Relevant Journal Articles

Jonathan S. Allan, "The Risk of Using Baboons as Transplant Donors: Exogenous and Endogenous Viruses," Annals of the New York Academy of Sciences, Vol. 862 (1998): 87–99.

Excerpt: "The inherent risks associated with primates because of their close genetic relatedness to humans (which increases the likelihood that simian viruses can infect humans), the monumental historical evidence of simian viruses' causing great harm to humans, and the lack of SPF [specific-pathogen-free] colonies to provide "clean" animals all favor [a] ban [on the use of nonhuman primate organs tissues and cells for transplantation]. . . .The primary aim of public health policy should be prevention."
Jonathan S. Allan is a virologist, Southwest Foundation for Biomedical Research, San Antonio, Texas.

Excerpt: "The news that an endogenous retrovirus can replicate in human cells raises the specter that PERVs [Porcine Endogenous Retroviruses] might be transmitted from pig organs to humans during xenotransplantation. Endogenous retroviruses are particularly troublesome because they are usually distributed in high copy number within the germline of that species. . . .[S]hould a pig organ be successfully implanted into humans, the possibility that this virus might be transmitted to adjacent human cells and then spread throughout the body cannot be discounted. . . .Even if the transplant recipient failed to develop any signs of disease associated with PERV, it may still be 20 years or more before detailed epidemiological studies can be completed to ascertain what the pathogenic potential might be of a virus that begins to circulate in the general population. . . .Public health officials should resist the transplant community's clamor for animal organs in light of this new data. Our first priority must be to protect the public health. These issues are of global concern and it would be prudent for all countries to responsibly act together to prevent the introduction of infectious diseases, because a new emerging pathogen has no regard for national borders."

Excerpt: "[The FDA/CDC xenotransplantation] . . . guidelines provide few real safeguards against the introduction and spread of new infectious diseases in the human population. . . There is no way to screen for viruses that have yet to be discovered . . . Seldom, if ever, have we had as much knowledge to prevent a future epidemic. What is lacking is the wisdom to act upon that knowledge."

Anon, "A Double-Edged Sword," New Scientist, 8 August 1998

Excerpt: "Sceptics point out that man has lived for so long with pigs that we should have encountered all the pig viruses by now. And others point out that surgeons have been using valves from pigs' hearts to replace human ones for 25 years. Unfortunately, neither argument is convincing. Viruses have unique opportunities to infect humans if they are in an organ inside the human body – especially if the individual is taking immunosuppressive drugs. Valves from pigs' hearts are irrelevant to the argument. They are soaked in glutaraldehyde before use and are no more alive than a toenail. . . . It would be a tragedy if genetically engineered pigs designed to have organs that fool the human immune system also produced viruses that fool the human immune system. . . . Nothing could be worse than if in trying to save lives we inadvertently engineered a plague."

Excerpt: "The possibility that xenotransplantation, such as from pigs to humans, could lead to an infection that spreads to the human population, possibly not unlike the AIDS epidemic, is generally accepted. . . Ethically, can we put the public at risk in order to help individual patients? . . . The suggestion of a moratorium to allow us to inform the public and gauge the response of society is not anti-xenotransplantation."
Fritz H. Bach is a xenotransplantation researcher and professor, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts.

Excerpt: "Porcine cells are already being transplanted into the brain of patients with neurological diseases, and the Food and Drug Administration has tentatively approved "bridge transplant" protocols to perfuse the blood of patients with liver failure through porcine livers . . . Neither the degree of risk nor the capacity of the medical community to deal with xenosis are known . . . We propose a moratorium on xenotransplantation including those procedures that could be practiced at any time, such as using a pig organ as a temporary "bridge" until an allogeneic organ is found, or as a support for patients with hepatic failure."

Excerpt: "Not all members of the medical profession may be comfortable with xenotransplantation. Several questions come to mind: Do we really need xenotransplantation?. . . Does life need to be prolonged at any price? What are the implications for society and future generations? What are the effects on animals? Do we care about animal suffering and genetic manipulation of animals? . . . [O]ther values are at stake with respect to xenotransplantation: respect for animals, security of patients and people in general, commercialization. As physicians and citizens, we cannot ignore the problems presented by xenotransplantation . . . These questions should not be hidden and should not be solved solely by bioethicists."
Gilles Beauchamp, M.D. is a surgeon, Department of Surgery, Maisonneuve-Rosemont Hospital, Montreal, Quebec.

