Xenotransplantation using pig organs may be associated with the transmission of porcine viruses that could cause disease in recipients. A well-known example is the porcine cytomegalovirus, which is actually a porcine roseolovirus, hence abbreviated as PCMV/PRV. This virus is related to human herpesviruses 6 and 7 and is not closely related to human cytomegalovirus, which causes significant complications in allotransplantation [1]. PCMV/PRV has been shown to drastically reduce the survival time of porcine organs in non-human primates (for review, see [2]). The virus was also transmitted to the first patient in Baltimore who received a pig heart; it replicated exponentially to high titers in the transplanted pig heart and likely contributed to the patient’s death [3]. Therefore, the transmission of PCMV/PRV and other potentially zoonotic porcine viruses should be prevented.