Characterization and Immunogenicity of Hepatitis C Virus Envelope Proteins
Date Issued
2010
Date
2010
Author(s)
Cheng, Ting
Abstract
It was estimated that about 3% of the worldwide population were infected with hepatitis C virus (HCV). The current therapy is ribavirin combined with pegylated interferon-α, and the effect was differential for infections with various HCV genotypes. Until now there is still no vaccine available.
The genome of HCV encodes a polyprotein which could be cleaved into structural and nonstructural proteins by host and viral proteases. The envelope proteins are structural proteins which are expressed on the viral surface and are comprised of heterodimers of E1 and E2. They play an important role in receptor binding and virus entry. HCV E1 and E2 proteins are highly glycosylated. Glycans may be crucial for protein folding or receptor binding or both. Glycans also can mask the functionally important region of protein so that proteins may not produce effective antibodies to defeat the viruses.
Our ultimate goal is to investigate the roles of glycans on HCV E1/E2 glycoproteins, especially on the immunogenicity. Recombinant HCV envelope proteins were produced from human 293T cells. The purified proteins are either used directly (fully-glycosylated) or digested with Endoglycosidase H to remove all the glycans except the first GlcNAc (mono-glycosylated). The glycosylation patterns of fully- and mono-glycosylated HCV envelope proteins were further examined by glycan profiling. Their structural and functional properties were also evaluated with circular dichroism spectroscopy and with binding activity to CD81, a receptor of HCV. In addition, the immunogenicity of HCV envelope proteins in various forms was investigated.
The results showed that the N-glycans of mono-glycosylated proteins were mostly one HexNAc, and the secondary structures of fully- and mono-glycosylated proteins were similar. Furthermore, the CD81 binding activity of mono-glycosylated proteins was higher than fully-glycosylated proteins. However, the immunogenicity of fully-glycosylated proteins was higher than mono-glycosylated HCV envelope proteins.
Subjects
HCV
envelope protein E1E2
glycosylation
Endo H
immunogenicity
SDGs
Type
thesis
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