Towards an understanding of the adjuvant action of aluminium

Prefusion F-Based Polyanhydride Nanovaccine Induces Both Humoral and Cell-Mediated Immunity Resulting in Long-Lasting Protection against Respiratory Syncytial Virus

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection in both young children and in older adults. Despite the morbidity, mortality, and high economic burden caused by RSV worldwide, no licensed vaccine is currently available. We have developed a novel RSV vaccine composed of a prefusion-stabilized variant of the fusion (F) protein (DS-Cav1) and a CpG oligodeoxynucleotide adjuvant encapsulated within polyanhydride nanoparticles, termed RSVNanoVax. A prime-boost intranasal administration of RSVNanoVax in BALB/c mice significantly alleviated weight loss and pulmonary dysfunction in response to an RSV challenge, with protection maintained up to at least 6 mo postvaccination. In addition, vaccinated mice exhibited rapid viral clearance in the lungs as early as 2 d after RSV infection in both inbred and outbred populations. Vaccination induced tissue-resident memory CD4 and CD8 T cells in the lungs, as well as RSV F-directed neutralizing Abs. Based on the robust immune response elicited and the high level of durable protection observed, our prefusion RSV F nanovaccine is a promising new RSV vaccine candidate.

Emerging concepts in the science of vaccine adjuvants

Adjuvants are vaccine components that enhance the magnitude, breadth and durability of the immune response. Following its introduction in the 1920s, alum remained the only adjuvant licensed for human use for the next 70 years. Since the 1990s, a further five adjuvants have been included in licensed vaccines, but the molecular mechanisms by which these adjuvants work remain only partially understood. However, a revolution in our understanding of the activation of the innate immune system through pattern recognition receptors (PRRs) is improving the mechanistic understanding of adjuvants, and recent conceptual advances highlight the notion that tissue damage, different forms of cell death, and metabolic and nutrient sensors can all modulate the innate immune system to activate adaptive immunity. Furthermore, recent advances in the use of systems biology to probe the molecular networks driving immune response to vaccines ('systems vaccinology') are revealing mechanistic insights and providing a new paradigm for the vaccine discovery and development process. Here, we review the 'known knowns' and 'known unknowns' of adjuvants, discuss these emerging concepts and highlight how our expanding knowledge about innate immunity and systems vaccinology are revitalizing the science and development of novel adjuvants for use in vaccines against COVID-19 and future pandemics.

Design and application of nanoparticles as vaccine adjuvants against human corona virus infection

In recent years, some viruses have caused a grave crisis to global public health, especially the human coronavirus. A truly effective vaccine is therefore urgently needed. Vaccines should generally have two features: delivering antigens and modulating immunity. Adjuvants have an unshakable position in the battle against the virus. In addition to the perennial use of aluminium adjuvant, nanoparticles have become the developing adjuvant candidates due to their unique properties. Here we introduce several typical nanoparticles and their antivirus vaccine adjuvant applications. Finally, for the combating of the coronavirus, we propose several design points, hoping to provide ideas for the development of personalized vaccines and adjuvants and accelerate the clinical application of adjuvants.

Dendritic Mesoporous Silica Nanoparticle Adjuvants Modified with Binuclear Aluminum Complex: Coordination Chemistry Dictates Adjuvanticity

Aluminum-containing adjuvants used in vaccine formulations suffer from low cellular immunity, severe aggregation, and accumulation in the brain. Conventional aluminosilicates widely used in the chemical industry focus mainly on acidic sites for catalytic applications, but they are rarely used as adjuvants. Reported here is an innovative "ligand-assisted steric hindrance" strategy to create a high density of six-coordinate ^VI Al-OH groups with basicity on dendritic mesoporous silica nanoparticles as new nanoadjuvants. Compared to four-coordinate ^IV Al-modified counterparts, ^VI Al-OH-rich aluminosilicate nanoadjuvants enhance cellular delivery of antigens and provoke stronger cellular immunity. Moreover, the aluminum accumulation in the brain is more reduced than that with a commercial adjuvant. These results show that coordination chemistry can be used to control the adjuvanticity, providing new understanding in the development of next-generation vaccine adjuvants.

