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Icon Genetics GmbH, a wholly owned subsidiary of Bayer Innovation GmbH, and
Bayer BioScience NV, a Belgian subsidiary of Bayer CropScience announce the
publication in Proceedings of the National Academy of Sciences of the USA
(A. Giritch et al., Proc. Natl. Acad. Sci. USA, pnas. 0606631103, September
2006) of the third of a series of research papers titled ?Rapid high-yield
expression of full-size IgG antibodies in plants coinfected with
noncompeting viral vectors? describing a new-generation expression
technology for plants developed by Icon and Bayer researchers, September
2006.

Since the discovery of this technology 17 years ago, the ability of plants
to express full-size human antibodies has not been exploited because of low
yields and the length of time necessary to generate just small amounts of
research material. Using two different plant viral vectors and transient
co-expression technology, our scientists have developed a process that
provides a high-yield expression of monoclonal antibodies (mabs) and takes
less than two weeks. The method is exemplified by producing the human
tumor-specific monoclonal antibody A5 IgG1. With yields as high as 0.5 grams
of IgG1 per kilogram of plant material, the proposed process is suitable for
the research, industrial scale-up and rapid manufacture of antibodies for
health care use. It is also applicable in situations requiring rapid
response such as pandemic events.

This new process represents a significant technical advancement that
broadens the versatility of our second-generation expression platform
technology, magnifection. This transient expression process is used to start
gene amplification in all mature leaves of a plant simultaneously, leading
to high expression levels. It is indefinitely scalable and can be done on an
industrial scale. This eclectic technology combines the advantages of three
biological systems: (1) vector efficiency and efficient systemic DNA
delivery of Agrobacterium, (2) speed and expression level/yield of a plant
RNA virus, and (3) posttranslational capabilities and low production costs
of plants. The two other versions of this technology have been described
previously by Icon Genetics researchers in Proceedings of the National
Academy of Sciences of the USA (Marillonnet et al., Proc. Natl. Acad. Sci.
USA, 101, 6852, 2004) and Nature Biotechnology (Marillonnet et al., Nat.
Biotechnol, 23, 718, 2005).

?We are taking the lead in moving plant-made biopharmaceuticals closer to
commercial reality,? says Dr. Wolfgang Plischke, member of the Board of
Management of Bayer AG. ?The acquisition of Icon Genetics not only brought
us a potentially disruptive manufacturing technology but also a highly
motivated team of talented scientists. I am glad to see that their work is
now being integrated into the broader innovation effort at Bayer.?

The Proceedings of the National Academy of Sciences can be accessed at:
[www.pnas.org].

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