Biological and immunological characteristics of hepatitis E virus-like particles based on the crystal structure

Abstract

Hepatitis E virus (HEV) is a causative agent of acute hepatitis. The crystal structure of HEV-like particles (HEV-LP) consisting of capsid protein was determined at 3.5-Å resolution. The capsid protein exhibited a quite different folding at the protruding and middle domains from the members of the families of Caliciviridae and Tombusviridae, while the shell domain shared the common folding. Tyr-288 at the 5-fold axis plays key roles in the assembly of HEV-LP, and aromatic amino acid residues are well conserved among the structurally related viruses. Mutational analyses indicated that the protruding domain is involved in the binding to the cells susceptive to HEV infection and has some neutralization epitopes. These structural and biological findings are important for understanding the molecular mechanisms of assembly and entry of HEV and also provide clues in the development of preventive and prophylactic measures for hepatitis E.capsid ͉ HEV ͉ VLP

Role of heat-shock protein 90 in hepatitis E virus capsid trafficking

“…Moreover, the interaction between p239 and the host cells was dependent on the dimeric conformation fit of p239 and the binding significantly inhibited HEV infectivity on HepG2 and Huh7 cells. The three-dimensional crystal structure of HEV VLP further demonstrates that this peptide is on the surface of the viral capsid protein, suggesting that it has an important functional role in cell entry (Guu et al, 2009;Li et al, 2009;Yamashita et al, 2009). …”

“…The Nterminal region of the capsid protein is postulated to interact with the negatively charged genomic RNA, while the C-terminal region of the protein contains several antigenic sites, including a neutralization epitope located from residues 452 to 617 (Meng et al, 2001). The determination of the three-dimensional crystal structure of HEV virus-like particles (VLPs) in recent studies showed that the N terminus of ORF2 also plays a key role in the assembly of the HEV particle (Guu et al, 2009;Yamashita et al, 2009). ORF3 overlaps extensively with ORF2, encoding a small immunogenic protein of 123 aa, recently suggested to be only a 114 aa (Graff et al, 2006;Huang et al, 2007) phosphoprotein that is currently of unconfirmed significance.…”

Structural basis for the neutralization of hepatitis E virus by a cross-genotype antibody

“…The capsid protein is responsible for virion assembly, host interaction and immunogenicity and is formed by homodimeric subunits, which comprise a protrusion domain [9,10] (E2s: npg www.cell-research.com | Cell Research aa 455-602 [11] or its N-terminal extension version E2: aa 394-606 [12]). These dimers project from the surface of the virus and initiate infection by interacting with host cells.…”

“…Structural comparisons of the E2s (aa 455-602) of genotype 1 [11] (resolution of 2.0 Å) with that of VLPs (T=1; aa 112-608) for genotype 3 [9] and genotype 4 [10] (3.5 Å) have revealed that the HEV capsid is formed by capsomeres comprising a homodimeric ORF2, and that virus infection is initiated through the interaction of this protruding homodimer with host cells. Cryo-electron microscopy studies [16] have additionally confirmed these structural findings.…”

High Prevalence of Hepatitis E Virus in Wild Boar (Sus scrofa) in Yamaguchi Prefecture, Japan

“…Anti-HEV IgG was detected in sera by ELISA, using virus-like particles (VLPs) as the coating antigen (Yamashita et al 2009). The VLPs were diluted in 0.1 M carbonate buffer (pH 9.6) to 1 mg/mL, and 100 mL per well was added to 96-well microplates (Nunc, Roskilde, Denmark).…”