Total Hepatitis C Virus Core Antigen Assay for Hepatitis C Virus Viremia and Comparison with RNA Assay

Park, Do Sim; Lee, Young Jin; Lee, Key Earn; Cho, Ji Hyun; Kim, Haak Cheoul; Jun, Chang Duk; Kwak, Byoung Hee

Abstract

BACKGROUND: Recently, trak - C (Total HCV core antigen test; Ortho Clinical Diagnostics, Raritan, NJ, USA) that is based on the enzyme- linked immnunosorbent assay was developed. So, we tried to compare the performance of the Hepatitis C virus (HCV) total core antigen test (HCVAg) with the qualitative in-house reverse transcription (RT) - polymerase chain reaction (PCR) assay and HCV- RNA Quantitation assay (HCVQn, Amplicor HCV monitor test version 2.0; Roche Diagnostics System, Basel, Switzerland).
METHODS
Dilution test was performed to evaluate the reproducibility and detection sensitivity of the methods. 87 sera of 70 Hepatitis C virus antibody (Ab) positive patients were tested to evaluate the diagnostic sensitivity and concordance of three methods, and to discover the quantity relationship of HCVAg and HCVQn. We also contained the results of 100 negative control specimens by HCV Ag to evaluate the specificity.
RESULTS
In the dilution test, the coefficient variation values of HCVAg were 41%, 29%, and 21% and HCVQn were 17%, 11%, and 150% of diluted sera respectively at 50, 5(-1), and 5(-2) dilution factor for four days running. The qualitative in - house HCV RT-PCR (5(-5) dilution factor) and HCVQn (5(-5) dilution factor) were more sensitive than the HCVAg (5(-2) dilution factor). And the diagnostic sensitivity was high in order on the qualitative in - house HCV RT-PCR; 97%, HCVQn; 91%, and HCVAg; 85%. The concordance rate between the three methods was 83.9%. The quantity of HCVAg and HCVQn showed a significant correlation (R =0.8, P<0.0001).
CONCLUSIONS
HCVAg showed reliable results and a significant correlation with the quantitative RNA level. HCVQn showed a quantitative result but less sensitivity than the qualitative in-house HCV RT-PCR. Even though the HCVAg has slightly lower sensitivity than the two methods, methodologically, it is the most cost-effective, is simple, and gives high throughput. So it should be a simple economic surrogate marker for viremia detection and viral load monitoring.