Excerpt: "It appears that the microbiological status of pigs is, as yet, not sufficiently characterized to allow for widespread application of this technology. Porcine retroviruses, and probably prions as well, are potentially dangerous agents that could be transmitted to man. . . . [T]he tools for accurate diagnosis of human infection with pig pathogens will have to be developed. Indeed, most current serological tests probably are of limited value in immunosuppressed patients."
(This excellent article provides a detailed analysis of the viral risks associated with porcine xenotransplants. It describes all of the known viruses, bacteria, fungi, and parasites that could be transmitted to humans as a result of these procedures.)

Excerpt: "It is hypothesized that xenotransplantation could facilitate the emergence of new human pathogens. Retroviruses might pose the greatest public health risk because of the possibility of undetected transmission within a population. Evidence from naturally occurring retroviral zoonoses and cross-species infections by animal retroviruses provides a basis for reasoned speculation on the risks posed by xenotransplantation."

Excerpt: ". . . we are preparing a new infectious 'Chernobyl.'"
Claude E. Chastel is a virologist, Virus Laboratory, Faculty of Medicine, Brest Cedex, France.

Excerpt: "Transplanting organs and tissues from animals to humans is one of the best experiments we could devise to 'create' new infectious agents."
Peter J. Collignon, Infectious Diseases Physician and Microbiologist; Infectious Diseases Unit, and Microbiology Department, Canberra Hospital, Canberra, ACT.

Microbes and Infection, 3, 2001, 341-348
Collignon P, Purdy L

"Xenografts: Are the Risks So Great That We Should Not Proceed?"

Excerpt: "In summary, the ethical concerns about xenotransplantation, thus far from mere obstructionism or moral blindness, deserve far more careful consideration than they have received. There is a serious risk that xenotransplantation would do more harm than good. Because the resolution of the ethical and scientific obstacles to xenotransplantation is not guaranteed, we need to consider whether resources now being directed to it would be better deployed elsewhere. It is also arguable that alternative approaches could reasonably be expected to help suffering patients with less risk both to themselves and to humanity as a whole. Some approaches could, in addition, help reorient our attention away from medicine and toward a broader focus on the prerequisites for health. Only such a reorientation will, in the long run, reduce the burden of disease and disability."

Excerpt: "Knowledge of the anatomy of the pig (Sus scrofa) is limited despite the general acceptance in the literature that it is similar to that of man . . . The porcine organ had a classic 'Valentine heart' shape, reflecting its location within the thorax and to the orientation of the pig's body . . . The human heart, in contrast, was trapezoidal in silhouette, reflecting man's orthograde posture. . . .Several potentially significant differences exist between porcine and human hearts. It is important that these differences are considered as the arguments continue concerning the use of pig hearts for xenotransplantation."

Excerpt: "[X]enotransplantation may result in a trans-species transmission of endogenous retroviruses derived from the donor animal . . .[and] may cause an AIDS-like disease in the immunosuppressed transplant recipient."
Joachim Denner, Paul Ehrlich Institut, Langen, Germany.

Excerpt: “In the light of all the potential problems described above, should xenotransplantation be pursued at all?  It does not seem to support the interests of human beings, and, in my view, does not justify the sacrifice of animals; the way in which they are raised and kept . . . is not conducive to their well-being and may cause pain or even suffering.  The argument that pigs have been bred for a long time as food has no ethical relevance and, in fact, is one of the most controversial subjects in today’s discussions on animal ethics. . . . Given that xenotransplantation will not be practicable for decades, there is enough time to come up with alternatives, instead of taking further steps in this direction.  But even if there were no alternatives, there is an alternative to transplantation, namely accepting the limits of medicine and our own mortality and finiteness.”
Dr. Eve-Marie Engels is a Professor of Biology and Director of a bioethics center at Tubingen University, Tubingen, Germany.

Excerpt: " . . . do we have a right to use animals as a source of organs? . . . are alternative methods to increase supply [of human organs] available? . . . If someone experiences herself differently as a consequence of having another creature's heart, then this is no trivial matter . . .It is not self-evidently true that any significant advance in knowledge is a good; to say this is to assume an absolute authority for science . . . science is a human enterprise . . . We are not human material for the sake of science . . . On one hand, the real implications of possible harm to people [from xenotransplantation] are recognized, while on the other, the need for knowledge without reference to human consequences, seems to prevail. . .. [There is no mention of] the possible conflict of interest between recipients of transplants and the science lobby."
Suzanne D. Fullbrook is a nurse and a barrister [lawyer]. Mike Wilkinson is a philosophy lecturer, University of Brighton, UK.

