Biology Reference
In-Depth Information
Chapter 20
Chimeric Recombinant Hepatitis E
Virus-like Particles Presenting Foreign
Epitopes as a Novel Vector of Vaccine
by Oral Administration
Yasuhiro Yasutomi
*
,†
Virus-like particles (VLPs) are useful for studies on virion formation, host
immune responses to viruses, and vaccines in no practical cell culture systems
to allow the growth of virus. Among the various non-replicating molecules,
VLP, an empty particle with a structure similar to that of an authentic virus
particle, offers the possibility of a new approach for these studies. Hepatitis
E virus (HEV) is an unclassified calicivirus-like, positive-strand RNA virus
that causes human acute hepatitis by fecal-oral transmission. HEV first
infects epithelial cells of the small intestine and then reaches the liver through
the portal vein. It has been reported that intact open reading frame 2
(ORF2) of HEV is expressed as a membrane glycoprotein when artificially
expressed in mammalian cells
in vitro
, probably because the N-terminal
amino acid sequence serves as a signal peptide.
1,2
On the other hand, the
intact ORF2 expression in insect cells resulted in various sizes of proteins
with cleavages on both N- and C-termini, of which 53 kD polypeptides
secreted in the culture supernatant.
3-5
It has also been reported that only
after cleavage of C-terminal, which results in molecular weight reduction to
*Laboratory of Immunoregulation and Vaccine Research, Tsukuba Primate Research Center,
National Institute of Biomedical Innovation, Tsukuba, Ibaraki 305-0843, Japan.
†
Department of Immunoregulation, Mie University Graduate School of Medicine, Mie 514-
8507, Japan. E-mail: yasutomi@nibio.go.jp; yasutomi@doc.medic.mie-u.ac.jp.
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