April Journal-2009.p65 - Association of Biotechnology and Pharmacy
April Journal-2009.p65 - Association of Biotechnology and Pharmacy
April Journal-2009.p65 - Association of Biotechnology and Pharmacy
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Current Trends in <strong>Biotechnology</strong> <strong>and</strong> <strong>Pharmacy</strong><br />
Vol. 3 (2) 113-127, <strong>April</strong> 2009. ISSN 0973-8916<br />
Molecular farming <strong>of</strong> Plant Derived Edible Vaccines<br />
D.K.Das<br />
Post Graduate Department <strong>of</strong> <strong>Biotechnology</strong><br />
T. M.Bhagalpur University, Bhagalpur-812007, India<br />
For correspondence - dilipdas@hotmail.com<br />
Abstract<br />
Vaccines have been one <strong>of</strong> the most farreaching<br />
<strong>and</strong> important public health initiatives <strong>of</strong><br />
the 20 th century. Edible vaccine, in particular,<br />
might overcome some <strong>of</strong> the difficult <strong>of</strong><br />
production, distribution <strong>and</strong> delivery associated<br />
with traditional vaccine. Transgenic potatoes<br />
expressing LT-B were found to induce both serum<br />
<strong>and</strong> secretory antibodies when fed to mice, these<br />
protective in bacterial toxin assays in vitro. This<br />
is the first pro<strong>of</strong> <strong>of</strong> concept for the edible vaccine.<br />
The selection <strong>of</strong> a plant system for delivery <strong>of</strong><br />
edible vaccines for human has been addressed.<br />
Recognising that it is necessary to express the<br />
desired protein in a food that is consumed raw<br />
(to avoid denaturation <strong>of</strong> the c<strong>and</strong>idate vaccine<br />
protein), a system to transform banana plant has<br />
been developed. The expression <strong>of</strong> c<strong>and</strong>idate<br />
vaccines in banana fruit will be dependant upon<br />
identification <strong>of</strong> suitable specific promoter to drive<br />
the desired gene expression. The concept <strong>of</strong> edible<br />
vaccine got impetus after Arntzen <strong>and</strong> co-workers<br />
expressed hepatitis B surface antigen in tobacco.<br />
Strategies for expression <strong>of</strong> foreign genes in high<br />
amounts in plants include use <strong>of</strong> strong <strong>and</strong> organ<br />
specific promoters targeting <strong>of</strong> the protein into<br />
endoplasmic reticulum by incorporating ERtargeting<br />
<strong>and</strong> ER-retention signals, creation <strong>of</strong><br />
optimized translation start site context as well as<br />
alleviation <strong>of</strong> codons to suit the expression <strong>of</strong><br />
prokaryotic genes in a plant. Retention <strong>of</strong> heat<br />
labile E.coli enterotoxin in ER <strong>of</strong> potato by using<br />
ER-retention signal has been reported to elevate<br />
the expression levels <strong>of</strong> the recombinant protein.<br />
Cholera toxin, which is very similar to E.coli LT,<br />
has also been expressed in plants generated<br />
tobacco plants expressing CT-A or CT-B subunits<br />
<strong>of</strong> the toxin. Hepatitis B surface antigen (HBsAG)<br />
has been reported to accumulate to 0.01% <strong>of</strong><br />
soluble protein level in transgenic tobacco. Edible<br />
vaccine <strong>of</strong>fer exciting possibilities for significantly<br />
reducing the burden <strong>of</strong> diseases like hepatitis <strong>and</strong><br />
diarrhoea, particularly in the developing world<br />
storing <strong>and</strong> administering vaccines are <strong>of</strong>ten major<br />
problems. NIAID have shown for the first time<br />
that an edible vaccine can safely trigger significant<br />
immune responses in people. Antibodies raised<br />
to the H protein after infection with the wild type<br />
measles virus (MV) have MV-neutralizing activity<br />
<strong>and</strong> correlate with immunological proteins. Recent<br />
studies have shown that mammalian protein can<br />
be expressed to high levels in transgenic rice.<br />
Key words - Edible vaccine, Antibodies,<br />
Enterotoxin, Surface antigen, Cholera toxin<br />
Introduction<br />
Vaccines are primary tools in programmes<br />
for health intervention for both humans <strong>and</strong><br />
animals. They would be more widely used<br />
especially in developing countries. It would be<br />
helpful for human society if cost <strong>of</strong> production<br />
could be reduced <strong>and</strong> they could be distributed<br />
without refrigeration. Vaccines couldn’t be very<br />
popular because <strong>of</strong> unavailability <strong>of</strong> electricity for<br />
its storage in remotest area in developing countries.<br />
Vaccines <strong>and</strong> antibodies play a key role in<br />
healthcare. However, the cost <strong>of</strong> production <strong>and</strong><br />
maintaining a chain for vaccine distribution has<br />
Plant Derived Edible Vaccines