Organic chemist Derek Lowe writes about XMRV at his blog, In the Pipeline:
…this isn’t looking good at all. It’s pretty typical, though, of how things are out at the frontiers in this business. There are always more variables than you think, and more reasons to be wrong than you’ve counted. A theory doesn’t hold up until everyone who wants to has had a chance to take some big piñata-shattering swings at it, with weapons of their choice. So, to people outside of research: you’re not seeing evidence of bad faith, conspiracy, or stupidity here. You’re seeing exactly how science gets done. It isn’t pretty, but it gets results in the end.
If you have never read Derek’s blog, you are missing his wonderful insights into drug discovery in the pharmaceutical industry.