Simple fluorescent enzyme immunoassay for detection and quantification of hepatitis C viremia

The viral load of hepatitis C virus, as reflected by hepatitis C virus viremia, has been shown to have important clinical implications. In this study the hepatitis C virus core protein level in serum was evaluated for the detection and quantification of hepatitis C virus viremia. Methods: Hepatitis C virus core protein in serum was detected using a simple and sensitive fluorescent enzyme immunoassay. Hepatitis C virus core protein was quantitated in 100 healthy subjects, 258 patients with hepatitis C virus infection and 108 patients with non-hepatitis-C-virus-related chronic liver diseases. HCV-RNA was determined using the branched DNA (bDNA) assay and reverse-transcription polymerase chain reaction. Results: The detection limit of this fluorescent enzyme immunoassay was found between 104–105 copies/ml HCV-RNA equivalent. There was a good correlation between the core protein and bDNA assay results (p<0.01). Hepatitis C virus core protein was detected in 81% of patients with hepatitis C virus infection (acute hepatitis , chronic hepatitis , cirrhosis and hepatocellular carcinoma ) but in none of the healthy subjects and patients with non-hepatitis C virus chronic liver diseases. The amount of hepatitis C virus core protein in patients with hepatitis-C-virus-related hepatocellular carcinoma was lower compared to chronic hepatitis and cirrhosis (p<0.05). All 26 patients treated with interferon-α showed parallel changes between HCV-RNA and core protein levels. Conclusions: This fluorescent enzyme immunoassay is simple and quick (assay time<3 h) with sensitivity at least matching the bDNA assay. Similar levels of hepatitis C virus core protein were detected in patients with chronic hepatitis and cirrhosis, but patients with hepatocellular carcinoma tended to have a lower level of hepatitis C virus core protein.