Sustained Release Of Antigen Research Articles

MIL-53(Al)–oil/water emulsion composite as an adjuvant promotes immune responses to an inactivated pseudorabies virus vaccine in mice and pigs

Although vaccination with inactivated vaccines is a popular preventive method against pseudorabies virus (PRV) infection, inactivated vaccines have poor protection efficiency because of their weak immunogenicity. The development of an effective adjuvant is urgently needed to improve the efficacy of inactivated PRV vaccines. In this study, a promising nanocomposite adjuvant named as MIL@A–SW01–C was developed by combining polyacrylic acid-coated metal–organic framework MIL-53(Al) (MIL@A) and squalene (oil)-in-water emulsion (SW01) and then mixing it with a carbomer solution. One part of the MIL@A was loaded onto the oil/water interface of SW01 emulsion via hydrophobic interaction and coordination, while another part was dispersed in the continuous water phase using carbomer. MIL@A–SW01–C showed good biocompatibility, high PRV (antigen)-loading capability, and sustained antigen release. Furthermore, the MIL@A–SW01–C adjuvanted PRV vaccine induced high specific serum antibody titers, increased splenocyte proliferation and cytokine secretion, and a more balanced Th1/Th2 immune response compared with commercial adjuvants, such as alum and biphasic 201. In the mouse challenge experiment, two- and one-shot vaccinations resulted in survival rates of 73.3 % and 86.7 %, respectively. After one-shot vaccination, the host animal pigs were also challenged with wild PRV. A protection rate of 100 % was achieved, which was much higher than that observed with commercial adjuvants. This study not only establishes the superiority of MIL@A–SW01–C composite nanoadjuvant for inactivated PRV vaccine in mice and pigs but also presents an effective method for developing promising nanoadjuvants. Statement of significanceWe have developed a nanocomposite of MIL-53(Al) and oil-in-water emulsion (MIL@A–SW01–C) as a promising adjuvant for the inactivated PRV vaccines. MIL@A–SW01–C has good biocompatibility, high PRV (antigen) loading capability, and prolonged antigen release. The developed nanoadjuvant induced much higher specific IgG antibody titers, increased splenocyte proliferation and cytokine secretion, and a more balanced Th1/Th2 immune response than commercial adjuvants alum and biphasic 201. In mouse challenge experiments, survival rates of 73.3 % and 86.7 % were achieved from two-shot and one-shot vaccinations, respectively. At the same time, a protection rate of 100 % was achieved with the host animal pigs challenged with wild PRV.

Dynamic Covalent Hydrogel as a Single-Dose Vaccine Adjuvant for Sustained Antigen Release and Significantly Elevated Humoral Immunity.

Vaccine is the most important way for fighting against infection diseases. However, multiple injections and unsatisfied immune responses are the main obstacles for current vaccine application. Herein, a dynamic covalent hydrogel (DCH) is used as a single-dose vaccine adjuvant for eliciting robust and sustained humoral immunity. By adjusting the mass ratio of the DCH gel, 10-30 d constant release of the loaded recombinant protein antigens is successfully realized, and it is proved that sustained release of antigens can significantly improve the vaccine efficacy. When loading SARS-CoV-2 RBD (Wuhan and Omicron BA.1 strains) antigens into this DCH gel, an over 32000 times and 8000 times improvement is observed in antigen-specific antibody titers compared to conventional Aluminum adjuvanted vaccines. The universality of this DCH gel adjuvant is confirmed in a Nipah G antigen test as well as a H1N1 influenza virus antigen test, with much improved protection of C57BL/6 mice against H1N1 virus infection than conventional Aluminum adjuvanted vaccines. This sustainably released, single-dose DCH gel adjuvant provides a new promising option for designing next-generation infection vaccines.

Modulating Adjuvant Release Kinetics From Scaffold Vaccines to Tune Adaptive Immune Responses.

