Peptides conjugated to 2-alkoxy-8-oxo-adenine as potential synthetic vaccines triggering TLR7

Systematic Dual Targeting of Dendritic Cell C-Type Lectin Receptor DC-SIGN and TLR7 Using a Trifunctional Mannosylated Antigen

“…C-terminal functionalization was achieved by selective removal of the Lys(Mmt) group, and subsequent coupling of an ethylene glycol spacer followed by introduction of the TLR7 agonist (Chan et al, 2009). Using our previously described protocol (Gential et al, 2019), we could introduce Boc protected TLR7-ligand 23 on-resin, resulting in functionalized solid support 25 . Release of the peptide-TLR7 ligand conjugate from the resin and concomitant global deprotection of the side chains under acidic conditions resulted in azido-peptide 26 , which was purified by HPLC.…”

“…Synthesis of trifunctional CLR-epitope-TLR conjugates. Reagents and conditions : (a) Fmoc-SPPS; (b) TFA, DCM; (c) Fmoc-SPPS; (d) 23 (Gential et al, 2019), HCTU, DIPEA, DMF; (e) TFA, TIS, H 2 O, octanethiol, phenol; (f) CuI, THPTA, DIPEA, DMSO, H 2 O, (+ NaAsc, Arg, H 2 O), CLR clusters ( 19–22 ).…”

“…The high affinity binders were used for conjugation to a model peptide antigen, containing the helper T cell epitope gp100 280−288 and effector T cell epitope gp100 44−59 , to generate conjugates that could be targeted to DCs. To enhance the presentation of the antigens embedded in the conjugates by the DCs, we equipped the conjugates with a previously reported 8-oxo-adenosine analog (Jin et al, 2006; Gential et al, 2019), a ligand for the endosomal TLR7 which resulted in trifunctional conjugates (CLR-antigen-TLR). Using monocyte-derived dendritic cells (moDCs) we showed that the generated trifunctional conjugates represent attractive vaccine modalities that effectively targeted and activated DCs allowing effective antigen presentation.…”

Multivalent, Stabilized Mannose‐6‐Phosphates for the Targeted Delivery of Toll‐Like Receptor Ligands and Peptide Antigens

“…The released amine was subsequently coupled with the spacer 33 and the Boc-protected TLR7 ligand building block 34. [21] After deprotection, release from the resin and RP-HPLC purification peptides 27 and 30 were obtained in a 2 % yield. Coupling of O-M6Po building block 9 to peptides 26, 27, 29 and 30 was performed using a cocktail of CuSO 4 , sodium ascorbate and tris(benzyltriazolylmethyl)amine in DMSO/H 2 O, [31] with the addition of a 20 mM Tris/150 mM NaCl buffer.…”

“…Our goal is to enhance the immune response by increasing endosomal trafficking of the peptide vaccine via the MPR which led to the design of bis-conjugates (2, 4, 6, and 8) in which the Toll-like receptor 7 ligand (TLR7L) 2alkoxy-8-oxo-adenine is added at either the N-or the Cterminus of the M6Po-SLP. [20,21] We coupled an α-configured spacer, [12,18,22] carrying an alkyne function to the O-M6Po building block 9 to allow for the copper mediated 1,3-dipolar cycloaddition to azide functions incorporated in the SLP, while C-M6Po building block 10 was used to generate the HAAHAconjugates via solid-phase peptide synthesis (SPPS). This building block is a C-analogue [23] of O-M6Po, in which the anomeric oxygen is replaced with a CH 2 , preventing hydrolysis under the acidic conditions used in SPPS.…”