Oral anti-IgE immunization with epitope-displaying phage

An essential requirement for oral vaccines is the ability to survive the ha rsh environment of the stomach in an antigenically intact form. As bacterio phages are adapted to this environment we used epitope-displaying M13 bacte riophages as carriers for an experimental oral anti-IgE vaccine. The feasib ility of this approach was tested in a simulated gastric fluid using two di fferent mimotopes as well as an anti-idiotypic Fab of the non-anaphylactoge nic monoclonal anti-IgE antibody BSW17. All phage clones remained infective after this treatment. However, only epitopes displayed on the pVIII protei n were still recognized by BSW17 whereas pill-expressed epitopes were rapid ly inactivated. Surprisingly, when used for oral immunization of mice all p hage clones induced anti-IgE antibodies. In contrast, oral immunization wit h the purified, pVIII protein displaying the mimotope induced anti-phage bu t no anti-IgE antibodies. After feeding a single dose of mimotope-displayin g bacteriophage, phage DNA could be detected in mouse feces for 10 days. Ou r results show that epitope-displaying bacteriophages can be used to induce an epitope-specific antibody response via the oral route.