Convergent synthetic methodology for the construction of self-adjuvanting lipopeptide vaccines using a novel carbohydrate scaffold

Abstract

SummaryA novel convergent synthetic strategy for the construction of multicomponent self-adjuvanting lipopeptide vaccines was developed. A tetraalkyne-functionalized glucose derivative and lipidated Fmoc-lysine were prepared by novel efficient and convenient syntheses. The carbohydrate building block was coupled to the self-adjuvanting lipidic moiety (three lipidated Fmoc-lysines) on solid support. Four copies of a group A streptococcal B cell epitope (J8) were then conjugated to the glyco-lipopeptide using a copper-catalyzed cycloaddition reaction. The approach was elaborated by the preparation of a second vaccine candidate which incorporated an additional promiscuous T-helper epitope.

Synthesis, Characterization and Immunological Evaluation of Self‐Adjuvanting Group A Streptococcal Vaccine Candidates Bearing Various Lipidic Adjuvanting Moieties

“…Submitted_Manuscript to those prepared previously, [8] yet purification of the final vaccine candidates was more readily achieved. [13] In the current study, a similar synthetic approach was employed to prepare four novel vaccine candidates, with each containing a different lipidic adjuvanting moiety. The uptake of antigens by professional antigen-presenting cells is crucial for the initiation of a fully developed, long-term immune response.…”

“…[6] The lipidic adjuvant contained in 1c (LLCP; Lysine Lipid Core Peptide) was recently reported as a simplified version of the LCP. [13] This adjuvanting system was used for the purpose of developing a novel synthetic methodology and, until now, has not been immunologically evaluated. The adjuvanting properties of similar systems containing palmitoyl lysines have been reported by Huang et al, but notable immunological responses could only be achieved by incorporating the constructs into liposomes or oilemulsions.…”

“…The PADRE T-helper epitope was flanked by additional lysine residues in order to increase the hydrophilicity of glyco-lipopeptides, thus improving their solubility. The TPGlc carbohydrate building block was prepared using a previously reported synthesis [13] and was coupled to the N-terminus of the peptide. Almost quantitative coupling was achieved when the TPGlc and diisopropyl ethyl amine (DIPEA) were added to the resin with stirring, followed by the addition of the HBTU coupling reagent.…”

“…The glycopeptide 2 was divided into four equal portions so that all four target compounds could be synthesized from one glycopeptide. This approach is more efficient compared to the non-branched approach reported previously, [13] since glycopeptide 2, consisting of the T-helper epitope and the TPGlc carbohydrate scaffold, needed to be synthesized only once. Similarly, by removing the ivDde group prior to dividing the resin, this relatively lengthy deprotection needed to be performed only once.…”

“…[12] Recently, we reported a new synthetic methodology for the preparation of large, multi-component carbohydrate core vaccine candidates against GAS. [13] First, glyco-lipopeptides were prepared, which contained a lipidic adjuvanting sequence, followed by a known promiscuous T-helper epitope (PADRE), and terminated with a tetra-propargyl glucose (TPGlc) moiety. The lipidic adjuvanting sequence contained three lipidated lysine residues and was a simplified version of the LCP system.…”