Poster Presentation 11th Australian Peptide Conference 2015

Dendritic cell (DC)-based vaccination boosting antigen-specific immunity is being explored for the treatment of many diseases, including cancer. Although DC-based immunotherapy can induce immunological responses, its clinical benefit has been limited, indicating that further improvement of DC vaccine potency is essential. DCs are antigen-presenting cells whose main function is to process antigenic material, presenting it on the cell surface to the T cells. Here, DCs act as messengers between innate and adaptive immunity. The mannose receptor on DCs is known to bind bacterial, fungal and viral O-linked glycosides, and is seen as one strategy to enhance the effectiveness of vaccination.^1,2This study focuses on the complex synthesis and analysis of a library of novel O-linked glycosylated or DC-targeting lipid-based peptides to investigate DC targeting properties for potential use as targeted self-adjuvanting vaccine candidates. A library of fluorescently-labelled peptide dendrimers containing mannose and/or fucose (or known DC-targeting peptides) conjugated to the ovalbumin (OVA) CD4 or CD8 peptide antigens was successfully synthesised using a combination of Fmoc solid phase peptide synthesis and azide-alkyne Huisgen cycloaddition. Characterisation was carried out using TEM and circular dichroism. In vitro studies performed on F4/80 (macrophage) and CD11c (DC) positive cells showed significant uptake for both glycosylated and DC-targeting peptide vaccine constructs when compared to the un-targeted controls. Furthermore, competition assays and Biacore technology confirmed receptor-mediated uptake. Preliminary in vivo analysis of the mannosylated constructs showed an increase in endogenous CD4⁺ T cells. Synthetic strategies, characterisation and preliminary results from in vivo studies, including cytokine analysis, antibody response and T cell proliferation will be discussed.