Characterization of the Antibody Reactivity to Synthetic Peptides from Different Parts of the Hepatitis C Virus Genome

Abstract

Infection by hepatitis C virus (HCV)*, the aetiologic agent responsible for the majority of non-A-non-B posttransfusion hepatitis, is detected by assaying for antibodies against structural and nonstructural recombinant proteins or synthetic peptides. The aim of this study was to characterize the antibody reactivity of selected sera against antigenic peptides spanning immunodominant regions of the core, NS4 and NS5 HCV proteins. Reactivity to synthetic peptides was determined by enzyme immunoassay (EIA) for 11 selected sera from blood donors (good responders), for 27 selected sera from hemodialysis patients (poor responders), all positive for HCV antibodies (tested by different second and third-generation assays), and for 7 negative sera. Some peptides from the core and the NS4 region were widely recognized by the tested sera. Sera not reactive with core, NS4, or NS5 region by some immunoblot assays exhibited reactivity against peptides from these proteins. Autoimmune reactivity associated with HCV infection was evaluated by using a synthetic peptide derived from the GOR peptide; 8/11 HCV-positive sera were found reactive against this peptide. No correlation was found between reactivity to any of the peptides tested and the presence of HCV RNA in the serum or with HCV genotype. The EIA reactivity of peptides from the core region suggested a multideterminant antigenic structure, where reactivity of each epitope may be differentially affected by neighboring amino acids depending on individual sera. This situation was particularly evidenced in selected sera from poor responder specimens where a more restricted antibody response to core peptides was observed. Reactivity of sera from HCV-infected patients with synthetic peptides from the core, NS4, and NS5 regions indicated the presence of multiple linear epitopes (particularly in the core region) that may be used in a mixture for immunodiagnosis; however, the length and exact position of the synthetic peptides must be chosen carefully.

Identification of antigenic sites on three hepatitis C virus proteins using phage-displayed peptide libraries

“…4B) and several antigenic amino acids within it. The NS5 antigenic region 2251-2260 identified in this study has not been previously reported in literature, although several other NS5 epitopes have been identified Khudyakov et al, 1995;Pujol et al, 1996].…”

“…Both sequences of Prezzi et al [1996] differ from the seven we have identified, although their second sequence is outside the scope of our affinity-purified antibody selection method, since our NS4 protein fragment encompasses only 1644-1812 amino acid residues. The HCV core protein has been well characterised antigenically using synthetic peptides, especially its Nterminal part [Okamoto et al, 1992;Goeser et al, 1994;Sallberg et al, 1994;Prezzi et al, 1996;Pujol et al, 1996]. The fact that it is possible to map core antigenic determinants using short peptides suggests a rather linear character for core epitopes.…”

“…The antigenic regions 34-49 and 19-26 revealed in our study also have been identified using overlapping synthetic peptides. Antigenic core peptides include 20-41 and 40-63 [Goeser et al, 1994], 38-74 [Okamoto et al, 1992], and 45-64 [Pujol et al, 1996]. The specific binding site at 73-83 ( Fig.…”

“…For this purpose, different methods of antigen mapping have been used. These include binding analysis of hepatitis C patients antisera to synthetic peptides [Okamoto et al, 1992;Simmonds et al, 1993;Goeser et al, 1994;Sallberg et al, 1994;Khudyakov et al, 1995;Bhattacherjee et al, 1995;Pujol et al, 1996], or short HCV polypeptides expressed in prokaryotic systems [Goeser et al, 1994;Mondelli et al, 1994;Claeys et al, 1995].…”

Hepatitis C epitopes from phage-displayed cDNA libraries and improved diagnosis with a chimeric antigen

“…Many attempts have been made to improve the HCV serodiagnosis. Studies of the HCV antigenic structure have allowed construction of diagnostic systems with improved assay specificity and sensitivity [Krajden, 1995;Roggendorf et al, 1996] The antigenic structure of HCV proteins has been studied using synthetic peptides [Okamoto et al, 1992;Simmonds et al, 1993;Goeser et al, 1994;Zhang et al, 1994;Bhattacherjee et al, 1995;Khudyakov et al, 1995;Pujol et al, 1996;Sallberg et al, 1996] and short HCV polypeptides expressed in prokaryotic systems [Goeser et al, 1994;Mondelli et al, 1994;Claeys et al, 1995].…”