Improved tuberculosis DNA vaccines by formulation in cationic lipids.

Area of Science:

• Immunology
• Vaccinology
• Molecular Biology

Background:

• Plasmid DNA (pDNA) vaccines are a promising strategy against Mycobacterium tuberculosis.
• Adjuvants are crucial for enhancing the immunogenicity of pDNA vaccines.
• Novel cationic and neutral colipid formulations (Vaxfectin, GAP-DLRIE:DOPE) have shown potential as adjuvants.

Purpose of the Study:

• To evaluate the immunogenicity and efficacy of pDNA vaccines encoding Mycobacterium tuberculosis antigens formulated with novel lipid-based adjuvants.
• To compare intramuscular and intranasal delivery routes for these DNA vaccines.
• To assess the impact of adjuvant formulation on antibody, T-cell, and protective immune responses.

Main Methods:

• Mice were vaccinated with pDNA encoding antigens 85A, 85B, or PstS-3.
• pDNA was formulated in saline, Vaxfectin (VC1052:DPyPE) for intramuscular injection, or GAP-DLRIE:DOPE for intranasal instillation.
• Immune responses were assessed by measuring antibody levels (IgG, isotypes), T-cell cytokine production (IL-2, IFN-γ), cytolytic T-lymphocyte activity, and protection against M. tuberculosis challenge.

Main Results:

• Vaxfectin formulation significantly increased Ag85-specific IgG levels (3- to 10-fold) and Th1-type cytokine production.
• Intranasal delivery with GAP-DLRIE:DOPE induced Th1 responses, though less potent than intramuscular Vaxfectin.
• Combined intramuscular and intranasal administration enhanced immune responses in spleen and lungs; Vaxfectin improved protective efficacy against M. tuberculosis challenge.

Conclusions:

• Lipid-based formulations like Vaxfectin and GAP-DLRIE:DOPE act as effective adjuvants for DNA vaccines against Mycobacterium tuberculosis.
• Intramuscular delivery with Vaxfectin generally yields stronger immune responses compared to intranasal delivery.
• These findings support the potential clinical application of formulated DNA vaccines for tuberculosis prevention.