I was Negative by both culture and serology, with moderate to severe CFS.
I believe it can be because of the two following things combined:
1) You might not have XMRV, but one of those MLV-related viruses, perhaps those found in the NIH/FDA study.
and
2) You're body might not produce antibodies to the virus right now.
I say that because the culture/PCR test is testing for XMRV only, so the PMRVs found in the NIH/FDA study won't be found there, and, it's true that the antibody test can detect antibodies against XMRV as well as against those PMRVs, but if you're body does not produce these antibodies right now, which is very possible as I (although I'm not a scientist, but from what I read) understand it, than the serology test would come back negative even if you have XMRV/PMRVs.
Now, there are a lot of other reasons why you can have one of these viruses and still test negative on both test. First, the tests are not finding any single one which is positive for XMRV; Second, the serology test by itself is far less good than serology+culture/PCR, but as I said, the culture/PCR would not detect the PMRVs, so if you have one of them, only the serology can detect them, and as I said, serology by itself is more probable to miss it (than if it was Serology plus a culture/PCR test that would be able to detect the PMRVs); And perhaps the most improtant thing: They're now checking for XMRV/PMRVs in the blood, and only there. But the study where 5 monkeys were delibarately infected with XMRV showed us that a little time after they were infected, XMRV was not detectable in the blood. However, it was very very detectable in lots of other organs, and when they injected these monkeys with foreign peptides (Dr. Cheney says that this mimics an acute infection, a vaccine or even mold exposure) XMRV was very detectable in their blood. So, it's possible that it's in you're blood but the amount is too little to detect, and it's also possible that it's not in your blood at all, but it is in other organs in your body.
I still think that there is a good chance that you're XMRV/PMRVs positive. A nice example is the example of Sue, who was found to be negative by both culture/PCR and the WPI's old serology test - and after a long while of not knowing if she's XMRV positive, she finally tested positive by the new serology test at VIP Dx.
So there is so much more to know - and sure, if you were found positive by these tests it would probably be better than to be found positive just in the future, but that's what we currently have, so I think you should wait and keep a very open mind.
