You make some good points. I had not seen their website. However, tenor of the website does contrast with the tenor of the paper. Every issue they raise about their paper - the assay differences, the cohorts - they basically negate. They call the assay differences minor
stating that the discrepancies in the findings"cannot be explained by minor differences in assays used in each study"
- an important statement given that it's hard otherwise to explain the differences.
They do leave open the question of regional differences in prevalence but that is hardly a central issue since we know that the WPI study participants came from across the US (if not from the South).
That statement does appear somewhat at odds with this statement on their website:
One important consideration is that XMRV is a newly identified virus, first reported in 2006, and much remains to be learned about this and related viruses. As additional research is done on XMRV and similar viruses, it is possible that new findings might emerge that differ from those reported in the Retrovirology and Science papers.
Given the fact that it is a newly identified virus I, as a laymen, wonder how they can be sure that "minor' differences in the assays do not make a larger than expected difference. Indeed the fact that this is a new virus seems to call out for a true replication study -something they suggest 'might
' be necessary under unspecified circumstances - which they leave unclear. (see below).
To pursue this objective, CDC, the Food and Drug Administration, the National Institutes of Health, and several non-federal laboratories are participating in an XMRV assay comparability study....When completed, the results of this process might help researchers to more precisely replicate past studies and further study a potential link between XMRV and adverse health outcomes, including CFS.
It sounds like a great process and it's gratifying that so many important players are involved, but why the need to compare assays in order to precisely replicate past
studies? Aren't the parameters for replication clearly stated in the original paper? I assume the study is taking place in order to determine if a replication study is warranted
not to more precisely replicate the original study.
Anyway within the context of the paper itself they do not appear to leave much reason to study XMRV further.
It's good to see on the website that they are leaving the XMRV question at least somewhat open - as indeed they should since they are part of the DHHS team that is producing validated study instruments.