Biodegradable microspheres as a vaccine delivery system.

Area of Science:

• Biomaterials Science
• Immunology
• Vaccine Development

Background:

• Biodegradable and biocompatible microspheres are explored as vaccine delivery systems.
• Induction of systemic and disseminated mucosal antibody responses is a key goal in vaccine development.

Purpose of the Study:

• To investigate the utility of poly(DL-lactide-coglycolide) (DL-PLG) microspheres for vaccine delivery.
• To evaluate the induction of systemic and mucosal antibody responses using a staphylococcal enterotoxin B (SEB) toxoid vaccine encapsulated in microspheres.

Main Methods:

• Microspheres (1-10 microns and 20-50 microns) of DL-PLG containing SEB toxoid were prepared.
• Mice were immunized intraperitoneally (ip) with free or microencapsulated SEB toxoid.
• Subsequent immunizations were performed perorally, intratracheally (it), or systemically.
• Antibody responses (IgM, IgG, IgA) in serum and mucosal secretions were measured.

Main Results:

• Intraperitoneal injection of microspheres potentiated circulating IgG anti-toxin antibody responses compared to free toxoid.
• Microsphere size influenced vaccine release and immune response, with larger microspheres delaying release.
• Single injection of mixed-size microspheres induced primary and secondary anti-toxin responses.
• Systemic immunization with microencapsulated toxoid primed for mucosal IgA responses upon oral or it boosting, unlike soluble toxoid.

Conclusions:

• Biodegradable microspheres act as an effective adjuvant system for inducing both systemic and mucosal immunity.
• Microsphere-based vaccines show potential for widespread application in vaccine delivery.
• Peroral immunization with microspheres successfully stimulated systemic and mucosal IgA responses.