306 Subject Recombinant proteins

Recombinant protein is a protein produced by a genetically modified cell or an organism, which expresses a DNA that was subjected to recombination and inserted into its genome. 

Historically, HCDC was first established for yeasts to produce single-ceU protein, ethanol, and biomass. Later, dense cultures of other mesophiles producing various types of products were developed, e.g.,by Suzuki et al. [96]. The combination of recombinant DNA technology and large-scale culture processes has enabled human proteins to be produced in a number of hosts, in particular in Escherichia coli [97-100]. Approaches to optimize the production of recombinant proteins are the subject of recent reviews from Winter et al. [101]. 

More information about this subject can be obtained in Chapter 6 (Post-translational modification of recombinant proteins). 

In this chapter the subject of scale-up is reviewed, which is taking small laboratory cultures (e.g. 10 ml) to industrial-scale processes (e.g. 10 000 litre), i.e. a 1 000 000-fold scale-up The aim of such scale-up is to provide more cells, and more cell product, in as efficient and cost-effective a manner as possible. Cell cultures have been used since 1954 for the production of human (e.g. polio, measles, mumps, rabies, rubella) and then veterinary (e.g. FMDV) vaccines (Griffiths, 1990a). Interferon was the next most important product to be developed, followed by monoclonal antibodies and a range of recombinant proteins. 

Human blood, given by blood donors, is a source not only of cellular material (red cells, white cells, platelets) but also of blood plasma, which is subjected to protein fractionation to give albumin, anti-hemophilia factors and immunoglobulins. The possibility of transmission of Creutzfeld-Jakob disease (CJD) - prions are not really understood - and acquired immune deficiency syndrome (AIDS), if sterilization procedures fail, combined with the feasibility of manufacturing proteins by recombinant DNA technology, mean that there is uncertainty about the long-term future of the blood products industry. Indeed, the problems with bovine spongiform encephalitis (BSE) and the related fatal human brain disorder, CJD, have led to unease about cattle-derived substances. 

In general, expression levels of recombinant proteins in transplastomic plants can be significantly higher than those in nuclear transformants, subject to optimal design of the expression cassette and depending on the nature of the recombinant protein of interest. Clear evidence of an impact of... 

Recombinant human lL-11 oprelvekin (Neumega) is a bacterially derived, 19,000-dalton polypeptide of 177 amino acids that differs from the native protein only because it lacks the amino terminal proline residue and is not glycosylated. The recombinant protein has a 7-hour half-life after subcutaneous injection. In normal subjects, daily administration of oprelvekin leads to a thrombopoietic response in 5 to 9 days. 

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