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Transgenics
Transgenic expression systems, either animals (milk) or plants, are increasingly gaining interest, and bring hope that this technology has the potential of providing large quantities of protein with correct post-translational modifications at low cost.
Examples of plant systems include, soybeans, tobacco and corn. Examples of animal systems are goats, cows, rabbits and mice. The time for development of the host can be considerable, and herd/crop control is essential. Transgenics can result in very high expression levels which is desirable but overproduction could also be a disadvantage due to higher risk of product aggregation. Production lot and expression level batch variation may lead to less consistent purification.
Potential issues during downstream processing and chromatography are host specific and also related to the various harvesting methods applied. Milk, for instance, offer specific processing problems since high levels of fat, casein, and lipoprotein are present.
The regulatory issues are being clarified and documents have been published by both The European Commission and FDA. Validation issues typically include viral clearance, herd and pathogen control.
Advantages
- Large volumes
- High expression levels & concentrated product
- Capable of complex protein processing
- Flexibility & scale up
- Low cost compared to cell culture
Disadvantages
- Herd/crop control
- Limited regulatory track record
- Unknown viral contamination
- Co-expression of host cell proteins
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Read more about how to produce recombinant proteins with bacteria, insect cells, mamalian cells, and yeast.
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