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Innate immune defense mechanisms against infection and cancer encompass the modulation of pattern recognition receptor (PRR)‐mediated inflammation, including upregulation of various transcription factors and the activation of pro‐inflammatory pathways important for immune surveillance. Dysfunction of PRRs‐mediated signaling has been implicated in cancer and autoimmune diseases, while the overactivation of PRRs‐driven responses during infection can lead to devastating consequences such as acute lung injury or sepsis. We used crystal structure‐based design to develop immunomodulatory lipopolysaccharide (LPS) mimetics targeting one of the ubiquitous PRRs, Toll‐like Receptor 4 (TLR4). Taking advantage of an exo‐anomeric conformation and specific molecular shape of synthetic nonreducing β,β‐diglucosamine, which was investigated by NMR, we developed two sets of lipid A mimicking glycolipids capable of either potently activating innate immune responses or inhibiting pro‐inflammatory signaling. Stereoselective 1,1′‐glycosylation towards fully orthogonally protected nonreducing GlcNβ(1↔1′)βGlcN followed by stepwise assembly of differently functionalised phosphorylated glycolipids provided biologically active molecules that were evaluated for their ability to trigger or to inhibit cellular innate immune responses. Two LPS mimetics, identified as potent TLR4‐specific inducers of the intracellular signaling pathways, serve as vaccine adjuvant‐ and immunotherapy candidates, while anionic glycolipids with TLR4‐inhibitory potential hold therapeutic promise for the management of acute or chronic inflammation. [ABSTRACT FROM AUTHOR]

Abstract Biomaterials are substances that can be injected, implanted, or applied to the surface of tissues in biomedical applications and have the ability to interact with biological systems to initiate therapeutic responses. Biomaterial-based vaccine delivery systems possess robust packaging capabilities, enabling sustained and localized drug release at the target site. Throughout the vaccine delivery process, they can contribute to protecting, stabilizing, and guiding the immunogen while also serving as adjuvants to enhance vaccine efficacy. In this article, we provide a comprehensive review of the contributions of biomaterials to the advancement of vaccine development. We begin by categorizing biomaterial types and properties, detailing their reprocessing strategies, and exploring several common delivery systems, such as polymeric nanoparticles, lipid nanoparticles, hydrogels, and microneedles. Additionally, we investigated how the physicochemical properties and delivery routes of biomaterials influence immune responses. Notably, we delve into the design considerations of biomaterials as vaccine adjuvants, showcasing their application in vaccine development for cancer, acquired immunodeficiency syndrome, influenza, corona virus disease 2019 (COVID-19), tuberculosis, malaria, and hepatitis B. Throughout this review, we highlight successful instances where biomaterials have enhanced vaccine efficacy and discuss the limitations and future directions of biomaterials in vaccine delivery and immunotherapy. This review aims to offer researchers a comprehensive understanding of the application of biomaterials in vaccine development and stimulate further progress in related fields. Graphical Abstract

Abstract As a major component of innate immunity and a positive regulator of interferons, the Stimulator of interferon gene (STING) has an immunotherapy potential to govern a variety of infectious diseases. Despite the recent advances regarding vaccines against COVID-19, nontoxic novel adjuvants with the potential to enhance vaccine efficacy are urgently desired. In this connection, it has been well-documented that STING agonists are applied to combat COVID-19. This approach is of major significance for boosting immune responses most likely through an autophagy-dependent manner in susceptible individuals against infection induced by severe acute respiratory syndrome Coronavirus (SARS‑CoV‑2). Given that STING agonists exert substantial immunomodulatory impacts under a wide array of pathologic conditions, these agents could be considered novel adjuvants for enhancing immunogenicity against the SARS-related coronavirus. Here, we intend to discuss the recent advances in STING agonists’ recruitment to boost innate immune responses upon vaccination against SARS-related coronavirus infections. In light of the primordial role of autophagy modulation, the potential of being an antiviral vaccine adjuvant was also explored.

With the COVID-19 pandemic, the importance of vaccines has been widely recognized and has led to increased research and development efforts. Vaccines also play a crucial role in cancer treatment by activating the immune system to target and destroy cancer cells. However, enhancing the efficacy of cancer vaccines remains a challenge. Adjuvants, which enhance the immune response to antigens and improve vaccine effectiveness, have faced limitations in recent years, resulting in few novel adjuvants being identified. The advancement of artificial intelligence (AI) technology in drug development has provided a foundation for adjuvant screening and application, leading to a diversification of adjuvants. This article reviews the significant role of tumor vaccines in basic research and clinical treatment and explores the use of AI technology to screen novel adjuvants from databases. The findings of this review offer valuable insights for the development of new adjuvants for next-generation vaccines. [ABSTRACT FROM AUTHOR]

Biomaterials are substances that can be injected, implanted, or applied to the surface of tissues in biomedical applications and have the ability to interact with biological systems to initiate therapeutic responses. Biomaterial-based vaccine delivery systems possess robust packaging capabilities, enabling sustained and localized drug release at the target site. Throughout the vaccine delivery process, they can contribute to protecting, stabilizing, and guiding the immunogen while also serving as adjuvants to enhance vaccine efficacy. In this article, we provide a comprehensive review of the contributions of biomaterials to the advancement of vaccine development. We begin by categorizing biomaterial types and properties, detailing their reprocessing strategies, and exploring several common delivery systems, such as polymeric nanoparticles, lipid nanoparticles, hydrogels, and microneedles. Additionally, we investigated how the physicochemical properties and delivery routes of biomaterials influence immune responses. Notably, we delve into the design considerations of biomaterials as vaccine adjuvants, showcasing their application in vaccine development for cancer, acquired immunodeficiency syndrome, influenza, corona virus disease 2019 (COVID-19), tuberculosis, malaria, and hepatitis B. Throughout this review, we highlight successful instances where biomaterials have enhanced vaccine efficacy and discuss the limitations and future directions of biomaterials in vaccine delivery and immunotherapy. This review aims to offer researchers a comprehensive understanding of the application of biomaterials in vaccine development and stimulate further progress in related fields. [ABSTRACT FROM AUTHOR]

Many natural saponins demonstrate immunostimulatory adjuvant activities, but they also have some inherent drawbacks that limit their clinical use. To overcome these limitations, extensive structure-activity-relationship (SAR) studies have been conducted. The SAR studies of QS-21 and related saponins reveal that their respective fatty side chains are crucial for potentiating a strong cellular immune response. Replacing the hydrolytically unstable ester side chain in the C28 oligosaccharide domain with an amide side chain in the same domain or in the C3 branched trisaccharide domain is a viable approach for generating robust semisynthetic saponin immunostimulants. Given the striking resemblance of natural momordica saponins (MS) I and II to the deacylated Quillaja Saponaria (QS) saponins (e.g., QS-17, QS-18, and QS-21), incorporating an amide side chain into the more sustainable MS, instead of deacylated QS saponins, led to the discovery of MS-derived semisynthetic immunostimulatory adjuvants VSA-1 and VSA-2. This review focuses on the authors' previous work on SAR studies of QS and MS saponins. [ABSTRACT FROM AUTHOR]

• Lactococcus lactis can express and display a flagellin mutant on its surface. • L. lactis expressing FliC131 stimulates hTLR5; has added adjuvanticity. • L. lactis expressing FliC131 induces IgA production in the mucosa and systemically. • Cell wall-derived particles from L. lactis contain biologically active FliC131. • Cell wall-derived particles can be stored long-term, retaining biological activity. Research on innovative mucosal adjuvants is essential to develop new vaccines for safe mucosal application. In this work, we propose the development of a Lactococcus lactis that expresses a variant of flagellin on its surface (FliC131*), to increase the adjuvanticity of the living cell and cell wall-derived particles (CWDP). We optimized the expression of FliC131*, and confirmed its identity and localization by Western blot and flow cytometry. We also generated CWDP containing FliC131* (CDWP-FliC131*) and evaluated their storage stability. Lastly, we measured the human TLR5 stimulating activity in vitro and assessed the adjuvanticity in vivo using ovalbumin (OVA) as a model antigen. As a result, we generated L. lactis/ pCWA-FliC131*, that expresses and displays FliC131* on its surface, obtained the corresponding CWDP-FliC131*, and showed that both activated hTLR5 in vitro in a dose-dependent manner. Furthermore, CWDP-FliC131* retained this biological activity after being lyophilized and stored for a year. Finally, intranasal immunization of mice with OVA plus live L. lactis/ pCWA-FliC131* or CWDP-FliC131* induced OVA-specific IgG and IgA in serum, intestinal lavages, and bronchoalveolar lavages. Our work demonstrates the potential of this recombinant L. lactis with an enhanced adjuvant effect, prompting its further evaluation for the design of novel mucosal vaccines. [ABSTRACT FROM AUTHOR]

