CORRELATION OF SERUM ANTIBODY-TITERS AGAINST HEPATITIS-C VIRUS CORE PROTEIN WITH CLINICAL-FEATURES BY WESTERN-BLOT (IMMUNOBLOT) ANALYSIS USING A RECOMBINANT VACCINIA VIRUS EXPRESSION SYSTEM

In order to study the relationships among the clinical features of hep atitis C patients, the presence of hepatitis C virus (HCV) RNA in thei r blood, and their serum antibody titers against the core protein of v irus and to study the antibody levels in asymptomatic HCV carriers, a recombinant vaccinia virus containing a core protein gene was construc ted. The recombinant virus expressed a protein with a molecular mass o f 22 kDa in RK-13 cells as determined by Western blot (immunoblot) ana lysis. By using the cell lysate of virus-infected cells and serially d iluted serum samples, core antibody titers in the groups of patients i n the chronic hepatitis phase and in the convalescent phase as well as in asymptomatic carriers were determined by enhanced chemiluminescenc e Western blot analysis. Almost all patients in the chronic phase were shown to have high antibody titers of more than 1:500,000 and with no exception had of HCV RNA in their sera. On the other hand, patients w ho had recovered naturally and were in the convalescent phase were sho wn to have significantly lower antibody titers, and the antibody was n ot detected in the lowest serum dilution of 1:500 in 43% of these pati ents (three of seven total patients). Antibody levels of patients who showed a good response to interferon treatment decreased to intermedia te levels between those of patients in the chronic phase and those of patients in convalescent phase. The antibody titers in asymptomatic ca rriers varied considerably from 1:500,000 to 1:500, and 41% (11 of 27 total individuals) of these carriers showed a high titer equivalent to that of those in the chronic phase. Core antibody was detected consis tently in the individuals in whom HCV RNA was detected. This system fo r core antibody might be useful for identifying the stage of an appare nt HCV infection.