They do leave open the possibility that XMR is there - and state it might be in a much lower frequency than found in the first paper and further study is needed including coded and blinded testing by multiple labs (BWG).
Acid Test Coming - this study certainly doesn't help XMRV at all but the acid test (BWG) will come when the WPI is given 60 or so samples (or whatever it is) and asked to state which ones are positive....If they can accurately pick out those - and not pick out the blood from the healthy controls then their test is correct and I imagine the entire field regroups tramps over to the WPI labs to figure out what the heck is going on. If they can't - I don't see how they can get by that...
They should be able to do it...they've been finding XMRV in CFS patients for over a year now. Its very basic and simple test...does your test actually tell you if XMRV is there?.... and I don't see anyway you can dispute the results.....They know storage doesn't effect XMRV (much). Even if there is the relapsing remitting question - some people should have the virus in their blood - after all they found it in a considerable number of people in the first paper.
MY guess is it's all down to the testing now. I don't think they have to get every sample right - they just need to get most of them......
I agree, the BWG study is important. However, I don't think we should minimize the findings of this study just because the BWG study is pending, or because people think all negative studies are somehow defective (scientifically improbable). With the variations in methods used, each study contributes a little insight into the bigger picture of what is happening. The BWG study will not be the last word either. Here are some points that stood out to me from reading through this new CD/CDC publication:
1. They dealt with the CFS definition problem. This was the FIRST negative study to use post-exertion malaise and the Bell scale of level of disability. So very difficult to argue about this cohort.
2. The study dealt with the regional difference problem. Another first, I believe this was the first negative study from the US that included a multi-state/area sample. That deals with regional differences.
3. They used a stronger PCR test than the others (larger sample, 10-83x more sensitive than WPI/FDA). Also, yes, this included a gag test, which some other researchers have struggled with (Danielson in particular had to work to get their gag PCR optimized), but gag is also what WPI used with a 10x lower sensitivity, when they found 67% positive. This was a PCR test equal to the task laid out by WPI for finding CFS in a highly infected patient population.
4. This study used 'live' XMRV samples in blood (not water) as controls (and had no problem finding those control antigens). They proved detection with live cells (VP62 and/or infected 22Rv1 cells). They validated their PCR the same way Lombardi et al did...with VP62.
5. The collection procedure was consistent (with one noted exception) and samples were drawn specifically for the study (not banked as in many of the studies, including possibly the original WPI Science study). I realize this is no longer considered a big issue by WPI, but FWIW, this is a better approach than other negative finding studies have taken.
6. They (CDC retrovirus group, NOT the CFS group) created a more powerful antibody test than any of the other studies to date. This approach would find evidence of ANY entrenched XMRV infection. This is a big finding, again, stronger than any of the other replication/validation studies to date. They used actual XMRV viral segments to stimulate an antibody response. This test should have had a positive finding even if the XMRV infection were entrenched in some remote area away from the blood and there was zero XMRV in PBMC (there would have still been antibodies produced after the original infection). If there was any antibody response at all, this test should have seen it, even if the virus was no longer active enough to be detected by PCR.
While I don't think the case is closed yet for XMRV, this study is a significantly better challenge to the hypothesis than the previous negative findings. To seriously attack this study you would have to find a lot of major problems, and I just don't see them. Maybe I missed something, that is certainly possible, but I think XMRV has an uphill battle at this point.