Xenotransplantation is considered a potential alternative to allotransplantation to relieve the current shortage of human organs. Due to their similar size and physiology, the organs of pigs are of particular interest for this purpose. Endogenous retroviruses are a result of integration of retroviral genomes into the genome of infected germ cells as DNA proviruses, which are then carried in all cells of the offspring of the organism. Porcine endogenous retroviruses (PERVs) are of special concern because they are found in pig organs and tissues that might otherwise be used for xenotransplantation. PERV proviruses can be induced to replicate and recombine in pigs, and have been shown to infect human cells in vitro. There are three subtypes of PERVs based on differences in the receptor binding domain of the env protein; PERV-A, PERV-B, and PERV-C. PERVs A and B can infect human cells in vitro and can recombine with PERV-C, resulting in a recombinant virus with a higher rate of replication in pig and human cell lines. In this study, we used a PCR-based analysis of 50 domestic and 35 feral pigs to study the distribution of PERVs A, B, and C in swine raised under domestic conditions, versus feral swine from rural areas. PERV-A and PERV-B were universal in both domestic and feral swine. Feral swine had a higher incidence of PERV-C (85.7%) compared to domestic swine (42.0%). Further studies in other feral swine herds are ongoing to verify this observation.

Xenotransplantation is considered an alternative to allotransplantation to relieve the current shortage of human organs. Due to their similar size and physiology, the organs of pigs are of particular interest for this purpose. Endogenous retroviruses are a result of integration of retroviral genomes into the genome of infected germ cells as DNA copies (proviruses), which are then carried in all cells of the offspring of the organism. Porcine Endogenous Retroviruses (PERVs) are of special concern because they are found in pig organs and tissue that might be used for xenotransplantation. PERV proviruses, already incorporated into the pig’s genome, can be induced to replicate and recombine in pigs, and have been shown to infect human cells in vitro. There are three classes of PERVs, namely PERV-A, PERV-B, and PERV-C. PERV-A and PERV-B can infect human cells in vitro and can recombine with PERV-C, resulting in a recombinant virus with a higher rate of replication in pig and human cell lines. In this study, a PCR based analysis of 50 domestic and 35 feral pigs was carried out to study the distribution of PERVs A, B, and C. PERV-A and PERV-B were universal in both domestic and feral pigs. The feral varieties of pigs displayed a higher frequency of 85.67% of PERV-C compared to 42.00% in domestic pigs. However, comparative study of presence of PERVs A, B, and C in different breeds of domestic pigs shows there is variation in distribution among breeds, and among individuals of same breeds. From the results of this study, I hypothesize that presence of endogenized PERV genomes in individuals of the same breed is dependent on genetic properties of individual pigs.