Quantification of serum hepatitis C virus core protein level in patients chronically infected with different hepatitis C virus genotypes.

BACKGROUND/AIM A novel fluorescent enzyme immunoassay (FEIA) for the detection and quantification of serum hepatitis C virus (HCV) core protein was developed. The aim of this study was to evaluate the relation among serum HCV core protein level, HCV RNA level, and HCV genotype in patients with chronic HCV infection. PATIENTS AND METHODS Serum HCV core protein, HCV RNA, HCV genotype were determined in 175 patients using the FEIA, branched DNA assay (Quantiplex HCV RNA ver 1.0), and serologically defined genotyping assay, respectively. For the specificity, all 13 patients seronegative for anti-HCV were negative for serum core antigen and HCV RNA by FEIA and bDNA, respectively. RESULTS FEIA assay seems to be more sensitive than bDNA for patients with HCV type 2 infection (detection: 83.4% v 63.4%, p < 0.01). There was a good overall correlation between the FEIA and bDNA results. However, when the patients were stratified into their HCV types, a correlation was observed in HCV type 1 but not in type 2 infection. Patients with HCV type 2 infection had a lower serum HCV core protein level (median 56 RFI) compared with type 1 infection (median 149 RFI, p < 0.01). Thirty seven patients subsequently received interferon alpha therapy, patients who showed a complete and sustained response had a lower pretreatment serum HCV core protein level compared with patients who had a relapse and nonresponders (36 v 338 RFI, p < 0.01). CONCLUSIONS This study showed that FEIA (1) is a good assay for the detection and quantification of serum HCV core protein level, (2) is also very sensitive in detecting HCV core protein in patients with HCV type 2 infection, and (3) may have a role as a predictor of subsequent response to interferon therapy.