Glycoconjugate Vaccines for Prevention of Haemophilus influenzae Type b Diseases

This review summarizes the experience in laboratory- and industrial-scale syntheses of glycoconjugate vaccines used for prevention of infectious diseases caused by Haemophilus influenzae type b bacteria based on the linear capsular polysaccharide poly-3-β-D-ribosyl-(1→1)-D-ribitol-5-phosphate (PRP) or related synthetic oligosaccharide ligands. The methods for preparation of related oligosaccharide derivatives and results of the studies evaluating effect of their length on immunogenic properties of the conjugates with protein carriers are overviewed.

Allergens and Adjuvants in Allergen Immunotherapy for Immune Activation, Tolerance, and Resilience

Allergen immunotherapy (AIT) is the only setting in which a vaccine is applied in patients allergic exactly to the active principle in the vaccine. Therefore, AIT products need to be not only effective but also safe. In Europe, for subcutaneous AIT, this has been achieved by the allergoid strategy in which IgE epitopes are destroyed or masked. In addition, adjuvants physically precipitate the allergen at the injection site to prevent too rapid systemic distribution. The choice of adjuvant critically shapes the efficacy and type of immune response to the injected allergen. In contrast to T_H2-promoting adjuvants, others clearly counteract allergy. Marketed products in Europe are formulated with aluminum hydroxide (alum) (66.7%), microcrystalline tyrosine (16.7%), calcium phosphate (11.1%), or the T_H1 adjuvant monophosphoryl lipid A (5.6%). In contrast to the European practice, in the United States mostly nonadjuvanted extracts and no allergoids are used for subcutaneous AIT, highlighting not only a regulatory but maybe a "historic preference." Sublingual AIT in the form of drops or tablets is currently applied worldwide without adjuvants, usually with higher safety but lower patient adherence than subcutaneous AIT. This article will discuss how AIT and adjuvants modulate the immune response in the treated patient toward immune activation, modulation, or-with new developments in the pipeline-immune resilience.

Prime-Pull Immunization with a Bivalent M-Protein and Spy-CEP Peptide Vaccine Adjuvanted with CAF®01 Liposomes Induces Both Mucosal and Peripheral Protection from covR/S Mutant Streptococcus pyogenes

Infections with Streptococcus pyogenes and their sequelae are responsible for an estimated 18 million cases of serious disease with >700 million new primary cases and 500,000 deaths per year. Despite the burden of disease, there is currently no vaccine available for this organism. Here, we define a combination vaccine P*17/K4S2 comprising of 20-mer B-cell peptide epitopes, p*17 (a mutant derived from the highly conserved C3-repeat region of the M-protein), and K4S2 (derived from the streptococcal anti-neutrophil factor, Spy-CEP). The peptides are chemically conjugated to either diphtheria toxoid (DT) or a nontoxic mutant form of diphtheria toxin, CRM197. We demonstrate that a prime-pull immunization regimen involving two intramuscular inoculations with P*17/K4S2 adjuvanted with a two-component liposomal adjuvant system (CAF01; developed by Statens Serum Institut [SSI], Denmark), followed by an intranasal inoculation of unadjuvanted vaccine (in Tris) induces peptide- and S. pyogenes-binding antibodies and protects from mucosal and skin infection with hypervirulent covR/S mutant organisms. Prior vaccination with DT does not diminish the response to the conjugate peptide vaccines. Detailed Good Laboratory Practice (GLP) toxicological evaluation in male and female rats did not reveal any gross or histopathological adverse effects.IMPORTANCE A vaccine to control S. pyogenes infection is desperately warranted. S. pyogenes colonizes the upper respiratory tract (URT) and skin, from where it can progress to invasive and immune-mediated diseases. Global mortality estimates for S. pyogenes-associated diseases exceeds 500,000 deaths per year. S. pyogenes utilizes antigenic variation as a defense mechanism to circumvent host immune responses and thus a successful vaccine needs to provide strain-transcending and multicompartment (mucosal and skin) immunity. By defining highly conserved and protective epitopes from two critical virulence factors (M-protein and Spy-CEP) and combining them with a potent immunostimulant, CAF®01, we are addressing an unmet clinical need for a mucosally and skin-active subunit vaccine. We demonstrate that prime-pull immunization (2× intramuscular injections followed by intranasal immunization) promotes high sustained antibody levels in the airway mucosa and serum and protects against URT and invasive disease.

