Immunogenicity of IRIV- versus alum-adjuvanted diphtheria and tetanus toxoid vaccines in influenza primed mice.

The immunogenicity and protectivity of two different toxoid vaccines were compared in mice. In one formulation, toxoids (diphtheria or tetanus) were adsorbed to alumoxid, whereas in the other formulation the toxoids were crosslinked to immunopotentiating reconstituted influenza virosomes (IRIVs). A preimmunization with influenza antigens is necessary for a good anti-toxoid antibody response when the IRIV formulation was administered. After two immunizations with the IRIV- or alum-based vaccines, the IRIV-based formulation induced a higher humoral immune response than toxoids adsorbed to alum. Using an in vitro test, diphtheria toxin neutralizing antibodies were tested. Di-IRIV induced a significantly (p = 0.002) higher titer of diphtheria toxin neutralizing antibodies than Di-alum. Tetanus challenge experiments showed, that the IRIV-based tetanus vaccine induced a threefold higher titer of protective antibodies than the tetanus toxoid adsorbed to alum. Therefore, the IRIV-based formulations appeared to be superior to the alum-based vaccines in terms of immunogenicity and protectivity.