NO EVIDENCE OF INFECTION WITH PORCINE ENDOGENOUS RETROVIRUS IN RECIPIENTS OF PORCINE ISLET-CELL XENOGRAFTS

Background The study of whether porcine xenografts can lead to porcine endogenous retrovirus (PERV) infection of recipients is critical for evaluating the safety of pig-to-man xenotransplantation. PERV is carri ed in the pig germline, and all recipients of porcine tissues or organ s will be exposed to the virus. Methods We studied 10 diabetic patient s who had received porcine fetal islets between 1990 and 1993, looking for evidence of PERV infection by using PCR serology, PCR, and revers e transcriptase assays. Prolonged xenograft survival (up to a year) wa s confirmed in five patients by porcine C-peptide excretion and detect ion of pig mitochondrial DNA (mtDNA) in serum. Findings Despite the ev idence for extended exposure to pig cells and despite concomitant immu nosuppressive therapy, we were unable to detect markers of PERV infect ion in any patient, Screening for two PERV sequences in peripheral blo od lymphocytes collected 4-7 years after the xenotransplantation was n egative. Markers of PERV expression, including viral RNA and reverse t ranscriptase, were undetectable in sera from both early (day 3 to day 180) and late (4-7 years) time points. Western blot analysis for antib odies was consistently negative, Interpretation These results suggeste d the absence of PERV infection in these patients. Also this study est ablishes a minimum standard for post-transplant surveillance of patien ts given porcine xenografts.