Adjuvantation of Influenza Vaccines to Induce Cross-Protective Immunity

Influenza poses a huge threat to global public health. Influenza vaccines are the most effective and cost-effective means to control influenza. Current influenza vaccines mainly induce neutralizing antibodies against highly variable globular head of hemagglutinin and lack cross-protection. Vaccine adjuvants have been approved to enhance seasonal influenza vaccine efficacy in the elderly and spare influenza vaccine doses. Clinical studies found that MF59 and AS03-adjuvanted influenza vaccines could induce cross-protective immunity against non-vaccine viral strains. In addition to MF59 and AS03 adjuvants, experimental adjuvants, such as Toll-like receptor agonists, saponin-based adjuvants, cholera toxin and heat-labile enterotoxin-based mucosal adjuvants, and physical adjuvants, are also able to broaden influenza vaccine-induced immune responses against non-vaccine strains. This review focuses on introducing the various types of adjuvants capable of assisting current influenza vaccines to induce cross-protective immunity in preclinical and clinical studies. Mechanisms of licensed MF59 and AS03 adjuvants to induce cross-protective immunity are also introduced. Vaccine adjuvants hold a great promise to adjuvant influenza vaccines to induce cross-protective immunity.

Safety and Utility of Rush Immunotherapy with Aqueous Allergen Extracts for Treatment of Respiratory Allergies

BACKGROUND

Generally, allergen immunotherapy must be administered for three to five years. Meanwhile, rush immunotherapy (RIT) shortens the required duration for the build-up phase, thereby improving the therapy's convenience compared with conventional immunotherapy (CIT). However, RIT is often performed with modified allergens. Therefore, this study aimed to investigate the safety and utility of RIT with aqueous allergens.

METHODS

Medical records of 98 patients sensitized with at least one inhalant allergen who had received subcutaneous immunotherapy for allergic rhinitis with or without asthma were retrospectively reviewed. All patients were classified into three groups: depot-RIT (n = 25), receiving RIT with depot allergen; aqueous-RIT (n = 48), receiving RIT with aqueous allergen; and aqueous-CIT (n = 25), receiving CIT with aqueous allergen. Patients who had received immunotherapy targeting only house dust mites were excluded.

RESULTS

The proportions of patients presenting with a systemic reaction to depot-RIT, aqueous-RIT, or aqueous-CIT were 80.0%, 85.4%, and 48.0%, respectively (P = 0.002). The proportions of patients experiencing severe systemic reaction were 4.0%, 16.7%, and 8.0% in depot-RIT, aqueous-RIT and aqueous-CIT, respectively (P = 0.223). The proportions of depot-RIT and aqueous-RIT patients presenting with systemic reaction or severe systemic reaction did not differ significantly (P = 0.553 and P = 0.118, respectively). Significantly fewer depot-RIT (1.0 ± 0.2) and aqueous-RIT patients (2.0 ± 1.3) required outpatient clinical visits during the build-up phase, compared to those administered aqueous-CIT (13.6 ± 1.9; P < 0.001). Moreover, the build-up phase decreased to 17.4 ± 1.8 days in depot-RIT and 23.7 ± 10.9 days in aqueous-RIT, compared to 92.0 ± 12.5 days in aqueous-CIT (P < 0.001).

CONCLUSION

RIT with aqueous allergen reduced the build-up phase duration and frequency of hospital visits, with acceptable safety levels. RIT with aqueous allergen may, therefore, be suitable for broad application to patients with respiratory allergies.