Vaccination is an effective way to control many infectious diseases in fish. Israeli fish farming has successfully used two vaccines over the last 30 years and has no problem with the side effects of vaccination. However, after introducing new species, a new problem emerged: these fish, after vaccination, demonstrated peritoneal lesions such as granulomas. At the same time, the fish did not show retarded growth or suffering during the fattening period. This study was conducted to establish the connection between vaccination and the appearance of granulomas. Evidence drawn from this research work and comparing vaccinated and non-vaccinated fish confirms that intraperitoneal granulomas do not impact the growth, performance, or fish fillet quality at harvest. [ABSTRACT FROM AUTHOR]

Adjuvants are of critical value in vaccine development as they act on enhancing immunogenicity of antigen and inducing long‐lasting immunity. However, there are only a few adjuvants that have been approved for clinical use, which highlights the need for exploring and developing new adjuvants to meet the growing demand for vaccination. Recently, emerging evidence demonstrates that the cGAS‐STING pathway orchestrates innate and adaptive immunity by generating type I interferon responses. Many cGAS‐STING pathway agonists have been developed and tested in preclinical research for the treatment of cancer or infectious diseases with promising results. As adjuvants, cGAS‐STING agonists have demonstrated their potential to activate robust defense immunity in various diseases, including COVID‐19 infection. This review summarized the current developments in the field of cGAS‐STING agonists with a special focus on the latest applications of cGAS‐STING agonists as adjuvants in vaccination. Potential challenges were also discussed in the hope of sparking future research interests to further the development of cGAS‐STING as vaccine adjuvants. [ABSTRACT FROM AUTHOR]

As a major component of innate immunity and a positive regulator of interferons, the Stimulator of interferon gene (STING) has an immunotherapy potential to govern a variety of infectious diseases. Despite the recent advances regarding vaccines against COVID-19, nontoxic novel adjuvants with the potential to enhance vaccine efficacy are urgently desired. In this connection, it has been well-documented that STING agonists are applied to combat COVID-19. This approach is of major significance for boosting immune responses most likely through an autophagy-dependent manner in susceptible individuals against infection induced by severe acute respiratory syndrome Coronavirus (SARS‑CoV‑2). Given that STING agonists exert substantial immunomodulatory impacts under a wide array of pathologic conditions, these agents could be considered novel adjuvants for enhancing immunogenicity against the SARS-related coronavirus. Here, we intend to discuss the recent advances in STING agonists' recruitment to boost innate immune responses upon vaccination against SARS-related coronavirus infections. In light of the primordial role of autophagy modulation, the potential of being an antiviral vaccine adjuvant was also explored. [ABSTRACT FROM AUTHOR]

Particulate aluminum salts have long occupied a central place worldwide as inexpensive immunostimulatory adjuvants that enable induction of protective immunity for vaccines. Despite their huge benefits and safety, the particulate structures of aluminum salts require transportation and storage at temperatures between 2 °C and 8 °C, and they all have exquisite sensitivity to damage caused by freezing. Here, we propose to solve the critical freezing vulnerability of particulate aluminum salt adjuvants by introducing soluble aluminum salts as adjuvants. The solubility properties of fresh and frozen aluminum chloride and aluminum triacetate, each buffered optimally with sodium acetate, were demonstrated with visual observations and with UV–vis scattering analyses. Two proteins, A244 gp120 and CRM197, adjuvanted either with soluble aluminum chloride or soluble aluminum triacetate, each buffered by sodium acetate at pH 6.5–7.4, elicited murine immune responses that were equivalent to those obtained with Alhydrogel®, a commercial particulate aluminum hydroxide adjuvant. The discovery of the adjuvanticity of soluble aluminum salts might require the creation of a new adjuvant mechanism for aluminum salts in general. However, soluble aluminum salts might provide a practical substitute for particulate aluminum salts as vaccine adjuvants, thereby avoiding the risk of inactivation of vaccines due to accidental freezing of aluminum salt particles. [ABSTRACT FROM AUTHOR]

Vaccine immunogenicity is affected by a variety of factors. Melatonin has been reported to affect immune responses to vaccines and infection. This was a randomized open-label trial – in which adults scheduled to receive the influenza vaccine were randomized to 5 mg melatonin or control to evaluate the effect of post-vaccination melatonin on humoral (hemagglutination-inhibition assays, HAI) and cellular (FluoroSpot) vaccine-specific cytokine responses 14–21 days post-vaccination. A total of 108 participants (melatonin treatment group: 53; control group: 55) completed the study. The groups were similar in baseline characteristics, including sleep as measured by the Pittsburgh Sleep Quality Index. Seroconversion rates or geometric mean fold rises (GMFR) in HAI titers did not vary by treatment group. There were also no statistically significant differences between pre- and post-vaccination levels of interferon gamma (IFN-γ) or granzyme B (GzB) by treatment; however, there was a significantly higher fold rise in the double secretor (IFN-γ + GzB) peripheral blood mononuclear cells for influenza vaccine in subjects taking daily melatonin (GMFR 1.7; 95% CI 1.3, 2.3) compared to those who did not (GMFR 0.9; 95% CI 0.7, 1.1) (p

The cGAS-STING pathway and the Mevalonate Pathway are druggable targets for vaccine adjuvant discovery. Manganese (Mn) and bisphosphonates are known to exert adjuvant effects by targeting these two pathways, respectively. This study found the synergistic potential of the two pathways in enhancing immune response. Risedronate (Ris) significantly amplified the Mn adjuvant early antibody response by 166-fold and fortified its cellular immunity. However, direct combination of Mn2+ and Ris resulted in increased adjuvant toxicity (40% mouse mortality). By the combination of doping property of hydroxyapatite (HA) and its high affinity for Ris, we designed Ris-functionalized Mn-HA micro-nanoparticles as an organic-inorganic hybrid adjuvant, named MnHARis. MnHARis alleviated adjuvant toxicity (100% vs. 60% survival rate) and exhibited good long-term stability. When formulated with the varicella-zoster virus glycoprotein E (gE) antigen, MnHARis triggered a 274.3-fold increase in IgG titers and a 61.3-fold surge in neutralization titers while maintaining a better long-term humoral immunity compared to the aluminum adjuvant. Its efficacy spanned other antigens, including ovalbumin, HPV18 VLP, and SARS-CoV-2 spike protein. Notably, the cellular immunity elicited by the group of gE + MnHARis was comparable to the renowned Shingrix®. Moreover, intratumoral co-administration with an anti-trophoblast cell surface antigen 2 nanobody revealed synergistic antitumor capabilities. These findings underscore the potential of MnHARis as a potent adjuvant for augmenting vaccine immune responses and improving cancer immunotherapy outcomes. Risedronate (Ris)-functionalized manganese (Mn2+)-HA adjuvant was designed, named MnHARis. The Mn2+ and Ris co-dopion successfully transformed HA crystalline rodlike precipitation into Mn/CaRis amorphous precipitates. MnHARis enhanced antigen presenting cells (APCs) activation and induced robust humoral and cellular immunity in subunit vaccines. Moreover, MnHARis demonstrated a synergistic anti-cancer effect when co-administered intratumorally with nanobody. [Display omitted] [ABSTRACT FROM AUTHOR]

Bacterial lipopolysaccharides (LPSs) have been shown to promote enteric viral infections. This study tested the hypothesis that elevated levels of bacterial LPS improve oral rotavirus vaccine replication in South African infants. Stool samples were collected from infants a week after rotavirus vaccination to identify vaccine virus shedders (n = 43) and non-shedders (n = 35). Quantitative real-time PCR was used to assay for selected LPS-rich bacteria, including Serratia marcescens, Pseudomonas aeruguinosa and Klebsiella pneumonia, and to measure the gene expression of bacterial LPS, host Toll-like Receptor 4 (TLR4) and Interleukin-8 (IL-8). The abundance of selected LPS-rich bacteria was significantly higher in vaccine shedders (median log 4.89 CFU/g, IQR 2.84) compared to non-shedders (median log 3.13 CFU/g, IQR 2.74), p = 0.006. The TLR4 and IL-8 gene expressions were increased four- and two-fold, respectively, in vaccine shedders versus non-shedders, but no difference was observed in the bacterial LPS expression, p = 0.09. A regression analysis indicated a significant association between the abundance of selected LPS-rich bacteria and vaccine virus shedding (Odds ratio 1.5, 95% CI = 1.10–1.89), p = 0.002. The findings suggest that harbouring higher counts of LPS-rich bacteria can increase the oral rotavirus vaccine take in infants. [ABSTRACT FROM AUTHOR]