Increasing the potency, quality, and durability of vaccines represents a major public health challenge. A critical parameter that shapes vaccine immunity is the spatiotemporal context in which immune cells interact with antigen and adjuvant. While various material-based strategies demonstrate that extended antigen release enhances both cellular and humoral immunity, the effect of adjuvant kinetics on vaccine-mediated immunity remains incompletely understood. Here, a previously characterized mesoporous silica rod (MPS) biomaterial vaccine is used to develop a facile, electrostatics-driven approach to tune in vivo kinetics of the TLR9 agonist cytosine phosphoguanosine oligodeoxynucleotide (CpG). It is demonstrated that rapid release of CpG from MPS vaccines, mediated by alterations in MPS chemistry that tune surface charge, generates potent cytotoxic T cell responses and robust, T helper type 1 (Th1)-skewed IgG2a/c antibody titers. Immunophenotyping of lymphoid organs after MPS vaccination with slow or fast CpG release kinetics suggests that differential engagement of migratory dendritic cells and natural killer cells may contribute to the more potent responses observed with rapid adjuvant release. Taken together, these findings suggest that vaccine approaches that pair sustained release of antigen with rapid release of adjuvants with similar characteristics to CpG may drive particularly potent Th1 responses.

In situ bio-mineralized Mn nanoadjuvant enhances anti-influenza immunity of recombinant virus-like particle vaccines

Virus like particles (VLPs) have been well recognized as one of the most important vaccine platforms due to their structural similarity to natural viruses to induce effective humoral and cellular immune responses. Nevertheless, lack of viral nucleic acids in VLPs usually leads the vaccine candidates less efficient in provoking innate immune against viral infection. Here, we constructed a biomimetic dual antigen hybrid influenza nanovaccines THM-HA@Mn with robust immunogenicity via in situ synthesizing a stimulator of interferon genes (STING) agonist Mn3O4 inside the cavity of a recombinant Hepatitis B core antigen VLP (HBc VLP) having fused SpyTag and influenza M2e antigen peptides (Tag-HBc-M2e, THM for short), followed by conjugating a recombinant hemagglutinin (rHA) antigen on the surface of the nanoparticles through SpyTag/SpyCatcher ligating. Such inside Mn3O4 immunostimulator-outside rHA antigen design, together with the chimeric M2e antigen on the HBc skeleton, enabled the synthesized hybrid nanovaccines THM-HA@Mn to well imitate the spatial distribution of M2e/HA antigens and immunostimulant in natural influenza virus. In vitro cellular experiments indicated that compared with the THM-HA antigen without Mn3O4 and a mixture vaccine consisting of THM-HA+MnOx, the THM-HA@Mn hybrid nanovaccines showed the highest efficacies in dendritic cells uptake and in promoting BMDC maturation, as well as inducing expression of TNF-α and type I interferon IFN-β. The THM-HA@Mn also displayed the most sustained antigen release at the injection site, the highest efficacies in promoting the DC maturation in lymph nodes and germinal center B cells activation in the spleen of the immunized mice. The co-delivery of immunostimulant and antigens enabled the THM-HA@Mn nanovaccines to induce the highest systemic antigen-specific antibody responses and cellular immunogenicity in mice. Together with the excellent colloid dispersion stability, low cytotoxicity, as well as good biosafety, the synthetic hybrid nanovaccines presented in this study offers a promising strategy to design VLP-based vaccine with robust natural and adaptive immunogenicity against emerging viral pathogens.

Enhancing cell-scale performance via sustained release of the varicella-zoster virus antigen from a microneedle patch under simulated microgravity.

The immune system of astronauts might become weakened in the microgravity environment in space, and the dormant varicella-zoster virus (VZV) in the body might be reactivated, seriously affecting their work and safety. For working in orbit for the long term, there is currently no efficient and durable delivery system of general vaccines in a microgravity environment. Accordingly, based on the previous foundation, we designed, modified, and synthesized a biodegradable and biocompatible copolymer, polyethylene glycol-polysulfamethazine carbonate urethane (PEG-PSCU) that could be mainly adopted to fabricate a novel sustained-release microneedle (S-R MN) patch. Compared with conventional biodegradable microneedles, this S-R MN patch could not only efficiently encapsulate protein vaccines (varicella-zoster virus glycoprotein E, VZV gE) but also further prolong the release time of VZV gE in a simulated microgravity (SMG) environment. Eventually, we verified the activation of dendritic cells by VZV gE released from the S-R MN patch in an SMG environment and the positive bioeffect of activated dendritic cells on lymphocytes using an in vitro lymph node model. This study is of great significance for the exploration of long-term specific immune responses to the VZV in an SMG environment.

