Commentary: Oral fluid testing can be used to monitor xenotransplant donor herds for porcine cytomegalovirus/roseolovirus status

Abstract

To address the shortage of human tissues and organs for treating organ failure, xenotransplantation is progressing toward clinical application. Pigs have been chosen as donor species for various reasons, and extensive genetic modifications are being implemented to prevent xenotransplant rejection. However, xenotransplantation may be associated with the transmission of pathogenic pig microorganisms. One such pathogen is porcine cytomegalovirus/porcine roseolovirus (PCMV/PRV), which has been shown to significantly reduce the survival time of pig organs in non-human primates (1). Although originally named PCMV because of the morphological similarities between infected cells and those infected with human cytomegalovirus (HCMV), subsequent research revealed that PCMV/PRV is a roseolovirus related to human herpesviruses 6 and 7, not HCMV. The International Committee on Taxonomy of Viruses (ICTV) has officially designated the virus as suid herpesvirus 2 (SuHV-2). This virus was also transmitted to the first human recipient of a genetically modified pig heart and contributed to his death (2). The virus had not been detected in the donor pig of the transplanted heart due to the use of an inappropriate detection method. A nasal swab from this donor pig has been tested using PCR; however, the virus can be detected using nasal swabs only in newly infected animals experiencing rhinitis (3). In one experiment infecting pigs with PCMV/PRV, the maximum duration of nasal virus excretion was recorded at 32 days (4). Therefore, for future clinical xenotransplantations, it is essential to implement highly sensitive and appropriate detection methods.