Introduction: Conventional foot-and-mouth disease (FMD) vaccines have been developed to enhance their effectiveness; however, several drawbacks remain, such as slow induction of antibody titers, short-lived immune response, and local side effects at the vaccination site. Therefore, we created a novel FMD vaccine that simultaneously induces cellular and humoral immune responses using the Dectin-2 agonist, D-galacto-D-mannan, as an adjuvant. Methods: We evaluated the innate and adaptive (cellular and humoral) immune responses elicited by the novel FMD vaccine and elucidated the signaling pathway involved both in vitro and in vivo using mice and pigs, as well as immune cells derived from these animals. Results: D-galacto-D-mannan elicited early, mid-, and long-term immunity via simultaneous induction of cellular and humoral immune responses by promoting the expression of immunoregulatory molecules. D-galacto-D-mannan also enhanced the immune response and coordinated vaccine-mediated immune response by suppressing genes associated with excessive inflammatory responses, such as nuclear factor kappa B, via Sirtuin 1 expression. Conclusion: Our findings elucidated the immunological mechanisms induced by D-galacto-D-mannan, suggesting a background for the robust cellular and humoral immune responses induced by FMD vaccines containing D-galacto- D-mannan. Our study will help to facilitate the improvement of conventional FMD vaccines and the design of next-generation FMD vaccines. [ABSTRACT FROM AUTHOR]

• Immunogenic Activity Study: Exploring how solvent removal impacts the immunogenic activity of vaccine antigens in SBA-15. • Effective antigen incorporation: The study shows BSA in SBA-15 enhances immunogenicity, surpassing pure antigen. • Powdered Storage Potential: SBA-15:BSA, a promising solid vaccine. Simplified storage, reduced costs, and ease of use. • Advancing Vaccine Industry: Insights on storage/stability boost vaccine production, advancing global health. In an effort to develop efficient vaccine formulations, the use of ordered mesoporous silica (SBA-15) as an antigen carrier has been investigated. SBA-15 has required properties such as high surface area and pore volume, including narrow pore size distribution to protect antigens inside its matrix. This study aimed to examine the impact of solvent removal methods, specifically freeze-drying and evaporation on the intrinsic properties of an immunogenic complex. The immunogenic complexes, synthesized and incorporated with BSA, were characterized by various physicochemical techniques. Small Angle X-ray Scattering measurements revealed the characteristic reflections associated to pure SBA-15, indicating the preservation of the silica mesostructured following BSA incorporation and the formation of BSA aggregates within the macropore region. Nitrogen Adsorption Isotherm measurements demonstrated a decrease in surface area and pore volume for all samples, indicating that the BSA was incorporated into the SBA-15 matrix. Fluorescence spectroscopy evidenced that the tryptophan residues in BSA inside SBA-15 or in solution displayed similar spectra, showing the preservation of the aromatic residues' environment. The Circular Dichroism spectra of BSA in both conditions suggest the preservation of its native secondary structure after the encapsulation process. The immunogenic analysis with the detection of anti-BSA IgG did not give any significant difference between the non-dried, freeze-dried or evaporated groups. However, all groups containing BSA and SBA-15 showed results almost three times higher than the groups with pure BSA (control group). These facts indicate that none of the BSA incorporation methods interfered with the immunogenicity of the complex. In particular, the freeze-dried process is regularly used in the pharmaceutical industry, therefore its adequacy to produce immunogenic complexes was proved Furthermore, the results showed that SBA-15 increased the immunogenic activity of BSA. [ABSTRACT FROM AUTHOR]

Co-delivery of antigens and adjuvants to the same antigen-presenting cells (APCs) can significantly improve the efficacy and safety profiles of vaccines. Here, we report amine-grafted silica nanoparticles (A-SNP) as a tunable vaccine co-delivery platform for TLR7/8 agonists along with the recombinant influenza antigen hemagglutinin H7 (H7) to APCs. A-SNP of two different sizes (50 and 200 nm) were prepared and coated with INI-4001 at different coating densities, followed by co-adsorption of H7. Both INI-4001 and H7 showed >90% adsorption to the tested A-SNP formulations. TNF-α and IFN-α cytokine release by human peripheral blood mononuclear cells as well as TNF-α, IL-6, and IL-12 release by mouse bone marrow-derived dendritic cells revealed that the potency of the INI-4001-adsorbed A-SNP (INI-4001/A-SNP) formulations was improved relative to aqueous formulation control. This improved potency was dependent on particle size and ligand coating density. In addition, slow-release profiles of INI-4001 were measured from INI-4001/A-SNP formulations in plasma with 30–50% INI-4001 released after 7 days. In vivo murine immunization studies demonstrated significantly improved H7-specific humoral and Th1/Th17-polarized T cell immune responses with no observed adverse reactions. Low-density 50 nm INI-4001/A-SNP elicited significantly higher IFN-γ and IL-17 induction over that of the H7 antigen-only group and INI-4001 aqueous formulation controls. In summary, this work introduces an effective and biocompatible SNP-based co-delivery platform that enhances the immunogenicity of TLR7/8 agonist-adjuvanted subunit influenza vaccines. [ABSTRACT FROM AUTHOR]

Abstract Aluminium adjuvants are commonly used in vaccines to stimulate the immune system, but they have limited ability to promote cellular immunity which is necessary for clearing viral infections like hepatitis B. Current adjuvants that do promote cellular immunity often have undesired side effects due to the immunostimulants they contain. In this study, a hybrid polymer lipid nanoparticle (HPLNP) was developed as an efficient adjuvant for the hepatitis B surface antigen (HBsAg) virus-like particle (VLP) vaccine to potentiate both humoral and cellular immunity. The HPLNP is composed of FDA approved polyethylene glycol-b-poly (l-lactic acid) (PEG-PLLA) polymer and cationic lipid 1, 2-dioleoyl-3-trimethylammonium-propane (DOTAP), and can be easily prepared by a one-step method. The cationic optimised vaccine formulation HBsAg/HPLNP (w/w = 1/600) can maximise the cell uptake of the antigen due to the electrostatic adsorption between the vaccine nanoparticle and the cell membrane of antigen-presenting cells. The HPLNP prolonged the retention of the antigen at the injection site and enhanced the lymph node drainage of antigen, resulting in a higher concentration of serum anti-HBsAg IgG compared to the HBsAg group or the HBsAg/Al group after the boost immunisation in mice. The HPLNP also promoted a strong Th1-driven immune response, as demonstrated by the significantly improved IgG2a/IgG1 ratio, increased production of IFN-γ, and activation of CD4 + and CD8 + T cells in the spleen and lymph nodes. Importantly, the HPLNP demonstrated no systemic toxicity during immunisation. The advantages of the HPLNP, including good biocompatibility, easy preparation, low cost, and its ability to enhance both humoral and cellular immune responses, suggest its suitability as an efficient adjuvant for protein-based vaccines such as HBsAg-VLP. These findings highlight the promising potential of the HPLNP as an HBV vaccine adjuvant, offering an alternative to aluminium adjuvants currently used in vaccines.

Particulate aluminum salts have long occupied a central place worldwide as inexpensive immunostimulatory adjuvants that enable induction of protective immunity for vaccines. Despite their huge benefits and safety, the particulate structures of aluminum salts require transportation and storage at temperatures between 2 °C and 8 °C, and they all have exquisite sensitivity to damage caused by freezing. Here, we propose to solve the critical freezing vulnerability of particulate aluminum salt adjuvants by introducing soluble aluminum salts as adjuvants. The solubility properties of fresh and frozen aluminum chloride and aluminum triacetate, each buffered optimally with sodium acetate, were demonstrated with visual observations and with UV–vis scattering analyses. Two proteins, A244 gp120 and CRM197, adjuvanted either with soluble aluminum chloride or soluble aluminum triacetate, each buffered by sodium acetate at pH 6.5–7.4, elicited murine immune responses that were equivalent to those obtained with Alhydrogel®, a commercial particulate aluminum hydroxide adjuvant. The discovery of the adjuvanticity of soluble aluminum salts might require the creation of a new adjuvant mechanism for aluminum salts in general. However, soluble aluminum salts might provide a practical substitute for particulate aluminum salts as vaccine adjuvants, thereby avoiding the risk of inactivation of vaccines due to accidental freezing of aluminum salt particles.

