title: Inactivation of porcine endogenous retrovirus by human serum as a function of complement activated through the classical pathway.
abstract: BACKGROUND: The clinical use of organs and cells of pig donors as a source of tissue for xenotransplantation and extracorporeal therapies has been problematic due to the risk for zoonotic infection of porcine endogenous retroviruses (PERV). METHODS: The effect of human serum on PERV was evaluated using an infectivity assay and virolysis assay. Cell-free PERV infection to human 293 cells was determined by the presence of proviruses 5 days post-infection by a highly sensitive nested PCR, and the lysis of PERV virions was determined by the reverse transcriptase activities released into the supernatant. RESULTS: Treatment of PERV-PK, the culture supernatant of a pig kidney cell line containing the virus titer of 10(2.8) TCID(50) units/ml, with a quarter volume of human serum completely inactivated the infectivity. This activity was heat-labile and sensitive to an anti-complement agent, nafamostat mesilate, and a Ca(2+)-chelator, EGTA, indicating the crucial involvement of complement activated through the classical pathway. Since a synthetic galactosyl alpha1-3 galalactose (Galalpha1-3Gal) largely absorbed the activity from the serum, natural antibodies to the Galalpha1-3Gal epitopes are likely to trigger the complement activation. CONCLUSION: Cell-free PERV seems no longer be infectious in human serum. This greatly encourages the clinical application of pig tissues in particular for extracorporeal therapies such as a bioartificial liver, in which pig cells do not come in direct contact with a recipient.
authors.affiliation: Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Medical Sciences, 1-7-1 Sakamoto, 852-8501, Nagasaki, Japan
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Fujita
authors.forename: Izumi
authors.initials: I
authors.lastname: Yamashita-Futsuki
authors.forename: Susumu
authors.initials: S
authors.lastname: Eguchi
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kamohara
authors.forename: Hikaru
authors.initials: H
authors.lastname: Fujioka
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Yanaga
authors.forename: Junichiro
authors.initials: J
authors.lastname: Furui
authors.forename: Ryozo
authors.initials: R
authors.lastname: Moriuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanematsu
authors.forename: Shigeru
authors.initials: S
authors.lastname: Katamine