title: Role of DNA methylation in expression and transmission of porcine endogenous retroviruses.
abstract: Porcine endogenous retroviruses (PERV) represent a major safety concern in pig-to-human xenotransplantation. To date, no PERV infection of a xenograft recipient has been recorded; however, PERVs are transmissible to human cells in vitro. Some recombinants of the A and C PERV subgroups are particularly efficient in infection and replication in human cells. Transcription of PERVs has been described in most pig cells, but their sequence and insertion polymorphism in the pig genome impede identification of transcriptionally active or silenced proviral copies. Furthermore, little is known about the epigenetic regulation of PERV transcription. Here, we report on the transcriptional suppression of PERV by DNA methylation in vitro and describe heavy methylation in the majority of PERV 5' long terminal repeats (LTR) in porcine tissues. In contrast, we have detected sparsely methylated or nonmethylated proviruses in the porcine PK15 cells, which express human cell-tropic PERVs. We also demonstrate the resistance of PERV DNA methylation to inhibitors of methylation and deacetylation. Finally, we show that the high permissiveness of various human cell lines to PERV infection coincides with the inability to efficiently silence the PERV proviruses by 5'LTR methylation. In conclusion, we suggest that DNA methylation is involved in PERV regulation, and that only a minor fraction of proviruses are responsible for the PERV RNA expression and porcine cell infectivity.
authors.affiliation: Department of Cellular and Viral Genetics, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Magda
authors.initials: M
authors.lastname: Matousková
authors.forename: Pavel
authors.initials: P
authors.lastname: Vesely
authors.forename: Petr
authors.initials: P
authors.lastname: Daniel
authors.forename: Giada
authors.initials: G
authors.lastname: Mattiuzzo
authors.forename: Ralph D
authors.initials: RD
authors.lastname: Hector
authors.forename: Linda
authors.initials: L
authors.lastname: Scobie
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: Jirí
authors.initials: J
authors.lastname: Hejnar
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D019175:DNA Methylation; D004279:DNA, Viral / Q000235:genetics; D020077:Endogenous Retroviruses / Q000235:genetics*; D044127:Epigenesis, Genetic; D006801:Humans; D007668:Kidney / Q000378:metabolism / Q000821:virology; D011533:Proviruses / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D013553:Swine Diseases / Q000235:genetics / Q000635:transmission* / Q000821:virology; D013556:Swine, Miniature / Q000235:genetics / Q000821:virology*; D020079:Terminal Repeat Sequences / Q000235:genetics; D014779:Virus Replication
chemical_list: D004279:DNA, Viral; D012333:RNA, Messenger