Background World Health Organization recommend the use of malaria vaccine, Mosquirix, as a malaria prevention strategy. However, Mosquirix has failed to reduce the global burden of malaria because of its inefficacy. The Mosquirix vaccine's modest effectiveness against malaria, 36% among kids aged 5 to 17 months who need at least four doses, fails to aid malaria eradication. Therefore, highly effective and efficacious malaria vaccines are required. The well-characterized P. falciparum circumsporozoite surface protein can be used to discover adjuvants that can increase the efficacy of Mosquirix. Therefore, the study sought to undertake an in-silico discovery of Plasmodium falciparum circumsporozoite surface protein inhibitors with pharmacological properties on Mosquirix using hierarchical virtual screening and molecular dynamics simulation. Results Monoclonal antibody L9, an anti-Plasmodium falciparum circumsporozoite surface protein molecule, was used to identify Plasmodium falciparum circumsporozoite surface protein inhibitors with pharmacological properties on Mosquirix during a virtual screening process in ZINCPHARMER that yielded 23 hits. After drug-likeness and absorption, distribution, metabolism, excretion, and toxicity property analysis in the SwissADME web server, only 9 of the 23 hits satisfied the requirements. The 9 compounds were docked with Plasmodium falciparum circumsporozoite surface protein using the PyRx software to understand their interactions. ZINC25374360 (-8.1 kcal/mol), ZINC40144754 (-8.3 kcal/mol), and ZINC71996727 (-8.9 kcal/mol) bound strongly to Plasmodium falciparum circumsporozoite surface protein with binding affinities of less than -8.0 kcal/mol. The stability of these molecularly docked Plasmodium falciparum circumsporozoite surface protein-inhibitor complexes were assessed through molecular dynamics simulation using GROMACS 2022. ZINC25374360 and ZINC71996727 formed stable complexes with Plasmodium falciparum circumsporozoite surface protein. They were subjected to in vitro validation for their inhibitory potential. The IC50 values ranging between 250 and 350 ng/ml suggest inhibition of parasite development. Conclusion Therefore, the two Plasmodium falciparum circumsporozoite surface protein inhibitors can be used as vaccine adjuvants to increase the efficacy of the existing Mosquirix vaccine. Nevertheless, additional in vivo tests, structural optimization studies, and homogenization analysis are essential to determine the anti-plasmodial action of these adjuvants in humans. [ABSTRACT FROM AUTHOR]

Aluminium adjuvants are commonly used in vaccines to stimulate the immune system, but they have limited ability to promote cellular immunity which is necessary for clearing viral infections like hepatitis B. Current adjuvants that do promote cellular immunity often have undesired side effects due to the immunostimulants they contain. In this study, a hybrid polymer lipid nanoparticle (HPLNP) was developed as an efficient adjuvant for the hepatitis B surface antigen (HBsAg) virus-like particle (VLP) vaccine to potentiate both humoral and cellular immunity. The HPLNP is composed of FDA approved polyethylene glycol-b-poly (l-lactic acid) (PEG-PLLA) polymer and cationic lipid 1, 2-dioleoyl-3-trimethylammonium-propane (DOTAP), and can be easily prepared by a one-step method. The cationic optimised vaccine formulation HBsAg/HPLNP (w/w = 1/600) can maximise the cell uptake of the antigen due to the electrostatic adsorption between the vaccine nanoparticle and the cell membrane of antigen-presenting cells. The HPLNP prolonged the retention of the antigen at the injection site and enhanced the lymph node drainage of antigen, resulting in a higher concentration of serum anti-HBsAg IgG compared to the HBsAg group or the HBsAg/Al group after the boost immunisation in mice. The HPLNP also promoted a strong Th1-driven immune response, as demonstrated by the significantly improved IgG2a/IgG1 ratio, increased production of IFN-γ, and activation of CD4 + and CD8 + T cells in the spleen and lymph nodes. Importantly, the HPLNP demonstrated no systemic toxicity during immunisation. The advantages of the HPLNP, including good biocompatibility, easy preparation, low cost, and its ability to enhance both humoral and cellular immune responses, suggest its suitability as an efficient adjuvant for protein-based vaccines such as HBsAg-VLP. These findings highlight the promising potential of the HPLNP as an HBV vaccine adjuvant, offering an alternative to aluminium adjuvants currently used in vaccines. [ABSTRACT FROM AUTHOR]

In mammals, the role of interleukin-18 (IL-18) in the immune response is to drive inflammatory and, normally therefore, anti-viral responses. IL-18 also shows promise as a vaccine adjuvant in mammals. Chicken IL-18 (chIL-18) has been cloned. The aim of this study was to investigate the potential of chIL-18 to act as a vaccine adjuvant in the context of a live recombinant Fowlpox virus vaccine (fpIBD1) against Infectious bursal disease virus (IBDV). fpIBD1 protects against mortality, but not against damage to the bursa of Fabricius caused by IBDV infection. The Fowlpox virus genome itself contains several candidate immunomodulatory genes, including potential IL-18 binding proteins (IL-18bp). We knocked out (Δ) the potential IL-18bp genes in fpIBD1 and inserted (::) the cDNA encoding chIL-18 into fpIBD1 in the non-essential ORF030, generating five new viral constructs –fpIBD1::chIL-18, fpIBD1ΔORF073, fpIBD1ΔORF073::chIL-18, fpIBD1ΔORF214, and fpIBD1ΔORF214::chIL-18. The subsequent protection from challenge with virulent IBDV, as measured by viral load and bursal damage, given by these altered fpIBD1 strains, was compared to that given by the original fpIBD1. Complete protection was provided following challenge with IBDV in chicken groups vaccinated with either fpIBDIΔ073::IL-18 or fpIBD1Δ214::IL-18, as no bursal damage nor IBDV was detected in the bursae of the birds. The results show that chIL-18 can act as an effective vaccine adjuvant by improving the fpIBD1 vaccine and providing complete protection against IBDV challenge. [ABSTRACT FROM AUTHOR]

Army Liposome Formulation with QS21 (ALFQ), a vaccine adjuvant preparation, comprises liposomes containing saturated phospholipids, with 55 mol% cholesterol relative to the phospholipids, and two adjuvants, monophosphoryl lipid A (MPLA) and QS21 saponin. A unique feature of ALFQ is the formation of giant unilamellar vesicles (GUVs) having diameters >1.0 µm, due to a remarkable fusion event initiated during the addition of QS21 to nanoliposomes containing MPLA and 55 mol% cholesterol relative to the total phospholipids. This results in a polydisperse size distribution of ALFQ particles, with diameters ranging from ~50 nm to ~30,000 nm. The purpose of this work was to gain insights into the unique fusion reaction of nanovesicles leading to GUVs induced by QS21. This fusion reaction was probed by comparing the lipid compositions and structures of vesicles purified from ALFQ, which were >1 µm (i.e., GUVs) and the smaller vesicles with diameter <1 µm. Here, we demonstrate that after differential centrifugation, cholesterol, MPLA, and QS21 in the liposomal phospholipid bilayers were present mainly in GUVs (in the pellet). Presumably, this occurred by rapid lateral diffusion during the transition from nanosize to microsize particles. While liposomal phospholipid recoveries by weight in the pellet and supernatant were 44% and 36%, respectively, higher percentages by weight of the cholesterol (~88%), MPLA (94%), and QS21 (96%) were recovered in the pellet containing GUVs, and ≤10% of these individual liposomal constituents were recovered in the supernatant. Despite the polydispersity of ALFQ, most of the cholesterol, and almost all of the adjuvant molecules, were present in the GUVs. We hypothesize that the binding of QS21 to cholesterol caused new structural nanodomains, and subsequent interleaflet coupling in the lipid bilayer might have initiated the fusion process, leading to creation of GUVs. However, the polar regions of MPLA and QS21 together have a "sugar lawn" of ten sugars, the hydrophilicity of which might have provided a driving force for rapid lateral diffusion and concentration of the MPLA and QS21 in the GUVs. [ABSTRACT FROM AUTHOR]

