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5-Animals: Allergen-free GE seafood announced



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TITLE:  Allergen-Free Shrimp? Seafood Marks a Place in Food Safety Research
SOURCE: American Association for the Advancement of Science
        http://www.aaas.org/news/releases/2003/0215food.shtml
DATE:   Feb 15, 2003

------------------ archive: http://www.gene.ch/genet.html ------------------


Dear GENET-news readers,

we are told that GE critics are affluent citizens from rich countries who
do not see any advantages in GMOs to improve their way of living. Well,
maybe the research on low-allergenic GE shrimps has been initiated to
convince those people. And to restore the joy on "a buffet of shrimp
cocktail, lobster on the half shell, and king crab" that "for people with
shellfish-food allergies [...] can be a nightmare". And of course to
bridge the "molecular divide" between the South and North as demanded by
the FAO three days after this AAAS announcement.

Yours,

Hartmut Meyer

*****


Allergen-Free Shrimp? Seafood Marks a Place in Food Safety Research

A buffet of shrimp cocktail, lobster on the half shell, and king crab
sounds like a seafood dream come true, but for people with shellfish-food
allergies, it can be a nightmare instead.

Now, new genetic studies show promise for putting allergen-free shrimp on
our dinner plates someday, scientists said today at the 2003 American
Association for the Advancement of Science (AAAS) Annual Meeting.

"It's definitely possible that we'll have foods that are less of a risk
for allergy," said Samuel B. Lehrer of Tulane University in New Orleans,
Louisiana, where shrimp is a key element of the local cuisine. "There's a
lot of work we need to do to be sure to know what to ask."

Lehrer and others are conducting studies on shrimp to better understand
the genetic basis for the proteins in foods that cause allergic responses
in some people. An expert in food allergens and allergen detection,
Lehrer also addressed issues of allergenicity in new products being
developed through genetic engineering, and gave an "understanding of the
framework that's involved and changing, and a sense of what's being
ensured so we don't have exposure to new allergens."

Research in shrimp allergenicity owes its recent strides to ongoing
research in plant foods, such as soy and peanuts.

Food allergies are immune responses to proteins from foods that somehow
did not get broken down by cooking or digestion. Instead, they entered
the bloodstream and interact with antibodies on cells lining the gut, and
in the nose, throat, skin, and lungs, for example. These cells then
release chemical mediators including histamines, which create unpleasant
and sometimes life-threatening allergic responses.

Lehrer has identified the major shrimp allergen and the epitopes - the
allergenic portion of the molecule - that bind with an antibody called
immunoglobulin E (IgE). The reaction that results from the allergen or
epitope causes classical allergic reactions of itchiness around the eyes,
throat, skin, and mouth.

Improved detection methods for unknown food allergens can also contribute
toward better safety for new food products that are altered through
genetic engineering, according to Lehrer, who is in the process of
developing an immunological test, with mice, to check foods for allergenicity.

Work on altering animal-based allergens is generally much less further
along than that for plant-based food allergens, for which breeding
programs and food processing have been used to address allergenicity.
Now, working directly at the gene level may put allergen-free peanuts,
soybeans, or shrimp on our dinner plates someday, according to Lehrer.
"There's concern that new epitopes can be made," Lehrer says of the
techniques used to transfer genes in and out of a food plant or animal.

While testing for known allergens has been established, testing proteins
that may be expressed in genetically modified foods, which have no
previous human exposure, is needed. This scenario raises an interest in
developing models for testing allergenicity, says Lehrer, who is
developing a mouse-based model to test exactly this. "If there's a way to
validate the mouse responses are similar to the human response, this
would be a useful way to screen novel proteins.... We saw very good
responses to peanut allergens and shrimp allergens and they seem to be
similar to human responses. Now, we want to look at responses on an
epitope level." Lehrer is also looking at less commonly allergenic
materials, like rice, beef and corn.

The biotechnology used to alter food products can also be used to improve
food safety by preventing the production of allergy-causing agents,
according to Lehrer, who describes his work with shrimp as an example.
Lehrer has located the gene sequence that encodes the shrimp allergen and
regions of the sequences for the different molecules that interact with
the antibody IgE. By altering the epitopes in shrimp allergens that bind
to IgE - by just one amino acid - the binding action could be stopped.
"This can possibly be used therapeutically or even in reducing the
allergenicity of a particular food," Lehrer says.