The sixth revolution in pediatric vaccinology: immunoengineering and delivery systems

Infection is the predominant cause of mortality in early life, and immunization is the most promising biomedical intervention to reduce this burden. However, very young infants fail to respond optimally to most vaccines currently in use, especially neonates. In 2005, Stanley Plotkin proposed that new delivery systems would spur a new revolution in pediatric vaccinology, just as attenuation, inactivation, cell culture of viruses, genetic engineering, and adjuvantation had done in preceding decades. Recent advances in the field of immunoengineering, which is evolving alongside vaccinology, have begun to increasingly influence vaccine formulation design. Historically, the particulate nature of materials used in many vaccine formulations was empiric, often because of the need to stabilize antigens or reduce endotoxin levels. However, present vaccine delivery systems are rationally engineered to mimic the size, shape, and surface chemistry of pathogens, and are therefore often referred to as "pathogen-like particles". More than a decade from his original assessment, we re-assess Plotkin's prediction. In addition, we highlight how immunoengineering and advanced delivery systems may be uniquely capable of enhancing vaccine responses in vulnerable populations, such as infants. IMPACT: Immunoengineering and advanced delivery systems are leading to new developments in pediatric vaccinology. Summarizes delivery systems currently in use and development, and prospects for the future. Broad overview of immunoengineering's impact on vaccinology, catering to Pediatric Clinicians and Immunologists.

A guide to vaccinology: from basic principles to new developments

Immunization is a cornerstone of public health policy and is demonstrably highly cost-effective when used to protect child health. Although it could be argued that immunology has not thus far contributed much to vaccine development, in that most of the vaccines we use today were developed and tested empirically, it is clear that there are major challenges ahead to develop new vaccines for difficult-to-target pathogens, for which we urgently need a better understanding of protective immunity. Moreover, recognition of the huge potential and challenges for vaccines to control disease outbreaks and protect the older population, together with the availability of an array of new technologies, make it the perfect time for immunologists to be involved in designing the next generation of powerful immunogens. This Review provides an introductory overview of vaccines, immunization and related issues and thereby aims to inform a broad scientific audience about the underlying immunological concepts.

This Review, aimed at a broad scientific audience, provides an introductory guide to the history, development and immunological basis of vaccines, immunization and related issues to provide insight into the challenges facing immunologists who are designing the next generation of vaccines.

High- and low-molecular-weight chitosan act as adjuvants during single-dose influenza A virus protein vaccination through distinct mechanisms

The investigation of new adjuvants is essential for the development of efficacious vaccines. Chitosan (CS), a derivative of chitin, has been shown to act as an adjuvant, improving vaccine-induced immune responses. However, the effect of CS molecular weight (MW) on this adjuvanticity has not been investigated, despite MW having been shown to impact CS biological properties. Here, two MW variants of CS were investigated for their ability to enhance vaccine-elicited immune responses in vitro and in vivo, using a single-dose influenza A virus (IAV) protein vaccine model. Both low-molecular-weight (LMW) and high-molecular-weight (HMW) CS-induced interferon regulatory factor pathway signaling, antigen-presenting cell activation, and cytokine messenger RNA (mRNA) production, with LMW inducing higher mRNA levels at 24 h and HMW elevating mRNA responses at 48 h. LMW and HMW CS also induced adaptive immune responses after vaccination, indicated by enhanced immunoglobulin G production in mice receiving LMW CS and increased CD4 interleukin 4 (IL-4) and IL-2 production in mice receiving HMW CS. Importantly, both LMW and HMW CS adjuvantation reduced morbidity following homologous IAV challenge. Taken together, these results support that LMW and HMW CS can act as adjuvants, although this protection may be mediated through distinct mechanisms based on CS MW.

Evaluation of a Series of Lipidated Tucaresol Adjuvants in a Hepatitis C Virus Vaccine Model

Hepatitis C virus (HCV) infections represent a global health challenge; however, developing a vaccine for treatment of HCV infection has remained difficult as heterogeneous HCV contains distinct genotypes, and each genotype contains various subtypes and different envelope glycoproteins. Currently, there is no effective preventive vaccine for achieving global control over HCV. In our efforts to improve upon current HCV vaccines we designed a synthetically accessible adjuvant platform, wherein we synthesized 11 novel lipidated tucaresol analogues to assess their immunological potential. Using a tucaresol-based adjuvant approach, truncated lipid-variants together with an engineered E1E2 antigen construct, namely E2ΔTM3, elicited antibody (Ab) responses that were significantly higher than tucaresol. In sum, antibody end-point titer values largely corroborated HCV neutralization data with a simplified lipidated tucaresol variant affording the highest end point titer and % neutralization. This study lays the groundwork for additional permutations in tucaresol adjuvant design, including the examination of other proteins in vaccine development.

