Self-adjuvanting Vaccine Research Articles

A vaccine combination of lipid nanoparticles and a cholera toxin adjuvant derivative greatly improves lung protection against influenza virus infection.

This is a proof-of-principle study demonstrating that the combination of a cholera toxin derived adjuvant, CTA1-DD, and lipid nanoparticles (LNP) can significantly improve the immunogenicity and protective capacity of an intranasal vaccine. We explored the self-adjuvanted universal influenza vaccine candidate, CTA1-3M2e-DD (FPM2e), linked to LNPs. We found that the combined vector greatly enhanced survival against a highly virulent PR8 strain of influenza virus as compared to when mice were immunized with FPM2e alone. The combined vaccine vector enhanced early endosomal processing and peptide presentation in dendritic cells and upregulated co-stimulation. The augmenting effect was CTA1-enzyme dependent. Whereas systemic anti-M2e antibody and CD4+ T-cell responses were comparable to those of the soluble protein, the local respiratory tract IgA and the specific Th1 and Th17 responses were strongly enhanced. Surprisingly, the lung tissue did not exhibit gross pathology upon recovery from infection and M2e-specific lung resident CD4+ T cells were threefold higher than in FPM2e-immunized mice. This study conveys optimism as to the protective ability of a combination vaccine based on LNPs and various forms of the CTA1-DD adjuvant platform, in general, and, more specifically, an important way forward to develop a universal vaccine against influenza.

Immunological Evaluation of Co-Assembling a Lipidated Peptide Antigen and Lipophilic Adjuvants: Self-Adjuvanting Anti-Breast-Cancer Vaccine Candidates.

Co-assembling vaccines composed of a lipidated HER2-derived antigenic CH401 peptide and either a lipophilic adjuvant, Pam3 CSK4 , α-GalCer, or lipid A 506, were evaluated as breast cancer vaccine candidates. This vaccine design was aimed to inherit both antigen multivalency and antigen-specific immunostimulation properties, observed in reported self-adjuvanting vaccine candidates, by using self-assembly and adjuvant-conjugated antigens. Under vaccination concentrations, respective lipophilic adjuvants underwent co-assembly with lipidated CH401, which boosted the anti-CH401 IgG and IgM production. In particular, α-GalCer was responsible for the most significant immune activation. Therefore, the newly developed vaccine design enabled the optimization of adjuvants against the antigenic CH401 peptide in a simple preparatory manner. Overall, the co-assembling vaccine design opens the door for efficient and practical self-adjuvanting vaccine development.

Biodegradable PLGA-b-PEG Nanoparticles Induce T Helper 2 (Th2) Immune Responses and Sustained Antibody Titers via TLR9 Stimulation.

Sustained immune responses, particularly antibody responses, are key for protection against many endemic infectious diseases. Antibody responses are often accompanied by T helper (Th) cell immunity. Herein we study small biodegradable poly (ethylene glycol)-b-poly (lactic-co-glycolic acid) nanoparticles (PEG-b-PLGA NPs, 25–50 nm) as antigen- or adjuvant-carriers. The antigen carrier function of PEG-b-PLGA NPs was compared against an experimental benchmark polystyrene nanoparticles (PS NPs, 40–50 nm), both conjugated with the model antigen ovalbumin (OVA-PS NPs, and OVA-PEG-b-PLGA NPs). The OVA-PEG-b-PLGA NPs induced sustained antibody responses to Day 120 after two immunizations. The OVA-PEG-b-PLGA NPs as a self-adjuvanting vaccine further induced IL-4 producing T-helper cells (Th2), but not IFN-γ producing T-cells (Th1). The PEG-b-PLGA NPs as a carrier for CpG adjuvant (CpG-PEG-b-PLGA NPs) were also tested as mix-in vaccine adjuvants comparatively for protein antigens, or for protein-conjugated to PS NPs or to PEG-b-PLGA NPs. While the addition of this adjuvant NP did not further increase T-cell responses, it improved the consistency of antibody responses across all immunization groups. Together these data support further development of PEG-b-PLGA NPs as a vaccine carrier, particularly where it is desired to induce Th2 immunity and achieve sustained antibody titers in the absence of affecting Th1 immunity.

