title: Performance of hepatitis C virus core antigen immunoassay in monitoring viral load after liver transplantation.
abstract: BACKGROUND
  In the liver transplantation (LTx) setting, there are several situations where measurement of hepatitis C virus (HCV)-RNA concentration may provide relevant information. However, HCV-RNA quantification is expensive and not routinely available in all laboratories. An assay to quantify total HCV core antigen in serum has been recently developed. The aim of this study was to compare the performance of HCV-RNA and HCV core antigen determination in a cohort of 116 HCV-infected patients who underwent LTx.
  
  
  METHODS
  HCV-RNA and HCV core antigen concentrations were determined in serum samples (n=435) obtained before LTx and at weeks 4, 12, and 48 after LTx.
  
  
  RESULTS
  There was an excellent correlation between HCV-RNA and HCV core antigen levels (r=0.802 P<0.001), with an equivalence of 9,900 IU/mL of HCV-RNA per pg/mL of HCV core antigen. The determination of core antigen was linear in samples containing between 20,000 and 2,500,000 IU/mL of HCV-RNA and highly reproducible (mean coefficient of variation, 15%). Overall, HCV core antigen tested positive in 378 (92%) of 410 samples with detectable HCV-RNA (>600 IU/mL); the percentage increased to 98% in samples taken later than 4 weeks after LTx. In fact, almost all samples (369 of 375 [98.4%]) with HCV-RNA levels higher than 20,000 IU/mL were positive for HCV core antigen, whereas 56 of 57 samples with undetectable core antigen had HCV-RNA levels below 50,000 IU/mL.
  
  
  CONCLUSIONS
  The performance of total HCV core antigen immunoassay is appropriate for monitoring viral load in HCV-infected patients undergoing LTx and might be considered a useful alternative to HCV-RNA testing.
authors.affiliation: Liver Unit, Institut de Malalties Digestives, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Massaguer
authors.forename: Xavier
authors.initials: X
authors.lastname: Forns
authors.forename: Josep
authors.initials: J
authors.lastname: Costa
authors.forename: Anna
authors.initials: A
authors.lastname: Feliu
authors.forename: Montserrat
authors.initials: M
authors.lastname: García-Retortillo
authors.forename: Miquel
authors.initials: M
authors.lastname: Navasa
authors.forename: Antoni
authors.initials: A
authors.lastname: Rimola
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: García-Valdecasas
authors.forename: José Maria
authors.initials: JM
authors.lastname: Sánchez-Tapias
mesh_terms: D015331:Cohort Studies; D004279:DNA, Viral / Q000097:blood; D016174:Hepacivirus / Q000235:genetics; D018936:Hepatitis C Antigens / Q000097:blood*; D006801:Humans; D007118:Immunoassay / Q000592:standards; D016031:Liver Transplantation; D016133:Polymerase Chain Reaction / Q000592:standards; D011159:Population Surveillance; D011184:Postoperative Period; D015203:Reproducibility of Results; D014758:Viral Core Proteins / Q000097:blood*; D019562:Viral Load
chemical_list: D004279:DNA, Viral; D018936:Hepatitis C Antigens; D014758:Viral Core Proteins