She and Dolly the cloned Finn Dorset sheep, are the first members of the new cloned barnyard. For scientists, the development of animal donors is exciting new territory. If an animal heart was available that had been genetically altered with a human gene, the possibility exists that the need for the anti-rejection drugs would be eliminated or reduced. But everybody isn t jumping on the xenotransplantation bandwagon. Humans are built with natural barriers to certain diseases.
Examples are the skin and the gastrointestinal tract.
Disease that might not have any effect on a pig, could kill a human being. The Macaque herpes virus is harmless to Macaque monkeys, but lethal to humans. If there is an animal virus residing in a xenograft recipient, their sneeze could broadcast a deadly new virus, infecting many people and possibly cause an epidemic worse than HIV, worldwide. Scientists have targeted pigs to use for replacement parts for humans, due to the similarity in size of the organs and because they are easy to breed, having large litters of piglets instead of single offspring. There are over 25 diseases in pigs that are dangerous to humans and to date no way to screen to see if the viruses exist.