Dr. Jay Levy is the difference. He has hundreds of publications to his name on HIV. Just like Stoye perked his ears up when he found out that Ruscetti was on board the Science paper, researchers will listen to Dr. Levy. Basically through the past couple of decades he's shown that he knows how to do a study correctly - time and time again. So if he does the culture everyone will assume he's done it correctly and that his results are valid and if he finds it that will change everything.
I think Levy simply wants to find the virus. Retrovirologists spend their entire careers and all their working hours researching retroviruses. And all of sudden another one pops up... I imagine another human infectious retrovirus should be like manna from heaven for them. We - the CFS population - the group it was found in, are secondary to them I imagine.
Dusty Miller, for instance, is a gammaretrovirologst - yet some people thought he didn't want to find the virus either. I know there's alot of wariness and I agree the stakes are huge - and we must be careful - but I really think its in their own selfish best interest that retroviroligists find the virus.
You can see it from the opposite side: They, the experienced retrovirologists - some of them are experienced gammaretrovirologists, have worked on retroviruses for decades, only to see other scientists finding the human pathogenic retroviruses, taking the glory from them? Even a retrovirologist which already found a human pathogenic retrovirus might feel: "hey, untill now they were two human pathogenic retroviruses, and I found 50% of them. Why would I want that number to decrease to 33%?".
It's all possible and we should not convict based on suspicion, but we should also not be naive - and therefore, whe should be suspicious, in my opinion. Anyway, in the studies until now it didn't even come to that: It's not that we say: "You faked the results of your replication study". It's that we say: "you have not done a replication study, and we have no conclusive proof that had XMRV or other MLV-related viruses been in the blood of the people that were checked, you would have found them". Same thing goes with Levy: He should do a complete replication study, including collection (storage is not reasonably possible, since we wouldn't like him to store it for 3 years and then check it, at least not currently), preperation, patient selection and assays - all of them should be done exactly, 100%, like they were done in the "Science" study. Only then would we even come to decide whether we should believe him or not (right now I tend to believe that he would not fake the results of his study).
Saying words like "culture" or "patients with post exertional malaise" is far from being enough. Since we don't know what can go wrong here - we should reproduce the entire process, because we don't know what could get us the wrong results (and that's a possibility, since no one has a method that is proven to be able to find HMRVs in clinical samples whenever it's there). If he would do a complete replication, besides the 3-year storage thing study and would come up with negative results, he would be able to say that his study is strong evidence against what the WPI found, unless the 3-year storage is what makes the difference without causing contamination (of antibodies

).