They also always said "a XMRV" in this response, it's the first time i hear this. Before it was always "XMRV". I don't know if that's because it was another person who wrote it or because they want to imply that there are different strains. Does anyone know what p-variant XMRV is? Does p stand for polytropic? I'm sure they know why they are calling it this way, but aren't polytropic and xenotropic mutually exclusive?