MEA:
"In the pivotal Royal Free Hospital outbreak of ME back in 1955, more than 7% of a previously healthy population of doctors and nurses contracted an unknown infection at roughly the same time (the hospital had to close due to lack of staff). This fact would question the role of retroviral infection as a key predisposing factor if it only occurs in 7% of the population.”
No it wouldn't.
If XMRV were already present in 7% of them and potentiated some other viral infection - like another MLVR - that acted in concert with XMRV, then XMRV would be the key predisposing factor.
If XMRV were able to infect a virus, or to infect an environmental toxin like toxic mold (both scenarios are, in general, possible) and if XMRV could only succeed in infecting roughly 7% of the population who lack the relevant APOBEC-related genes to control XMRV, then XMRV would again be the key factor.
If the health staff at Royal Free had all received an early vaccine that was infected, and for either of the reasons I've suggested only 7% of them were vulnerable to the effect, this again would make sense.
I'm reminded of the endless bozo arguments about nature vs nurture that wound me up so much in younger years. Round and round in circles go the specialists, forever arguing against any theory on the basis that there is other evidence that suggests it can't be the whole truth. Decades we wait for somebody who hasn't been so blinded by specialisation that they can synthesise the various true observations made by people who've spent their careers arguing with each other instead of trying to figure out how they can both be right.
That comment from the MEA strikes me as the reasoning of somebody who hasn't really thought intelligently about the possibilities. It's the sort of reasoning that really winds me up, because it just holds back progress.
What the observations about Royal Free
do suggest to me is that, fair enough, there are other co-factors involved. Whether genetic, whether a 2-strike theory with multiple MLRs, or whatever, it's clear that XMRV on its own is highly unlikely to tell the entire story of ME.
The other thing that Royal Free suggests to me is the involvement of either vaccines or toxic mold. Why didn't the patients get sick? That points the finger straight at the question: what could the health staff possibly have been exposed to that the patients weren't? And the only answers that seem to arise are (1) some kind of environmental contamination in a "staff room" that they shared, or (2) some vaccine that they all received as health workers. A third possibility, (3) the condition can't infect people who are already sick, for some reason (eg their immune systems are active) can't be ruled out, but seems less likely to me.
There is an answer to this question. When the answer is known it will be a
simple answer. There will be 2 or 3 components to the story and that's it. Complexity arises out of simplicity, as every modern mathematician should understand very well. All those pretty fractals are generated from the very simplest of equations. ME will be no different, when we understand it. But arguing against one of the pieces in the puzzle because there have to be at least one or two more, just seems dense to me.
For what it's worth, my guess is that the answer is: genetic vulnerabilities and multiple MLVs. XMRV in concert with other MLVs, which some people can't fight off. XMRV seems to be a keymaster, with access to most cells in the human body. It also has RNA transcription capability which could be used by other viruses in tandem. Hook it up with other MLVs that have other key pieces of the puzzle, and like a train engine, it could carry its coaches straight to the heart of the human immune system. I've even read somewhere that this is precisely how some of the cancer-causing MLV family are believed to work in mice. So it seems to be the first and most obvious hypothesis to me.
Black and white reasoning, the perennial enemy...
