A major obstacle to islet xenotransplantation right now is the potential risk posed by porcine endogenous retroviruses (or PERVs), which exist in the genetic material found in every pig cell. In 1997 it was discovered that PERVs can infect human cells in the laboratory, and although scientists do not know how dangerous PERV infection might be, there is concern that it could spread beyond the transplant recipient and cause an AIDS-like pandemic. More research must be conducted to discover whether PERVs, along with other viruses from transplanted pig tissue, really pose a threat to humans.
