Screening and analysis of porcine endogenous retrovirus in Chinese Banna minipig inbred line.

Pigs have been the most likely animal as the source of cells, tissues, and organs for xenotransplantation. But the use of pigs in xenotransplantation is associated with the risk of porcine endogenous retrovirus (PERV) transmission. Previous studies have identified that the proviruses are integrated into the genome of normal pigs and that virus particles released from the porcine cells can infect human cells in vitro. As a unique inbred pig, Banna minipig inbred (BMI) has a huge potential value for xenotransplantation and medical research. It has been the focal experimental animal for pig-to-human xenotransplantation in China, due to its clear genetic background and tiny individual differences. To evaluate whether the potential risk of PERV exists in inbred pigs, a series of screening experiments were performed herein. The results of PCR with primers specific for gag, pol, and env showed that proviruses existed in the genome of BMI, and the PERV subtypes were PERV-A and PERV-B. PERV mRNA was expressed functionally in BMI. Positive results of an RT assay identified that PERV in BMI had potential infectivity, but the concentration of PERV reverse transcriptase in BMI was almost 20 times lower than that of HIV. These results suggested that gag, pol and env genes of PERV were not lost during inbreeding, which created favorable conditions to produce viral particles that could possibly infect human cells in xenotransplantation.