Seems to me, that since it is in the blood, disappears and then goes into cells, then moves around to different types of tissue (see the macaques study), I would think there is period it can be passed in blood, then not. Possibly, then, a time of replication, immune system down, it goes into the blood again. (has to travel to other tissue somehow.)
It seems the disappearance in the blood may have to do with immune system response to it. But, there may come a pivotal point, as in HIV, where the damage done to immune system is too much for antibodies to get back under control. But since this virus has triggers (progesterone, cortisol, etc.) then it might go dormant, or at least not be replicating much. Immune system has it under control. But another trigger happens, and immune system loses ground again, symptoms come back, it's out in the blood again. Mikovits spoke about the sudden cytokine response, like you're walking in the grocery hat can store, and a flood of cytokines are released.
So the flood helps in getting the virus under control again. It is at low level. Isn't floating in the blood. But then, we feel better, we do some cortisol stuff, or our progesterone goes up with monthly cycle, and there we go again. Another round.
So maybe infectivity, saliva and blood, comes and goes. All matches to our good days / bad days scenario and the chronic nature, as opposed to HIV, that just gets in, keeps replicating until immune system keeps up, two years later, if no treatment, person is dead from co-infection or cancer.
Which brings up the other issue. I agree that FeLV is likely more transmissible than XMRV. But relating to HIV would bring fear of imminent death if no treatment. And HIV has connotation of immoral activity. So I don't like that comparison.
Any other ideas. I thought FeLV was most like XMRV, in that many cats have it but don't get sick. It causes immune system and cancer problems. Of course, if a cat has the immune system problem with FeLV, very likely, that cat will die. But some have a mild form.
Can we say XMRV has some features similar to HIV and some similar to FeLV?
Got to come up with something.
Tina