so the cdc still says they can not find xmrv? i read on another thread (where?) that they now can find it. but at this FDA meeting they only reported that they can not find it?
Here's a possible interpretation. They found XMRV in about 1% of
tissue samples from prostate cancers. This was reported at a conference months ago. It looks like this allows them to say: 1) yes, we know how to find XMRV; 2) no, it is not in the blood supply. Had they failed to find it anywhere, they would have lost credibility. In this case, it seems the test assay was improved just enough to satisfy policy objectives.
I doubt we are out of the woods w.r.t. testing. Evidence for hypermutation, to say nothing of possible recombination, means finding specific sequences may be considerably more difficult than anticipated. If, as I suspect, most sequences were mutated prior to collection, the role of activation and biological amplification could be more important than simply increasing the number of copies.
If activation caused the virus to insert new copies of its genes, these would not be immediately subject to mutation. Assume, for the moment, biological amplification goes through four generations. If the sequences were already present, you might see a change from a single copy to 16. In this case, chance alone would suggest finding some XMRV, not 0%. On the other hand, if all preexisting inserted sequences were mutated, you might see a difference between zero copies and 16.
This idea may well be wrong, but it fits published results pretty well.