Host production system, development

By developing a series of generic host production organisms, fermentation development time can be minimized when these host systems are used for production of multiple products. The investment of time and resources in developing the initial fermentation and recovery system can be recovered in subsequent programs in the form of more rapid commercial development timelines. 

Both H- and L-NHase genes are expressed under the control of a lac promoter in E. coli only when the transformants are cultured in the presence of CoCl2 [63], However, the level of NHase activity in their cell-free extracts is much lower than those of H- and L-NHases in R. rhodochrous Jl. Most of H-NHase is produced as an insoluble form in the E. coli transformant, and there is only a little L-NHase in either the supernatants or precipitates of the extracts. Establishment of an effective host-vector system in Rhodococcus [71] facilitates the development of strains with improved NHase activities. In this connection, the transformation system in Rhodococcus has been investigated. Enzyme assays of recombinant Rhodococcus cells showed that a downstream region of the Rhodococcus sp. N-774 NHase gene is indispensable for the production of active... 

The success of vaccination depends primarily on the method of presenting the antigen to the host immune system. Antigens have usually been delivered by parenteral (such as intravenous, intramuscular, intraperito-neal, intradermal, and subcutaneous) administration, but recent studies have shown that other routes of delivery such as intranasal, oral, and transdermal delivery have also been effective. In some cases, vaccination through mucosal routes resulted in better responses in IgA production. Because non-parenteral vaccine delivery presents many obvious advantages, numerous attempts have been made on the development of non-parenteral delivery of vaccines. 

As the biotechnology industry comes of age, and protein-based therapeutics become a practical reahty, the importance of protein-stabilizing technologies comes increasingly to the fore. The therapeutic efficacy of many of these biopharmaceuticals is impeded by the hosts natural immune defense system [23]. When a host encounters a foreign protein in its circulation, the hosts immune system initiates an immune response, which results in the production of protein-inactivating antibodies that dear the protein from the circulation. When the immune system develops an abihty to inactivate the protein, the therapy becomes ineffective. Hence, to counteract... 

Today, recombinant protein production involves many options. In addition to E. coli, several yeast systems (see Part IV, Chapter 13), insect cells (see Part IV, Chapter 14), different mammalian expression systems (CHO, BHK, NSO, HKBll, PER.C6) (see Part II, Chapter 3 and Part IV, Chapters 1 and 3) other alternative expression systems are currently under development for the production of biopharmaceuticals. These include transgenic animals or plants, and will be discussed in Part IV, Sub-Part 2 of this book. This chapter will focus on E. coli, a still-modern secretory Saccharomyces ccrevisiac system, and the recently developed mammalian HKBll expression system. An E. coli host/vector system is described that was originally developed for the efficient production of an interleukin-4 variant Later, it transpired that this system is ideally suited to the expression of other proteins and Fab fragments. The secretory... 

Mature human interleukin-4 (IL-4) is composed of 129 amino acids. IL-4 variants that are able to block both IL-4 and IL-13 activities have been described [1]. These antagonistic properties are regarded as useful for the treatment of diseases which involve Th2 development and/or IgE production [2]. For the set-up of a viable commercial production system for an IL-4 variant (IL-4 v), a broad screening of host organisms and expression systems on a small scale was conducted (data not shown). 

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