Inhaled SARS-CoV-2 vaccine for single-dose dry powder aerosol immunization.

The COVID-19 pandemic has fostered major advances in vaccination technologies1-4; however, there are urgent needs for vaccines that induce mucosal immune responses and for single-dose, non-invasive administration4-6. Here we develop an inhalable, single-dose, dry powder aerosol SARS-CoV-2 vaccine that induces potent systemic and mucosal immune responses. The vaccine encapsulates assembled nanoparticles comprising proteinaceous cholera toxin B subunits displaying the SARS-CoV-2 RBD antigen within microcapsules of optimal aerodynamic size, and this unique nano-micro coupled structure supports efficient alveoli delivery, sustained antigen release and antigen-presenting cell uptake, which are favourable features for the induction of immune responses. Moreover, this vaccine induces strong production of IgG and IgA, as well as a local T cell response, collectively conferring effective protection against SARS-CoV-2 in mice, hamsters and nonhuman primates. Finally, we also demonstrate a mosaic iteration of the vaccine that co-displays ancestral and Omicron antigens, extending the breadth of antibody response against co-circulating strains and transmission of the Omicron variant. These findings support the use of this inhaled vaccine as a promising multivalent platform for fighting COVID-19 and other respiratory infectious diseases.

Biodegradable scaffolds for enhancing vaccine delivery.

Sustained release of vaccine components is a potential method to boost efficacy compared with traditional bolus injection. Here, we show that a biodegradable hyaluronic acid (HA)-scaffold, termed HA cryogel, mediates sustained antigen and adjuvant release in vivo leading to a durable immune response. Delivery from subcutaneously injected HA cryogels was assessed and a formulation which enhanced the immune response while minimizing the inflammation associated with the foreign body response was identified, termed CpG-OVA-HAC2. Dose escalation studies with CpG-OVA-HAC2 demonstrated that both the antibody and T cell responses were dose-dependent and influenced by thecompetency of neutrophils to perform oxidative burst. In immunodeficient post-hematopoietic stem cell transplanted mice, immunization with CpG-OVA-HAC2 elicited a strong antibody response, three orders of magnitude higher than dose-matched bolus injection. In a melanoma model, CpG-OVA-HAC2 induced dose-responsive prophylactic protection, slowing the tumor growth rate and enhancing overall survival. Upon rechallenge, none of the mice developed new tumors suggesting the development of robust immunological memory and long-lasting protection against repeat infections. CpG-OVA-HAC2 also enhanced survival in mice with established tumors. The results from this work support the potential for CpG-OVA-HAC2 to enhance vaccine delivery.

Efficiency of Chitosan Nanocarriers in Vaccinology for Mucosal Immunization.

The mucosal barrier constitutes a huge surface area, close to 40 m2 in humans, located mostly in the respiratory, gastrointestinal and urogenital tracts and ocular cavities. It plays a crucial role in tissue interactions with the microbiome, dietary antigens and other environmental materials. Effective vaccinations to achieve highly protective mucosal immunity are evolving strategies to counteract several serious diseases including tuberculosis, diphtheria, influenzae B, severe acute respiratory syndrome, Human Papilloma Virus infection and Acquired Immune Deficiency Syndrome. Interestingly, one of the reasons behind the rapid spread of severe acute respiratory syndrome coronavirus 2 variants has been the weakness of local immunization at the level of the respiratory mucosa. Mucosal vaccines can outperform parenteral vaccination as they specifically elicit protective mucosal immune responses blocking infection and transmission. In this scenario, chitosan-based nanovaccines are promising adjuvants-carrier systems that rely on the ability of chitosan to cross tight junctions and enhance particle uptake due to chitosan-specific mucoadhesive properties. Indeed, chitosan not only improves the adhesion of antigens to the mucosa promoting their absorption but also shows intrinsic immunostimulant abilities. Furthermore, by finely tuning the colloidal properties of chitosan, it can provide sustained antigen release to strongly activate the humoral defense. In the present review, we agnostically discuss the potential reasons why chitosan-based vaccine carriers, that efficiently elicit strong immune responses in experimental setups and in some pre-clinical/clinical studies, are still poorly considered for therapeutic formulations.

