Characterization of insertional variation of porcine endogenous retroviruses in six different pig breeds

Pigs may need to be exploited as xenotransplantation donors due to the shortage of human organs, tissues and cells. Porcine endogenous retroviruses (PERVs) are a significant obstacle to xenotransplantation because they can infect human cells in vitro and have the potential for transmission of unexpected pathogens to humans. In this research, 101 pigs, including four commercial breeds (23 Berkshire, 13 Duroc, 22 Landrace and 14 Yorkshire pigs), one native breed (19 Korean native pigs) and one miniature breed (10 NIH miniature pigs) were used to investigate insertional variations for 11 PERV loci (three PERV-A, six PERV-B and two PERV-C). Over 60% of the pigs harbored one PERV-A (907F8) integration and five PERV-B (B3-3G, B3-7G, 742H1, 1155D9 and 465D1) integrations. However, two PERV-A loci (A1-6C and 1347C1) and one PERV-B locus (B3-7F) were absent in Duroc pigs. Moreover, two PERV-C loci (C2-6C and C4-2G) only existed in Korean native pigs and NIH miniature pigs. The results suggest that PERV insertional variations differ among pig breeds as well as among individuals within a breed. Also, the results presented here can be used for the selection of animals that do not have specific PERV integration for xenotransplantation research.