Correlation ofSerumAntibody Titers against Hepatitis C VirusCoreProtein withClinical Features byWesternBlot (Immunoblot) Analysis Usinga Recombinant Vaccinia VirusExpression System

Inorder tostudy therelationships among theclinical features ofhepatitis Cpatients, thepresenceofhepatitis C virus(HCV)RNA intheir blood, andtheir serum antibody titers against thecoreprotein ofvirus andto studytheantibody levels inasymptomatic HCV carriers, a recombinant vaccinia viruscontaining a core protein genewas constructed. Therecombinant virus expressed aprotein witha molecular mass of22kDain RK-13cells asdetermined byWestern blot(immunoblot) analysis. Byusing thecell lysate ofvirus-infected cells andserially diluted serum samples, coreantibody titers inthegroupsofpatients inthechronic hepatitis phase andintheconvalescent phase aswell asinasymptomatic carriers were determined byenhanced chemiluminescenceWestern blotanalysis. Almost allpatients inthechronic phase wereshowntohavehighantibody titers ofmore than1:500,000 andwithnoexception hadofHCV RNA intheir sera.Ontheother hand,patients who hadrecovered naturally andwere intheconvalescent phase were showntohavesignificantly lowerantibody titers, andtheantibody was notdetected inthelowest serum dilution of1:500in43%ofthese patients (three ofseventotal patients). Antibody levels ofpatients whoshoweda goodresponsetointerferon treatment decreased tointermediate levels between thoseofpatients inthechronic phaseandthoseofpatients in convalescent phase. Theantibody titers inasymptomatic carriers varied considerably from1:500,000 to1:500, and41% (11of27total individuals) ofthese carriers showed a hightiter equivalent tothatofthose inthe chronic phase. Coreantibody was detected consistently intheindividuals inwhomHCV RNA was detected. Thissystem forcoreantibody mightbeuseful foridentifying thestage ofan apparent HCV infection.