Biphasic lipid vesicles as a subcutaneous delivery system for protein antigens and CpG oligonucleotides.

One of the major drawbacks to the development of novel vaccines has been the lack of safe yet effective adjuvants. Biphasic lipid vesicles are formulations suitable for the delivery of proteins, peptides and oligo/polynucleotides. They constitute a new class of delivery system into which antigens and adjuvants can be incorporated.

Biphasic lipid vesicles (Biphasix) enhance the adjuvanticity of CpG oligonucleotides following systemic and mucosal administration.

CpG oligonucleotides (ODNs) are potent mucosal and systemic adjuvants. For practical applications however, improvements in delivery need to be developed. A mouse model was used to determine if the biological activity of CpG ODNs could be enhanced using a novel delivery system of biphasic lipid vesicles (Biphasix Vaccine-Targeting Adjuvant; VTA).

Increased gene expression and inflammatory cell infiltration caused by electroporation are both important for improving the efficacy of DNA vaccines.

One potential reason for the enhancement of immune responses to DNA vaccines following electroporation is increased gene expression. However, the inflammatory response and accompanying cellular infiltration stimulated by electroporation may also be essential for enhancing immune responses to DNA vaccines. These parameters were investigated in pigs, using different electroporation conditions to induce different levels of gene expression and inflammation.

Needle-free topical electroporation improves gene expression from plasmids administered in porcine skin.

Electroporation has been shown to increase the potency of DNA vaccines that have demonstrated significant potential in mice. However, there is a need to develop noninvasive or minimally invasive vaccination methods. In pigs, in vivo gene expression was assessed to compare intradermal needle injection to a needle-free dermal BioJect as a means of delivery of plasmids.

Topical delivery of plasmid DNA using biphasic lipid vesicles (Biphasix).

The development of non-invasive methods for the delivery of vaccines through the skin will greatly improve the safety and the administration of human and veterinary vaccines. In this study we examined the efficiency of topical delivery of plasmids by assessing the localization of gene expression using luciferase as a reporter gene and induction of immune responses using a plasmid encoding for the bovine herpesvirus type-1 glycoprotein D (pgD). Topical administration of plasmids in a lipid-based delivery system (biphasic lipid vesicles--Biphasix) resulted in gene expression in the lymph node, whereas with intradermal injection, antigen expression was found in the skin.

The haemopoietic growth factor, Flt3L, alters the immune response induced by transcutaneous immunization.

Topical application of antigen induces antigen-specific humoral and cellular immune responses. In this study we examined whether expansion of dendritic cells (DC) by Flt3 ligand (Flt3L) treatment influences the induction of immune responses following transcutaneous immunization. Mice were treated intraperitoneally with Flt3L or phosphate-buffered saline (PBS) and immunized transcutaneously with hen egg lysozyme (HEL).

Electroporation improves the efficacy of DNA vaccines in large animals.

It is generally recognized that DNA vaccines are often less effective in large animals than in mice. One possible reason for this reduced effectiveness may be transfection efficiency and the low level of expression elicited by plasmid vectors in large animals. A possible way to improve plasmid gene expression in vivo is electroporation.