Porcine endogenous retrovirus and other viruses  in xenotransplantation.
OBJECTIVE
Potential transmission of zoonotic porcine viruses is a major safety issue in xenotransplantation. This review will first summarize recent studies involving transmission and control of the major concern, porcine endogenous retrovirus (PERV). Second, the potential for zoonotic transfer and safety measures required against other viruses of concern will be discussed.


RESULTS
As studies on PERV genomics continue, distribution of PERV, particularly porcine endogenous retrovirus-C in individual pigs in relation to their ability to transmit PERV in vitro, is becoming clearer. However, further study is required to establish pig lines devoid of problematic copies of PERV. As an extra level of safety, several strategies have been sought, with some success, to reduce PERV infectivity and be used to produce transgenic, PERV-suppressed pigs. Porcine herpesviruses, hepatitis E virus, arenaviruses and an Anellovirus, Torque teno virus, have been highlighted as other viruses of potential risk.


CONCLUSIONS
Xenotransplantation is a unique situation in which pathogen monitoring may be required to be more comprehensive than that required for specific pathogen-free sources. With evidence of transmission of novel viruses via allotransplantation, significant attention should be paid to emerging and as yet unknown viruses.
Scobie
Linda
L
Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, UK.
Takeuchi
Yasuhiro
Y
D000818:Animals; D030801:Animals, Genetically Modified; D020077:Endogenous Retroviruses / Q000235:genetics / Q000472:pathogenicity*; D016751:Hepatitis E / Q000635:transmission / Q000821:virology; D006566:Herpesviridae Infections / Q000635:transmission / Q000821:virology; D006801:Humans; D016377:Organ Transplantation / Q000009:adverse effects*; D012192:Retroviridae Infections / Q000517:prevention & control / Q000635:transmission* / Q000821:virology; D013552:Swine / Q000235:genetics / Q000821:virology*; D013553:Swine Diseases / Q000635:transmission* / Q000821:virology; D022783:Torque teno virus / Q000472:pathogenicity; D014183:Transplantation, Heterologous; D015047:Zoonoses