Evaluation of a total hepatitis C virus (HCV) core antigen assay for the detection of antigenaemia in anti‐HCV positive individuals

A new, sensitive enzyme immunoassay has been developed for detecting and quantifying total hepatitis C virus (HCV) core antigen in anti‐HCV positive or negative sera (“ trak ‐ C ™”, Ortho Clinical Diagnostics, Raritan, NJ). The purpose of this study was to evaluate the performance of trak ‐ C as an additional laboratory diagnostic marker of viraemia. The performance was compared to HCV‐RNA detection in the “screening” of sera from a large heterogeneous population of hospitalised patients and outpatients. Six hundred and eighteen anti‐HCV negative sera, 405 anti‐HCV positive/HCV‐RNA negative sera, 604 anti‐HCV positive/HCV‐RNA positive sera and 67 anti‐HCV negative sera containing antigens or antibodies potentially interfering with the performance of the assay were analysed. Supplemental HCV antibody testing was performed using a commercial strip immunoblot assay. HCV‐RNA was investigated using a qualitative commercial assay. A quantitative commercial RT‐PCR was used for the analysis of selected samples. Sensitivity and specificity values were 94.7 and 100%, respectively. The latter was also confirmed when anti‐HCV negative samples containing potentially interfering antigens/antibodies were examined. Sensitivity below 100% was probably due to an antigenaemia below the detection limit of trak ‐ C . Besides, because 65.6% of HCV‐RNA positive/ trak ‐ C negative samples presented specific antibodies against all four RIBA antigens, the hypothesis was raised that, in some cases, the dissociation step efficiency could be sub‐optimal. In conclusion, trak ‐ C seems suitable for identifying HCV infection on large based populations. It is a rapid to perform, reliable and specific assay that can be adapted to any laboratory setting. J. Med. Virol. 73:397–403, 2004. © 2004 Wiley‐Liss, Inc.