Mapping of serotype-specific, immunodominant epitopes in the NS-4 region of hepatitis C virus (HCV): use of type-specific peptides to serologically differentiate infections with HCV types 1, 2, and 3

Abstract

The effect of sequence variability between different types of hepatitis C virus (HCV) on the antigenicity of the NS-4 protein was investigated by epitope mapping and by enzyme-linked immunosorbent assay with branched oligopeptides. Epitope mapping of the region between amino acid residues 1679 and 1768 in the HCV polyprotein revealed two major antigenic regions (1961 to 1708 and 1710 to 1728) that were recognized by antibody elicited upon natural infection of HCV. The antigenic regions were highly variable between variants of HCV, with only 50 to 60% amino acid sequence similarity between types 1, 2, and 3. Although limited serological cross-reactivity between HCV types was detected between peptides, particularly in the first antigenic region of NS-4, type-specific reactivity formed the principal component of the natural humoral immune response to NS-4. Type-specific antibody to particular HCV types was detected in 89% of the samples from anti-HCV-positive blood donors and correlated almost exactly with genotypic analysis of HCV sequences amplified from the samples by polymerase chain reaction. Whereas almost all blood donors appeared to be infected with a single virus type (97%), a higher proportion of samples (40%) from hemophiliacs infected from transfusion of non-heat-inactivated clotting factor contained antibody to two or even all three HCV types, providing evidence that long-term exposure may lead to multiple infection with different variants of HCV.

10-year follow-up after interferon-α therapy for chronic hepatitis C

“…17 HCV genotyping was done using the reverse hybridization assay (line probe assay, LiPA; Innogenetics, Ghent, Belgium) 18 and serotyping by immunoassays based on serological differences in antibody to the NS4 region of the genome. 19 As a part of the initial study, all patients underwent liver biopsy before treatment and again after 1 year of treatment. Subsequently, follow-up liver biopsies were done on all 10 patients between 5 and 11 years after starting therapy.…”

Increased frequency of the HLA‐DR15 (B1*15011) allele in German patients with self‐limited hepatitis C virus infection

“…All patients were characterized with respect to the infecting HCV subtype either using the INNOLIPA test (Innogenetics, Zwijndrecht, Belgium) or, because of the absence of HCV-RNA in sera from subjects with self-limited infection, using serotype-specific antibodies to the NS4 region (Murex, Groß Burgwedel, Germany) [20]. Thus, at least HCV genotypes, but not subtypes, could be determined in the patients with previous HCV infection.…”

Hepatitis C virus genotypes in multi‐transfused individuals

“…Although the immune response to HCV in chimpanzees may differ from that of humans, it is likely that in haemophiliacs multiple exposure from long-term use of non-heated concentrates may have led to several episodes of reinfection, and possibly an increased likelihood of acquiring highly pathogenic variants when compared with singly exposed individuals. Multiple episodes of acute hepatitis, associated with reinfection with homologous genotypes have been documented in multi-transfused thalassaemic children [36] and multiple infections have been detected in a variety of polytransfused patients [ 11, [37][38][39].…”

“…The patient samples described above were also tested for type-specific antibody by an indirect ELlSA [37]. We have found that many patients showing changes in genotype often showed parallel but delayed changes in type-specific antibodies to NS-4 peptides [32].…”