Evaluation of a new quantitative test for HCV core Ag

Introduction.The quantitative determination of viral antigens is a diagnostic innovation. The availability of an automated test for detecting the “core” antigen of the hepatitis C virus (HCV) allowed to assess its characteristics and potential applications. Methods.The Abbott ARCHITECT HCV core Ag assay is a fully automated CMIA measuring HCV core antigen at concentrations between 3 and 180,000 fmol / L. The evaluation has been conducted on anti-HCV positive samples at various levels: on samples for which the quantitative (bDNA) and / or qualitative (TMA) HCV-RNA have been tested and on samples of hemodialysis patients. Results.A positivity for HCV Ag was detectable in 10/142 (7.0%) sera with single anti-core reactivity at additional RIBA 3 test while 58 samples reactive to NS3 or NS4 or NS5 were all HCV Ag negative.The frequency of Ag positivity was correlated with the anti-HCV signal (at anti-HCV ARCHITECT), ranging from 71% in samples with S / CO> 5 to 6% in samples with S / CO <5. The antigen was detectable at low concentrations (average 50±1.17 fmol / L) in 8 / 53 samples (15.1%) with viremia below 500 IU / mL. On samples with quantifiable HCV-RNA, the correlation between bDNA and HCV Ag was very good. Of the 65 examined hemodialysis patients, 46 were positive for both antibodies and antigen, 15 for only antibodies, 3 negative for both and one was highly positive for HCV Ag (and HCV-RNA), but anti-HCV negative. Conclusion. The sensitivity and the practicality of the new quantitative test for HCV Ag allow to envisage the use for the evaluation of active HCV infection in anti-HCV positive patients, monitoring patients at risk of infection and as a complement of quantitative viremia.