Performance of HCV-Core Antigen Testing in Liver Transplanted Patients

Abstract

Introduction: A new HCV core Antigen (HCVcoreAg) assay has recently been re-introduced as a diagnostic tool. We and others have shown a good performance in untreated immunocompetent patients (Mederacke et al, J Clin Virol. 2009 Nov;46(3):210-5). The aim of this study was to (i) evaluate the performance of the HCVcoreAg-assay in routine diagnostic settings in the context of immunosuppressed patients and (ii) to compare HCVcoreAg and HCV RNA kinetics early after liver transplantation. Methods: HCV core Ag was quantified by a fully automated immunoassay (Architect HCV Ag, Abbott, Germany). A concentration of HCVcoreAg of ≥3.00 fmol/L was considered reactive. HCV-RNA quantification was performed using the Cobas TaqMan assay with a lower limit of detection of 15 IU/ml (Roche Diagnostics, Germany). 601 samples from 415 patients were measured. 154 samples tested negative for both HCV-RNA and HCVcoreAg were excluded from the analysis. 66 patients underwent liver transplantation (LTX), 11 kidney transplantation (NTX) and 231 had no history of solid organ transplantation. In 12 patients HCV RNA and HCVcoreAg kinetics were measured early after liver transplantation (Day 0-8). Results: HCV-RNA and HCVcoreAg showed high correlations in LTX patients (r=0.71, p< 0.0001), in patients after NTX (r=0.97, p< 0.0001) and in patients with no history of transplantation (r=0.77, p< 0.0001). HCV RNA was tested positive in 37 samples being HCVcoreAg negative (median HCV RNA levels of those patients were 57 IU/mL). All patients positive for HCV-RNA were also tested positive for HCVcoreAg. After LTX kinetics of HCV-RNA and HCVcoreAg paralleled almost exactly in all patients. In 11 out of 12 patients HCV RNA and HCVcoreAg levels did not reach pretransplant levels one week after LTX. Conclusions: HCVcoreAg showed a very good performance in our study with very good correlations in all of our three patient groups. As the HCVcoreAg assay is cheaper compared to HCV RNA quantification, it might be used for frequent determinations of HCV-viremia which may have impact in LTX setting.