title: Selection of different 5' untranslated region hepatitis C virus variants during post-transfusion and post-transplantation infection.
abstract: BACKGROUND
  Hepatitis C virus (HCV) translation is initiated in a cap-independent manner by an internal ribosome entry site (IRES) located within the 5' untranslated region (5'UTR). Sequence changes in this region could affect translation efficiency and presumably viral replication.
  
  
  OBJECTIVE
  To determine translation efficiency of 5'UTR variants developing during post-transfusion hepatitis C in two immunocompetent subjects and in two immunosuppressed liver recipients with recurrent HCV.
  
  
  METHODS
  Sequential samples were screened for 5'UTR changes by single-strand conformation polymorphism followed by cloning and sequencing whenever band pattern suggested sequence changes. 5'UTR variants were tested for IRES activity using a bicistronic dual luciferase expression plasmid transfected into HepG2 and Huh7 cell-lines.
  
  
  RESULTS
  In the transfused patients, translation efficiency of 5'UTR variants from early post-transfusion samples was 5.1- to 13.7-fold higher than that of predominant variants found in late follow-up samples. Post-transplant variants in the other two patients had 2.6- to 5.9-fold higher translation efficiency than those present only in pretransplant samples.
  
  
  CONCLUSIONS
  In the immunocompetent host there may be selection of low translation efficiency HCV variants over the course of infection. However, in immunosuppressed subjects the opposite seems to be true as low translation efficiency variants are superseded by high translation efficiency variants.
authors.affiliation: Division of Transplantation Medicine, Mayo Clinic, Scottsdale, AZ 85259, USA. gallegos.juan@mayo.edu
authors.forename: J F
authors.initials: JF
authors.lastname: Gallegos-Orozco
authors.forename: J I
authors.initials: JI
authors.lastname: Arenas
authors.forename: H E
authors.initials: HE
authors.lastname: Vargas
authors.forename: K V
authors.initials: KV
authors.lastname: Kibler
authors.forename: J K
authors.initials: JK
authors.lastname: Wilkinson
authors.forename: M
authors.initials: M
authors.lastname: Nowicki
authors.forename: M
authors.initials: M
authors.lastname: Radkowski
authors.forename: J
authors.initials: J
authors.lastname: Nasseri
authors.forename: J
authors.initials: J
authors.lastname: Rakela
authors.forename: T
authors.initials: T
authors.lastname: Laskus
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics*; D000328:Adult; D001483:Base Sequence; D005260:Female; D016174:Hepacivirus / Q000235:genetics*; D006526:Hepatitis C / Q000209:etiology / Q000821:virology*; D006801:Humans; D016031:Liver Transplantation / Q000009:adverse effects*; D008875:Middle Aged; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D065227:Transfusion Reaction
chemical_list: D020121:5' Untranslated Regions