Recent advances in self-adjuvanting glycoconjugate vaccines

Compared to traditional vaccines that are formulated into mixtures of an adjuvant and an antigen, a self-adjuvanting vaccine consists of an antigen that is covalently conjugated to a well-defined adjuvant. In self-adjuvanting vaccines, innate immune receptor ligands are usually used as adjuvants. Innate immune receptor ligands effectively trigger acquired immunity through the activation of innate immunity to enhance host immune responses to antigens. When a self-adjuvanting vaccine is used, immune cells simultaneously uptake the antigen and the adjuvant because they are covalently linked. Consequently, the adjuvant can specifically induce immune responses against the conjugated antigen. Importantly, self-adjuvanting vaccines do not require co-administration of additional adjuvants or immobilization to carrier proteins, which enables avoidance of the use of highly toxic adjuvants or the induction of undesired immune responses. Given these excellent properties, self-adjuvanting vaccines are expected to serve as candidates for the next generation of vaccines. Herein, we review vaccine adjuvants, with a focus on the adjuvants used in self-adjuvanting vaccines, and then overview recent advances made with self-adjuvanting conjugate vaccines.

Design, production and immunomodulatory potency of a novel allergen bioparticle

Allergen immunotherapy (AIT) is the only disease-modifying treatment with evidence for sustained efficacy. However, it is poorly developed compared to symptomatic drugs. The main reasons come from treatment duration implying monthly injections during 3 to 5 years or daily sublingual use, and the risk of allergic side-effects. To become a more attractive alternative to lifelong symptomatic drug use, improvements to AIT are needed. Among the most promising new immunotherapy strategies is the use of bioparticles for the presentation of target antigen to the immune system as they can elicit strong T cell and B cell immune responses. Virus-like particles (VLPs) are a specific class of bioparticles in which the structural and immunogenic constituents are from viral origin. However, VLPs are ill-suited for use in AIT as their antigenicity is linked to structure. Recently, synthetic biology has been used to produce artificial modular bioparticles, in which supramolecular assemblies are made of elements from heterogeneous biological sources promoting the design and use of in vivo-assembling enveloped bioparticles for viral and non-viral antigens presentation. We have used a coiled-coil hybrid assembly for the design of an enveloped bioparticle (eBP) that present trimers of the Der p 2 allergen at its surface, This bioparticle was produced as recombinant and in vivo assembled eBPs in plant. This allergen biotherapeutic was used to demonstrate i) the capacity of plants to produce synthetic supramolecular allergen bioparticles, and ii) the immunomodulatory potential of naturally-assembled allergen bioparticles. Our results show that allergens exposed on eBPs induced a very strong IgG response consisting predominantly of IgG2a in favor of the TH1 response. Finally, our results demonstrate that rDer p 2 present on the surface of BPs show a very limited potential to stimulate the basophil degranulation of patient allergic to this allergen which is predictive of a high safety potential.

A highly immunogenic and effective measles virus-based Th1-biased COVID-19 vaccine

The COVID-19 pandemic has already caused over 1 million deaths. Therefore, effective vaccine concepts are urgently needed. In search of such a concept, we have analyzed a measles virus-based vaccine candidate targeting SARS-CoV-2. Using this well-known, safe vaccine backbone, we demonstrate here induction of functional immune responses in both arms of adaptive immunity, yielding antiviral efficacy in vivo with the desired immune bias. Consequently, no immunopathologies became evident during challenge experiments. Moreover, the candidate still induces immunity against the measles, recognized as a looming second menace, when countries are forced to stop routine vaccination campaigns in the face of COVID-19. Thus, a bivalent measles-based COVID-19 vaccine could be the solution for two significant public health threats.

