Absence of PERV specific humoral immune response in baboons after transplantation of porcine cells or organs

Xenotransplantation of pig organs seems a promising way of overcoming the prevailing limitation on allotransplantation due to donor numbers. However, as porcine endogenous retroviruses (PERVs) can infect human cells in vitro, there is substantial concern regarding the risk of a PERV infection in xenogeneic transplant recipients. Cultured porcine endothelial cells, stimulated peripheral blood mononuclear cells, and pancreatic islet cells can release PERV infectious for human cells in vitro, but it is currently unknown whether PERV is released in vivo, whether these viral particles can infect the transplant recipient, and whether they are pathogenic. In a retrospective study 15 immunosuppressed baboons were tested for a specific immune response against PERV after transplantation of porcine endothelial cells, mononuclear blood cells, and lungs. Anti-PERV antibody expression was analyzed with peptide-based, enzyme-linked immunosorbent assays and highly sensitive Western Blot assays. This xenotransplantation study using nonhuman primates found no evidence of PERV specific humoral immune response. Our data suggest that no productive PERV infection and no continuous PERV release takes place in the nonhuman primates analyzed in this study.