Ewen Callaway describes work probing the biology of a chimpanzee endogenous retrovirus: "Ancient chimp virus 'brought back to life'"
The ancient virus exploits a transport protein that normally pipes copper molecules into and out of cells, the authors report in the October 25 issue of Proceedings of the National Academy of Sciences.
However, the copper transporter cannot explain why chimpanzee ancestors were infected with the virus while humans' early relations were spared. Several types of human cell are susceptible to the resurrected virus, and the human version of the copper-transporter protein is identical to that of chimpanzees.
The null hypothesis, which Callaway discusses, is chance: We didn't get it because we luckily didn't come into contact with infected chiimps several million years ago.
Of course, if that's true then a revived version of the virus would potentially be even more threatening to us than a run-of-the-mill chimpanzee virus, because the ancient chimpanzees that served as its reservoir were evolutionarily closer to us than are today's chimpanzees.
Would that be a "paleozoonosis?"