title: Characterisation of a human cell-adapted porcine endogenous retrovirus PERV-A/C.
abstract: BACKGROUND
  Porcine endogenous retroviruses (PERVs) pose a potential risk for xenotransplantation using pig cells, tissues or organs. A special threat comes from viruses generated by recombination between human-tropic PERV-A and ecotropic PERV-C. Serial passages of a recombinant PERV-A/C on human 293 cells resulted in increased infectious titers and a multimerization of transcription factor binding sites in the viral long terminal repeat (LTR). In contrast to the LTR, the sequence of the env gene did not change, indicating that the LTR represents the determinant of high infectivity.
  
  
  METHODS
  The virus was further propagated on human cells and characterized by different methods (titration, sequencing, infection experiments, electron microscopy).
  
  
  RESULTS
  Further propagation on human 293 cells resulted in deletions and mutations in the LTR. In contrast to low-titer viruses, the high-titer virus was infectious for cells from non-human primates including chimpanzees. Scanning electron microscopy revealed clustering of budding virions at the cell surface of infected human cells and transmission electron microscopy indicated that the virus infects them via receptor-mediated endocytosis.
  
  
  CONCLUSIONS
  After propagation of PERV on human cells without selection pressure, viruses with different LTR were generated. High titer PERV was shown to infect cells from non-human primates. The experiments performed here simulate the situation in vivo and give an extended characterization of human cell-adapted PERVs.
authors.affiliation: Robert Koch Institute, Berlin, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Karlas
authors.forename: Markus
authors.initials: M
authors.lastname: Irgang
authors.forename: Jörg
authors.initials: J
authors.lastname: Votteler
authors.forename: Volker
authors.initials: V
authors.lastname: Specke
authors.forename: Mushin
authors.initials: M
authors.lastname: Ozel
authors.forename: Reinhard
authors.initials: R
authors.lastname: Kurth
authors.forename: Joachim
authors.initials: J
authors.lastname: Denner
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004279:DNA, Viral / Q000235:genetics; D020077:Endogenous Retroviruses / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity* / Q000648:ultrastructure; D006801:Humans; D008253:Macaca mulatta; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D002679:Pan troglodytes; D012326:RNA Splicing; D012367:RNA, Viral / Q000235:genetics; D011995:Recombination, Genetic; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D013552:Swine / Q000821:virology*; D020079:Terminal Repeat Sequences; D014776:Virus Cultivation
chemical_list: D004279:DNA, Viral; D012367:RNA, Viral