Nanovaccines against Viral Infectious Diseases.

Infectious diseases have always been regarded as one of the greatest global threats for the last century. The current ongoing COVID-19 pandemic caused by SARS-CoV-2 is living proof that the world is still threatened by emerging infectious diseases. Morbidity and mortality rates of diseases caused by Coronavirus have inflicted devastating social and economic outcomes. Undoubtedly, vaccination is the most effective method of eradicating infections and infectious diseases that have been eradicated by vaccinations, including Smallpox and Polio. To date, next-generation vaccine candidates with novel platforms are being approved for emergency use, such as the mRNA and viral vectored vaccines against SARS-CoV-2. Nanoparticle based vaccines are the perfect candidates as they demonstrated targeted antigen delivery, improved antigen presentation, and sustained antigen release while providing self-adjuvanting functions to stimulate potent immune responses. In this review, we discussed most of the recent nanovaccines that have found success in immunization and challenge studies in animal models in comparison with their naked vaccine counterparts. Nanovaccines that are currently in clinical trials are also reviewed.

Nanoparticle formulation of the fusion protein virus like particles of respiratory syncytial virus stimulates enhanced in vitro antigen presentation and autophagy

Respiratory Syncytial Virus (RSV) is one of the leading causes of bronchiolitis and pneumonia in childrenunder one year globally. As a result, RSV poses a severe burden on healthcare services. Thus, a vaccine for RSV is a global need. Utilizing polymeric nanoparticles as a delivery system for vaccine antigen holds a lot of promise. In this study, the virus like particles of RSV fusion protein (F-VLP) was encapsulated in poly (D, L-lactide-co-glycolide) (PLGA) nanoparticles (NP). The F-VLP NP was formulated using a double emulsion solvent evaporation technique. The optimized NPs had a particle size of 525 ± 10.5 nm and an antigen encapsulation efficiency of 73% ± 10.5. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis showed that the F-VLP was stable post formulation. The F-VLP NP showed a sustained release of the F-VLP antigen for up to a week. In vitro study revealed that the F-VLP NP were non-cytotoxic, and the cellular uptake of the NPs by dendritic cells was observed within 3 h. The F-VLP NP with adjuvant monophosphoryl lipid A (MPL) NP and without MPL NP showed enhanced expression of antigen presentation molecule major histocompatibility complex (MHC)-I and autophagosomes in dendritic cells. In summary, the sustained release of the antigen from the F-VLP NP and the particulate nature of the vaccine resulted in enhanced antigen presentation and induction of autophagy in antigen-presenting cells (APCs).

Differential Dual‐Release Bilayer Microneedles Loaded with Aluminum Adjuvants as a Safe and Effective Vaccine Platform

AbstractAluminum adjuvants are currently the most widely used adjuvants for human vaccines. However, concerns about their safety, such as local irritation at the vaccination site and potential neurotoxicity, have been raised over recent years. Herein, the bilayer microneedles are fabricated using commercially available materials and a simple micromolding preparation method in a differential dual‐release manner for sustained antigen release in the outer layer, and fast release of aluminum in the inner layer. The outer layer here replaces aluminum adjuvants to form an antigen depot, and the rapidly released adjuvants of the inner layer can activate dendritic cells, which effectively reduces the amount of aluminum while retaining their effect. The use of ovalbumin in vivo as the model antigen demonstrates that compared with subcutaneous and intramuscular injections, the bilayer microneedles achieve effective humoral immunity and relatively balanced immune response with less aluminum (1/25 of the dose), which may be related to the mechanical adjuvant effect of the microneedles. Mice treated with the bilayer microneedles show little to no aluminum accumulation in different organs, and no local irritation such as granuloma is observed. The superior vaccination safety and strong immunity using bilayer microneedles make it a promising vaccine platform.

