Human antibodies from plant seeds?

Genetically modified plants produce medicinal substances

From the seeds of such genetically modified Arabidopsis plants, the researchers isolated human antibody variants. © ECOD-BIO / EUSEM
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Most of the drugs are now produced biotechnologically using genetically modified bacteria, yeasts or cell cultures. But now, Dutch researchers have demonstrated another alternative: using genetic engineering, researchers have made plants target specific proteins in their seeds that act like antibodies. The advantage: No high-tech laboratories are needed to produce these antibody variants. The results have now been published in the journal Proceedings of the National Academy of Sciences.

Many of today's drugs are based on human proteins as active ingredients, such as antibodies for cancer therapy. Previous bacterial, yeast or cell culture based production methods work well but are sometimes expensive and relatively expensive as they require well-equipped laboratories and cell culture care personnel and have limited capacity.

Plants as an alternative?

For several years now, researchers Bart Van Droogenbroeck, Ann Depicker and Geert De Jaeger from the Flanders Interuniversity Institute for Biotechnology (VIB) at the University of Ghent in Belgium have been looking for ways to produce the required proteins from plants. This is because plants offer several advantages over traditional processes: they do not require high-tech laboratories and can be grown in large numbers without costly fermenters and other equipment. Experts estimate that plant production costs could be ten to a hundred times lower than previously. In addition, the plant seeds containing the protein could be stored for a long time without Qualitätsverlsut. The active ingredient only needs to be isolated when needed.

Antibody variant in the plant seed

The researchers at de Jäger have succeeded in producing plants that produce a high concentration of an antibody variant of humans in their seeds. Although this variant has the crucial characteristics and effects of an antibody, it does not reproduce the entire structure of these proteins. The yield of plants so altered was high: more than one-third of the total amount of protein in the seeds consisted of the antibody. This is already a huge step forward compared to previous trials, where the yield was a maximum of one percent.

Successful in the test against Hepatitis-A

The antibody variant first produced belonged rather to the simpler type, with only one binding site and a very simple structure. But now scientists have been able to create more complex variants in the seeds of the Arabidopsis plant. After all, the antibodies accounted for ten percent of the total protein content. Similar to full antibodies, these analogues have two binding sites. Antibody variants of this type thus provide the best prerequisites for therapeutic purposes, but also be used as diagnostic aids. display

Initial tests of the efficacy of these herbal antibodies have shown that the unusual route of production does not appear to affect the effectiveness of the drugs. In extensive laboratory tests, they effectively protect animal cells against infection with the hepatitis A virus like conventional human antibodies. Thus, these studies could represent a first step towards a new production method for biotechnological drugs.

(VIB, Flanders Interuniversity Institute of Biotechnology, 17.01.2007 - NPO)