Structure–Activity Relationship of a Series of Synthetic Lipopeptide Self-Adjuvanting Group A Streptococcal Vaccine Candidates

Abstract

The development of 16 self-adjuvanting group A streptococcal vaccine candidates, composed of (i) a universal helper T-cell epitope (P25), (ii) a target GAS B-cell epitope (J14), and (iii) a lipid moiety, is described. Systemic J14-specific IgG antibodies were detected following subcutaneous immunization of BALB/c (H-2 (d)) mice with each construct without the need for an additional adjuvant. The effect of changing the order of P25, J14, and lipid moiety attachment or incorporation of P25 and J14 into a lipid-core peptide system on antibody titers was assessed. The point of lipid moiety attachment had the greatest influence on systemic J14-specific IgG antibody titers. Overall, the best vaccines featured a C-terminal lipid moiety, conjugated through a lysine residue to P25 at the N-terminus, and J14 on the lysine side chain.

Lipid core peptide targeting the cathepsin D hemoglobinase ofSchistosoma mansonias a component of a schistosomiasis vaccine

“…Such variation in antibody production has been reported for Streptococcus LCPs, 35,36 and was overcome by inclusion of the universal T helper cell epitope, P25. 37 Future Sm-CatD constructs will incorporate T helper epitopes in an effort to boost IgG titers as well as consistency between individual animals.…”

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

“…[17] Following structure-activity relationship studies about the number of LAAs and their chain length, the LCP adjuvant was developed into the lipidic adjuvanting sequence in compound 1b (Figure 1), herein referred to as Lipid Core Peptide 2 (LCP2). [6,23] Immunization with constructs containing the LCP2 adjuvanting sequence resulted in antibody titers that were comparable to that of constructs containing the LCP lipidic adjuvant. [6] The lipidic adjuvant contained in 1c (LLCP; Lysine Lipid Core Peptide) was recently reported as a simplified version of the LCP.…”

“…[6,23] Immunization with constructs containing the LCP2 adjuvanting sequence resulted in antibody titers that were comparable to that of constructs containing the LCP lipidic adjuvant. [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.…”

“…After dividing the resin, the lysine Fmoc protecting group was removed using piperidine, and the lipidic adjuvanting moiety could be incorporated (Scheme 2). The lipidic adjuvanting moieties of glyco-lipopeptides 3a and 3b have been prepared previously using Boc [6,8] or Dde [31] protected synthetic LAAs. In this case, Dde protected LAAs were employed (Dde-C12-OH, Dde-C16-OH) and prepared according to the procedure of Ross et al [32] The lipidated lysine amino acid (Fmoc- 10.1002/cbic.201600639 ChemBioChem K(C12)-OH) was synthesized according to the procedure reported by Fagan et al, [13] and was used to prepare the lipidic sequence of glyco-lipopeptide 3c by standard Fmoc SPPS.…”

Comparison of Fluorinated and Nonfluorinated Lipids in Self-Adjuvanting Delivery Systems for Peptide-Based Vaccines

“…For this purpose, fluorinated and nonfluorinated lipids ( Figure 1) were conjugated to B-cell epitope derived from the M protein of group A streptococcus (GAS). Fluorinated lipids 1−2 were designed based on common features found in many peptide vaccine delivery systems that incorporate two lipidic chains (e.g., Pam2Cys (dipalmitoyl-Sglycerol cysteine), 14 lipoamino acids, 15 and dipalmitoyl serine (DPS) 16 ). In contrast to these previously reported moieties, the new fluorinated lipids 1−2 have (1) stable ether bonds instead of the hydrolyzable ester linkage found, for example, in Pam2Cys, (2) no chiral center and therefore exists as a single isomer, (3) oxygen atoms in the hydrocarbon chain to enhance the solubility of the final compounds and (4) an alkyne moiety, allowing easy conjugation through CuAAC reaction.…”