The COVID-19 pandemic is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and has spread worldwide, with millions of cases and more than 1 million deaths to date. The gravity of the situation mandates accelerated efforts to identify safe and effective vaccines. Here, we generated measles virus (MeV)-based vaccine candidates expressing the SARS-CoV-2 spike glycoprotein (S). Insertion of the full-length S protein gene in two different MeV genomic positions resulted in modulated S protein expression. The variant with lower S protein expression levels was genetically stable and induced high levels of effective Th1-biased antibody and T cell responses in mice after two immunizations. In addition to neutralizing IgG antibody responses in a protective range, multifunctional CD8⁺ and CD4⁺ T cell responses with S protein-specific killing activity were detected. Upon challenge using a mouse-adapted SARS-CoV-2, virus loads in vaccinated mice were significantly lower, while vaccinated Syrian hamsters revealed protection in a harsh challenge setup using an early-passage human patient isolate. These results are highly encouraging and support further development of MeV-based COVID-19 vaccines.

Inflammasomes within Hyperactive Murine Dendritic Cells Stimulate Long-Lived T Cell-Mediated Anti-tumor Immunity

Central to anti-tumor immunity are dendritic cells (DCs), which stimulate long-lived protective T cell responses. Recent studies have demonstrated that DCs can achieve a state of hyperactivation, which is associated with inflammasome activities within living cells. Herein, we report that hyperactive DCs have an enhanced ability to migrate to draining lymph nodes and stimulate potent cytotoxic T lymphocyte (CTL) responses. This enhanced migratory activity is dependent on the chemokine receptor CCR7 and is associated with a unique transcriptional program that is not observed in conventionally activated or pyroptotic DCs. We show that hyperactivating stimuli are uniquely capable of inducing durable CTL-mediated anti-tumor immunity against tumors that are sensitive or resistant to PD-1 inhibition. These protective responses are intrinsic to the cDC1 subset of DCs, depend on the inflammasome-dependent cytokine IL-1β, and enable tumor lysates to serve as immunogens. If these activities are verified in humans, hyperactive DCs may impact immunotherapy.

Immunogenicity and Protective Efficacy of a Non-Living Anthrax Vaccine versus a Live Spore Vaccine with Simultaneous Penicillin-G Treatment in Cattle

Sterne live spore vaccine (SLSV) is the current veterinary anthrax vaccine of choice. Unlike the non-living anthrax vaccine (NLAV) prototype, SLSV is incompatible with concurrent antibiotics use in an anthrax outbreak scenario. The NLAV candidates used in this study include a crude recombinant protective antigen (CrPA) and a purified recombinant protective antigen (PrPA) complemented by formalin-inactivated spores and Emulsigen-D^®/Alhydrogel^® adjuvants. Cattle were vaccinated twice (week 0 and 3) with NLAVs plus penicillin-G (Pen-G) treatment and compared to cattle vaccinated twice with SLSV alone and with Pen-G treatment. The immunogenicity was assessed using ELISA against rPA and FIS, toxin neutralisation assay (TNA) and opsonophagocytic assay. The protection was evaluated using an in vivo passive immunisation mouse model. The anti-rPA IgG titres for NLAVs plus Pen-G and SLSV without Pen-G treatment showed a significant increase, whereas the titres for SLSV plus Pen-G were insignificant compared to pre-vaccination values. A similar trend was measured for IgM, IgG1, and IgG2 and TNA titres (NT₅₀) showed similar trends to anti-rPA titres across all vaccine groups. The anti-FIS IgG and IgM titres increased significantly for all vaccination groups at week 3 and 5 when compared to week 0. The spore opsonising capacity increased significantly in the NLAV vaccinated groups including Pen-G treatment and the SLSV without Pen-G but much less in the SLSV group with Pen-G treatment. Passive immunization of A/J mice challenged with a lethal dose of 34F2 spores indicated significant protective capacity of antibodies raised in the SLSV and the PrPA + FIS + adjuvants vaccinated and Pen-G treated groups but not for the NLAV with the CrPA + FIS + adjuvants and the SLSV vaccinated and Pen-G treated group. Our findings indicate that the PrPA + FIS + Emulsigen-D^®/Alhydrogel^® vaccine candidate may provide the same level of antibody responses and protective capacity as the SLSV. Advantageously, it can be used concurrently with Penicillin-G in an outbreak situation and as prophylactic treatment in feedlots and valuable breeding stocks.