Fabrication and characterization of Chinese yam polysaccharides PLGA nanoparticles stabilized Pickering emulsion as an efficient adjuvant

The Chinese yam polysaccharides PLGA nanoparticles were applied as stabilizers in this study to prepare O/W Pickering emulsion. The optimized preparation conditions were PLGA concentration of 5 mg/mL, ultrasonic power of 50 %, and ultrasonic time of 2 min. The CYP-PPAS emulsion exhibits a raspberry-like morphology with a large number of nanoparticles surrounding the oil droplets. The CYP-PPAS emulsion exhibited outstanding stability at 4 °C and 37 °C for 28 days with high antigen loading efficiency and provided a controlled and sustained release of Chinese yam polysaccharides and OVA antigen in vitro. CYP-PPAS/OVA elicited robust antigen-specific immune response and induced a mixed Th1/Th2 immune response after immunization. Furthermore, CYP-PPAS/OVA caused a high CD4+/CD8+ ratio leading in increased activation of splenic T lymphocytes subpopulations. Moreover, CYP-PPAS is a safe vaccination adjuvant with high safety profile in vivo. Thus, the novel designed Pickering emulsion CYP-PPAS was a safe and effective adjuvant for inducing the strong and long-term immune response.

Programmed polymersomes with spatio-temporal delivery of antigen and dual-adjuvants for efficient dendritic cells-based cancer immunotherapy

Since antigen and adjuvant are rapid clearance in vivo, insufficient delivery to induce dendritic cells (DCs) maturation and cross-presentation, as well as limited migration efficiency of DCs to secondary lymph organs, greatly hinders the development of DCs-based immunotherapy. Herein, PCL-PEG-PCL polymersomes (PCEP-PS) as antigen and adjuvants delivery nanoplatforms (IMO-PS) were well-designed, which can electrostatically adsorb OVA antigen on the surface via DOTAP lipid and effectively encapsulate OVA antigen into the inner hydrophilic cavity to achieve both initial antigen exposure as well as slow and sustained antigen release, incorporate MPLA within the lipid layer to ligate with extracellular TLR4 of DCs as well as encapsulate IMQ in the hydrophobic membrane to ligate with intracellular TLR7/8 of DCs for activating synergistic immune responses via different signaling pathways. The IMO-PS significantly improved antigen uptake, promoted DCs maturation and cytokines production. DCs treated with IMO-PS could enhance migration into draining lymphoid nodes, and eventually induced antigen-specific CD8+ and CD4+ T cell responses and OVA-specific cytotoxic T lymphocyte (CTL) responses. Prophylactic vaccination of EG7-OVA tumor-bearing mice by IMO-PS + DCs significantly extended tumor-free time, effectively suppressed tumor growth, and greatly extended median survival time. The strategy may provide an effective nanoplatform for co-delivery antigen and dual-adjuvants in a spatio-temporally programmed manner for DC-based cancer immunotherapy.

Enhanced cancer immunotherapy by microneedle patch-assisted delivery of HBc VLPs based cancer vaccine

