title: Stem-loop structures II-IV of the 5' untranslated sequences are required for the expression of the full-length hepatitis C virus genome.
abstract: The 5' and 3' untranslated regions (UTR) of the hepatitis C virus (HCV) genome contain stem-loop structures, which are important in viral gene expression and replication. In this study, the functional roles of the predicted stem-loop structures of HCV 5' UTR and 3' UTR in viral gene expression were examined using a chimeric clone of full-length HCV genomic cDNA clone and the gene for green fluorescent protein (GFP). High level expression of the HCV-GFP chimera in Huh-7 cells was accomplished by using a replication defective adenovirus that expresses T7 RNA polymerase and transcription plasmid containing full-length HCV-GFP chimera under the control of a T7 promoter. The HCV-GFP clone, with deletion of stem-loop I, expressed proteins in transfected Huh-7 cells at comparable levels to the wild type HCV clone. Other mutations of the 5' UTR, which either deleted or altered the base pairing of stem-loops II to IV, completely abolished the expression of HCV-GFP chimera. In contrast, deletion of 3' UTR sequences had no effect on HCV protein expression. These findings suggest that the stem-loop structures II to IV of HCV 5' UTR are necessary for protein expression, but that stem loop I is dispensable for protein translation. The stem-loop structures of 3' UTR of HCV genome appear to have no direct role in viral gene expression.
authors.affiliation: Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, U.S.A.
authors.forename: Z T
authors.initials: ZT
authors.lastname: Qi
authors.forename: G
authors.initials: G
authors.lastname: Kalkeri
authors.forename: J
authors.initials: J
authors.lastname: Hanible
authors.forename: R
authors.initials: R
authors.lastname: Prabhu
authors.forename: F
authors.initials: F
authors.lastname: Bastian
authors.forename: R F
authors.initials: RF
authors.lastname: Garry
authors.forename: S
authors.initials: S
authors.lastname: Dash
mesh_terms: D020413:3' Untranslated Regions / Q000737:chemistry / Q000235:genetics; D020121:5' Untranslated Regions / Q000737:chemistry* / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral; D049452:Green Fluorescent Proteins; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D008164:Luminescent Proteins; D012367:RNA, Viral; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; D049452:Green Fluorescent Proteins