Anti-bioterror vaccines will likely be based on recombinant proteins, synthetic peptides or DNA, and will probably require potent immunological adjuvants in order to render them effective. CD40 antibody conjugated to antigen has a very strong adjuvant effect, but such conjugates pose problems in terms of reproducible production, and because of the generation of antibody responses against the CD40 mAb itself, which may limit its effectiveness when used with subsequent immunisations. A number of alternative CD40 binding proteins have emerged, which should have similar potent adjuvant effects, but offer the advantage that they can be produced as straightforward, monomeric, in-frame fusions with the vaccine antigen. In addition, the number of these proteins available, having very little amino-acid homology with each other, means that different adjuvant proteins could be used with different vaccinations, thus circumventing the potential negative effect of anti-adjuvant responses on adjuvanticity. The project described here will provide proof of principle with up to three of this group of CD40 binding proteins, produced as recombinant chimeric fusions with the hemagglutinin of A/PR/8/34 influenza virus. The fusion proteins will be delivered via DNA vaccines, and in one case at least also as a recombinant protein vaccine. Hemagglutinin will be used as a model bioterror antigen, as influenza virus is a potential bioterror agent. However, this group of novel adjuvants will be widely applicable for use with a range of recombinant protein and DNA vaccines. Potential side effects, such as induction of IgE and polyclonal antibody responses will be assessed. Positive adjuvant effects will be assessed on antibody and T cell responses, as well as by challenge studies with live influenza virus. The proposed research may demonstrate the usefulness of this novel technique to enhance the immunogenicity of both DNA and protein based vaccines. The research therefore is applicable to the improvement of public health, not just in terms of protection against bioterrorism, but also in protection against naturally occurring infectious diseases, and possibly also in therapeutic vaccination for cancer. ? ? ?
