Spatial configuration of hepatitis E virus antigenic domain.
Hepatitis E virus (HEV) is a human pathogen that causes acute hepatitis. When an HEV capsid protein containing a 52-amino-acid deletion at the C terminus and a 111-amino-acid deletion at the N terminus is expressed in insect cells, the recombinant HEV capsid protein can self-assemble into a T=1 virus-like particle (VLP) that retains the antigenicity of the native HEV virion. In this study, we used cryoelectron microscopy and image reconstruction to show that anti-HEV monoclonal antibodies bind to the protruding domain of the capsid protein at the lateral side of the spikes. Molecular docking of the HEV VLP crystal structure revealed that Fab224 covered three surface loops of the recombinant truncated second open reading frame (ORF2) protein (PORF2) at the top part of the spike. We also determined the structure of a chimeric HEV VLP and located the inserted B-cell tag, an epitope of 11 amino acids coupled to the C-terminal end of the recombinant ORF2 protein. The binding site of Fab224 appeared to be distinct from the location of the inserted B-cell tag, suggesting that the chimeric VLP could elicit immunity against both HEV and an inserted foreign epitope. Therefore, the T=1 HEV VLP is a novel delivery system for displaying foreign epitopes at the VLP surface in order to induce antibodies against both HEV and the inserted epitope.
Molecular and Cellular Biology, University of California, 1 Shields Ave., Davis, CA 95616, USA.
Li
L
Xing
Joseph C
JC
Wang
Tian-Cheng
TC
Li
Yasuhiro
Y
Yasutomi
James
J
Lara
Yury
Y
Khudyakov
Darren
D
Schofield
Suzanne U
SU
Emerson
Robert H
RH
Purcell
Naokazu
N
Takeda
Tatsuo
T
Miyamura
R Holland
RH
Cheng
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D036022:Capsid Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D020285:Cryoelectron Microscopy; D000939:Epitopes / Q000276:immunology*; D005260:Female; D016752:Hepatitis E virus / Q000276:immunology*; D007091:Image Processing, Computer-Assisted; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D011485:Protein Binding; D055503:Protein Multimerization; D017384:Sequence Deletion; D018411:Spodoptera; D022701:Virosomes / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D000939:Epitopes; D022701:Virosomes