Detection of HCV core antigen and its diagnostic significance

Objective To compare the abilities of the hepatitis C virus(HCV) core antigen(cAg) test and the HCV RNA assay for confirming anti-HCV presence in order to determine the clinical utility of the HCV-cAg as an alternative or confirmatory diagnostic tool.Methods Serum samples collected from 158 patients diagnosed with HCV infection were subjected to the enzyme-linked immunosorbent assay-based HCV-cAg test.The optical density(OD) measured values were used to calculate the ratio of specimen absorbance to the cutoff value(S/CO).Simultaneously,the serum samples were subjected to PCR-based nucleic acid amplification quantitative fluorescence detection of HCV RNA.Results None of the serum samples had a S/CO value 1 for the HCV-cAg test(100% negative),but all of the samples had a S/CO value 5(100% positive).The HCV-cAg test sensitivity was 87.05%,specificity was 76.67%,positive predictive value was 96.53%,and negative predictive value was 44.23%.As the S/CO value gradually increased,the significantly higher positive coincident rate of the HCV RNA test decreased.The HCV RNA negative coincident rate was significantly higher than that of the HCV-cAg test.HCV-cAg S/CO values between 1 and 2 corresponded to an HCV RNA values between 1.0×103 copies/ml and 1.0×104 copies/ml.The highest S/CO value obtained was 1.992.Conclusion The HCV-cAg test is comparable to the HCV RNA assay for diagnosing HCV infection.