Oral vaccine delivery vehicles

This chapter illustrated the broad spectrum of uses for plant-derived vaccines and therapeutic proteins. Many of the biopharmaceuticals listed in this chapter were developed in transgenic tobacco or potato plants. While tobacco is not ideal for the expression of vaccine proteins nor is raw potato ideal for oral consumption, they are both relatively easy to work with and have been well characterized, making them useful for proof-of-concept studies. The use of plants for production systems and delivery vehicles holds great promise for future biopharmaceutical development. Proteins can be produced in plants while remaining biologically functional they can be scaled up for large production and purified inexpensively and with relative ease. The following chapters describe the many attributes of plant-made biopharmaceuticals in more detail. 

PECs are the association complexes mainly formed between oppositely charged particles (e.g., polymer-polymer, polymer-drug, polymer-surfactant, polymer-protein). These complexes are formed due to electrostatic interaction between oppositely charged polyions. This interaction avoids the use of chemical cross-linking agents that can reduce the possible toxicity and other undesirable effects of the reagents. The PECs formed between a poly acid and poly base are less affected by the pH variation of the dissolution medium. The complexation, between DNA and chitosan, has been extensively studied in the development of delivery vehicle for gene therapy and oral vaccination. 

In order to establish the extent to which the native conformation of the protein is retained when in contact with functional silicones, proteins are entrapped within water-in-silicone oil emulsions and their biological activity assessed. The objective is to elucidate the nature of the interaction between the biological and synthetic polymers, the role of different polar groups on the silicones, the denaturation rate of the proteins in contact with the functionalised silicones, and the role of different polar groups on the silicone polymer. Through the use of modified silicones in conjunction with proteins at these water-oil interfaces, it may possible to increase the stability of not only the interface, but of the protein as well. The results presented, combined with the ability to entrap more than one protein in the emulsion droplets at time, offers a great potential for using these systems as delivery vehicles in oral vaccinations. 9 refs. 

Polymer-based colloidal drug delivery carriers include polymeric micelles, nano- and micro- particles, or coated particles, and hydrogels [886,890,891]. These are being developed for vaccines and anti-cancer drugs, for targeting of specific treatment sites within the body, and as vehicles for ophthalmic and oral delivery. Methods for the creation of multi-layer coatings are reviewed by Sukhorukov [892] (see also Figure 14.4). Numerous examples are cited by Ravi Kumar [893]. 

Following intramuscular (IM) administration, drugs must cross one or more biological membranes in order to enter the systemic circulation. Intramuscular injection is used mainly for drugs and vaccines that are not absorbed orally, for example, aminoglycosides, insulin, and hepatitis vaccine. The IM route is often used for sustained medication and specialized vehicles, such as aqueous suspensions, oily vehicles, complexes and microencapsulation, which has been developed for slow delivery of drugs by this route. ... 

The methods of production of archeosomes are by lipid hydration method, detergent dialysis method, reverse phase evaporation method, sonication, membrane extrusion, freeze and thaw method (Weiner and Cannon, 1989 Relini et al, 1994 Watwe and Bellare, 1995). As carrier vehicles in vaccine formulations, as delivery systems for drugs, genes, or cancer screening agents (Allen, 1997). Primary work on mouse has been carried out which consists of intravenous, oral and subcutaneous administration of these archaeosomes and it has reported to be non-toxic and safe (Patel et al., 2004). 

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