Excerpt: "The [Nuffield Council] report boldly assumes that nurses in [xenotransplantation] units would carry out the work . . . It might well be that the numbers inclined to this type of work would dramatically decrease, acting as a more effective brake on such transplants than any academic argument. . . The risk of infection will be a major consideration both for patients . . . and those who would care for them. . . . nurses are the ones most likely . . . to [be] infected." . . .Companies will be producing animals for organs . . . and will do so for profit . . .who comes first? Consumer patients or the profits of shareholders? . . . For all these reasons, there seems an overwhelming need for a moratorium on any advances and for delaying clinical trials. The issues are too wide-ranging for society to be represented with a fait accompli."

Excerpt: "The incompatibility of allografts [human-to-human transplants] is restricted to immunologic factors . . . This is completely different in xenografts . . .The upright position of man is unique in nature. Gravity therefore exerts a different impact on the anatomic situation of organs such as lung, heart, liver and kidney. More pronounced are differences on the humoral and enzymatic basis . . . Examples are growth hormones which could stimulate the xenografts to unrestricted growth, as in pig hearts in the human patient. . . .It is not sufficiently investigated whether under such physiological and anatomic differences a long –term survival of xenograft or recipient is possible . . ."
Claus Hammer, Institut fur Chirurgische Forschun, Ludwig, Maximilians Universitat, Munich, Germany.

Excerpt: "[T]he donor animals are non-consenting parties. . . we might conclude that if it is acceptable to raise and kill animals for food, then it must be acceptable to raise and kill them for medical purposes . . . A weakness in this argument is that we are not all agreed on the acceptability of eating meat . . .in addition to the donor animals themselves, significant numbers of animals will be needed for experimental subjects in order to develop the necessary genetic manipulations and transplantation techniques and to investigate disease transmission . . . we would have to judge that animals' interests matter very little indeed for the direct harm that xenotransplantation would impose on them . . . The suggestion that measures for increasing human organs be explored before resorting to xenotransplantation is alos supported by the arguments of the previous section, since it would avoid . . . the risk of transmitting infectious diseases from animals to the human population."
Jonathan Hughes, University of Manchester, Manchester, UK.

Excerpt: "[T]here are grounds to believe that education programs aimed at increasing the rate of further human organ donation would be at least somewhat successful in increasing supply. . . Several nations . . . have adopted such "presumed consent" or "opt out" schemes, and the results indeed have been an increase in organs supplied for transplantation . . . [I]ncreasing the numbers of either transplantations or xenotransplantations would drive up Medicare and other federal health costs. . . Moreover, . . . the major expenditure of health care dollars on a very few, to the arguable neglect of basic care for the many, is an ongoing . . . issue.. . . $20.3 billion. If that is truly the annual cost of a procedure likely to benefit a patient population of no more than 50,000, the cost/benefit analysis may tilt against increasing the use of xenotransplantation . . . [A]nimals must be continually monitored and tested, using biopsies, blood, fecal, and other examinations . . . All of this means a more massive intrusion into the lives of these animals . . . there is an additional burden on [xenotransplantation's] proponents to prove that its potential benefits outweigh these animal life costs. . . . Given the poor survival rates of those receiving xenografts today, it would be fair to conclude that early recipients are being used primarily as experimental subjects . . . Patients who have been told they will surely die without receiving a transplant are likely to "consent" to virtually any "treatment" at all, but, for that very reason, their consent is not truly free. . . . Another unanswered legal issue involves questions of responsibility and liability in the event of . . . people inadvertently contract[ing] infections from xenograft recipients . . . There has been little decided about this so far . . . Clearly, the possible long-term consequences of xenotransplants for the human gene pool require further consideration and investigation . . . [T]here is the question of whether local institutions have the abilities to effectively conduct the ambitious duties with which they are charged. . . .[T]oday's optimistic xenotransplant researchers may promote the benefits of the operation too aggressively."
Jack M. Kress, Special Counsel for Ethics, U.S. Department of Health and Human Services, appointed 1990.

Excerpt: "[X]enotransplants represent an unquantifiable risk to the health and well-being of the general public. . . .who would be responsible for paying compensation to persons damaged as a result of [xenotransplantation] or to secondary victims exposed to . . . viruses . . . The best long-term solution to organ transplants in general is preventive medicine. Viable alternatives to animal organ transplants do exist, but they need to be explored in much greater depth."
Andre Menache is a veterinarian and President, Doctors and Lawyers for Responsible Medicine, London.

Excerpt: "Opposition to xenotransplantation is not limited to acute care nurses, but is also expressed by others, including animal rights activists, actual transplant recipients, potential transplant recipients . . . and the general community."
Paula J. Mohacsi, Department of Public Health and Community Medicine, University of Sydney, Australia.