Vaccine adjuvants enhance and prolong pathogen-specific protective immune responses. Recent reports indicate that host factors-such as aging, pregnancy, and genetic polymorphisms-influence efficacies of vaccines adjuvanted with Toll-like receptor (TLR) or known pattern-recognition receptor (PRR) agonists. Although PRR independent adjuvants (e.g., oil-in-water emulsion and saponin) are emerging, these adjuvants induce some local and systemic reactogenicity. Hence, new TLR and PRR-independent adjuvants that provide greater potency alone or in combination without compromising safety are highly desired. Previous cell-based high-throughput screenings yielded a small molecule 81 [N-(4-chloro-2,5-dimethoxyphenyl)-4-ethoxybenzenesulfonamide], which enhanced lipopolysaccharide-induced NF-κB and type I interferon signaling in reporter assays. Here compound 81 activated innate immunity in primary human peripheral blood mononuclear cells and murine bone marrow-derived dendritic cells (BMDCs). The innate immune activation by 81 was independent of TLRs and other PRRs and was significantly reduced in mitochondrial antiviral-signaling protein (MAVS)-deficient BMDCs. Compound 81 activities were mediated by mitochondrial dysfunction as mitophagy inducers and a mitochondria specific antioxidant significantly inhibited cytokine induction by 81. Both compound 81 and a derivative obtained via structure-activity relationship studies, 2F52 [N-benzyl-N-(4-chloro-2,5-dimethoxyphenyl)-4-ethoxybenzenesulfonamide] modestly increased mitochondrial reactive oxygen species and induced the aggregation of MAVS. Neither 81 nor 2F52 injected as adjuvants caused local or systemic toxicity in mice at effective concentrations for vaccination. Furthermore, vaccination with inactivated influenza virus adjuvanted with 2F52 demonstrated protective effects in a murine lethal virus challenge study. As an unconventional and safe adjuvant that does not require known PRRs, compound 2F52 could be a useful addition to vaccines.

Bacterial lipopolysaccharides (LPSs) have been shown to promote enteric viral infections. This study tested the hypothesis that elevated levels of bacterial LPS improve oral rotavirus vaccine replication in South African infants. Stool samples were collected from infants a week after rotavirus vaccination to identify vaccine virus shedders (n = 43) and non-shedders (n = 35). Quantitative real-time PCR was used to assay for selected LPS-rich bacteria, including Serratia marcescens, Pseudomonas aeruguinosa and Klebsiella pneumonia, and to measure the gene expression of bacterial LPS, host Toll-like Receptor 4 (TLR4) and Interleukin-8 (IL-8). The abundance of selected LPS-rich bacteria was significantly higher in vaccine shedders (median log 4.89 CFU/g, IQR 2.84) compared to non-shedders (median log 3.13 CFU/g, IQR 2.74), p = 0.006. The TLR4 and IL-8 gene expressions were increased four- and two-fold, respectively, in vaccine shedders versus non-shedders, but no difference was observed in the bacterial LPS expression, p = 0.09. A regression analysis indicated a significant association between the abundance of selected LPS-rich bacteria and vaccine virus shedding (Odds ratio 1.5, 95% CI = 1.10–1.89), p = 0.002. The findings suggest that harbouring higher counts of LPS-rich bacteria can increase the oral rotavirus vaccine take in infants.

Foot-and-mouth disease (FMD) is a rapidly propagating infectious disease of cloven-hoofed animals, especially cattle and pigs, affecting the productivity and profitability of the livestock industry. Presently, FMD is controlled and prevented using vaccines; however, conventional FMD vaccines have several disadvantages, including short vaccine efficacy, low antibody titers, and safety issues in pigs, indicating the need for further studies. Here, we evaluated the efficacy of a novel bivalent vaccine containing zinc sulfate as an immunostimulant and FMD type O and A antigens (O PA2 and A YC, respectively) against FMD virus in mice and pigs. Zinc sulfate induced cellular immunity in murine peritoneal exudate cells (PECs) and porcine peripheral blood mononuclear cells (PBMCs) by increasing IFNγ secretion. Additionally, FMD vaccine containing O PA2 and A YC antigens and zinc sulfate induced early, mid-, and long-term immune responses in mice and pigs, and enhanced cellular and humoral immunity by regulating the expression of pathogen recognition receptors (PRRs), transcription factors, co-stimulatory molecules, and cytokines in porcine PBMCs from vaccinated pigs. Overall, these results indicated that the novel immunostimulant zinc sulfate induced potent cellular and humoral immune responses by stimulating antigen-presenting cells (APCs) and T and B cells, and enhanced long-term immunity by promoting the expression of co-stimulatory molecules. These outcomes suggest that zinc sulfate could be used as a novel vaccine immunostimulant for difficult-to-control viral diseases, such as African swine fever (ASF) or COVID-19.

Integrating antigen-encoding mRNA (Messenger RNA) and immunostimulatory adjuvant into a single formulation is a promising approach to potentiating the efficacy of mRNA vaccines. Here, we developed a scheme based on RNA engineering to integrate adjuvancy directly into antigen-encoding mRNA strands without hampering the ability to express antigen proteins. Short double-stranded RNA (dsRNA) was designed to target retinoic acid-inducible gene-I (RIG-I), an innate immune receptor, for effective cancer vaccination and then tethered onto the mRNA strand via hybridization. Tuning the dsRNA structure and microenvironment by changing its length and sequence enabled the determination of the structure of dsRNA-tethered mRNA efficiently stimulating RIG-I. Eventually, the formulation loaded with dsRNA-tethered mRNA of the optimal structure effectively activated mouse and human dendritic cells and drove them to secrete a broad spectrum of proinflammatory cytokines without increasing the secretion of anti-inflammatory cytokines. Notably, the immunostimulating intensity was tunable by modulating the number of dsRNA along the mRNA strand, which prevents excessive immunostimulation. Versatility in the applicable formulation is a practical advantage of the dsRNA-tethered mRNA. Its formulation with three existing systems, i.e., anionic lipoplex, ionizable lipid–based lipid nanoparticles, and polyplex micelles, induced appreciable cellular immunity in the mice model. Of particular interest, dsRNA-tethered mRNA encoding ovalbumin (OVA) formulated in anionic lipoplex used in clinical trials exerted a significant therapeutic effect in the mouse lymphoma (E.G7-OVA) model. In conclusion, the system developed here provides a simple and robust platform to supply the desired intensity of immunostimulation in various formulations of mRNA cancer vaccines. [ABSTRACT FROM AUTHOR]

Monophosphoryl lipid A (MPL), mainly isolated from Salmonella minnesota R595, has been used as adjuvant in several vaccines. In this study, an Escherichia coli strain that can efficiently produce the MPL has been constructed. The gene clusters related to the biosynthesis of O‐antigen, core oligosaccharide, enterobacterial common antigen, and colanic acid were sequentially removed to save the carbon source and to increase the activity of PagP in E. coli MG1655. Then, the genes pldA, mlaA, and mlaC related to the phospholipid transport system were further deleted, resulting in the strain MW012. Finally, the genes lpxE from Francisella novicida and pagP and pagL from Salmonella were overexpressed in MW012 to modify the structure of lipid A, resulting in the strain MW012/pWEPL. Lipid A species were isolated from MW012/pWEPL and analyzed by thin‐layer chromatography and liquid chromatography–mass spectrometry. The results showed that mainly two MPL species were produced in E. coli MW012/pWEPL, one is hexa‐acylated, and the other is penta‐acylated. More importantly, the proportion of the hexa‐acylated MPL, which is the most effective component of lipid A vaccine adjuvant, reached 75%. E. coli MW012/pWEPL constructed in this study provided a good alternative for the production of lipid A vaccine adjuvant MPL. [ABSTRACT FROM AUTHOR]

The rapid mutation and spread of SARS-CoV-2 variants recently, especially through the emerging variants Omicron BA5, BF7, XBB and BQ1, necessitate the development of universal vaccines to provide broad spectrum protection against variants. For the SARS-CoV-2 universal recombinant protein vaccines, an effective approach is necessary to design broad-spectrum antigens and combine them with novel adjuvants that can induce high immunogenicity. In this study, we designed a novel targeted retinoic acid-inducible gene-I (RIG-I) receptor 5′triphosphate double strain RNA (5′PPP dsRNA)-based vaccine adjuvant (named AT149) and combined it with the SARS-CoV-2 Delta and Omicron chimeric RBD-dimer recombinant protein (D-O RBD) to immunize mice. The results showed that AT149 activated the P65 NF-κB signaling pathway, which subsequently activated the interferon signal pathway by targeting the RIG-I receptor. The D-O RBD + AT149 and D-O RBD + aluminum hydroxide adjuvant (Al) + AT149 groups showed elevated levels of neutralizing antibodies against the authentic Delta variant, and Omicron subvariants, BA1, BA5, and BF7, pseudovirus BQ1.1, and XBB compared with D-O RBD + Al and D-O RBD + Al + CpG7909/Poly (I:C) groups at 14 d after the second immunization, respectively. In addition, D-O RBD + AT149 and D-O RBD + Al + AT149 groups presented higher levels of the T-cell-secreted IFN-γ immune response. Overall, we designed a novel targeted RIG-I receptor 5′PPP dsRNA-based vaccine adjuvant to significantly improve the immunogenicity and broad spectrum of the SARS-CoV-2 recombinant protein vaccine. [ABSTRACT FROM AUTHOR]

