Liposomal Hepatitis A Vaccine and Liposomal Multiantigen Combination Vaccines

Abstract

Many antigens are only weak immunogens, and they require adjuvants to reach a satisfactory immune response as vaccines. This is especially true for modern antigens, such as products of gene technology or synthetic peptides. Also, classically produced antigens such as diphtheria or tetanus-antigens are coupled on aluminium phosphate or aluminium hydroxide – to this day practically the only adjuvant class which is routinely used in vaccinology. Aluminium phosphate was first used in the 1920s as an immunopotentiator for the diphtheria vaccine. Since then, and up until now, it has not been possible to fully replace this unsatisfactory adjuvant. exclusion of epitope-specific suppression by the individual components, it was evident that particularly the diphtheria and tetanus constituents exerted “antigenic competition” on the HAV antigen and possibly also on the HBs antigen. By reducing the diphtheria and tetanus toxoid subunit molecules per IRIV particle, it was possible not only to increase significantly the immune response to these antigens but also to remove completely the antigenic competition on the HAV and HBs antigens. Once the optimum composition of the vaccine had been achieved (careful dosing of antigens per IRIV particle), an immunological effect clearly superior to that of comparable, aluminium-adsorbed products was obtained (Table II). The tolerability of this “supercombi vaccine” was significantly better than the commercial alum adsorbed products (Table III).