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BACKGROUND Nonhuman primates are potential permissive animals for studying the risk of in vivo infection with porcine endogenous retrovirus (PERV). Anti-alphaGal natural antibodies are considered one of the barriers for preventing PERV infection, and it has been postulated that reduction of these antibodies could increase the risk of this infection. The aim of this study was to investigate the role of GAS 914, which depletes anti-alphaGal antibodies, in the potential in vivo transfer of PERV after pig-to-baboon organ xenotransplantation. METHODS Twenty-seven baboons underwent xenotransplantation with hDAF or hMCP/hDAF transgenic pig organs, including heterotopic heart (n = 14) and kidney (n = 13) transplants. All of them received GAS 914 along with different immunosuppression protocols. PERV sequences were investigated by reverse-transcriptase polymerase chain reaction and by polymerase chain reaction assays in samples obtained at autopsy. The presence of PERV-specific antibodies and/or pig xenomicrochimerism was also evaluated. RESULTS PERV RNA was not detected in any baboon plasma sample. In addition, all plasma samples were negative for PERV antibodies. However, PERV DNA sequences were detected in peripheral blood mononuclear cells from 6 of 14 (43%) animals investigated. Porcine mitochondrial DNA was also found in all of these positive samples and in six of the eight (75%) samples with negative PERV DNA, indicating that the detection of PERV sequences was attributable to xenochimerism. PERV-positive cells as a result of xenochimerism were also found in eight of nine (89%) spleen and lymph node tissue samples tested. CONCLUSIONS Sustained depletion of anti-alphaGal antibodies does not augment the risk of PERV infection in pig-to-baboon organ transplantation.

This study investigated the potential transmission of porcine endogenous retrovirus (PERV) to solid-organ transplant recipients and abattoir workers in contact with pigs. Blood samples were obtained from volunteer healthy blood donors (Group A; n=33); pig-breeding farmers who had undergone a liver transplant (Group B; n=14); and pig abattoir workers (Group C; n=49). A second blood sample was obtained 1 year after the first sample from 10 of the abattoir workers (Group D). Tests included investigation for PERV-DNA, PERV-RNA, pig-specific mitochondrial DNA, a quantitative detection of PERV nucleic acids, and antibodies to PERV by two different Western Blots. All polymerase chain reaction and Western Blots assays were negative for PERV or antibodies to PERV. Therefore, the risks of cross-species transmission of PERV appear to be negligible for immunocompetent individuals and allotransplant recipients, even if they are in close and repeated contact with live pigs or pig tissues.