Zoonoses are diseases that can be transmitted from animals to humans, and there are many examples, including the AIDS pandemic, of this phenomenen. With the advent of xenotransplantation, the definition of zoonoses must be broadened to include "xenozoonoses" or "xenoses", the inadvertent transmissionof pathogens and diseases from animal cells, tissues or organs into human recipients as the result of medical manipulations. Xenotransplantation is defined as the transplantation of live cells, tissues, or organs from one species to another species and includes ex vivo perfusion, the temporary contact outside its own body of blood of one species with cells, tissues or organs of another. Twomain sources of transplants are of clinical relevance for man: transgenic pigs and non-human primates…

Keywords: porcine endogenous retroviruses,, PERVs, Xenotransplantation, Xenozoonoses, animal models