Vaccines & Vaccination

Biography

Biography: Geert Vanden Bossche

Abstract

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 often variable (e.g., conformational Bc epitopes) and/ or subject to immunogenetic restriction (e.g., linear, cell-bound 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 has been associated with immune pathology. Priming of CD4+ T helper cells by adjuvant vaccines is, therefore, increasingly raising safety concerns. On the other hand, Ags that are highly conserved, universal and of vital importance to the pathogen (hence, called ‘protective’) are either not included in contemporary vaccines or not effectively recognized by the host immune system since capable of imitating self-molecules and outcompeted by other pathogen-derived ‘decoy’ epitopes for binding to MHC molecules. Hence, we consider that new technologies enabling immune targeting of such protective epitopes by natural, universal (i.e., nonallotype-specific) immune helper cells is the new Holy Grail for modern vaccinology.