Plasmid vaccines in the fight against allergies
The incidence of allergic diseases such as asthma and chronic rhinosinusitis has seen a large increase in the past three decades. In line with this is a demand for preventive therapy measures in the form of allergen-based DNA vaccines. Partners from an EU project used common allergens from the dust mite and Parietaria officinalis pollen to construct plasmid based vaccines. The consortium of scientists under the umbrella of ALLDNAVAC completed research to develop and evaluate vaccines that modulate allergic responses. Specifically, project partners at DRFZ in Germany have developed a DNA vaccine that delivers the antigen directly into the major histocompatability complex (MHC) Class II. This region encodes for proteins that modulate antigen loading onto the MHC proteins themselves in the lysosomal compartment. This was achieved by the binding of the antigen ovalbumin with an invariant chain peptide which shows promiscuous binding to a great variety of MHC class II allotypes. Two features of the system prevent the activation of the humoral immune system which is based on antibody production. First, the plasmid DNA induced strong T cell differentiation without an antibody response. Second, the antigen is retained in the transfected cells and may therefore be a safer option. Overall, this plasmid based DNA vaccine may offer a means by which Th2 T helper cell action may be harnessed without triggering allergic reactions. Furthermore, it may be able to target desired T cell responses to tackle autoimmune reactions.
