An efficient, chemically-defined semisynthetic lipid-adjuvanted nanoparticulate vaccine development system

A novel vaccine development platform that enables the site-specific conjugation of synthetic lipid adjuvants to recombinant proteins was produced. This technology facilitates the simple and efficient production of homogeneous, chemically-defined, semisynthetic lipoprotein vaccines. Using a polytope 'string-of-beads' approach, a synthetic gene incorporating seven Streptococcus pyogenes M protein strain-specific antigens, and a conserved M protein antigen (J14) was produced, expressed, and attached to a lipoamino acid based adjuvant (lipid core peptide; LCP). Nanoparticles (40 nm diameter) of an optimal size for stimulating antibody-mediated immunity were formed upon the addition of these lipoproteins to aqueous buffer (PBS). Systemic antigen-specific IgG antibodies were raised against all eight antigens in C57BL/6 J mice, without the need to formulate with additional adjuvant. These antibodies bound cell surface M proteins of S. pyogenes strains represented within the polytope sequence, with higher antibody levels observed where a dendritic cell targeting peptide (DCpep) was incorporated within the LCP adjuvant. Crown Copyright (C) 2013 Published by Elsevier Inc. All rights reserved

Self-adjuvanting modular virus-like particles for mucosal vaccination against group A streptococcus (GAS)

Group A streptococcus (GAS) causes a wide range of diseases, some of them related to autoimmune diseases triggered by repeated GAS infections. Despite the fact that GAS primarily colonizes the mucosal epithelium of the pharynx, the main mechanism of action of most vaccine candidates is based on development of systemic antibodies that do not cross-react with host tissues, neglecting the induction of mucosal immunity that could potentially block disease transmission. Peptide antigens from GAS M-surface protein can confer protection against infection; however, translation of such peptides into immunogenic mucosal vaccines that can be easily manufactured remains a challenge. In this work, a modular murine polyomavirus (MuPyV) virus-like particle (VLP) was engineered to display a GAS antigenic peptide, J8i. Heterologous modules containing one or two J8i antigen elements were integrated with the MuPyV VLP, and produced using microbial protein expression, standard purification techniques and in vitro VLP assembly. Both modular VLPs, when delivered intranasally to outbred mice without adjuvant, induced significant titers of J8i-specific IgG and IgA antibodies, indicating significant systemic and mucosal responses, respectively. GAS colonization in the throats of mice challenged intranasally was reduced in these immunized mice, and protection against lethal challenge was observed. This study shows that modular MuPyV VLPs prepared using microbial synthesis have potential to facilitate cost-effective vaccine delivery to remote communities through the use of mucosal immunization

Preclinical immunogenicity and safety of a Group A streptococcal M protein-based vaccine candidate

Streptococcus pyogenes (group A streptococcus, GAS) causes a wide range of clinical manifestations ranging from mild self-limiting pyoderma to invasive diseases such as sepsis. Also of concern are the post infectious immune-mediated diseases including rheumatic heart disease. The development of a vaccine against GAS would have a large health impact on populations at risk of these diseases. However, there is a lack of suitable models for the safety evaluation of vaccines with respect to post-infectious complications. We have utilized the Lewis Rat model for cardiac valvulitis to evaluate the safety of the J8-DT vaccine formulation in parallel with a rabbit toxicology study. These studies demonstrated that the vaccine did not induce abnormal pathology. We also show that in mice the vaccine is highly immunogenic but that doses are required to induce protection from a GAS skin challenge even though 2 doses are sufficient to induce a high antibody titer

Polymer–peptide hybrids as a highly immunogenic single-dose nanovaccine

Aim: To explore four-arm star poly(t-butyl)acrylate (P(t)BA)-peptide and linear P(t)BA-peptide conjugates as a vaccine-delivery system against Group A Streptococcus. Materials & methods: P(t)BA nanoparticles bearing J14 peptide epitopes were prepared via alkyne-azide 1,3-dipolar cycloaddition click' reaction. The conjugated products were self-assembled into small or large nanoparticles. These nanoparticle vaccine candidates were evaluated in vivo and J14-specific antibody titers were assessed. Results & discussion: Mice vaccinated with the nanoparticles were able to produce J14-specific IgG antibodies without the use of an external adjuvant after a single immunization. We have demonstrated for the first time that the immune responses against self-assembled P(t)BA nanoparticles are stronger for the smaller sized (20 nm) nanoparticles compared with the larger (500nm) P(t)BA nanoparticles. Conclusion: PtBA analogs have the potential to be developed as potent carrier systems for single-dose synthetic vaccines. Original submitted 29 August 2012; Revised submitted 6 December 2012; Published online 23 April 201

Evaluation of safety and immunogenicity of a group A streptococcus vaccine candidate (MJ8VAX) in a randomized clinical trial

<div><p>Background</p><p>Group A streptococcus (GAS) is a serious human pathogen that affects people of different ages and socio-economic levels. Although vaccination is potentially one of the most effective methods to control GAS infection and its sequelae, few prototype vaccines have been investigated in humans. In this study, we report the safety and immunogenicity of a novel acetylated peptide-protein conjugate vaccine candidate MJ8VAX (J8-DT), when delivered intramuscularly to healthy adults.</p><p>Methods</p><p>A randomized, double-blinded, controlled Phase I clinical trial was conducted in 10 healthy adult participants. Participants were randomized 4:1 to receive the vaccine candidate (N = 8) or placebo (N = 2). A single dose of the vaccine candidate (MJ8VAX), contained 50 μg of peptide conjugate (J8-DT) adsorbed onto aluminium hydroxide and re-suspended in PBS in a total volume of 0.5 mL. Safety of the vaccine candidate was assessed by monitoring local and systemic adverse reactions following intramuscular administration. The immunogenicity of the vaccine was assessed by measuring the levels of peptide (anti-J8) and toxoid carrier (anti-DT)—specific antibodies in serum samples.</p><p>Results</p><p>No serious adverse events were reported over 12 months of study. A total of 13 adverse events (AEs) were recorded, two of which were assessed to be associated with the vaccine. Both were mild in severity. No local reactogenicity was recorded in any of the participants. MJ8VAX was shown to be immunogenic, with increase in vaccine-specific antibodies in the participants who received the vaccine. The maximum level of vaccine-specific antibodies was detected at 28 days post immunization. The level of these antibodies decreased with time during follow-up. Participants who received the vaccine also had a corresponding increase in anti-DT serum antibodies.</p><p>Conclusions</p><p>Intramuscular administration of MJ8VAX was demonstrated to be safe and immunogenic. The presence of DT in the vaccine formulation resulted in a boost in the level of anti-DT antibodies.</p><p>Trial registration</p><p>ACTRN12613000030774</p></div

J8-specific (Panel A) and DT-specific (Panel B) serum IgG concentrations for each participant at Days 0, 28, 180, 266 and 350.

<p>J8-specific (Panel A) and DT-specific (Panel B) serum IgG concentrations for each participant at Days 0, 28, 180, 266 and 350.</p

Participation flow.

<p>Ten (10) out of 38 participants that were screened for this study, were randomized to receive either the vaccine candidate or placebo. None of the participants received a second vaccination. Five of participants that received a vaccine candidate withdrew from the study by Day 287. All efficacy and safety data recorded at different time points for the participants in this study were included in the analysis.</p

Demographic profile of enrolled participants.

<p>Demographic profile of enrolled participants.</p