Transmission of porcine encephalomyocarditis virus (EMCV) to mice by transplanting EMCV-infected pig tissues.

We recently demonstrated that pigs infected with porcine encephalomyocarditis virus (EMCV) develop a persistent infection (up to 90 days post-infection (PI)) in the heart and brain that is accompanied by virus-induced pathologic changes, and that EMCV productively infects human cardiomyocytes in vitro, suggesting that EMCV may pose a risk to humans following transplantation of pig tissues to humans (Brewer et al. J Virol 2001; 75: 11621-11629). In this report, we demonstrate that intra-abdominal of myocardial or pancreatic sections from acutely-EMCV infected pigs (2 days PI) in either non-mutant C57BL/6 or C57BL/6-RAG-1-/- mice that lack B or T lymphocytes, resulted in transmission of the virus and acute fatal disease in all mice. In recipient RAG-1-/- mice, fatal EMCV disease occurred within 2 days post-transplantation, and it was accompanied by high virus titers in brain, heart, liver, spleen, kidneys and skeletal muscle, whereas in non-mutant C57BL/6 mice, disease occurred 5 to 6 days post-transplantation and was accompanied by lower virus titers. Transplantation of myocardial or pancreatic tissues from chronically EMCV-infected pigs (21 and 50 days PI) did not induce clinical disease, but resulted in detection of EMCV RNA in the brain of recipient RAG-1-/- mice, no viral RNA was detected in non-mutant C57BL/6 mice. Intra-abdominal transplantation of uninfected porcine myocardial tissues into RAG-1-/- mice followed by intramuscular inoculation with EMCV induced acute clinical disease but did not result in transmission of virus to the xenograft. These results show that EMCV can be efficiently transmitted from pig myocardial and pancreatic tissues to mice, providing a model of pig-to-human viral xenozoonosis that can be used to develop and test prophylactic and therapeutic measures against such infection.