Xenotransplantation is a promising strategy to alleviate the shortage of organs for human transplantation. In addition to the concerns about pig-to-human immunological compatibility, the risk of cross-species transmission of porcine endogenous retroviruses (PERVs) has impeded the clinical application of this approach. We previously demonstrated the feasibility of inactivating PERV activity in an immortalized pig cell line. We now confirm that PERVs infect human cells, and we observe the horizontal transfer of PERVs among human cells. Using CRISPR-Cas9, we inactivated all of the PERVs in a porcine primary cell line and generated PERV-inactivated pigs via somatic cell nuclear transfer. Our study highlights the value of PERV inactivation to prevent cross-species viral transmission and demonstrates the successful production of PERV-inactivated animals to address the safety concern in clinical xenotransplantation.

This study is mainly funded by eGenesis Inc. and was funded by NIH grant P50 HG005550. Y.L. was funded by Danish Research Council for Independent Research (DFF-1337-00128) and Sapere Aude Young Research Talent Prize (DFF-1335-00763). M.G. was funded by a Human Frontiers Science Program Long Term fellowship. Some of the pig production was funded by Major Program on Basic Research Projects of Yunnan Province, China (Grant No. 2014FC006). PERV elements genotyping illumina miseq data have been uploaded to the European Nucleotide Archive (ENA) hosted by the European Bioinformatics Institute (EBI) with the submission reference PRJEB11222