Transmission of porcine endogenous retrovirus to human cells in nude mouse.

Xenotransplantation is associated with the risk of Porcine endogenous retrovirus (PERV) transmission, since it has been shown that PERV can infect human cells in vitro (Specke et al., Virology 285, 177-180, 2001). We evaluated the possibility of PERV infection of human cells in nude mice model. Porcine kidney cells PK15 carrying PERV and human liver cancer cells SMMC-7721 were injected separately into the right and left axilla of nude mice, respectively. Two months later, pig cytochrome oxidase II (COII) gene, PERV DNA, PERV mRNA, and PERV-Gag protein were detected in the mass formed in both axillas and in several organs of nude mice. The pig COII genes were detected in the right and left axilla, but not in other organs of nude mice implicating that the microchimerism of pig cells occurred in human SMMC-7721 cells and induced the formation of the mass. PERV gene and gag protein were detected in all mouse tissues except liver. These data indicated that (i) PERV may be transmitted from porcine to mouse cells, (ii) PERV genes and proteins were detectable in the mass formed by injection of human cells and consequently (iii) there was a possibility of PERV transmission to human cells after xenotransplantation.