[Comparative analysis of hepatitis C virus core protein in the plasma and serum samples from HCV-infected blood donors and patients with hepatitis C].

The aim of the study was to develop a sensitive and specific method for revealing the direct marker of hepatitis C virus (HCV)--core protein in the serum and to test it in the laboratory setting. Experiments were made on plasma and serum samples from asymptomatic HCV-seropositive blood donors (n=65), patients with acute (AHC) and chronic (CHC) hepatitis C (n=295), and HCV-seronegative blood donors (n=20). The processing protocol for serum included their concentration by means of polyethylene glycol and subsequent treatments of pellets to detect core protein in free virions, nonenveloped nucleocapsids, and immune complexes. This allowed an assay to be developed for the detection of core protein, by using a sandwich ELISA. Inclusion of a combination of three original monoclonal antibodies into the sandwich could reveal in the samples core proteins of at least 3 genotypes of HCV (1, 2, and 3) with a sensitivity of 20 pg/ml in the majority of HCV-infected subjects. The results of determination of core protein and HCV RNA correlated with a high degree of sensitivity. To detect HCV in the blood of patients with AHC, it was shown to be sufficient to find freely circulating virions whereas an analysis of immune complexes should be included in cases of CHC to achieve more sensitivity. The findings are a basis for developing a test system for the diagnosis of hepatitis C, including its early stages before seroconversion and for determining a viral load during interferon therapy. Introduction of the method into practice increases the reliability of the diagnosis of hepatitis C and virus-free safety of blood transfusions.