Ancient origin and complex evolution of porcine endogenous retroviruses

Porcine endogenous retroviruses (PERVs) are proviruses that have medical value in xenotransplantation. However, the evolutionary process leading to the generation of modern PERVs is not well understood. In this study, we in silico mined 14 pig genomes and other available 304 mammalian genomes, which led to the documentation of 185 full-length PERVs or PERV-like sequences. Notably, we found that lesser Egyptian jerboa (Jaculus jaculus), rock hyrax (Procavia capensis) and eight Muridae species all harbored ancestral PERV-like sequences, indicative of ancient cross-species transmission events from none-porcine species to pigs. We also revealed that 11 genomic rearrangement events were mediated via PERVs, during the process of porcine evolution. In conclusion, these new findings help us to understand the complex evolution of the modern PERVs.