Opsonic Activity of Conservative Versus Variable Regions of the Group A Streptococcus M Protein.

Group A Streptococcus (GAS) and GAS-associated infections are a global challenge, with no licensed GAS vaccine on the market. The GAS M protein is a critical virulence factor in the fight against GAS infection, and it has been a primary target for GAS vaccine development. Measuring functional opsonic antibodies against GAS is an important component in the clinical development path for effective vaccines. In this study, we compared the opsonic activity of two synthetic, self-adjuvanting subunit vaccines containing either the J8- or 88/30-epitope in Swiss outbred mice using intranasal administration. Following primary immunization and three boosts, sera were assessed for IgG activity using ELISA, and opsonization activity against seven randomly selected clinical isolates of GAS was measured. Vaccine constructs containing the conservative J8-epitope showed significant opsonic activity against six out of the seven GAS clinical isolates, while the vaccine containing the variable 88/30-epitope did not show any significant opsonic activity.

Glycolipid-peptide vaccination induces liver-resident memory CD8+ T cells that protect against malaria

Abstract Liver resident-memory CD8+ T cells (TRM cells) can kill liver-stage Plasmodium-infected cells and prevent malaria, but simple vaccines for generating this important immune population are lacking. Here, we report the development of a fully synthetic self-adjuvanting glycolipid-peptide conjugate vaccine designed to efficiently induce liver TRM cells. Upon cleavage in vivo, the glycolipid-peptide conjugate vaccine releases an MHC I-restricted peptide epitope (to stimulate Plasmodium-specific CD8+ T cells) and an adjuvant component, the NKT cell agonist a-galactosylceramide (a-GalCer). Following transfer of a transgenic CD8+ T cell population, a single dose of this vaccine induced substantial numbers of intrahepatic CD8+ T cells expressing canonical markers of liver TRM cells (CD69, CXCR6 and CD101), and these cells could be further increased in number upon vaccine boosting. We show that modifications to the peptide, such as addition of proteosomal-cleavage sequences or epitope-flanking sequences, or the use of alternative conjugation methods to link the peptide to the glycolipid, improved liver TRM cell generation and led to the development of a vaccine able to induce sterile protection in C57BL/6 mice against P. berghei sporozoite challenge after a single dose. Incorporation of a cognate malaria antigen into the vaccine resulted in the generation of large numbers of long-lived liver TRM cells derived from the endogenous T cell population that were capable of providing sterile immunity. Our findings describe an ideal synthetic vaccine platform for generating large numbers of liver TRM cells for effective control of liver-stage malaria and, potentially, a variety of other hepatotropic infections

Uptake and activation profile of murine dendritic cells in response to stimulation with functionalized iron oxide nanoparticles

Abstract Subunit vaccines typically have better safety profiles than live attenuated or killed whole-cell vaccines, but are often less immunogenic and less efficacious when deployed alone. Thus, immunological adjuvants are frequently formulated with subunit vaccines to improve efficacy. However, few vaccine adjuvants are FDA-approved; and for many adjuvants their mechanisms of action are poorly understood. We previously explored the use of iron oxide (IO) nanoparticles (NPs) in subunit vaccine delivery and show that the IO NPs also possess adjuvant-like qualities, eliminating the need for additional adjuvants in the vaccine formulation. This study further dissects the mode of action of IO NPs as immunological adjuvants by examining the relationship of particle size and uptake on the activation profile of murine bone marrow derived dendritic cells (BMDCs) in response to in vitro stimulation with functionalized IO NPs. Using IO NPs of sizes ranging 5 – 30 nm, we showed by flow cytometry immunophenotyping that only IOs of 20nm and 30nm could induce an activated BMDC subset. The level of NP uptake by BMDCs, as measured by Prussian Blue staining, also varied with particle size, with IO of 5nm being the most efficiently internalized. Intriguingly, the levels of BMDC activation did not correlate with the level of IO NP uptake. We hypothesize only IO NPs taken up via selective endocytic pathways will activate BMDCs. The production of cytokine/chemokines by these BMDCs as further characterizations of the adjuvant-like profiles of IO NPs in relation to particle size and cellular uptake is currently being examined. These studies begin to dissect the mode of action of IO NPs as a self-adjuvanted vaccine delivery system on the innate-adaptive immune interface.

