissue test was antibody based, where animal antibodies are used to colour the virus in tissues, and this can be visibly seen under a microscope. The blood tests use slightly different principles, and copy number is important here. There is a lot of virus in tissue, almost none in blood. This will affect the test.

    Of course I can hear some saying "but Lombardi used blood" and that is correct. If there are no delays (and delays seem to be common) then we might have results by New Year from the BWG and Lipkin.

    Bye,
    Alex
  3. insearchof

    insearchof Senior Member

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    Hi Mya and Alex

    Can someone tell me whether there was a need to use different assays?
  4. alex3619

    alex3619 Senior Member

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    Logan, Queensland, Australia
    Hi insearchof, this is just my opinion, but I think there was a need. Immunohistochemistry techniques are great for tissues, not so good for blood. You are not looking for a pebble in a field of wheat, you just have to spraypaint the barn door.

    I would like to add something though. If XMRV is associated with ME/CFS, and Singh cannot find it in blood, it is very clear that finding the virus is a really hard thing to do, much harder than we were thinking it was. Of course if its all a mistake, then we need to find out why it happened so it wont happen again.

    Bye,
    Alex
  5. insearchof

    insearchof Senior Member

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    Thanks for the reply Alex. I suspected such, because of her reference to different samples - tissue and blood.

    Hopefully they will persist to iron out all the bumps and reconcile these strange differences - than just write it off as - nothing to see here- therefore must not be here - time to move on.

    The take home message just might be that the virus is hard to find in the blood full stop.

    The Monkey study supports this.

    Difficulty in finding virema in blood long after infectious onset, is not news to science. So why is this not being acknowledged also? It is not an excuse not to go looking for it in tissues - espeically when there is evidence it is there and XMRV aside, there are other studies associated with viruses that are difficult to detect in serology - but notwithstanding this, have shown virema in tissue and it being much easier to find there.

    She also found evidence of XMRV and then dismissed it as a mistake - contamination. What if, she was mistaken about that? Remember the CORI where - was it the CDC who dismissed their findings as such - only to question that subsequently and have their lab techs tested?

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