Geert Vanden Bossche
Univac NV, Belgium
Posters & Accepted Abstracts: Curr Synthetic Sys Biol
To eliminate safety risks related to infectivity, inactivated pathogens and more suitably, well-characterized pathogen derived antigens (Ags) have increasingly been used as immunogens in ‘modern’ vaccines. The selection of these Ags is usually based on their capacity to naturally induce immune responses that ‘correlate’ with protection. These Ags, however, are known to be antigenically variable (e.g., conformational Bc epitopes) and/or subject to immunogenetic restriction (e.g., linear, Tc epitopes). In addition, the immunogenicity of ‘good’ vaccinal Ags is largely dependent on memory CD4+ T helper cells. However, activation of the latter upon natural infection or foreign Ag exposure of genetically predisposed subjects can occasionally lead to immune pathology. Priming of CD4+ T helper cells by adjuvanted vaccines is, therefore, increasingly raising safety concerns. On the other hand, Ags that are highly conserved and vulnerable because of their exposure on the surface of infected or pathologically altered host cells are not effectively or durably recognized by the host immune system and hence, not included in contemporary vaccines. Chemical polypeptide epitope synthesis combined with multimeric presentation of the selected polypeptide on a synthetic polyelectrolyte carrier enables Univac to develop novel and fully synthetic vaccines, the latter aim to prime ‘Natural Killer’ cells that universally target vulnerable pathogen specific epitopes across a broad spectrum of different pathogen strains and host specific MHC allotypes.
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