A Hybrid Eukaryotic-Prokaryotic Nanoplatform with Photothermal Modality for Enhanced Antitumor Vaccination.

Cytomembrane-derived nanoplatforms are an effective biomimetic strategy in cancer therapy. To improve their functionality and expandability for enhanced vaccination, a eukaryotic-prokaryotic vesicle (EPV) nanoplatform is designed and constructed by fusing melanoma cytomembrane vesicles (CMVs) and attenuated Salmonella outer membrane vesicles (OMVs). Inheriting the virtues of the parent components, the EPV integrates melanoma antigens with natural adjuvants for robust immunotherapy and can be readily functionalized with complementary therapeutics. In vivo prophylactic testing reveals that the EPV nanoformulation can be utilized as a prevention vaccine to stimulate the immune system and trigger the antitumor immune response, combating tumorigenesis. In the melanoma model, the poly(lactic-co-glycolic acid)-indocyanine green (ICG) moiety (PI)-implanted EPV (PI@EPV) in conjunction with localized photothermal therapy with durable immune inhibition shows synergetic antitumor effects as a therapeutic vaccine. The eukaryotic-prokaryotic fusion strategy provides new perspectives for the design of tumor-immunogenic, self-adjuvanting, and expandable vaccine platforms.

Poly(amino acids) as a potent self-adjuvanting delivery system for peptide-based nanovaccines.

To be optimally effective, peptide-based vaccines need to be administered with adjuvants. Many currently available adjuvants are toxic, not biodegradable; they invariably invoke adverse reactions, including allergic responses and excessive inflammation. A nontoxic, biodegradable, biocompatible, self-adjuvanting vaccine delivery system is urgently needed. Herein, we report a potent vaccine delivery system fulfilling the above requirements. A peptide antigen was coupled with poly-hydrophobic amino acid sequences serving as self-adjuvanting moieties using solid-phase synthesis, to produce fully defined single molecular entities. Under aqueous conditions, these molecules self-assembled into distinct nanoparticles and chain-like aggregates. Following subcutaneous immunization in mice, these particles successfully induced opsonic epitope-specific antibodies without the need of external adjuvant. Mice immunized with entities bearing 15 leucine residues were able to clear bacterial load from target organs without triggering the release of soluble inflammatory mediators. Thus, we have developed a well-defined and effective self-adjuvanting delivery system for peptide antigens.

A Self-Adjuvanting Vaccine Platform: Optimization of Site-Specific Sortase A Mediated Conjugation of Toll-Like Receptor 2 Ligands onto the Carboxyl or Amino terminus of Recombinant Protein Antigens.

Self-adjuvanting vaccines, consisting of recombinant protein antigens and covalently attached Toll-like receptor (TLR) agonists, have the ability to simultaneously and efficiently deliver antigen and TLR adjuvant to antigen presenting cells (APCs). Here, an enzyme-mediated ligation approach was used to overcome difficulties in producing homogeneous, molecularly defined self-adjuvanting vaccine products under native conditions. This process was optimized to allow the incorporation of the lipopeptide TLR2 agonist fibroblast-stimulating lipopeptide (FSL)-1 onto the N- or C-termini of recombinant protein antigens, employing the enzyme Staphylococcus aureus sortase A (SrtAsa) penta mutant. In addition, because SrtAsa-mediated ligations are reversible, a tryptophan zipper derived sequence was introduced into both reactants, which was demonstrated to improve ligation efficiency through the formation of a β-hairpin structure that hinders the reverse reaction. Finally, it was demonstrated that N- or C-terminal conjugation, and the incorporation of the β-hairpin structure, did not affect the TLR2-agonist activities of protein antigen TLR agonist conjugates. Overall, this SrtAsa-mediated ligation platform enabled production of antigen TLR2 agonist conjugates with enhanced ligation efficiency, with the conjugates demonstrating potent TLR2 signaling activation (EC50 <1nM).

