Expression and immunological characterization of peptides from the N-terminus of the Hepatitis C Virus polyprotein

Abstract

HCV is characterized by a high degree of nucleotide sequence variability between types and subtypes. This variability extends to functional and immunological determinants. Serological tests using peptides derived from the HCV polyprotein have been widely used for the diagnosis of HCV infection. However, available diagnostic Kits do not necessarily take this variability into account and are not optimized for HCV genotype 4a (HCV4a), the predominant genotype in Egypt. This study aimed to express some HCV4a-derived peptides in order to identify those with immunodiagnostic utilities. Six cDNA overlapping segments corresponding to 100-266 amino acid peptides encompassing regions from the core (peptide 1), envelope 1 (E1; peptide 2), envelope 2 (E2; peptides 4, 5 and 6) and E1/E2 (peptide 3) of the HCV polyprotein were selected for in vitro expression as glutathione S-transferase (GST)-fusion proteins. The immunoreactivity of the expressed peptides was evaluated against sera from both HCV4a-infected and uninfected individuals using Dot blot, Western blot and enzyme-linked immunosorbent assay (ELISA). The expressed peptides revealed a remarkable immunoreactivity towards HCV4a infected sera, while showing no immunoreactivity towards serum from a healthy individual. Peptides 1, 2, 3 and 4 were found to be the most immunoreactive among the tested peptides towards HCV4a infected sera with peptide 1 having the highest immunoreactive capability. Our findings strongly suggest that the expressed peptides hold good potential for the development of highly HCV4a specific immunodiagnostics.