title: Strategy for the maximization of clinically relevant information from hepatitis C virus, RT-PCR quantification.
abstract: BACKGROUND
  The increasing clinical application of viral load assays for monitoring viral infections has been an incentive for the development of standardized tests for the hepatitis C virus.
  
  
  OBJECTIVE
  To develop a simple model for the prediction of baseline viral load in individuals infected with the hepatitis C virus.
  
  
  METHODS
  Viral load quantification of each patient's first sample was assessed by RT-PCR-ELISA using the Roche MONITOR assay in triplicate. Genotype of the infecting virus was identified by reverse line probe hybridization, using amplicons resulting from the qualitative HCV Roche AMPLICOR assay.
  
  
  RESULTS
  Retrospective evaluation of first quantitative values suggested that 82.4% (n=168/204) of individuals had a viral load between 4.3 and 6.7 log(10) viral copies per ml. A few patients (3.4%; n=7/204) have a serum viremia less than the lower limit of the linear range of the RT-PCR assay. Subsequent, prospective evaluation of hepatitis C viral load of all new patients using a model based on the dynamic range of viral load in the retrospective group correctly predicted the dynamic range in 75.9% (n=33/54).
  
  
  CONCLUSIONS
  The dynamic range of hepatitis C viremia extends beyond the linear range of the Roche MONITOR assay. Accurate determination of serum viremia is substantially improved by dilution of specimens prior to quantification.
authors.affiliation: Hepatitis C Unit, Department of Medicine, Clinical Sciences Building, Cork University Hospital, University College, Cork, Ireland.
authors.forename: J
authors.initials: J
authors.lastname: Levis
authors.forename: E
authors.initials: E
authors.lastname: Kenny-Walsh
authors.forename: K
authors.initials: K
authors.lastname: O'Sullivan
authors.forename: M
authors.initials: M
authors.lastname: Horgan
authors.forename: M
authors.initials: M
authors.lastname: Whelton
authors.forename: F
authors.initials: F
authors.lastname: Shanahan
authors.forename: L
authors.initials: L
authors.lastname: Fanning
mesh_terms: D004279:DNA, Viral / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics*; D006526:Hepatitis C / Q000821:virology*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012367:RNA, Viral / Q000097:blood; D011933:Reagent Kits, Diagnostic; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019562:Viral Load; D014766:Viremia / Q000821:virology
chemical_list: D004279:DNA, Viral; D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic