Advances in vaccine formulation have seen a trend towards the use of subunit antigens, ideally incorporated into particulate carriers. These systems are usually in the nanometer size range to facilitate uptake into antigen-presenting cells and to mimic the nature of pathogens. In addition, adjuvants can be incorporated into the same carrier and therefore result in the simultaneous delivery of antigen and adjuvant to the same antigen-presenting cell. A wide variety of particulate carriers have been investigated for vaccine delivery ranging from biological-based particles such as bacterial ghosts and virus-like particles to more simple polymer- or lipid-based systems. In this review we will focus on lipid-based particulate carriers as these offer great potential as regards immune stimulation and due to the simple formulation techniques involved are likely to be more easily scaled-up for manufacture. Another advantage of such systems is versatility in that in addition to the subcutaneous administration of these vaccine formulations, there is also potential for transdermal or even oral delivery. Examples of such delivery systems include liposomes, ethosomes, transfersomes, bilosomes, and immune stimulating complexes. The physico-chemical properties of such systems will be reviewed as will their potential to stimulate immune responses. In addition, we will summarise the recent developments in lipid-based sustained delivery systems for antigens.
Keywords: Vaccine, immune response, lipids, particulate delivery, scale-up
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