Architect HCV Ag assay is an efficient alternative tool to RNA qRT-PCR quantification for assessing viral load in HCV infection

Abstract

Objective To evaluate the performance characteristics of the automated Architect hepatitis C virus (HCV) core Ag assay versus HCV RNA by PCR among Egyptian patients and to assess its use for valuable clinical workup. Background HCV diagnosis by conventional anti-HCV assays has high rate of false positivity, false negativity, and a limited sensitivity for detection. Although HCV RNA assays are a reliable method for HCV diagnosis, they need technical skills and may also have false-positive results because of contamination. Moreover, the test is time consuming and more expensive. In contrast, the HCV core antigen test detects circulating HCV core antigen and identifies individuals who are actively infected with HCV. A commercialized test (the Architect HCV core antigen test) is supposed to have a sensitivity to detect ∼0.06 pg/ml and consequently a significant increase in sensitivity over the previous assay and a stronger correlation with HCV RNA testing. Patients and methods A descriptive, cross-sectional study was conducted on 60 HCV antibody-positive patients attending the outpatient clinic of Tropical Medicine Department, Al-Hussein University Hospital, Cairo, Egypt. The patients were classified into four groups based on the level of HCV viremia: group A included five patients with PCR below detection limit (12 IU/ml), group B included 39 patients with low viremia (<100 000 IU/ml), group C included 13 patients with moderate viremia (100 000–10 000 000 IU/ml), and group D included three patients with high viremia (>10 000 000 IU/ml). Each case was subjected to thorough clinical evaluation, HCV RNA quantification by Abbott Real Time HCV assay, and HCV Ag quantification by Architect HCV core antigen test. Results HCV Ag was found to be negative only in five of 55 HCV RNA-positive patients who had low level of viremia. The levels of HCV Ag showed a good correlation with those from the HCV RNA quantification (r=0.913, P≤0.001). Regarding HCV core antigen/HCV RNA ratio, it was not fixed for all patients. In most of them, each 1 pg/ml core Ag was equal to ∼10 000 IU/ml of RNA. Conclusion The Architect HCV Ag assay could be used as an alternative tool to HCV RNA PCR quantification in assessing viral load in HCV infection, and it has the advantages of lower cost, easy testing, and rapid reporting.