A set of three reports in the August 29 issue of The Lancet adds to the ongoing debate concerning whether pig viruses could infect humans who are transplanted with pig organs. While one report warns that transmission is possible with xenotransplantation, two others found no evidence of pig viruses in diabetic patients and patients on renal dialysis.
In the first report, Ulrich Martin, PhD, of Hannover Medical School in Hannover, Germany, and colleagues found that pig endogenous retrovirus (PERV) is produced by cells from pig aortas, livers, lung, and skin, all of which are tissues that are likely to be used for transplantation. They said their findings suggest "a serious risk of retrovirus transfer after xenotransplantation" and that producing PERV-free swine could be "difficult or impossible" (1998;352:692-694).
The second report, by Walid Heneine, PhD, of the Centers for Disease Control and Prevention and his colleagues, focused on ten diabetic patients who had received porcine fetal islet cells between 1990 and 1993. Despite extended exposure to pig cells and despite concomitant immunosuppressive therapy that could have reduced the patients' ability to suppress PERV, the authors were unable to detect PERV in blood samples taken from the patients (1998;352:695-699). (See "UK Issues Xenotransplantation Guidelines as Imutran Plans Human Use of Pig Livers" at Transplant News Network, August 15.)
The third report found no evidence of pig DNA or retroviral infection in two patients on kidney dialysis whose circulation had been linked extracorporeally to pig kidneys. Clive Patience, PhD, of London's Institute of Cancer Research and coauthors said that the patients had no signs of porcine cells even in samples taken as early as six hours after the perfusion (1998;352:699-701). In an accompanying commentary, Jonathan Stoye of London's National Institute for Medical Research wrote that "care must be taken not to draw too broad a set of conclusions" from the studies by Heneine and Patience. "Nevertheless, it seems reasonable to conclude that the PERVs will not show the very high levels of transmission associated with some viruses" (1998;352:666-667).
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