3R-Project 56-96

Development of a mimotope-based tetanus and diphtheria vaccine

Beda M. Stadler
Institute of Immunology and Allergology, Inselspital, University of Berne, 3010 Bern, Switzerland
stadler@insel.unibe.ch

Keywords: immunology: monoclonal antibody production

Duration: 3 years Project Completion: 2000

Background and Aim
In Switzerland, many animal experiments are performed to ensure the quality of bacterial toxin vaccines. In the sense of "refine" and "reduce", we aim to develop an in vitro assay in order to reduce animal experimentation. Finally, the aim of our project is to develop synthetic tetanus and diphtheria vaccines.

Method and Results
Our first goal was the isolation of mimotopes (peptides that mimic antigen epitopes) recognised by human monoclonal anti-tetanus toxoid antibodies. Indeed we identified mimotopes for five protective antibodies by screening phage display libraries; their specificity was confirmed by in vitro assays. However, immunisation studies have shown that these mimotopes do not induce protection in vivo although a weak anti-tetanus toxoid response was observed in vitro.
We concluded that mimotope affinity to the human anti-tetanus toxoid antibodies is only weak. We therefore intend to screen additional phage display libraries displaying peptides of various lengths. Moreover, we aim to isolate mimotopes recognised by anti-diphtheria antibodies. As there are currently no monoclonal antibodies available, we purified polyclonal anti-diphtheria antibodies by affinity chromatography. So far we have shown that these antibodies have high toxin neutralising activity.

Conclusions and Relevance for 3R
We ultimately expect to completely replace animal experiments in the quality control of tetanus and diphtheria vaccine production. In addition, the project is expected to have a positive impact on the use of animals in the production of various other vaccines.

References
1. Vogel M., Miescher S., Kuhn S., Zurcher A.W., Stadler B.M. (2000) Mimicry of human IgE epitopes by anti-idiotypic antibodies. J Mol Biol 298, 729-35.

2. Vogel M., Tschopp C., Bobrzynski T., Fux M., Stadler B.M. (2004) A highly conserved interspecies V(H) in the human genome. J Mol Biol 341, 477-89.