Genomic Validation of PERV-C-Free Pigs to Support Xenotransplantation

Porcine endogenous retroviruses (PERVs) are present in the germ lines of domesticated pigs (Sus scrofa) and related suids. There are three types of PERVs, PERV-A, -B, and -C, which differ in their host range. PERV-A and -B can infect human and porcine cells, while PERV-C only infects porcine cells. PERV-A and -B are found in the genomes of all pigs, while PERV-C is found in most but not all pigs. Although many PERV provirus insertions are defective, in vitro culture of porcine cells has produced infectious virions of all three types as well as PERV-A/C recombinants, which show enhanced replication competence. Identifying pigs that are PERV-C negative could help prevent such recombination events and would advance the development of porcine germplasm as a safer source of xenografts for humans. Here, we present the results of extensive screening involving 142 Landrace, Duroc, Large White, and crossbred pigs using up to nine primer pairs to identify putative PERV-C-negative animals. Long-read whole genome sequencing was conducted on a subset of four pigs (one PERV-C PCR positive and three PERV-C PCR putative negatives), which confirmed their status as PERV-C positive or negative, respectively. Our results confirmed that the screened pigs were truly PERV-C negative, establishing the existence of PERV-C-negative germplasm within the herd. These findings support the feasibility of developing or selecting PERV-C-negative pigs as a source of germplasm for xenotransplantation and other biomedical applications.