Biology Reference
In-Depth Information
A. Anti-tag
B. Anti-HEV
8
8
4
4
2
2
< 2
< 2
G1
G2a
G2b
G3
A
M
G1
G2a
G2b
G3
A
M
Fig. 7. Isotypes of antibodies specific to the tag epitope (A) and HEV (B)
in intestinal fluids in orally immunized mice sacrificed at 10 wpi. Levels of
IgA (A), IgM (M), and IgG subclasses (G1, G2a, G2b and G3) were exam-
ined by ELISA using isotype-specific secondary antibodies and are shown as
end-point titers. Solid and open bars indicate antibody levels of each mouse
immunized with the chimeric VLP and VLP without the tag epitope inser-
tion, respectively.
administration to overcome the difficulties of a severe environment
through the digestive tract. It is plausible that HEV-VLPs, which are
derived from an orally transmissible virus, were incorporated into HEV-
permissive epithelial cells in the small intestine because they retained
structures and properties similar to those of HEV particles, producing
an infection similar to that induced naturally. 17 It has been shown that
the VLP structure should provide resistance to severe environments in
the digestive tracts and enable specific binding to the mucosal surface if
an appropriate VLP is chosen. 23 The delivery of a vaccine antigen (Ag)
for induction of mucosal immune responses is usually achieved through
the upper nasopharynx-associated lymphoid tissue (NALT), upper air-
way, salivary glands and tonsils. 24,25 Despite its obvious convenience,
oral administration is rarely successful since it is quite difficult to pro-
tect vaccine Ag from the environment in the digestive tract.
The results of immunoprecipitation and ELISA using intact
chimeric VLPs suggest that the tag epitope is exposed on the surface
of the HEV-VLP. The successful induction of antibodies to the tag
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