title: Molecular virology of hepatitis C virus: an update with respect to potential antiviral targets.
abstract: Hepatitis C virus (HCV), a positive-strand enveloped RNA virus, is a major cause of chronic liver disease worldwide. Cis-acting RNA elements and virus-encoded polypeptides required for HCV replication represent attractive targets for the development of antiviral therapies. Internal ribosome entry site-directed translation of HCV genome RNA produces a long polyprotein which is co- and post-translationally processed to yield at least 10 viral proteins. A host signal peptidase is responsible for maturation of the structural proteins located in the N-terminal one-third of the polyprotein. Thus far, four enzymatic activities encoded by the non-structural (NS) proteins have been reported. The NS2-3 region encodes an autoproteinase responsible for cleavage at the 2/3 site. The N-terminal one-third of NS3 functions as the catalytic subunit of a serine proteinase which cleaves at the 3/4A, 4A/4B, 4B/5A and 5A/5B sites, and NS4A is an essential cofactor for some of these cleavages. NS3 also encodes an RNA-stimulated NTPase/RNA helicase at its C terminus, and NS5B has been shown to possess an RNA-dependent RNA polymerase activity. To date, no functions have been reported for NS4B or NS5A in RNA replication, however, NS5A has been implicated in modulating the sensitivity of HCV to interferon. Sequence and structural conservation within the 3' terminal 98 bases of genomic RNA suggest a functional importance in the virus life-cycle and hence another target for antiviral intervention. Recently, HCV infection was shown to be initiated in chimpanzees following intrahepatic inoculation of RNA transcribed from cloned HCV cDNA. The ability to generate large quantities of infectious HCV RNA may facilitate the development of reliable cell culture replication systems useful for the evaluation of antiviral drugs.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110-1093, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Blight
authors.forename: A A
authors.initials: AA
authors.lastname: Kolykhalov
authors.forename: K E
authors.initials: KE
authors.lastname: Reed
authors.forename: E V
authors.initials: EV
authors.lastname: Agapov
authors.forename: C M
authors.initials: CM
authors.lastname: Rice
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003546:Cysteine Endopeptidases / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D005809:Genes, Regulator; D016679:Genome, Viral; D016174:Hepacivirus / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000821:virology; D002679:Pan troglodytes; D014176:Protein Biosynthesis / Q000187:drug effects; D021382:Protein Sorting Signals / Q000494:pharmacology; D014162:Transfection; D014709:Vero Cells; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism; D015678:Viral Structural Proteins / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D003546:Cysteine Endopeptidases; D018076:DNA, Complementary; D004279:DNA, Viral; D021382:Protein Sorting Signals; D017361:Viral Nonstructural Proteins; D015678:Viral Structural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C107824:NS2-3 protease