Design of synthetic peptides for oral vaccination

The rational design of effective oral vaccines based on synthetic peptides is a very ambitious undertaking, and involves the solution of huge problems related to protection of the antigens against degradation in the alimentary tract, efficient uptake of the antigens by the relevant cells, and efficient induction of long lasting systemic immunity, local immunity, or both. This paper summarises the steps, necessary to develop such synthetic oral vaccines. These steps involve: (1) the definition of B-cell epitopes; (2) the definition of T-cell epitopes; (3) definition of the carrier or backbone molecule; (4) definition of an immunomodulating element; (5) definition of an adjuvant element; and (6) definition of a targeting element. Good progress is being made with respect to the first three steps, the other steps still provide major challenges, notably the definition of targeting elements. Nevertheless, the first synthetic oral vaccines may become reality in the near future, depending on the speed by which new technology in the area of molecular recognition will develop, i.e. the appropriate chemistry, organic chemistry, molecular modelling, resolution of the molecular interaction of key molecules in microbiology and immunology.