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é-Plants: GE tomatoes produce contraceptive vaccine against animals pests

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TITLE:  GM Tomatoes Could Help Keep Pesky Animals Down
SOURCE:, sent by AgBioView, USA
DATE:   April 2003

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GM Tomatoes Could Help Keep Pesky Animals Down 

Early results from a study suggest that transgenic tomatoes carrying a
fusion protein could help control animal pests by providing a contraceptive
vaccine. Amanda Walmsley of Arizona State University and collaborators there and at
Boyce Thompson Institute for Plant Research and Queensland Agricultural
Biotechnology Centre expressed a fusion protein consisting of the B subunit of
the Escherichia coli heat-labile enterotoxin (LTB) and an immunocontraceptive
epitope in tomatoes, and showed that the antigen was present in both fresh and
processed fruit. The study appears in Plant Cell Reports

"The aim behind the entire project is to develop a vaccine that would
control the population of a specific species (our targets were mice as the model,
white tailed deer in the US and brushtail possums in New Zealand),". says
Walmsley. "These species are seen as "pests" in the areas mentioned as they cause
harmful impact to the envirnoment (eating crops, causing road accidents,
killing specific trees, eating eggs of endangered bird species, harboring
disease such as TB or lyme disease etc)."

"The purpose of the fusion protein was to target a species-specific,
immuncontraceptive epitope to the mucosal immunes system's effector sites, i.e.
target our epitope of interest to the mucosal immune system in order to increase
the chance of inducing an immune response against the sperm docking protein
on the egg, specifically in mice," she says.

Are tomatoes preferable to other plants for producing antigens? "It is
difficult to say whether tomato has advantages over other crops for producing
antigens since different antigens are stable under different conditions and hence
stable in different plants," she explains. "Certainly, tomato was the better
choice (over potato) for expressing LTB or an LTB fusion protein since we
saw no harmful effects to the transgenic plants' morphology and we also saw
good expression levels, says Walmsley."

Could fresh tomatoes be used to vaccinate? "Since tomato fruit are
perishable, it is more likely that vaccination will be with processed materials
(freeze-dried)," says Walmsley. "Freeze-drying also allows batch processing which
produces a large quantity of material with a consistent antigen expression

Walmsley and her team are now going to test the immunocontraceptive ability
of this vaccine in studies with mice studies.

The paper, "Expression of the B subunit of Escherichia coli heat-labile
enterotoxin as a fusion protein in transgenic tomato", by A. M. Walmsley, M. L.
Alvarez, Y. Jin, D. D. Kirk, S. M. Lee, J. Pinkhasov, M. M. Rigano, C. J.
Arntzen and H. S. Mason, appears in Plant Cell Reports.


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