Citation

In recent years, therapeutic proteins, such as vaccines, antigens, and hormones, have made significant advances using sophisticated biotechnological techniques like recombinant technology. However, the mode of administration has been a limiting factor. Frequent injections and low patient acceptability make even the simplest parenteral administration of these drugs problematic, thus there is a need for new delivery systems to deliver these drugs more effectively. Oral delivery of proteins and peptides has long been hailed the holy grail of drug delivery for obvious reasons (i.e. ease and cost of administration, patient compliance and acceptability) but has remained a challenge due to enzymatic degradation in the gastro-intestinal (GI) tract and low bioavailability. Here we evaluate a microsphere based controlled-release delivery system that appears to have promising results. PolyMicrospheres successfully developed an oral delivery system for a recombinant vaccine that resulted in an antibody titre count three times higher than parenteral delivery. The microsphere based delivery system greatly enhanced immunity: 100% survival of mice against the toxin and 88% survival of rabbits against the live bacterial spores, compared with 0% survival with the aqueous recombinant protective antigen (RPA) system. OBJECTIVES The objective of this work was to develop novel antigen-adjuvant delivery systems to enhance the efficacy of RPA via oral immunisation against anthrax. To demonstrate that effective protection against anthrax spores can be achieved by alternative oral, needle-free vaccination, PolyMicrospheres developed and evaluated the efficacy of microsphere based delivery systems. The efficacy of vaccination can be considerably improved, not only by incorporating the antigen in a matrix, but also by incorporating potent adjuvants in the matrix to provide long-term delivery of antigen together with an adjuvant for further potentiation of the immune response. The goal was to design and develop an oral RPA delivery system with controlled-release kinetics over a period of months, stimulating an enhanced antibody response at many distinct time points for long lasting protection.