www.checkbiotech.org ; www.raupp.info ; www.czu.cz

How about eating a ripe appetizing banana fruit and getting rid of all your
worries about catching hepatitis B at the same time? A scientist?s dream, or
just a step away from reality? December 2005 by Daniela Jenni, Checkbiotech.

Over 20 million people become infected with Hepatitis B every year.
Hepatitis B is a serious disease caused by a virus that attacks the liver,
and can cause lifelong infection, cirrhosis (scarring) of the liver, liver
cancer, liver failure, and death. Most of the infections occur in the
developing world.

Fortunately there are vaccines available against Hepatitis B. However, at
present such are gained from microbes, and are expensive to produce. This
restricts their availability in those countries where they are needed most.

Right now, researchers are busy working out other solutions, such as
producing a vaccine against Hepatitis B in plants. There is for example a
team from India which succeeded in producing a Hepatitis B antigen in
bananas. The antigen can then be used to make a vaccine against Hepatitis B.

Bananas are an ideal host since most of the edible bananas do not set seeds
and fruits develop parthenocarpically, which means directly from the
maternal tissue of the flower. This prevents the imported gene from being
transferred to other vegetation.

Equally important, the banana is an ideal meal for infants, and is available
year-round in the tropics and subtropics ? precisely where economical
vaccines are required most urgently.

The researchers working on the banana vaccine are from the Bhabha Atomic
Research Centre in Mumbai, India, and the Shantha Biotechnics Ltd,
Hyderabad, India. Their paper ?Expression of hepatitis B surface antigen in
transgenic banana plants? was recently published in Planta, an international
journal of Plant Biology.

The group succeeded in transferring a Hepatitis B antigen to bananas.
However, according to Dr. Bapat, the amount of antigen produced by the
genetically engineered bananas still has to be significantly increased to
provide sufficient protection in humans ? which is the goal of their
research.

Dr. Bapat?s team is working out strategies to enhance the amount of
Hepatitis B surface antigen a given banana can produce, and feel that the
use of certain promoters, codon optimization and the use of banana UTRs
(un-translated regions) may increase the level of antigen produced in future
bananas. All these methods support the gene expression in one way or the
other.

Promoters are sequences that enable and promote the translation of a gene,
while codon optimization seeks to improve expression when a gene is moved
into a foreign genome that exhibits different codon usage from its native
genome, by adapting certain codons to the uncommon surrounding. UTRs
(un-translated regions) again are parts of a gene that are not translated,
but often contain key regulatory elements.

Dr. Bapat, relating to the question about the next stage of the research,
told Checkbiotech, ?We would like to enhance the expression levels by using
abundant pulp protein promoters and by incorporating certain regulatory
sequences.? Pulp protein is produced in large amounts in bananas, because it
has a strong promoter. Thus his logic is that hopefully the promoter will
have the same effect with the Hepatitis B antigen.

When asked what would help his research team reach their goal sooner, Dr.
Bapat replied, ?Collaboration with different research groups of the world,
ample funding to carry out research and to recruit research and support
staff is necessary to hasten this research program and to reach the goal
sooner.?

With the right partners and the right financial support, Dr. Bapat is
certain that a Hepatitis B vaccine can be produced in bananas.

Dr. Bapat also told Checkbiotech, ?Shantha Biotechnics is well-known
world-wide as the manufacturer of Shanvac B, an efficacious and affordable
hepatitis B vaccine, which is certified by WHO (Geneva) and is exported to
many countries through UNICEF.?

?Shantha Biotechnics is preparing to commercialize its quadrivalent vaccine
(DTPW-Hepatitis B) and pentavalent vaccine comprising DTP, hepatitis B and
Hib soon. The company is very supportive of initiatives for making vaccines
cost effective affordable to people at large.?

Moreover the team is working on other projects. ?Apart from producing
vaccine in banana, we have research programs to produce mucosal adjuvants,
nutritional quality improvement with special reference to iron fortification
and disease resistance.? Another of their aims is to optimize regeneration
and transformation protocols for other commercial varieties of bananas.

Daniela Jenni is a biologist and Chief Science Writer for Checkbiotech.
Contact her at Daniela.Jenni@stud.unibas.ch

G. B. Sunil. Kumar, T. R. Ganapathi, C. J. Revathi, L. Srinivas and V. A.
Bapat. Expression of hepatitis B surface antigen in transgenic banana
plants. Planta, an International Journal of Plant Biology. Springer-Verlag
2005, 10.1007/s00425-005-1556-y.

Link to the abstract:
Expression of hepatitis B surface antigen in transgenic banana plants
[www.ncbi.nlm.nih.gov]
stract&list_uids=15918027&query_hl=1

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