The hemolytic activity, in vitro as well as in vivo toxicity, and immunomodulatory potential of saponins-rich fraction of Asparagus adscendens Roxb. fruit (AA-SRF) have been assessed in this study in order to explore AA-SRF as an alternative safer adjuvant to standard Quil-A saponin. The AA-SRF showed lower hemolytic activity (HD50 = 301.01 ± 1.63 µg/ml) than Quil-A (HD50 = 17.15 ± 2.12 µg/ml). The sulforhodamine B assay also revealed that AA-SRF was less toxic to VERO cells (IC50≥200 ± 4.32 µg/ml) than Quil-A (IC50 = 60 ± 2.78 µg/ml). The AA-SRF did not lead to mortality in mice up to 1.6 mg and was much safer than Quil-A for in vivo use. Conversely, mice were subcutaneously immunized with OVA 100 μg alone or along with Alum (200 μg) or Quil-A (10 μg) or AA-SRF (50 μg/100 μg/200 μg) on days 0 and 14. The AA-SRF at 100 μg dose best supported the LPS/Con A primed splenocyte proliferation activity, elevated the serum OVA-specific total IgG antibody, IL-12, CD4 titer and upsurged CD3/CD19 expression in spleen as well as lymph node sections which in turn advocated its adjuvant potential. Thus, AA-SRF can be further studied for use as a safe alternative adjuvant in vaccines. [ABSTRACT FROM AUTHOR]

Astragaloside VII (AST VII), a triterpenic saponin isolated from Astragalus species, shows promise as a vaccine adjuvant, as it supported a balanced Th1/Th2 immune response in previous in vivo studies. However, the underlying mechanisms of its adjuvant activity have not been defined. Here, we investigated the impact of AST VII and its newly synthesized semi-synthetic analogs on human whole blood cells, as well as on mouse bone marrow-derived dendritic cells (BMDCs). Cells were stimulated with AST VII and its derivatives in the presence or absence of LPS or PMA/ionomycin and the secretion of cytokines and the expression of activation markers were analyzed using ELISA and flow cytometry, respectively. AST VII and its analogs increased the production of IL-1β in PMA/ionomycin-stimulated human whole blood cells. In LPS-treated mouse BMDCs, AST VII increased the production of IL-1β and IL-12, and the expression of MHC II, CD86, and CD80. In mixed leukocyte reaction, AST VII and derivatives increased the expression of the activation marker CD44 on mouse CD4+ and CD8+ T cells. In conclusion, AST VII and its derivatives strengthen pro-inflammatory responses and support dendritic cell maturation and T cell activation in vitro. Our results provide insights into the mechanisms of the adjuvant activities of AST VII and its analogs, which will be instrumental to improve their utility as a vaccine adjuvant. [ABSTRACT FROM AUTHOR]

Co-delivery of antigens and adjuvants to the same antigen-presenting cells (APCs) can significantly improve the efficacy and safety profiles of vaccines. Here, we report amine-grafted silica nanoparticles (A-SNP) as a tunable vaccine co-delivery platform for TLR7/8 agonists along with the recombinant influenza antigen hemagglutinin H7 (H7) to APCs. A-SNP of two different sizes (50 and 200 nm) were prepared and coated with INI-4001 at different coating densities, followed by co-adsorption of H7. Both INI-4001 and H7 showed >90% adsorption to the tested A-SNP formulations. TNF-α and IFN-α cytokine release by human peripheral blood mononuclear cells as well as TNF-α, IL-6, and IL-12 release by mouse bone marrow-derived dendritic cells revealed that the potency of the INI-4001-adsorbed A-SNP (INI-4001/A-SNP) formulations was improved relative to aqueous formulation control. This improved potency was dependent on particle size and ligand coating density. In addition, slow-release profiles of INI-4001 were measured from INI-4001/A-SNP formulations in plasma with 30–50% INI-4001 released after 7 days. In vivo murine immunization studies demonstrated significantly improved H7-specific humoral and Th1/Th17-polarized T cell immune responses with no observed adverse reactions. Low-density 50 nm INI-4001/A-SNP elicited significantly higher IFN-γ and IL-17 induction over that of the H7 antigen-only group and INI-4001 aqueous formulation controls. In summary, this work introduces an effective and biocompatible SNP-based co-delivery platform that enhances the immunogenicity of TLR7/8 agonist-adjuvanted subunit influenza vaccines.

Abstract Current strategies for porcine reproductive and respiratory syndrome (PRRS) control are inadequate and mainly restricted to immunization using different PRRS virus (PPRSV) vaccines. Although there are no safety concerns, the poor performance of inactivated PRRSV vaccines has restricted their practical application. In this research, we employed the novel PRRSV-specific IgM monoclonal antibody (Mab)-PR5nf1 as a vaccine adjuvant for the formulation of a cocktail composed of inactivated PRRSV (KIV) and Mab-PR5nf1 along with a normal adjuvant to enhance PRRSV-KIV vaccine-mediated protection and further compared it with a normal KIV vaccine and modified live virus vaccine (MLV). After challenge with highly pathogenic (HP)-PRRSV, our results suggested that the overall survival rate (OSR) and cell-mediated immunity (CMI), as determined by serum IFN-γ quantification and IFN-γ ELISpot assay, were significantly improved by adding PRRSV-specific IgM to the PRRSV-KIV vaccine. It was also notable that both the OSR and CMI in the Mab-PR5nf1-adjuvanted KIV group were even higher than those in the MLV group, whereas the CMI response is normally poorly evoked by KIV vaccines or subunit vaccines. Compared with those in piglets immunized with the normal KIV vaccine, viral shedding and serum neutralizing antibody levels were also improved, and reduced viral shedding appeared to be a result of enhanced CMI caused by the inclusion of IgM as an adjuvant. In conclusion, our data provide not only a new formula for the development of an effective PRRSV-KIV vaccine for practical use but also a novel method for improving antigen-specific CMI induction by inactivated vaccines and subunit vaccines.

Heat shock proteins (HSPs), which have a variety of functions, are one of the stress protein families. In recent years, They have been reported to play a dual role in hepatitis B virus (HBV) which as persistent infection which is associated with, cirrhosis and liver cancer. In this article, we have summarized the regulatory mechanisms between HSPs and viruses, especially HBV and associated diseases based on HSP biological functions of in response to viral infections. In view of their potential as broad-spectrum antiviral targets, we have also discuss current progress and challenges in drug development based on HSPs, as well as the potential applications of agents that have been evaluated clinically in HBV treatment.

Introduction: Sulfavant A (SULF A) is a synthetic derivative of naturally occurring sulfolipids. The molecule triggers TREM2-related maturation of dendritic cells (DCs) and has shown promising adjuvant activity in a cancer vaccine model. Methods: the immunomodulatory activity of SULF A is tested in an allogeneic mixed lymphocyte reaction (MLR) assay based on monocyte-derived dendritic cells and naïve T lymphocytes from human donors. Flow cytometry multiparametric analyses and ELISA assays were performed to characterize the immune populations, T cell proliferation, and to quantify key cytokines. Results: Supplementation of 10 µg/mL SULF A to the co-cultures induced DCs to expose the costimulatory molecules ICOSL and OX40L and to reduce release of the pro-inflammatory cytokine IL-12. After 7 days of SULF A treatment, T lymphocytes proliferated more and showed increased IL-4 synthesis along with downregulation of Th1 signals such as IFNg, T-bet and CXCR3. Consistent with these findings, naïve T cells polarized toward a regulatory phenotype with upregulation of FOXP3 expression and IL-10 synthesis. Flow cytometry analysis also supported the priming of a CD127-/CD4+/CD25+ subpopulation positive for ICOS, the inhibitory molecule CTLA-4, and the activation marker CD69. Discussion: These results prove that SULF A can modulate DC-T cell synapse and stimulate lymphocyte proliferation and activation. In the hyperresponsive and uncontrolled context of the allogeneic MLR, the effect is associated to differentiation of regulatory T cell subsets and dampening of inflammatory signals. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) encapsulate various bioactive molecules, and much effort has been directed towards developing a novel EV-based therapy. Although recent studies reported the secretion of EVs from probiotics baker's yeast Saccharomyces cerevisiae (S. cerevisiae), their properties and functions remain obscure. The aim of this study was to clarify the usefulness of EVs from S. cerevisiae (S-EVs) as a novel vaccine material by defining their physicochemical properties and biological functions. The collected S-EVs contained β-D-glucan and showed particle sizes and zeta potentials approximately 128.8 nm and -7.39 mV, respectively. S-EVs were positive for heat shock protein 70 kDa (HSP70). These S-EVs considerably enhanced the production of proinflammatory tumor necrosis factor-α and interleukin 6 from RAW264.7 cells (mouse macrophage-like cells) and DC2.4 cells (mouse dendritic cells). The expression of maturation markers CD40, CD80 and CD86 on the surface of these immune cells incubated with S-EVs was remarkably upregulated. Immune cells endocytosed S-EVs, and toll like receptor 2 on immune cells was involved in immune activation by S-EVs. These results indicate that extracellular vesicles derived from baker's yeast Saccharomyces cerevisiae are an attractive source as a novel vaccine material for immune cells maturation. [Display omitted] [ABSTRACT FROM AUTHOR]