Excerpt: "Known pathogenic viruses that might pose a risk in xenotransplantation include many adenoviruses, papovaviruses, papillomaviruses, parvoviruses, hepadnaviruses, morbilliviruses, filoviruses, hantaviruses, arenaviruses, arteriviruses, flaviviruses, and togaviruses . . .[I]t will not be easy to determine which viruses represent a risk to the xenograft recipient alone, which represent a risk to society as a whole as a result of species jumping and which may be dismissed as representing a minimal risk. An important aspect of policy development should be the construction of a list of the viruses of concern and an evaluation of the relative risk each poses in various xenotransplantation settings – this is a task that has not yet been done in a comprehensive way. . . .Will xenotransplantation be the cause of the epidemic emergence of "new" viruses? Will the immunosuppression induced in xenograft patients amplify this risk? Here, another HIV-like virus/AIDS-like epidemic replaces prion diseases as the ultimate threat."
Frederick A. Murphy is Dean and Professor of Virology, School of Veterinary Medicine, University of California, Davis.

Excerpt: "Population-based interventions to encourage Americans to reduce dietary intake of saturated fat may prevent tens of thousands of cases of coronary heart disease and save billions of dollars in related costs."
Gerry Oster is Vice President and David Thompson is Senior Economist at Policy Analysis Inc., Brookline, MA.

Excerpt: “Xenotransplantation is . . . dangerous, full of strain and stress for persons who have no direct part in it, and weighted with many ethical problems.  Under these circumstances, to injure animals, to subject them to pain and suffering, to cause them great fear, and to damage their well-being severely . . . presupposes their entire devaluation and complete instrumentalisation.  The legal provision limiting research on animals to the indispensable degree . . . does not provide any solid obstacle, because indispensability is tied to the set goals. However, the goals, from the perspective of animal ethics, are no longer justifiable: they imply an offence against the principle of dignity of creatures . . .; they go against the principles of fairness, of not harming, of beneficence, and they leave the realm of proportionality. . .  From the perspective of animal ethics, the xenotransplantation project must be terminated.”
Beat Sitter-Liver is a Professor of philosophy at the University of Fribourg, Switzerland and is the Secretary General of the Swiss Academy of Humanities and Social Sciences.

Excerpt: "We and others have detected expression of endogenous proviruses in a variety of [porcine] tissues including liver, lung, heart, kidney, spleen and thymus . . .These proviruses are therefore likely to be present in the potential donor herds for xenotransplantation . . . [I]t is therefore imperative that we consider the threat posed by retrovirus replication both to the individual transplant recipient as well as to society as a whole if the infectious agent should spread from initial recipients."
Jonathan P. Stoye is a researcher/virologist, National Institute for Medical Research, London.

Excerpt: "Two sets of pig retrovirus, PERV-A and PERV-B, capable of in-vitro replication in certain human cell lines . . . are widely distributed in different pig breeds and expressed in different tissues . . . Ulrich Martin and colleagues . . . add four more cell or tissue types (aortic, endothelial cells, hepatocytes, skin and lung) to the list of PERV mRNA expressors and also show that primary aortic endothelial cells from several different pig breeds produce infectious PERV-A and PERV-B . . . fetal porcine islet cells also express PERVs. Because of the way these elements are inherited in pigs, they will be virtually impossible to eliminate from source herds. Taken together, these data show that most if not all transplanted porcine tissues will express one or more retroviruses capable of infecting human cells. . . . It has been suggested that trials in nonhuman primates might shed light on [the] question [of the potential for cross-species infection]; unfortunately recent results . . . [provide] evidence against the value of such studies."

Journal of Virology 2001 May; 75(10): 4551-7
Takefman DM, Wong S, Maudru T, Peden K, Wilson CA.

"Detection and characterization of porcine endogenous retrovirus in porcine plasma and porcine factor VIII."

Excerpt: "The pig genome contains porcine endogenous retroviruses (PERVs) capable ofinfecting human cells. Detection of infectious retrovirus in porcineperipheral blood mononuclear cells and endothelial cells suggested to usthat pig plasma is likely to contain PERV. . . Detection of infectious virusin porcine plasma confirms and extends the previous findings that certainporcine cells express PERV when manipulated in vitro and clearlydemonstrates that there are porcine cells that express infectious PERV constitutively in vivo.

Excerpt: Transgenic pigs may provide an opportunity for animal viruses to adapt to a human host range."
Robin A. Weiss is a virologist, Institute of Cancer Research, London.