Self-Adjuvanting Peptide Vaccines Against Cervical Cancer

Background Cervical cancer is a common cause of cancer-related deaths in women worldwide, with a fatality rate second only to breast cancer. Human papillomaviruses (HPVs) are the main causative agents of cervical cancer, and are therefore obvious targets for vaccine development. Although two prophylactic HPV vaccines have been commercialized, therapeutic vaccines against HPVs have not been developed yet. Current vaccine technologies emphasize the power of small particles in targeting immune cells, and particles of 20-50 nm have been reported to induce optimal immune responses against a variety of pathogens and cancers. Methods We synthesized new nanoparticle-based vaccines against cervical cancer by using antigenic 8Qmin peptide epitope derived from HPV-16 E7 protein, a hydrophilic poly-(L-glutamic acid) (PGA) linker, and an 8-arm poly (tert-butyl acrylate) dendrimer-based delivery system (D8). Results Four different peptides containing 8Qmin and PGA of different lengths were successfully synthesized with high yield and purity. These were then conjugated to alkyne-functionalized D8 by copper-catalyzed alkyne-azide cycloaddition “click” reaction. The conjugates self-assembled into nanoparticles, with decreased particle size corresponding to a greater number of Glu units. The four vaccine candidates were tested in C57 black 6 (C57BL/6) mice bearing well-established (7-day-old) tumors to examine their therapeutic effects. Conclusion Interestingly, only one conjugate delayed tumor growth, and montanide adjuvanted antigen, used as a positive control, failed to demonstrate any therapeutic effect.

Fully Synthetic Invariant NKT Cell-Dependent Self-Adjuvanting Antitumor Vaccines Eliciting Potent Immune Response in Mice.

Constructing an effective therapeutic cancer vaccine is very attractive and promising for cancer immunotherapy. However, the poor immunogenicity of tumor antigens and suppression of the immune system in the tumor microenvironment are two major obstacles for developing effective cancer vaccines. Invariant NKT cells (iNKT cells), which are essential bridges between the innate and adaptive immune systems, can be rapidly activated by their agonists and, consequently, evoke whole immune systems. Herein, we conjugated a potent agonist of the iNKT cell, α-galactosylceramide (α-GalCer), with the tumor-associated MUC1 glycopeptide antigens as novel self-adjuvanting cancer vaccines through click chemistry. Immunological studies revealed that the mouse immune system was potently evoked and that high levels of tumor-specific IgG antibodies were elicited by vaccine conjugates without an external adjuvant. The produced antibodies could specifically recognize and bind to antigen-expressing cancer cells and, subsequently, induce cytotoxicity through complement-dependent cytotoxicity. Thus, the insertion of α-GalCer significantly improved the immunogenicity of the MUC1 glycopeptide and induced strong antigen-specific antitumor responses, indicating that α-GalCer is an effective built-in adjuvant for constructing potent chemical synthetic antitumor vaccines.