Tumor vaccines have made a significant breakthrough in clinical trials of cancer therapy, but have shown limited efficacy. Herein, we develop a novel tumor vaccine delivery strategy through a biodegradable microneedle patch (MN), which allows sustained release of tumor antigen and induces long term anti-tumor response. A tumor antigen peptide (OVA257–264: SIINFEKL) was fused with hepatitis B core (HBc) protein virus like particles (OVA-HBc VLPs) to increase the immunogenicity of tumor antigen. Mesoporous silica nanoparticles (MSN) were adopted as a vaccine adjuvant for enhancing the function of dendritic cells (DCs). OVA-HBc VLPs and MSN were capsulated into microneedles together [MSN/OVA-HBc@MN]. MSN/OVA-HBc@MN could significantly stimulate DC maturation and increase the presentation of OVA on DCs in vitro. MSN/OVA-HBc@MN can effectively stimulate antigen specific anti-tumor immune response and be used as prophylactic vaccines to effectively inhibit tumor formation. Moreover, the addition of CpG-DNA can enhance the therapeutic effect of MSN/OVA-HBc@MN in distant tumors and long term immune memory effect. Our results thus demonstrate that MSN-CpG/OVA-HBc@MN could be as a potential tumor-specific vaccination platform for tumor therapy.

A recombinant commensal bacteria elicits heterologous antigen-specific immune responses during pharyngeal carriage.

The human nasopharynx contains a stable microbial ecosystem of commensal and potentially pathogenic bacteria, which can elicit protective primary and secondary immune responses. Experimental intranasal infection of human adults with the commensal Neisseria lactamica produced safe, sustained pharyngeal colonization. This has potential utility as a vehicle for sustained release of antigen to the human mucosa, but commensals in general are thought to be immunologically tolerated. Here, we show that engineered N. lactamica, chromosomally transformed to express a heterologous vaccine antigen, safely induces systemic, antigen-specific immune responses during carriage in humans. When the N. lactamica expressing the meningococcal antigen Neisseria Adhesin A (NadA) was inoculated intranasally into human volunteers, all colonized participants carried the bacteria asymptomatically for at least 28 days, with most (86%) still carrying the bacteria at 90 days. Compared to an otherwise isogenic but phenotypically wild-type strain, colonization with NadA-expressing N. lactamica generated NadA-specific immunoglobulin G (IgG)- and IgA-secreting plasma cells within 14 days of colonization and NadA-specific IgG memory B cells within 28 days of colonization. NadA-specific IgG memory B cells were detected in peripheral blood of colonized participants for at least 90 days. Over the same period, there was seroconversion against NadA and generation of serum bactericidal antibody activity against a NadA-expressing meningococcus. The controlled infection was safe, and there was no transmission to adult bedroom sharers during the 90-day period. Genetically modified N. lactamica could therefore be used to generate beneficial immune responses to heterologous antigens during sustained pharyngeal carriage.

Programmed nanoparticle-loaded microparticles for effective antigen/adjuvant delivery

A microscale vaccine containing SiO2 nanoparticles loaded in CaCO3 microparticles was constructed using the co-precipitation method. The antigen ovalbumin (OVA) was covalently conjugated with SiO2 nanoparticles, and these nanoparticles and CpG were co-encapsulated into CaCO3 microparticles, generating a vaccine with a size of approximately 5.2μm. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), elemental mapping, and Fourier transform infrared (FTIR) analyses confirmed the successful preparation of the microscale vaccine; the vaccine had good storage stability without sustained antigen release, and negligible cytotoxicity to dendritic cells (DCs) and macrophages. Compared to SiO2 nanoparticles, the microscale vaccine can significantly improve antigen/adjuvant uptake. DCs internalized the entire microscale vaccine into lysosomes via macropinocytosis, and an increase in antigen endo/lysosomal escape was observed by confocal laser scanning microscopy (CLSM). Specifically, DCs pulsed with the vaccine were fully mature, expressing high levels of costimulatory molecules (CD40, CD80, and CD86), MHC II, and MHC I and secreting high levels of proinflammatory cytokines (IL-12, TNF-α, IL-1β, and IL-6). In addition, the vaccine had good in vivo biocompatibility, could protect the antigen from rapid degradation, and increased the retention time in lymph nodes. SiO2 nanoparticles-in-CaCO3 microparticles were an excellent carrier for antigen and adjuvant delivery. Hopefully, this study can provide some information on the design of microscale carriers for vaccine delivery systems.

