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Tobacco has a bright future ? not in cigarettes, but as a pharmaceutical
production factory for anti-cavities medicine. The US company Planet
Biotechnology is using transgenic tobacco plants to cultivate the human
protein CaroRx, which could prevent tooth decay in the future, May 2005 by
Edda Grabar translated by Tea Jankovic, Checkbiotech.
Tobacco plants are the basis for new medicines. The cultivation of active
and additional substances in plants ? the so called ?molecular farming? ?
was the topic of discussion among medical practitioners at this year?s
Intern Congress in Wiesbaden. For the first time in this country, attention
was not focused on the risks of green biotechnology, but rather on its
?CaroRx was the first active substance clinically tested on patients with
promising success and no side effects so far,? said Eva Stoeger of the
University of Aachen.
Scientists at St. George Hospital London were in charge of the development
of the anti-cavity agent, but both Stoeger?s group and the Fraunhofer
Institue for molecular biology and applied ecology in Aachen contributed to
the project decisively.
Cavities, or tooth decay, is caused by a bacterium, called Streptococcus
mutans. It adheres to enamel proteins by means of small protein antennas and
processes food sugars into milk acid, which in turn attacks the enamel.
CaroRx recognizes these antennas and blocks them ?making it impossible for
bacteria to dock onto the tooth,? said Eva Stoeger.
Safe and Cheap Bio-Factories
Fighting diseases with biologically active proteins is a well-known
strategy. Market leaders such as Genentech or Chiron produce so-called
biologicals for the treatment of rheumatism or multiple sclerosis, but their
production makes use of transgenic microorganisms, or mammalian cells,
rather than tobacco plants.
The problem with using microorganisms is that bacteria deliver the proteins
in the form of useless clumps and mammalian cells need to be tested for
pathogens that could possibly infect humans. Plants, acting as
pharmaceutical factories, are much more economical and flexible, according
to the opinion of experts such as Val Glidinger, American Biotechnology
Association?s vice president for nutrition and agriculture.
?It?s important to optimize the technical filtering of the proteins from the
plants,? said Eva Stoeger. ?Guidelines for production will have to be
developed, that would have to be valid for traditional pharmaceutical
companies, as well. If these obstacles are overcome, plants will turn out to
be promising, safe and economical bio-factories,? said Stoeger.
This attitude is greeted with doubt by biotechnology experts in Germany.
?The most important thing with therapeutically used proteins is that they
have to be constructed and folded precisely,? said Ludger Wess from the
information service Biocentury.
?This process is not carried out in identical ways in plants and humans. It
is not clear if plants always produce the active substances in the same way
and in the same amounts. The vaccine-banana, or the cloned sheep Tracy, that
produces an active substance against pulmonary congestion in its milk failed
on exactly these accounts,? said Wess.
Promising cavity-prohibiting tobacco tincture
The study results for the anti-cavity tobacco plant agent are nevertheless
promising. Dentistry students who applied it at the beginning of the study
were cavity-free for one year. For it to be allowed on the market, it will
need to prove effective in a phase 3 study with a larger number of patients.
The suspicion toward genetically modified plants is widespread in Europe. It
was only a short while ago that the German government passed a law regarding
genetic engineering. Many biotechnologists think this law is an effort to
stifle their research, as it allows institutes and farmers who sow
genetically manipulated seeds to be sued if a neighboring field is
contaminated by windborne transgenic pollen by more than 0,9 percent?for
most, an incalculable risk. At the same time, the European Union is
supporting a new project to develop vaccines against rabies, tuberculosis,
diabetes and HIV from plants. The first tests with these medications are
expected in 2009.
Ingo Potrykus thinks all of this is progressing much too slowly. The
researcher from the Swiss Federal Institute in Zurich succeeded in inserting
pro-vitamin A into plain rice. In regions of the world where there are
vitamin A deficiencies, his transgenic ?Golden Rice? could save people?s
lives and keep them from going blind. It has been six years since his
breakthrough and ?the risk-obsessed legal guidelines are still keeping
Golden Rice from reaching the people that need it,? noted Potrykus. ?At the
beginning, high security standards with regards to genetic engineering were
completely reasonable. But now we are looking back on 20 years worth of
experience with transgenic plants.?
This article originally appeared in the Financial Times German edition as
?Pflanzen auf Rezept?
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