Aluminum salt (AS), one of the most commonly used vaccine adjuvants, has immuno-modulatory activity, but how the administration of AS alone may impact the activation of the skin immune system under inflammatory conditions has not been investigated. Here, we studied the therapeutic effect of AS injection on two distinct skin inflammatory mouse models: an imiquimod (IMQ)-induced psoriasis-like model and an MC903 (calcipotriol)—induced atopic dermatitis-like model. We found that injection of a high dose of AS not only suppressed the IMQ-mediated development of T-helper 1 (Th1) and T-helper 17 (Th17) immune responses but also inhibited the IMQ-mediated recruitment and/or activation of neutrophils and macrophages. In contrast, AS injection enhanced MC903-mediated development of the T-helper 2 (Th2) immune response and neutrophil recruitment. Using an in vitro approach, we found that AS treatment inhibited Th1 but promoted Th2 polarization of primary lymphocytes, and inhibited activation of peritoneal macrophages but not bone marrow derived neutrophils. Together, our results suggest that the injection of a high dose of AS may inhibit Th1 and Th17 immune response-driven skin inflammation but promote type 2 immune response-driven skin inflammation. These results may provide a better understanding of how vaccination with an aluminum adjuvant alters the skin immune response to external insults. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLR) belong to the pattern recognition receptors (PRR). TLR7 and the closely correlated TLR8 affiliate with toll-like receptors family, are located in endosomes. They recognize single-stranded ribonucleic acid (RNA) molecules and synthetic deoxyribonucleic acid (DNA)/RNA analogs—oligoribonucleotides. TLRs are primarily expressed in hematopoietic cells. There is compiling evidence implying that TLRs also direct the formation of blood cellular components and make a contribution to the pathogenesis of certain hematopoietic malignancies. The latest research shows a positive effect of therapy with TRL agonists on the course of hemato-oncological diseases. Ligands impact activation of antigen-presenting cells which results in production of cytokines, transfer of mentioned cells to the lymphoid tissue and co-stimulatory surface molecules expression required for T-cell activation. Toll-like receptor agonists have already been used in oncology especially in the treatment of dermatological neoplastic lesions. The usage of these substances in the treatment of solid tumors is being investigated. The present review discusses the direct and indirect influence that TLR7/8 agonists, such as imiquimod, imidazoquinolines and resiquimod have on neoplastic cells and their promising role as adjuvants in anticancer vaccines. [ABSTRACT FROM AUTHOR]

A vaccine adjuvant known as Adjuvant System 01 (AS01) consists of liposomes containing a mixture of natural congeners of monophosphoryl lipid A (MPL®) obtained from bacterial lipopolysaccharide, and a tree saponin known as QS21. Two vaccines containing AS01 as the adjuvant have been licensed, including a malaria vaccine (Mosquirix®) approved by World Health. Organization and European Medicines Agency for use in sub-Saharan Africa, and a shingles vaccine (Shingrix®) approved by the U.S. Food and Drug Administration. The success of the AS01 vaccine adjuvant has led to the development of another liposomal vaccine adjuvant, referred to as Army Liposome Formulation with QS21 (ALFQ). Like AS01, ALFQ consists of liposomes containing monophosphoryl lipid A (as a synthetic molecule known as 3D-PHAD®) and QS21 as adjuvant constituents, and the polar headgroups of the liposomes of AS01 and ALFQ are similar. We compare here AS01 with ALFQ with respect to their similar and different liposomal chemical structures and physical characteristics with a goal of projecting some of the likely mechanisms of safety, side effects, and mechanisms of adjuvanticity. We hypothesize that some of the side effects exhibited in humans after injection of liposome-based vaccines might be caused by free fatty acid and lysophospholipid released by enzymatic attack of liposomal phospholipid by phospholipase A2 at the injection site or systemically after injection. [ABSTRACT FROM AUTHOR]

Synthetic double-stranded RNA analogs recognized by Toll-like receptor 3 (TLR3) are an attractive adjuvant candidate for vaccines, especially against intracellular pathogens or tumors, because of their ability to enhance T cell and antibody responses. Although poly(I:C) is a representative dsRNA with potent adjuvanticity, its clinical application has been limited due to heterogeneous molecular size, inconsistent activity, poor stability, and toxicity. To overcome these limitations, we developed a novel dsRNA-based TLR3 agonist named NexaVant (NVT) by using PCR-coupled bidirectional in vitro transcription. Agarose gel electrophoresis and reverse phase-HPLC analysis demonstrated that NVT is a single 275-kDa homogeneous molecule. NVT appears to be stable since its appearance, concentration, and molecular size were unaffected under 6 months of accelerated storage conditions. Moreover, preclinical evaluation of toxicity under good laboratory practices showed that NVT is a safe substance without any signs of serious toxicity. NVT stimulated TLR3 and increased the expression of viral nucleic acid sensors TLR3, MDA-5, and RIG-1. When intramuscularly injected into C57BL/6 mice, ovalbumin (OVA) plus NVT highly increased the migration of dendritic cells (DCs), macrophages, and neutrophils into inguinal lymph node (iLN) compared with OVA alone. In addition, NVT substantially induced the phenotypic markers of DC maturation and activation including MHC-II, CD40, CD80, and CD86 together with IFN-β production. Furthermore, NVT exhibited an appropriate adjuvanticity because it elevated OVA-specific IgG, in particular, higher levels of IgG2c (Th1- type) but lower IgG1 (Th2-type). Concomitantly, NVT increased the levels of Th1- type T cells such as IFN-γ+ CD4+ and IFN-γ+ CD8+ cells in response to OVA stimulation. Collectively, we suggest that NVT with appropriate safety and effectiveness is a novel and promising adjuvant for vaccines, especially those requiring T cell mediated immunity such as viral and cancer vaccines. [ABSTRACT FROM AUTHOR]

The urgent task of creating new, enhanced adjuvants is closely related to our comprehension of their mechanisms of action. A few adjuvants have shown sufficient efficacy and low toxicity to be allowed for use in human vaccines, despite the fact that they have a long history and an important function. Adjuvants have long been used without a clear understanding of how precisely they augment the immune response. The rational production of stronger and safer adjuvants has been impeded by this lack of information, which necessitates more mechanistic research to support the development of vaccines. Carbohydrate structures–polygalactans, fructans, β-D-glucans, α-D-glucans, D-galactose, and D-glucose–are desirable candidates for the creation of vaccine adjuvants and immunomodulators because they serve important functions in nature and are often biocompatible, safe, and well tolerated. In this review, we have discussed recent advances in microbial-derived carbohydrate-based adjuvants, their immunostimulatory activity, and the implications of this for vaccine development, along with the critical view on the microbial sources, chemical composition, and biosynthetic pathways. • Selecting an appropriate adjuvant is deemed to be a significant challenge in vaccinology. • Toxicity and adverse effects of known adjuvants impede their human use. • Carbohydrates (β-glucan) can effectively involve the immune system. • Carbohydrate-based adjuvants function as a promising vaccine adjuvant candidate. [ABSTRACT FROM AUTHOR]

