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XMRV Vip Inconclusive

Discussion in 'XMRV Testing, Treatment and Transmission' started by hensue, Dec 2, 2009.

  1. mojoey

    mojoey Senior Member

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    Me too

    Called VIP and they said Lombardi was re-doing my test. I'm guessing it was also inconclusive. Said result should be ready within a week.

    I don't know about this re-testing business in order to rule out false negatives or positives. I know this has been the case for other viruses/bacteria (such as EBV, HHV-6, and lyme) but Peterson said there was no point in getting tested for antibodies if my PCR was negative for treatment consideration.
  2. nora_n

    nora_n

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    same with lyme, patients usually have to be tested several times before they test positive.
  3. starryeyes

    starryeyes Senior Member

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    Geez Hensue, that's too bad. You're the first here to report about a response, right? I hope Lombardi can figure it out. It's interesting to hear how other pathogens need multiple runs to test positive too. That makes sense. I'll be watching this space. I'm on the edge of my seat (well, bed) lol.

    tee
  4. Jimk

    Jimk

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    I have to agree with Aus- PCR tests are extremely sensitive, but hugely prone to errors in exactitude of method as well as the kind of primers used. This is why PCR tests for a number of illnesses can vary widely across different labs: the primers are different and the lab technicians vary in skill. Antibody tests are less sensitive, but also less prone to technician errors and more reliable across labs as the standards are more uniform.

    Both are sensitive to sampling problems. For example, if your infection is more or less dormant, or your immune system is suppressed for response to that agent, you will not have a significant response to an antibody test. Some people, for example with an intracellular infection, only show antibodies after they have a course of antibiotics (called seroconversion) because the die-off of infected host cells exposes enough protein to the immune system to induce a significant antibody response. With PCR tests the blood sample may not tap enough protein because the infection is sequestered.

    Dr. Stratton, head of Microbiology Pathology at Vanderbilt U., says that a positive antibody test is mostly useful but a negative one doesn't tell you much (you don't know why it was negative), and PCR results depend on the lab and method.
  5. spit

    spit Senior Member

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    For anybody who is interested in the basic idea of PCR, here's kind of a cute tutorial -- idealized and lacking in the problematic steps of primer design, etc, of course, but still good to give an idea of what PCR is essentially doing.

    http://learn.genetics.utah.edu/content/labs/pcr/

    Also have to agree with asus that we're dealing with science that really isn't solid yet in the first place. I'm hopeful that the WPI results will be able to be replicated and that the exact assays will be refined and validated over the next little while, but in the meantime, we're going to have to accept that everything going on here is in the very early stages. And the jury is still way, way out on the physiological meaning of XMRV, even if the correlation between it and CFS holds up and even if the testing for it is refined and well backed up across many labs. We have a long way to go yet.

    Getting tested now is a choice I do totally understand, but it also comes with the chance that the testing will still have problems, and the meaning of the results is still a big question mark.

    Which is absolutely not meant to minimize your frustration, hensue. I would personally be really impatient for a result better than "we dunno", too.
  6. fds66

    fds66 Senior Member

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    Thanks Spit for that tutorial, it helped me understand more of the PCR process.

    Now can someone please explain in simple terms what the culture test does please.

    Thanks
  7. dannybex

    dannybex Senior Member

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    ???

    So then the $64,000,000 question is, if this testing 'isn't exactly solid', if it's so difficult, so potentially problematic, etc., then how does that reflect on the results reported in both the Science study and the subsequent reports?

    Haven't they been saying for almost a couple of months now that subsequent testing has already been 'refined'...or wasn't it at least described as 'refined'?

    I don't get it.

    ???
  8. joyscobby

    joyscobby Senior Member

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    no more one test or other now only both

    Not sure but perhaps it has something to do with VIPdx no longer offering the option of one test. The only one offered now seems to be

    XAND - XMRV screen by PCR with virus culture confirmation: Test Code XAND ($650)


    I was under the impression that the first looks for virus DNA (RNA) and the second test for antibodies.

    some one scientific please explain if I got this wrong
  9. _Kim_

    _Kim_ Guest

    Joyscobby, thanks for pointing that out. I called to be put on the waiting list about a month ago and at that time, they were offering the tests separately. I was going to get both anyway.
  10. dannybex

    dannybex Senior Member

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    I'm certainly no scientist either, but I guess I'm assuming this is the same 'refined' testing they used that found the higher numbers --95%...98%...?

    ???
  11. kurt

    kurt Senior Member

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    Refined testing? That makes no sense to me if you read the Science article carefully. The antibody test is for some type of MLV, which they later call XMRV in the article without much explanation as to why. I don't believe there even is an XMRV antibody discovered yet, although WPI and probably some other labs are working on that.

    So if you test positive on PCR, how does a subsequent test for an MLV antibody in any way 'refine' that result? All an MLV antibody does is support the case that you have an MLV-related infection, but certainly that does not validate an XMRV finding.