Semisynthetic, self-adjuvanting vaccine development: Efficient, site-specific sortase A-mediated conjugation of Toll-like receptor 2 ligand FSL-1 to recombinant protein antigens under native conditions and application to a model group A streptococcal vaccine

Protein antigens are, in general, weakly immunogenic, and therefore require co-delivery with adjuvants to stimulate potent immune responses. The fusion of (poly)peptide antigens to immunostimulatory adjuvants (e.g. Toll-like receptor (TLR) agonists) has been demonstrated to greatly improve vaccine potency compared to mixtures of antigen and adjuvant. Chemical approaches, to enable the rapid, site-specific and high-yielding linkage of TLR2 ligands to recombinant protein antigens, have been previously optimized. These approaches require the use of denaturing conditions to ensure high reaction yields, which limits their application, as maintenance of native protein folding is necessary to elicit antibodies against conformational epitopes. Here, this work aimed to optimize an alternative method, to ensure the efficient bioconjugation of TLR2 ligands onto folded protein antigens. An enzyme-mediated approach, using Staphylococcus aureus sortase A (or a penta mutant with enhanced efficiency), was optimized for reaction yield and time, as well as enzyme type and amount. This approach enabled the site-specific conjugation of the TLR2-agonist fibroblast-stimulating lipopeptide-1 (FSL-1) onto a model group A Streptococcus (GAS) recombinant polytope antigen under conditions that maintain protein folding, yielding a homogeneous, molecularly-defined product, with ligation yields as high as 90%. Following intramuscular (IM) administration of the ligation product to humanized plasminogen AlbPLG1 mice, high-titer, antigen-specific IgG antibodies were observed, which conferred protection against subcutaneous challenge with GAS strain 5448. In comparison, mixtures of the GAS antigen with aluminum hydroxide or FSL-1 failed to provide protection, with the FSL-1 mixture yielding ~1000-fold lower antigen-specific IgG antibody titers, and the mixture with alum yielding a Th2-biased response compared to the more balanced Th1/Th2 responses observed with the FSL-1 conjugate. Overall, a FSL-1 bioconjugation method for the efficient production of antigen-TLR2 agonist conjugates, which maintain protein folding, was produced, with broad utility for the development of self-adjuvanting vaccines against subunit protein antigens.

Modular platforms for the assembly of self-adjuvanting lipopeptide-based vaccines for use in an out-bred population

To facilitate the preparation of synthetic epitope-based self-adjuvanting vaccines capable of eliciting antibody responses in an out-bred population, we have developed two modular approaches. In the first, the Toll-like receptor 2 agonist Pam2Cys and the target antibody epitope are assembled as a module which is then coupled to a carrier protein as a source of antigens to stimulate T cell help. A vaccine candidate made in this way was shown to induce a specific immune response in four different strains of mice without the need for extraneous adjuvant. In the second approach, three vaccine components in the form of a target antibody epitope, a T helper cell epitope and Pam2Cys, were prepared separately each carrying different chemical functional groups. By using pH-mediated chemo-selective ligations, the vaccine was assembled in a one-pot procedure. Using this approach, a number of vaccine constructs including a lipopeptide-protein conjugate were made and also shown to elicit immune responses in different strains of mice. These two modular approaches thus constitute a powerful platform for the assembly of self-adjuvanting lipopeptide-based vaccines that can potentially be used to induce robust antibody responses in an outbred population. Finally, our study of the impact of chemical linkages on immunogenicity of a lipopeptide vaccine shows that a stable covalent bond between Pam2Cys and a B cell epitope, rather than between Pam2Cys and T helper cell epitope is critical for the induction of antibody responses and biological efficacy, indicating that Pam2Cys functions not only as an adjuvant but also participates in processing and presentation of the immunogen.

Syntheses and Functional Studies of Self-Adjuvanting Anti-HER2 Cancer Vaccines.

