A bombshell has just gone off in the continuing debate over XMRV, the virus that may or may not cause chronic fatigue syndrome. Actually, 4 bombshells.
A set of papers out today in Retrovirology (1,2,3,4) claim that many previous studies claiming to have found the virus haven't actually been detecting XMRV at all.
Here's the rub. XMRV is a retrovirus, a class of bugs that includes HIV. Retroviruses are composed of RNA, but they can insert themselves into the genetic material of host cells as DNA. This is how they reproduce: once their DNA is part of the host cell's chromosomes, that cell is ends up making more copies of the virus.
But there are lots of retroviruses out there, and there used to be yet others that are now extinct. So bits of retroviral DNA are scattered throughout the genome of animals. These are called
endogenonous retro-viruses (ERVs).
XMRV ...
