Immunogenicity studies on diphtheria toxoid loaded biodegradable microspheres

Diphtheria toxoid loaded polylactide microspheres were prepared using the solvent evaporation method. The vaccine loaded microspheres were subjected to in vitro antigen release studies and in vivo immune response tests. The immunogenicity of the vaccine after microencapsulation was compared to that against diphtheria toxoid given in the conventional three injection schedule on alum as an adjuvant. The antibody response seen in the two cases is compared. The duration of the immune response from the two schedules is exhibited.