The 9-mer peptide MFCH401 (N: 165-173: DTILWKDIF), which is located in the extracellular domain of HER2, has been predicted to be a novel epitope. Self-adjuvanting anti-HER2 vaccine constructs were designed and synthesized via covalently attaching MFCH401 or its linear tandem repeats (2×MFCH401, 3×MFCH401) to a lipopeptide Pam3 CSK4 via iterative condensation reaction. The in vivo results showed the Pam3 CSK4 -MFCH401 vaccine construct can induce higher antibody titers of IgG and IgM than those of other conjugates, and the analysis of changes in plasma cytokines level indicate the activation of Th1 cells and NK cells. In addition, the Pam3 CSK4 -MFCH401 vaccine conjugate induced a specific immune response to HER2-overexpressing human BT474 cells. Our data clearly indicated that MFCH401 is a promising epitope; moreover, its linear tandem repeats were unsuitable for anticancer vaccine design when conjugating with Pam3 CSK4 , which provided useful evidence for developing further anti-HER2 cancer vaccines.

Mucosal Vaccination with a Self-Adjuvanted Lipopeptide Is Immunogenic and Protective against Mycobacterium tuberculosis.

Tuberculosis (TB) remains a staggering burden on global public health. Novel preventative tools are desperately needed to reach the targets of the WHO post-2015 End-TB Strategy. Peptide or protein-based subunit vaccines offer potential as safe and effective generators of protection, and enhancement of local pulmonary immunity may be achieved by mucosal delivery. We describe the synthesis of a novel subunit vaccine via native chemical ligation. Two immunogenic epitopes, ESAT61-20 and TB10.43-11 from Mycobacterium tuberculosis (Mtb), were covalently conjugated to the TLR2-ligand Pam2Cys to generate a self-adjuvanting lipopeptide vaccine. When administered mucosally to mice, the vaccine enhanced pulmonary immunogenicity, inducing strong Th17 responses in the lungs and multifunctional peripheral T-lymphocytes. Mucosal, but not peripheral vaccination, provided substantial protection against Mtb infection, emphasizing the importance of delivery route for optimal efficacy.

Targeting self and neo-epitopes with a modular self-adjuvanting cancer vaccine.

Induction of a potent CD4 and CD8 T-cell response against tumor-specific and tumor-associated antigen is critical for eliminating tumor cells. Recent vaccination strategies have been hampered by an inefficacious and low amplitude immune response. Here we describe a self-adjuvanted chimeric protein vaccine platform to address these challenges, characterized by a multidomain construction incorporating (i) a cell penetrating peptide (CPP) allowing internalization of several multiantigenic Major Histocompatibility Complex (MHC)-restricted peptides within (ii) the multiantigenic domain (Mad) and (iii) a TLR2/4 agonist domain (TLRag). Functionality of the resulting chimeric protein is based on the combined effect of the above-mentioned three different domains for simultaneous activation of antigen presenting cells and antigen cross-presentation, leading to an efficacious multiantigenic and multiallelic cellular immune response. Helper and cytotoxic T-cell responses were observed against model-, neo- and self-antigens, and were highly potent in several murine tumor models. The safety and the immunogenicity of a human vaccine candidate designed for colorectal cancer treatment was demonstrated in a non-human primate model. This newly engineered therapeutic vaccine approach is promising for the treatment of poorly infiltrated tumors that do not respond to currently marketed immunotherapies.

Self-assembly of trimethyl chitosan and poly(anionic amino acid)-peptide antigen conjugate to produce a potent self-adjuvanting nanovaccine delivery system.

Short peptides derived from virulent pathogen proteins are promising antigens for the development of vaccines against infectious diseases. However, in order to mimic the danger signals associated with natural infection and stimulate an adaptive immune response, peptide antigens must be co-delivered with immune adjuvants. In this study, a group A streptococcus (GAS) M-protein derived B-cell epitope: J8, and universal T-helper epitope P25 containing peptides, were chemically coupled with different anionic amino acid-based polymers. The poly(anionic amino acid)-peptide antigen conjugates were mixed with trimethyl chitosan (TMC) to produce self-adjuvanting nanoparticulate vaccine candidates. TMC from two different sources were used to analyse their effect on immunogenicity. The nanoparticles produced from a peptide modified with 10 residues of polyglutamic acid and fungal TMC (NP5) stimulated production of the highest levels of serum antibodies in outbred mice. These antibodies were opsonic against all clinical GAS isolates tested.