Nonthermal plasma as part of a novel strategy for vaccination

Vaccination has been one of the most effective health intervention mechanisms to reduce morbidity and mortality associated with infectious diseases. Vaccines stimulate the body's protective immune responses through controlled exposure to modified versions of pathogens that establish immunological memory. However, only a few diseases have effective vaccines. The biological effects of nonthermal plasma on cells suggest that plasma could play an important role in improving efficacy of existing vaccines and overcoming some of the limitations and challenges with current vaccination strategies. This review summarizes the opportunities for nonthermal plasma for immunization and therapeutic purposes.

Soil-Transmitted Helminth Vaccines: Are We Getting Closer?

Parasitic helminths infect over one-fourth of the human population resulting in significant morbidity, and in some cases, death in endemic countries. Despite mass drug administration (MDA) to school-aged children and other control measures, helminth infections are spreading into new areas. Thus, there is a strong rationale for developing anthelminthic vaccines as cost-effective, long-term immunological control strategies, which, unlike MDA, are not haunted by the threat of emerging drug-resistant helminths nor limited by reinfection risk. Advances in vaccinology, immunology, and immunomics include the development of new tools that improve the safety, immunogenicity, and efficacy of vaccines; and some of these tools have been used in the development of helminth vaccines. The development of anthelminthic vaccines is fraught with difficulty. Multiple lifecycle stages exist each presenting stage-specific antigens. Further, helminth parasites are notorious for their ability to dampen down and regulate host immunity. One of the first significant challenges in developing any vaccine is identifying suitable candidate protective antigens. This review explores our current knowledge in lead antigen identification and reports on recent pre-clinical and clinical trials in the context of the soil-transmitted helminths Trichuris, the hookworms and Ascaris. Ultimately, a multivalent anthelminthic vaccine could become an essential tool for achieving the medium-to long-term goal of controlling, or even eliminating helminth infections.

Morphology and protein adsorption of aluminum phosphate and aluminum hydroxide and their potential catalytic function in the synthesis of polymeric emulsifiers

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Aluminum gel structure was associated with adsorption and catalytic ability.

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Crystalline Al(OH)₃ is a suitable adjuvant for antigen adsorption.

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Amorphous AlPO₄ is an efficient catalyst for polymeric emulsifier synthesis.

Aluminum-containing salts are commonly used as antacids and vaccine adjuvants; however, key features of functional activities remain unclear. Here, we characterized vaccine formulations based on aluminum phosphate and aluminum hydroxide and investigated the respective modes of action linking physicochemical properties and catalytic ability. TEM microscopy indicated that aluminum phosphate gel solutions are amorphous, whereas aluminum hydroxide gel solutions have a crystalline structure consistent with boehmite. At very low BSA concentrations, 100 % adsorption of the protein on aluminum hydroxide could be achieved. As the protein concentration increased, the amount of adsorbed BSA decreased as fewer vacant sites were available on the surface of the adjuvants. Notably, less than 20 % adsorption was observed in aluminum phosphate. The protein adsorption profiles should confront the requirements for vaccine immunoavailability. In terms of catalytic ability, the prepared aluminum salts were tested for their ability to drive the amphiphilic engineering of oligo(lactic acid) (OLA) onto methoxy poly(ethylene glycol). It was concluded that aluminum hydroxide, rather than aluminum phosphate, is suitable to be a vaccine adjuvant according to the morphology and antigen adsorption efficiency results; on the other hand, aluminum phosphate may be a more efficient catalyst for the synthesis of polymeric emulsifiers than aluminum hydroxide. The results provide critical mechanistic insight into aluminum-containing salts in vaccine formulations.

