Profiles of HCV core protein and viremia in chronic Hepatitis C: possible protective role of core antigen in liver damage

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Abstract
The relation between HCV core antigen and HCV RNA has been confirmed in patients with chronic hepatitis C and a parallel behavior of the two markers has been described in early kinetics analysis during antiviral therapy. Variations of the core antigen to HCV RNA ratio have been reported in individual patients and the existence of nucleocapsid particles, not always associated with viral genomes, have been described. To assess the characteristics of HCV core antigen reactivity in relation to viremia in patients with different clinical profiles, 233 patients with chronic hepatitis C were studied serially. Group A included 54 asymptomatic HCV carriers, group B included 8 viremic patients with biochemical long‐term response after antiviral therapy, while group C was composed of 171 patients with chronic liver disease and 75 were treated with combination therapy. Core antigen levels were not significantly different in the three groups of patients and a wide range of antigenic reactivity was observed in individual patients. A close relationship was observed between core antigen and HCV RNA, although their ratio was significantly higher in biochemical long‐term responders (group B), compared to the other groups (P < 0.05). Physicochemical characterization of core antigen reactivity by equilibrium CsCl density gradient identified two distinct peaks migrating at 1.08–1.12 g/ml CsCl density and at 1.18–1.31 CsCl density, respectively. The first one, corresponding to the lipid‐associated fraction, contained higher amounts of core antigen reactivity and was associated with clinical remission of liver damage, while the second peak, corresponding to naked nucleocapsids, was observed mainly in sera with active disease. In conclusion, a close relationship between core and HCV RNA was documented both in treated and untreated patients. The finding of an excess of lipid‐associated core particles in a subset of viremic patients without biochemical activity of liver disease suggests their protective effect in liver cell damage. J. Med. Virol. 76:55–60, 2005.