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

Covalent linking of immunogenic oligopeptides with synthetic Toll-like receptor ligands is a useful approach to develop self-adjuvanting vaccines. In particular, small-molecule based agonists of Toll-like receptor 7 (TLR7) that are derived from 8-oxo-adenine core are potentially promising because these chemically robust TLR7 ligands can be connected to peptide T-cell epitopes via straightforward solid-phase peptide synthesis. In this contribution we present the synthesis of a Boc-protected 9-benzyl-2-alkoxy-8-oxo-adenine building block and its application in the online solid phase synthesis of three peptide conjugates that differ in the position of the TLR7 ligand within the peptide. The conjugates are able to induce dendritic cell maturation and T cell proliferation while the position of the ligand impacts T cell proliferation potency.

Synthesis of a Self-Adjuvanting MUC1 Vaccine via Diselenide-Selenoester Ligation-Deselenization.

Access to lipopeptide-based vaccines for immunological studies remains a significant challenge owing to the amphipathic nature of the molecules, which makes them difficult to synthesize and purify to homogeneity. Here, we describe the application of a new peptide ligation technology, the diselenide-selenoester ligation (DSL), to access self-adjuvanting glycolipopeptide vaccines. We show that rapid ligation of glyco- and lipopeptides is possible via DSL in mixed organic solvent-aqueous buffer and, when coupled with deselenization chemistry, affords rapid and efficient access to a vaccine candidate possessing a MUC1 glycopeptide epitope and the lipopeptide adjuvant Pam2Cys. This construct was shown to elicit MUC1-specific antibody and cytotoxic T lymphocyte responses in the absence of any other injected lipids or adjuvants. The inclusion of the helper T cell epitope PADRE both boosted the antibody response and resulted in elevated cytokine production.

Polyglutamic acid-trimethyl chitosan-based intranasal peptide nano-vaccine induces potent immune responses against group A streptococcus

Peptide-based vaccines have the potential to overcome the limitations of classical vaccines; however, their use is hampered by a lack of carriers and adjuvants suitable for human use. In this study, an efficient self-adjuvanting peptide vaccine delivery system was developed based on the ionic interactions between cationic trimethyl chitosan (TMC) and a peptide antigen coupled with synthetically defined anionic α-poly-(l-glutamic acid) (PGA). The antigen, possessing a conserved B-cell epitope derived from the group A streptococcus (GAS) pathogen and a universal T-helper epitope, was conjugated to PGA using cycloaddition reaction. The produced anionic conjugate formed nanoparticles (NP-1) through interaction with cationic TMC. These NP-1 induced higher systemic and mucosal antibody titers compared to antigen adjuvanted with standard mucosal adjuvant cholera toxin B subunit or antigen mixed with TMC. The produced serum antibodies were also opsonic against clinically isolated GAS strains. Further, a reduction in bacterial burden was observed in nasal secretions, pharyngeal surface and nasopharyngeal-associated lymphoid tissue of mice immunized with NP-1 in GAS challenge studies. Thus, conjugation of defined-length anionic polymer to peptide antigen as a means of formulating ionic interaction-based nanoparticles with cationic polymer is a promising strategy for peptide antigen delivery. Statement of SignificanceA self-adjuvanting delivery system is required for peptide vaccines to enhance antigen delivery to immune cells and generate systemic and mucosal immunity. Herein, we developed a novel self-adjuvanting nanoparticulate delivery system for peptide antigens by combining polymer-conjugation and complexation strategies. We conjugated peptide antigen with anionic α-poly-(l-glutamic acid) that in turn, formed nanoparticles with cationic trimethyl chitosan by ionic interactions, without using external crosslinker. On intranasal administration to mice, these nanoparticles induced systemic and mucosal immunity, at low dose. Additionally, nanoparticles provided protection to vaccinated mice against group A streptococcus infection. Thus, this concept should be particularly useful in developing nanoparticles for the delivery of peptide antigens.