Leishmaniasis is the 3rd most challenging vector-borne disease after malaria and lymphatic filariasis. Currently, no vaccine candidate is approved or marketed against leishmaniasis due to difficulties in eliciting broad immune responses when using sub-unit vaccines. The aim of this work was the design of a particulate sub-unit vaccine for vaccination against leishmaniasis. The poly (D,L-lactide) nanoparticles (PLA-NPs) were developed in order to efficiently adsorb a recombinant L. major histone H2B (L. major H2B) and to boost its immunogenicity. Firstly, a study was focused on the production of well-formed nanoparticles by the nanoprecipitation method without using a surfactant and on the antigen adsorption process under mild conditions. The set-up preparation method permitted to obtain H2B-adsorbed nanoparticles H2B/PLA (adsorption capacity of about 2.8% (w/w)) with a narrow size distribution (287 nm) and a positive zeta potential (30.9 mV). Secondly, an in vitro release assay performed at 37 °C, pH 7.4, showed a continuous release of the adsorbed H2B for almost 21 days (30%) from day 7. The immune response of H2B/PLA was investigated and compared to H2B + CpG7909 as a standard adjuvant. The humoral response intensity (IgG) was substantially similar between both formulations. Interestingly, when challenged with the standard parasite strain (GLC94) isolated from a human lesion of cutaneous leishmaniasis, mice showed a significant reduction in footpad swelling compared to unvaccinated ones, and no deaths occurred until week 17th. Taken together, these results demonstrate that PLA-NPs represent a stable, cost-effective delivery system adjuvant for use in vaccination against leishmaniasis. [ABSTRACT FROM AUTHOR]

Searching appropriate adjuvants for vaccine is a potent method to intense the immune efficacy. In the present study, we developed a novel Hepatitis E virus (HEV) vaccine by utilizing chitosan modified nano-graphene oxide (GO-CS) as an adjuvant to support HEV antigen P239 protein (GO/CS/P239). The characterization of GO/CS/P239 was observed by atomic force microscope. The safety of GO/CS/P239 was measured by CCK-8 method, hemolysis test and acute challenge test. The anti-HEV titers and cytokines production were analyzed by double antibody sandwich ELISA. As the results showed, by contrast with a vaccine that contained only the P239 protein, GO/CS/P239 vaccine can promote immune cells to produce more IgG antibodies and cytokines, which were able to stimulate the organism to produce stronger both cellular and humoral immunity. Collectively, GO/CS/P239 particles have been demonstrated to be safe both in vitro and in vivo, and can facilitate sufficient immune response to protect organisms from virus infection, which suggested that our exploration offers a promising alternative vaccine that can control HEV infection. [ABSTRACT FROM AUTHOR]

NOD2 is an innate immune receptor that constitutes an important target for the development of small molecule immunopotentiators with great potential to be used as vaccine adjuvants. We report here the results of an in vivo study of the adjuvant properties of a desmuramylpeptide NOD2 agonist SG29 and its lipidated analogs featuring an adamantyl moiety or a stearoyl group. These compounds have been synthesized, incorporated into liposomes, and evaluated for their in vivo adjuvant activity. The characterization of liposome formulations of examined compounds revealed that their size increased in comparison to that of empty liposomes. The introduction of a stearoyl or an adamantane lipophilic anchor into the structure of SG29, to produce SG115 and ZSB63, respectively, substantially improved the in vivo adjuvant activity. Of note, the attachment of the stearoyl moiety produced a Th2-biased immune response, while the incorporation of the adamantyl moiety greatly enhanced the production of total IgG but mostly augmented the production of IgG2a antibodies, which indicated a shift toward a Th1 immune response. The identified bona fide capacity of ZSB63 to initiate a cellular immune response thus highlights its untapped potential as an alternative vaccine adjuvant. [ABSTRACT FROM AUTHOR]

[Display omitted] The suspension stability of aluminum-based adjuvant (Alum) plays an important role in determining the Alum-antigen interaction and vaccine efficacy. Inclusion of excipients has been shown to stabilize antigens in vaccine formulations. However, there is no mechanistic study to tune the characteristics of Alum for improved suspension stability. Herein, a library of self-assembled rice-shaped aluminum oxyhydroxide nanoadjuvants i.e. , nanorices (NRs), was synthesized through intrinsically controlled crystallization and atomic coupling-mediated aggregations. The NRs exhibited superior suspension stability in both water and a saline buffer. After adsorbing hepatitis B surface antigen (HBsAg) virus-like particles (VLPs), human papillomavirus virus (HPV) VLPs, or bovine serum albumin, NR-antigen complexes exhibited less sedimentation. Further mechanistic study demonstrated that the improved suspension stability was due to intraparticle aggregations that led to the reduction of the surface free energy. By using HBsAg in a murine vaccination model, NRs with higher aspect ratios elicited more potent humoral immune responses. Our study demonstrated that engineered control of particle aggregation provides a novel material design strategy to improve suspension stability for a diversity of biomedical applications. [ABSTRACT FROM AUTHOR]

Abstract Background Highly contagious respiratory diseases caused by viral infections are a constantly emerging threat, particularly the elderly with the higher risk of developing serious complications. Vaccines are the best strategy for protection against influenza-related diseases. However, the elderly has lower vaccine efficacy than young population and the age-driven decline of the influenza vaccine efficacy remains unresolved. Objectives This study investigates the effect of an adjuvant, poly-γ-glutamic acid and alum (PGA/Alum) on vaccine efficacy in aged mice (18-months) and its mechanism is investigated using ovalbumin as a model antigen and a commercial pandemic H1N1 (pH1N1) flu vaccine. Antigen trafficking, dendritic cell (DC) activation, and the DC-mediated T cell activation were analyzed via in vivo imaging and flow cytometry. Antigen-specific humoral and cellular immune responses were evaluated in sera and splenocytes from the vaccinated mice. Also, we analyzed gene expression profiles of splenocytes from the vaccinated mice via single-cell transcriptome sequencing and evaluated the protective efficacy against pH1N1 virus challenge. Results Aged mice had lower antigen trafficking and DC activation than younger mice (6-weeks), which was ameliorated by PGA/Alum with increased antigen uptake and DC activation leading to improved antigen-specific IFN-γ+CD8+ T lymphocyte frequencies higher in the vaccinated aged mice, to a similar extent as PGA/Alum adjuvanted vaccine-immunized young mice. The results of single-cell transcriptome sequencing display that PGA/Alum also reduced the proportion of age-associated CD8+ T cell subsets and gene levels of inhibitory regulators in CD8+ T cells, which may play a role in the recovery of CD8+ T cell activation. Finally, PGA/Alum adjuvanted pH1N1 vaccine-immunized aged mice were completely protected (100% survival) compared to aged mice immunized with vaccine only (0% survival) after pH1N1 virus challenge, akin to the efficacy of the vaccinated young mice (100% survival). Conclusions PGA/Alum adjuvanted pH1N1 vaccine-immunized aged mice showed a significant increase in vaccine efficacy compared to aged mice administered with vaccine only. The enhanced vaccine efficacy by PGA/Alum is associated with significant increases of activation of DCs and effector CD8+ T cells and a decrease in age-associated CD8+ T cell proportion of splenocytes. Collectively, PGA/Alum adjuvanted flu vaccine may be a promising vaccine candidate for the elderly.

In mammals, the role of interleukin-18 (IL-18) in the immune response is to drive inflammatory and, normally therefore, anti-viral responses. IL-18 also shows promise as a vaccine adjuvant in mammals. Chicken IL-18 (chIL-18) has been cloned. The aim of this study was to investigate the potential of chIL-18 to act as a vaccine adjuvant in the context of a live recombinant Fowlpox virus vaccine (fpIBD1) against Infectious bursal disease virus (IBDV). fpIBD1 protects against mortality, but not against damage to the bursa of Fabricius caused by IBDV infection. The Fowlpox virus genome itself contains several candidate immunomodulatory genes, including potential IL-18 binding proteins (IL-18bp). We knocked out (Δ) the potential IL-18bp genes in fpIBD1 and inserted (::) the cDNA encoding chIL-18 into fpIBD1 in the non-essential ORF030, generating five new viral constructs –fpIBD1::chIL-18, fpIBD1ΔORF073, fpIBD1ΔORF073::chIL-18, fpIBD1ΔORF214, and fpIBD1ΔORF214::chIL-18. The subsequent protection from challenge with virulent IBDV, as measured by viral load and bursal damage, given by these altered fpIBD1 strains, was compared to that given by the original fpIBD1. Complete protection was provided following challenge with IBDV in chicken groups vaccinated with either fpIBDIΔ073::IL-18 or fpIBD1Δ214::IL-18, as no bursal damage nor IBDV was detected in the bursae of the birds. The results show that chIL-18 can act as an effective vaccine adjuvant by improving the fpIBD1 vaccine and providing complete protection against IBDV challenge.