The Southwest Foundation supplies animals for transplantation, and Allan knows primates can carry undiscovered viruses. In 1994, eight or nine baboons at Southwest were infected with a mysterious nervous-system virus which was later identified as a new virus.
As the Federal government finishes guidelines on xenotransplantation (defined), Allan and a few other scientists question the wisdom of transplanting organs between species. Ironically, their major argument is nothing other than HIV itself.
HIV probably evolved from the simian immunodeficiency virus (SIV), meaning that a jump from primate to human helped cause 17 to 18 million HIV infections around the world. Furthermore, Allan says, "Almost all the monkeys in Africa have their own kind of AIDS virus [which don't make them ill]. If you introduce them into Asian monkeys, they cause AIDS. If you introduce them into humans, they cause AIDS."
Indeed, animal viruses can turn lethal if they infect another species: A relative of herpes B virus that causes fever blisters in monkeys, Allan says, is invariably fatal to humans.
"The overwhelming body of evidence points to non-human primates in Africa as the natural reservoirs [sources] of HIV," Allan says. "The proposed [federal] guidelines will not significantly reduce the risk of introducing a new human disease through xenotransplantation."
A Menace or a "Theoretical Risk"?
Allan says transplanted cells or organs are the ideal pathway for infection since any virus they contain would bypass mucosal and skin barriers to infection. "It circumvents all the natural barriers."
For more on his views, see Xenotransplantation at a crossroads.
To date, no human disease has been traced to a transplant and the baboon used in the Getty transplant was carefully screened beforehand. And, says John Atkinson (who does research into xenotransplants) at the School of Medicine at Washington University in St. Louis, humans and pigs, another animal that is a reservoir of viruses that can infect humans, have lived in close proximity for eons. The emergence of a new virus is "a theoretical possibility, but I can't imagine that with all our contact with pigs over thousands of years, that it would be a major problem."
Here's another cautious view of the future of xenotransplantation.