title: A comparison of hepatitis C virus (HCV)-RNA and--antibody as markers of infection and predictors of infectivity.
abstract: BACKGROUND
  The diagnosis of hepatitis C virus (HCV) infection currently relies on the detection of antibody to HCV (anti-HCV). However, anti-HCV positivity may indicate past infection, current infection or possibly non-specific reactivity. For confirmation of current infection the virus needs to be assayed directly and this is possible by the polymerase chain reaction (PCR).
  
  
  OBJECTIVE
  The aims were to compare HCV RNA and anti-HCV as markers of infection in two groups of individuals: (i) a heterogeneous group with suspected HCV infection and (ii) a small group of blood and bone marrow donors, and their respective recipients.
  
  
  METHODS
  Serum samples were tested for alanine aminotransferase (ALT) as part of a liver function screen, for anti-HCV by ELISA II, and HCV RNA was detected by PCR. Single round and nested PCR was performed using primers designed from the sequence of the 5'-untranslated region of the HCV genome.
  
  
  RESULTS
  Of the 36 subjects in the heterogeneous group, 19/22 anti-HCV-positive patients with chronic non-A non-B hepatitis (NANBH) were viraemic, and the majority (17/19) demonstrated elevated ALT. However, HCV RNA was undetected in seven anti-HCV-positive patients, four of whom suffered autoimmune hepatitis Type I and three were low risk blood donors. Of the remaining subjects (seven/36) who were anti-HCV-negative, three/seven were HCV-RNA-positive and included two with acute post-transfusion (PT) NANBH and a recent needlestick victim who contracted HCV. In the second group, four individuals (donors), including a mother with a history of drug use, were implicated in transmission to three recipients. ALT levels were normal in all donors but raised in two of the recipients. PCR determined which of two anti-HCV-negative blood donors was infectious, confirmed transmission between a bone marrow donor and recipient, and indicated that anti-HCV detected in a newborn child represented passive transfer of antibody.
  
  
  CONCLUSIONS
  Anti-HCV detected by ELISA II is a useful marker of chronic HCV infection, particularly in association with raised ALT. However, HCV RNA is a superior marker of acute HCV infection, a more reliable predictor of infectivity and is more specific.
authors.affiliation: Division of Medical Virology, Institute of Medical and Veterinary Science, Adelaide, SA.
authors.forename: A M
authors.initials: AM
authors.lastname: Beardsley
authors.forename: J T
authors.initials: JT
authors.lastname: LaBrooy
authors.forename: L
authors.initials: L
authors.lastname: Rozen
authors.forename: E J
authors.initials: EJ
authors.lastname: Gowans
mesh_terms: D000208:Acute Disease; D000410:Alanine Transaminase / Q000032:analysis / Q000378:metabolism; D001483:Base Sequence; D015415:Biomarkers / Q000097:blood; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay; D016174:Hepacivirus / Q000276:immunology / Q000302:isolation & purification*; D006508:Hepatitis Antibodies / Q000032:analysis*; D006526:Hepatitis C / Q000097:blood / Q000175:diagnosis* / Q000635:transmission; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000032:analysis*; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D006508:Hepatitis Antibodies; D012367:RNA, Viral; D000410:Alanine Transaminase