A dual-adjuvanting strategy for peptide-based subunit vaccines against group A Streptococcus: Lipidation and polyelectrolyte complexes.

In order to improve the immunogenicity of peptide-based vaccines against group A Streptococcus (GAS), lipid moieties (C16 lipoamino acid and cholic acid) were conjugated with peptide antigen (P25-J8) and further modified with α-poly(glutamic acid) (α-PGA). Thus, positively charged lipopeptide vaccine candidates LCP-1 (P25-K(J8)-SS-C16-C16) and LCP-2 (P25-K(J8)-SS-K(cholic acid)) were synthesized. Negatively charged LCP-3 (P25-K(PGA-J8)-SS-K(cholic acid)) was also produced by attaching α-PGA to the J8 N-terminus of LCP-2. Polyelectrolyte complex (PEC) nanoparticles were formulated with heparin and/or trimethyl chitosan (TMC) for delivery of the lipopeptide vaccine candidates. The ability of the antigen-loaded nanoparticles to induce humoral immune responses was examined in outbred female Swiss mice following intranasal immunization. The antibodies produced were opsonic against all clinical GAS isolates tested.

Mannose in vaccine delivery.

Adjuvants and vaccine delivery systems are used widely to improve the efficacy of vaccines. Their primary roles are to protect antigen from degradation and allow its delivery and uptake by antigen presenting cells (APCs). Carbohydrates, including various structures/forms of mannose, have been broadly utilized to target carbohydrate binding receptors on APCs. This review summarizes basic functions of the immune system, focusing on the role of mannose receptors in antigen recognition by APCs. The most popular strategies to produce mannosylated vaccines via conjugation and formulation are presented. The efficacy of mannosylated vaccines is discussed in detail, taking into consideration factors, such as valency and number of mannose in mannose ligands, mannose density, length of spacers, special arrangement of mannose ligands, and routes of administration of mannosylated vaccines. The advantages and disadvantages of mannosylation strategy and future directions in the development of mannosylated vaccines are also debated.

Development of Multilayer Nanoparticles for the Delivery of Peptide-Based Subunit Vaccine against Group A Streptococcus.

Peptide-based subunit vaccines include only minimal antigenic determinants, and, therefore, are less likely to induce allergic immune responses and adverse effects compared to traditional vaccines. However, peptides are weakly immunogenic and susceptible to enzymatic degradation when administered on their own. Hence, we designed polyelectrolyte complex (PEC)-based delivery systems to protect peptide antigens from degradation and improve immunogenicity. Lipopeptide (LCP-1) bearing J8 B-cell epitope derived from Group A Streptococcus (GAS) M-protein was selected as the model peptide antigen. In the pilot study, LCP-1 incorporated in alginate/cross-linked polyarginine-J8-based PEC induced high J8-specific IgG antibody titres. The PEC system was then further modified to improve its immune stimulating capability. Of the formulations tested, PEC-4, bearing LCP-1, alginate and cross-linked polylysine, induced the highest antibody titres in BALB/c mice following subcutaneous immunisation. The antibodies produced were more opsonic than those induced by mice immunised with other PECs, and as opsonic as those induced by antigen adjuvanted with powerful complete Freund's adjuvant.

In vivo and in silico evaluation of antinociceptive activities of seed extract from the Holarrhena antidysenterica plant.

The objective of the study was to investigate the analgesic activity of seeds extracted from the Holarrhena antidysenterica plant (Family: Apocynaceae). The seeds of H. antidysenterica were extracted with pure ethanol and administered to the experimental Swiss albino mice at three different doses (50, 100, and 150 mg/kg body weight) in pain models. Peripheral analgesic activity was evaluated using the acetic acid-induced writhing test, and heat-induced (hot plate and tail immersion test) pain models were applied for central anti-nociceptive activity evaluation. Formalin induced licking test was applied to evaluate both peripheral and central anti-nociceptive activity on mice. Computational studies were performed by Schrödinger Maestro v10.1 for molecular docking and the SwissADME online server for ADME prediction of compounds. In acetic acid-induced writhing test, dose-dependent reduction of writhing response was observed with 43.94% (p < 0.001) writhing inhibition at 150 mg/kg dose compared to standard 60.98% (p < 0.001). 150 mg/kg caused a maximum decrease in licking and biting time in both early and late phases of the formalin-induced licking test (71.2 ± 5.67, p < 0.05, and 36.6 ± 5.62, p < 0.01 respectively). In both tests of central analgesic activity, the extract also showed dose-dependent anti-nociceptive activity. In the hot plate method, the highest %MPE was 67.39 (p < 0.001) at 30 min at 150 mg/kg dose, which was even better than the standard drug. In the case of the tail immersion method, the highest %MPE was 69.84 at a dose of 150 mg/kg at 30 min (p < 0.001). In molecular docking study, Conimine, Conarrhimin, Conessine, and Funtudienine showed the best binding affinities against the COX-1 enzyme. The study indicates that the ethanolic seed extract of H. antidysenterica has the strong potentiality of having central analgesic activity and moderate peripheral analgesic activity due to the presence of bioactive compounds in its seeds.