Engineering a sustained release vaccine with a pathogen-mimicking manner for robust and durable immune responses

Sustained release vaccine carriers can facilitate an increased interaction time between the antigen and immune system to strengthen immune responses, but their promotion on adaptive immune responses, especially cellular immunity, are still unfavorable. Herein, we report a sustained antigen delivery vector, which carries abundant antigens, a nucleic acid adjuvant and pathogen-associated molecular patterns to simulate a natural pathogen to reinforce immune responses. Specifically, murine colorectal cancer cells MC38 lysate and Toll-like receptor 9 agonist CpG are loaded into yeast derived β-glucan particles (GPs). After vaccination, these particles can form a vaccine depot that continuously release the antigen similar to the traditional aluminum hydroxide gel, but recruit more immune cells and induce more cytokine secretion at the injection site. Stronger antibody responses, Th1 and Th17 biased cellular immunity and immune memory are achieved compared with aluminum hydroxide gel. More importantly, treatment with these particles significantly suppress tumor growth in a therapeutic tumor model. This work shed light on the efficacy of combining sustained antigen release with pathogen-mimicking manner in vaccine design.

Development and optimisation of hepatitis B recombinant antigen loaded chitosan nanoparticles as an adjuvant using the response surface methodology

The main purpose of this Letter was to develop and optimise recombinant hepatitis B antigen-loaded chitosan nanoparticles (rHBsAg-CS NPs) as a new adjuvant for hepatitis B vaccine through designing by response surface methodology (RSM). The NPs were prepared by employing ionic gelation technique. RSM was utilised by selecting the independent variablesincluding the concentration of CS, tripolyphosphate and antigen concentration as well as pH and homogenisation speed to obtain maximum encapsulation efficiency (EE) and loading capacity (LC). EE and LC of the optimised preparation were 93.2 ± 1.1 and 25.6 ± 1.38%, respectively. Optimised NPs showed spherical shape, particle size of 187 ± 14 nm and positive zeta potential (+31.3 ± 1.5 mV). In vitro release profile of optimised formulation revealed an initial burst, followed by a slow sustained antigen release. Cell viability assay indicated that the toxicity of NPs was concentration-dependent. SDS-PAGE analysis confirmed the structural stability and integrity of the released antigen. ELISA and Ouchterlony double immunodiffusion tests of released antigen showed that the antigenicity was preserved during the process of NP formation.

Development of Nanogel-based Nasal Vaccine against Pneumonia

Abstract Streptococcus pneumoniae (S. pneumoniae) cause pneumococcal disease in children and adults all over the world. Although there are vaccines comprising several pneumococcal polysaccharides in clinical use, they cannot cover the broad protections. Recently we established the cationic nanogel-based nasal vaccine against Pneumonia using a recombinant protein of pneumococcal surface protein A (PspA). We have designed three PspA chimeric antigens for trivalent vaccine and combined them with a cationic nanogel, a novel drug delivery system which adhere to the epithelial layer of the nasal cavity after nasal immunization and elicit the effective immunity by sustained antigen release. Indeed, the PspA nanogel vaccine induced not only the antigen-specific IgG in the body but also the antigen-specific secretory IgA (SIgA) at the mucosal surfaces such as nasal cavity where the entrance of pathogens. Both induced antigen-specific IgG and SIgA could bind to various serotypes of S. pneumoniae, indicating that these antibodies have neutralizing activity against broad types of S. pneumoniae. Moreover, the vaccinated mice were protected from infections by a several types of S. pneumoniae, and the nasal vaccine exhibited protective efficacy in some strains which cannot be covered by the current vaccines. Thus, our findings demonstrated the nasally administered PspA nanogel vaccine effectively elicit a protective immunity and provide a broad protection against S. pneumoniae infections.

Injectable Polypeptide Hydrogel Depot System for Assessment of the Immune Response–Inducing Efficacy of Sustained Antigen Release Alone

Injectable Polypeptide Hydrogel Depot System for Assessment of the Immune Response–Inducing Efficacy of Sustained Antigen Release Alone