Hepatitis C core antigen highly correlated to HCV RNA.

Hepatitis C virus core antigen (HCV-Ag) immunoassay has been proposed as a more cost and time efficient one-step alternative to the current two-step screening and diagnostic process. This study investigates the correlation between the HCV-Ag immunoassay and the current gold standard of Hepatitis C Virus (HCV) ribonucleic acid (RNA) molecular assay. Stored sera of 221 consecutive treatment-naive patients tested anti-HCV positive were selected to undergo both HCV-Ag immunoassay and HCV RNA molecular assay. Active infection status and HCV genotype were determined using both assays, and correlation was calculated using a logarithmic scale. Among 221 anti-HCV-positive sera, 197 were positive for both HCV Ag (≥3 fmol/L) and HCV RNA (>15 IU/mL), 22 were negative for both tests, while 2 were positive to HCV RNA only. The sensitivity and specificity for HCV Ag in predicting HCV RNA were 99% and 100%, respectively. Out of 199 patients (90%) tested positive for HCV viremia, 107 (56%) were of genotype 1, 77 (38.7%) of genotype 2 and 15 of other genotypes. Analysis of 221 anti-HCV-positive patient sera found a strong positive correlation between HCV RNA and HCV-Ag (r = 0.960, p < 0.001). Genotype 1 (log [HCV RNA] = 0.988 x log [HCV-Ag] + 2.768), with correlation coefficient 0.945, exhibited a stronger correlation than genotype 2 (log [HCV RNA] = 0.859 x log [HCV-Ag] + 2.859; r = 0.862). Given the strong positive correlation between HCV-Ag immunoassay and HCV RNA molecular assay in genotyping affected individuals, we propose that HCV-Ag immunoassay is a more cost and time efficient alternative to the current two-step diagnostic process.