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 …

In a recent issue of Science, the group of George Church at Harvard Medical School and
Luhan Yang at the Boston-based company eGenesis, in collaboration with groups in China,
published the live birth of pigs in which the genes for PERV were inactivated using the
CRISPR-Cas9 gene-editing technology. 1 This paper is a logical follow-up of their earlier
publication in Science, 2015, in which the successful inactivation of PERV genes in the
porcine PK15 cell line was documented. 2 Joachim Denner has written a commentary about …