Performance of hepatitis C virus core antigen immunoassay in monitoring viral load after liver transplantation.
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.
Massaguer
Anna
A
Liver Unit, Institut de Malalties Digestives, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.
Forns
Xavier
X
Costa
Josep
J
Feliu
Anna
A
García-Retortillo
Montserrat
M
Navasa
Miquel
M
Rimola
Antoni
A
García-Valdecasas
Juan Carlos
JC
Sánchez-Tapias
José Maria
JM
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
D004279:DNA, Viral; D018936:Hepatitis C Antigens; D014758:Viral Core Proteins