[Summary and evaluation of genome and antibody diagnosis in hepatitis C virus infection]

Hepatitis C virus (HCV) infection can be diagnosed by antibody assay systems using recombinant antigens since the HCV genome has been identified. It is still impossible to detect viral antigens associated with HCV. Therefore, the polymerase chain reaction (PCR) has been widely used in practical laboratory examinations. Because HCV is an RNA virus and the reverse transcription process is required prior to the PCR reaction, the process of HCV RNA detection has a risk of contamination and the detection rate may differ with the PCR condition. There are several genome diagnostic methods for HCV infection; that is, genome detection by nested PCR, HCV subtyping using mixed primer, quantitation of HCV genome using competitive PCR, Quant-Amp and branched DNA probe. To clarify what factors are responsible, the efficacy of interferon therapy against chronic hepatitis C was examined. The normalization rate of serum ALT level and clearance rate of HCV RNA in serum at six months after the end of the treatment were correlated to the titer of HCV RNA genome and the HCV subtype. The patients with HCV RNA titers of less than 10(4) copies/50 microliters and with subtype group III showed a high response to interferon administration. On the other hand, the results of quantitation of the HCV core antibody titer were closely associated with the presence of HCV RNA using core protein with the recombinant vaccinia expression system or recombinant E. coli system (JCC-2). Especially, in the group of high responders to interferon treatment, the antibody titer against core protein was apparently decreased after the end of interferon therapy.(ABSTRACT TRUNCATED AT 250 WORDS)