3.4.2 The health risk to the recipient

A number of risks are already evident. First, there is the chance of rejection. At present, this chance is high and the suppression of the immune system will therefore have to be more radical. It is certain that the recipient has a high chance of physical and mental damage from the rejection as such, as well as from the immunosuppressive therapy. One also fears that xenotransplantation can cause animal viruses to be transmitted to human recipients. The risks of transmission of the Porcine Endogenous Retrovirus (PERV) and Hepatitis E (HEv) are not fully clear [16: L. Scobie and Y. Takeuchi. Porcine endogenous retrovirus and other viruses in xenotransplantation. Curr Opin Organ Transplant. 2009/05/27 ed 2009, 14, 175-179 doi:10.1097/mot.0b013e328327984d.]. No transmission of these viruses was observed in initial studies of humans who had had contact with pig tissues or studies in which pig tissues were transplanted to non-human primates (monkeys) [17: D.K.C. Cooper, R. Gaston, D. Eckhoff, J. Ladowski, T. Yamamoto, L. Wang, H. Iwase, H. Hara, M. Tector and A.J. Tector. Xenotransplantation-the current status and prospects. Br Med Bull. 2017/12/12 ed 2018, 125, 5-14 doi:10.1093/bmb/ldx043.]. However, to completely avoid the problem of virus transmission, good practices regarding selection of not severely infected animals and possibly genetic modification of these animals still need to be developed.