Controlled delivery of diphtheria toxoid using biodegradable poly(D,L-lactide) microcapsules

Area of Science:

• Biomaterials Science
• Immunology
• Vaccine Technology

Background:

• Diphtheria toxoid is crucial for immunization programs in developing nations.
• Effective vaccine delivery systems are needed to improve antigen stability and immune response.
• Microencapsulation offers a promising approach for controlled vaccine release.

Purpose of the Study:

• To microencapsulate diphtheria toxoid using poly(D,L,-lactide) and the in-water drying technique.
• To evaluate the in vitro antigen release kinetics and in vivo immunogenicity of the microencapsulated diphtheria toxoid.
• To compare the immune response elicited by the microencapsulated vaccine with conventional diphtheria toxoid formulations.

Main Methods:

• Diphtheria toxoid was microencapsulated using poly(D,L,-lactide) (49,000 MW) via in-water drying.
• In vitro antigen release was assessed using enzyme-linked immunosorbent assay (ELISA).
• Antibody titers in Balb/C mice were determined by direct ELISA, and microcapsule degradation was visualized using SEM.

Main Results:

• Microencapsulated diphtheria toxoid demonstrated controlled antigen release, evidenced by in vitro degradation studies.
• Antibody titers in mice immunized with microencapsulated toxoid were comparable to those receiving conventional three-dose injections with adjuvant up to day 75.
• The study successfully developed a sensitive ELISA for antigen release and antibody titer determination.

Conclusions:

• Poly(D,L,-lactide) microencapsulation provides a viable method for developing controlled-release diphtheria toxoid vaccines.
• The microencapsulated vaccine elicits an immune response comparable to conventional formulations, suggesting potential for improved vaccine delivery.
• This technology could enhance the efficacy and stability of vaccines in immunization programs, particularly in resource-limited settings.