    Maybe I misread that or missed something in that Science article, but I have been curious about the discussion of MLV antibodies in that study and why WPI calls them an XMRV finding since I first read that study.
  12. joyscobby

    joyscobby Senior Member

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    I thought PCR was used in Science study with 67% positive and

    the secound unpublished 95% was using the refined virus culture confirmation.

    I also remember that this was further refined to 98% positive which was in relation to antibodies rather xmrv in cells using PCR.

    A lot of info in a relatively short time and foggy brain makes me almost sure but also doubting the accuracy of my memory.

    Could someone clarify.
  13. dannybex

    dannybex Senior Member

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    Hi Kurt...

    Makes no sense to me either, but that's how it's been repeatedly described (perhaps erroneously)... :)
  14. 2Long

    2Long

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    This is very upsetting, to say the least. We have at least 2 confirmed people that are being "re-tested". That would fall into the margin of error but their descriptions of VIP reaction does not support that.

    I'm thinking of a couple things here. Worst case scenario...

    1. Their "real life" results are nowhere close to their "Science article" results, so they are digging to find any trace of a virus. Since they are directly tied to the WPI, it begs the question. Will they even be able to achieve a 25 or 50% infection rate ?

    2. Their lab is not able to perform the very expensive task at hand. Which, again, leads back to the Science article. If they cannot perform a relatively small number of accurate tests, like those numbers published, then how can we bank on this as being as major a discovery they claim it is ?


    Does anyone know if the Science article was a "mean" measurement between all 3 research facilities, or if it was just the WPI results ?

    Did the CC and NCI use the "samples" that WPI provided ? The reason they had similar/identical results could be due to WPI stacking the deck.


    I'd hate to think all of this was an elaborate fund-raiser by the WPI :(


    Again, this is just my "worst case" mindset. VIP has my blood now and I am getting both panels run, hence my concern.

    I can tell you there is going to be a lot problems if we all come back negative. WPI will be out of business before it starts.
  15. glenp

    glenp "and this too shall pass"

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    ?

    I would like to know why they are not posting some kind of explanation???

    What is the reason they they are not posting something to ease our minds?

    It doesn't make sense to me.
  16. kurt

    kurt Senior Member

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    I definitely can not clarify what WPI is doing. But I do know that this just seems backwards. The PCR is the more accurate test. so the way I would expect this to work is that you run the antibody test first, that is the least 'refined' test, in fact it is for MLV, which I assume they know is cross-reactive with XMRV.

    Of course this brings up the issue that if MLV antibodies are cross-reacting with XMRV, what else to they respond to?

    Anyway, if you have a positive on the MLV antibody, you run the PCR to confirm if it is an active infection. IF you do NOT have a positive the first time you run the MLV antibody, you run a culture study to amplify the sample, then run an antibody study again. If that is positive then you run the PCR.

    The PCR is the most accurate, or it should be. So that is how one refines the result.

    I am sure I am over-simplifying this, maybe even missing some important issues.

    I guess this issue is moot now that WPI just runs all the tests, the order probably does not matter, they are not trying to be conservative at all, they want to test everything every time.
  17. Eric Johnson from I&I

    Eric Johnson from I&I Senior Member

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    67% is PCR

    98% is using PCR plus three further assays, classing subjects as positive if they were positive on one or more or them

    95% is using a test for patient antibodies developed after the paper was submitted -- in the paper the same sort of assay was done, but apparently with different (worse) materials, and it was not even close to 95% positive
  18. Eric Johnson from I&I

    Eric Johnson from I&I Senior Member

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    Anti-MuLV antibody is acceptable here, though anti-xeno-MuLV and anti-SSFV were also used. Patient antibody was also used, which is presumably anti-XMRV, though SFFV was used to detect that antibody.

    1. Its accepted that normal people arent randomly infected with a bunch of retroviruses, let alone MuLVs or MuLV derivatives. Zero of seven normals had antibodies that bound to SFFV in the paper, and I'm sure (literally) they have done way more normals by now.

    2. Its actually not trivially true that actual anti-XMRV will be any more specific than anti-MuLV or anti-xeno-MuLV. In other words, anti-XMRV may well bind to other MuLVs just as other anti-MuLVs bind to XMRV. However, they are now doing an antibody assay more sensitive than the one done in the paper: presumably this can only be mixing patient antibodies with XMRV itself (or proteins from it) rather than with SFFV. Perhaps XMRV+ healthies are positive on this assay too -- that would be rather more expected than unexpected.
  19. Alice Band

    Alice Band PWME - ME by Ramsay

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    Could any drugs or supplements stop the tests from working or give these Inconclusive results?
  20. gracenote

    gracenote All shall be well . . .

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    high percentage of false negatives

    I have heard the following from a reliable source.

    A doctor who has been using the commercial test from VIP with his patients, feels the PCR test being done, while a good one, is still too insensitive. He is receiving a high percentage of what he feels are false negative results.

    I do not know the identity of this doctor and have been asked not to reveal the name of this source. This person added, "I know people are anxious, and I wish we had better answers."

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