Xenotransplantation, endogenous pig retroviruses and the precautionary principle

Xenotransplantation poses challenges to scientists, ethicists and clinicians. Recent studies of the role of endogenous retroviruses suggest that these agents could threaten the safety of porcine xenotransplantation both for the recipient of a transplant, and possibly for people who have contact with that patient. Although the risk of such complications is low, the history of recent infectious diseases suggests that the precautionary principle should be invoked.