Question re XMRV testing - Rich? anyone?

Discussion in 'Fibromyalgia Main Forum' started by mbofov, Aug 29, 2010.

  1. mbofov

    mbofov Active Member

    I am seriously considering having the testing done. It is quite expensive, I’m on SSDI like many here but I have a small savings account. (The test would take about 1/3 of that.)

    However, whatever CFS is, it has already taken more than 1/3 of my life. At this point I just want to know what’s going on, what demon I have been fighting. So I’m not going to debate here whether people think it’s a good idea or not to get tested on this post, and I don’t know what I would do if I tested positive. I just want to know what has been going on for the past 25 years.

    My question is, does anyone know if getting the serology test alone (cost $249) would show the presence of antibodies if one had ever been infected even if the retrovirus was not currently active? (is that the correct term?) The following blurb from PH would indicate that is not the case:

    “As we understand it, the serology (antibody) test may not produce a positive result if the body is not currently producing antibodies, while the PCR test would culture/grow the virus if it is present. Some say this is the current 'gold standard' test for XMRV.”

    If the body is not currently producing antibodies, I would assume one would not have a current infection and the virus would not be present at this time. In that case, if the PH blurb is correct, one could have been infected with XMRV in the past, but not currently producing antibodies to it, and therefore these tests will not show if one had had an infection in the past. $549 is a lot of money to find out that they have no way of telling if something may or may not have occurred (whether one may have ever had XMRV or related retroviruses).

    I guess this is a question better posed to VIP dx lab itself?


  2. richvank

    richvank New Member

    Hi, Mary.

    Yes, I think it would be best to ask the people at the VIP Dx lab about this. I understand that Marguerite Ross in the office there is pretty knowledgeable and helpful. Beyond her, Vince Lombardi at the lab would be the most knowledgeable about the current testing, I think.

    As I understand it, there have been several types of tests used in the research projects involving these retroviruses:

    1. PCR (polymerase chain reaction) type tests on either the viral RNA or on the complementary DNA that the virus inserts into the human chromosomes. These tests look for the presence of the virus's genetic material. As such, they can find viruses that are in their latent state in the human cells, if they are sensitive enough, and if the viruses are present at high enough levels in the cells that are tested. These tests are usually run on peripheral blood mononuclear cells, which include lymphocytes and monocytes. This fraction is usually the one tested, because it is relatively easy and noninvasive to take a blood sample, and there is a relatively easy way to separate the mononuclear cells from the other blood cells. Also the mononuclear cells do have nuclei, so they do have DNA and RNA, unlike the more abundant red blood cells, which are separated out. These tests require use of primers, which are specific to the particular DNA or RNA that is sought. If the wrong primers are used for the virus that is sought, it will not be detected.

    2. Culture testing. This type of testing seeks to see if the virus will grow in a laboratory culture that is designed to encourage its growth. If it grows, i.e., moves to other cells in the culture, that shows that it is present and that it is infectious.

    3. Protein analysis. This looks for proteins that are made by the virus. If they are present, this means that the virus has been able to transcribe its genetic material in order to cause its translation into making viral proteins.

    4. Antibody testing. This type of testing looks to see if the person's immune system has raised antibodies against viral proteins. This would indicate that the virus has been in the blood serum, and that the immune system has responded by making antibodies to components of the virus. In general, IgM antibodies reflect a recent or ongoing infection, while IgG antibodies reflect an infection that occurred some time earlier. I don't know how long the antibodies to these retroviruses will persist, but given that it is a retrovirus and its complementary DNA is integrated into the human DNA, if antibodies are present, the retrovirus must also still be present. Antibody testing is very specific, and it is important to be testing for antigens that are present in the particular virus being sought.

    I think the relative sensitivity of these tests will depend on a number of factors, so that as the saying goes, "the devil is in the details." So I think that asking the people who are most familiar with the details of the tests being offered, as well as the experience they have had with the testing so far, would be the way to get the best information as to which test or tests would be the best to get.

    [This Message was Edited on 08/30/2010]
  3. mbofov

    mbofov Active Member

    for all the info. I e-mailed the lab this morning, so hopefully will get answers soon.

    A retrovirus would certainly explain the intractability of this illness.

    Glad you are still with us -

  4. mbofov

    mbofov Active Member

    Amazing - I just e-mailed this morning and just got a very detailed response from Marguerite Ross, answering all my questions. They do recommend having both tests done. She said it is possible to have the virus even though your body has not produced any antibodies, and it's also possible to have the virus but at such low levels that it won't be detected by the PCR. So both tests are recommended.

    They will bill Medicare for the PCR test, before billing the patient, but say it's doubtful that Medicare will pay for it. But they will give it a shot. Can't ask for anything more.

    I think I'm going to go ahead, and now just have get my doctor to order the test, which I am sure he will do.