LONG TERM IMMUNOGENICITY AND IMMUNOLOGIC PRIMING OF ANIMALS TO PULSED CONTROLLED-RELEASE SYSTEM FOR TETANUS TOXOID VACCINE DELIVERY

AIM To evaluate the immunogenicity of tetanus toxoid (TT) encapsulated in biodegradable polymer microspheres composed of polylactide (PLA). METHODS The antibody levels elicited by microsphere formulations in mice for 1 year were examined, the anamnestic responses to a low dose booster 1 year after priming were also examined. RESULTS Microsphere formulations made from PLA were characterized by pulse controlled-release models, differing in polymer molecular weight, protein loading and particle size of the microspheres. Microsphere formulations elicited significantly higher IgG antibody levels than a single injection of soluble TT. The antibody levels elicited by microsphere formulations were similar to those elicited by three doses of soluble TT. CONCLUSION A single-dose tetanus toxoid based on pulsed release from biodegradable and biocompatible polymer microspheres has been developed. The formulations showed great benefits and pharmaceutical application.