Adhesion-mediated enhancement of the adjuvant activity of alum

Abstract

Alum, the only adjuvant currently licensed for use in humans, fails to adsorb influenza virus haemagglutinin (BHA) and is a poor adjuvant for this antigen. A specific monoclonal anti-BHA antibody adsorbed to alum promoted adhesion of the antigen to the adjuvant. The 'alum-anti-BHA-BHA' complex was found to be 1500-fold more immunogenic in mice and 5-fold more immunogenic in rabbits than a mixture of alum and BHA lacking the anti-BHA antibody. The biotin-binding protein, avidin, also mediated adsorption of biotinylated BHA to alum, and enhanced its immunogenicity to a comparable extent. These results indicate that the adjuvant activity of alum can be markedly enhanced by promoting a physical association between the antigen and the adjuvant.