Transcutaneous immunization studies in mice using diphtheria toxoid-loaded vesicle formulations and a microneedle...

Area of Science:

• Vaccinology
• Nanotechnology
• Immunology

Background:

• Transcutaneous immunization (TCI) offers a needle-free vaccine delivery route.
• Microneedle arrays can enhance antigen penetration through the skin.
• Diphtheria toxoid (DT) is a key component in routine vaccinations.

Purpose of the Study:

• To evaluate the immunogenicity of DT formulated in cationic liposomes and anionic vesicles using TCI.
• To assess the impact of microneedle array pretreatment on TCI efficacy.
• To investigate the role of cholera toxin as an adjuvant in TCI.

Main Methods:

• Preparation and characterization of DT-loaded liposomes and vesicles.
• Application of formulations onto intact or microneedle-pretreated mouse skin.
• Measurement of IgG and neutralizing antibody titers, and assessment of dendritic cell activity.

Main Results:

• Stable liposomes (~150 nm) and vesicles (~100 nm) with high DT association were prepared.
• Substantial antibody titers were achieved only with microneedle pretreatment during TCI.
• Cholera toxin significantly augmented immune responses, while vesicle formulations showed limited enhancement.

Conclusions:

• Microneedle pretreatment is crucial for effective TCI of DT.
• Cholera toxin acts as a potent adjuvant, boosting TCI immunogenicity.
• Antigen association with vesicles did not improve topical DT immunogenicity.