April Journal-2009.p65 - Association of Biotechnology and Pharmacy

Current Trends in Biotechnology and Pharmacy
Vol. 3 (2) 113-127, April 2009. ISSN 0973-8916
Molecular farming of Plant Derived Edible Vaccines
D.K.Das
Post Graduate Department of Biotechnology
T. M.Bhagalpur University, Bhagalpur-812007, India
For correspondence - dilipdas@hotmail.com
Abstract
Vaccines have been one of the most farreaching
and important public health initiatives of
the 20 th century. Edible vaccine, in particular,
might overcome some of the difficult of
production, distribution and delivery associated
with traditional vaccine. Transgenic potatoes
expressing LT-B were found to induce both serum
and secretory antibodies when fed to mice, these
protective in bacterial toxin assays in vitro. This
is the first proof of concept for the edible vaccine.
The selection of a plant system for delivery of
edible vaccines for human has been addressed.
Recognising that it is necessary to express the
desired protein in a food that is consumed raw
(to avoid denaturation of the candidate vaccine
protein), a system to transform banana plant has
been developed. The expression of candidate
vaccines in banana fruit will be dependant upon
identification of suitable specific promoter to drive
the desired gene expression. The concept of edible
vaccine got impetus after Arntzen and co-workers
expressed hepatitis B surface antigen in tobacco.
Strategies for expression of foreign genes in high
amounts in plants include use of strong and organ
specific promoters targeting of the protein into
endoplasmic reticulum by incorporating ERtargeting
and ER-retention signals, creation of
optimized translation start site context as well as
alleviation of codons to suit the expression of
prokaryotic genes in a plant. Retention of heat
labile E.coli enterotoxin in ER of potato by using
ER-retention signal has been reported to elevate
the expression levels of the recombinant protein.
Cholera toxin, which is very similar to E.coli LT,
has also been expressed in plants generated
tobacco plants expressing CT-A or CT-B subunits
of the toxin. Hepatitis B surface antigen (HBsAG)
has been reported to accumulate to 0.01% of
soluble protein level in transgenic tobacco. Edible
vaccine offer exciting possibilities for significantly
reducing the burden of diseases like hepatitis and
diarrhoea, particularly in the developing world
storing and administering vaccines are often major
problems. NIAID have shown for the first time
that an edible vaccine can safely trigger significant
immune responses in people. Antibodies raised
to the H protein after infection with the wild type
measles virus (MV) have MV-neutralizing activity
and correlate with immunological proteins. Recent
studies have shown that mammalian protein can
be expressed to high levels in transgenic rice.
Key words - Edible vaccine, Antibodies,
Enterotoxin, Surface antigen, Cholera toxin
Introduction
Vaccines are primary tools in programmes
for health intervention for both humans and
animals. They would be more widely used
especially in developing countries. It would be
helpful for human society if cost of production
could be reduced and they could be distributed
without refrigeration. Vaccines couldn’t be very
popular because of unavailability of electricity for
its storage in remotest area in developing countries.
Vaccines and antibodies play a key role in
healthcare. However, the cost of production and
maintaining a chain for vaccine distribution has
Plant Derived Edible Vaccines