Critical Adjuvant Influences on Preventive Anti-Metastasis Vaccine Using a Structural Epitope Derived from Membrane Type Protease PRSS14

We tested how adjuvants effect in a cancer vaccine model using an epitope derived from an autoactivation loop of membrane-type protease serine protease 14 (PRSS14; loop metavaccine) in mouse mammary tumor virus (MMTV)-polyoma middle tumor-antigen (PyMT) system and in 2 other orthotopic mouse systems. Earlier, we reported that loop metavaccine effectively prevented progression and metastasis regardless of adjuvant types and T_H types of hosts in tail-vein injection systems. However, the loop metavaccine with Freund's complete adjuvant (CFA) reduced cancer progression and metastasis while that with alum, to our surprise, were adversely affected in 3 tumor bearing mouse models. The amounts of loop peptide specific antibodies inversely correlated with tumor burden and metastasis, meanwhile both T_H1 and T_H2 isotypes were present regardless of host type and adjuvant. Tumor infiltrating myeloid cells such as eosinophil, monocyte, and neutrophil were asymmetrically distributed among 2 adjuvant groups with loop metavaccine. Systemic expression profiling using the lymph nodes of the differentially immunized MMTV-PyMT mouse revealed that adjuvant types, as well as loop metavaccine can change the immune signatures. Specifically, loop metavaccine itself induces T_H2 and T_H17 responses but reduces T_H1 and T_reg responses regardless of adjuvant type, whereas CFA but not alum increased follicular T_H response. Among the myeloid signatures, eosinophil was most distinct between CFA and alum. Survival analysis of breast cancer patients showed that eosinophil chemokines can be useful prognostic factors in PRSS14 positive patients. Based on these observations, we concluded that multiple immune parameters are to be considered when applying a vaccine strategy to cancer patients.

Characterization of the UK anthrax vaccine and human immunogenicity

The manufacture of the UK Anthrax vaccine (AVP) focuses on the production of Protective Antigen (PA) from the Bacillus anthracis Sterne strain. Although used for decades, several of AVP’s fundamental properties are poorly understood, including its exact composition, the extent to which proteins other than PA may contribute to protection, and whether the degree of protection varies between individuals.

This study involved three innovative investigations. Firstly, the composition of AVP was analyzed using liquid chromatography tandem mass-spectrometry (LC-MS/MS), requiring the development of a novel desorption method for releasing B. anthracis proteins from the vaccine’s aluminum-containing adjuvant. Secondly, computational MHC-binding predictions using NetMHCIIpan were made for the eight most abundant proteins of AVP, for the commonest HLA alleles in multiple ethnic groups, and for multiple B. anthracis strains. Thirdly, antibody levels and toxin neutralizing antibody (TNA) levels were measured in sera from AVP human vaccinees for both PA and Lethal Factor (LF).

It was demonstrated that AVP is composed of at least 138 B. anthracis proteins, including PA (65%), LF (8%) and Edema Factor (EF) (3%), using LC-MS/MS. NetMHCIIpan predicted that peptides from all eight abundant proteins are likely to be presented to T cells, a pre-requisite for protection; however, the number of such peptides varied considerably between different HLA alleles.

These analyses highlight two important properties of the AVP vaccine that have not been established previously. Firstly, the effectiveness of AVP within humans may not depend on PA alone; there is compelling evidence to suggest that LF has a protective role, with computational predictions suggesting that additional proteins may be important for individuals with specific HLA allele combinations. Secondly, in spite of differences in the sequences of key antigenic proteins from different B. anthracis strains, these are unlikely to affect the cross-strain protection afforded by AVP.

Immunogenicity of Antigen Adjuvanted with AS04 and Its Deposition in the Upper Respiratory Tract after Intranasal Administration

Adjuvant system 04 (AS04) is in injectable human vaccines. AS04 contains two known adjuvants, 3-O-desacyl-4'-monophosphoryl lipid A (MPL) and insoluble aluminum salts. Data from previous studies showed that both MPL and insoluble aluminum salts have nasal mucosal vaccine adjuvant activity. The present study was designed to test the feasibility of using AS04 as an adjuvant to help nasally administered antigens to induce specific mucosal and systemic immunity as well as to evaluate the deposition of antigens in the upper respiratory tract when adjuvanted with AS04. Alhydrogel, an aluminum (oxy)hydroxide suspension, was mixed with MPL to form AS04, which was then mixed with ovalbumin (OVA) or 3× M2e-HA2, a synthetic influenza virus hemagglutinin fusion protein, as an antigen to prepare OVA/AS04 and 3× M2e-HA2/AS04 vaccines, respectively. In mice, AS04 enabled antigens, when given intranasally, to induce specific IgA response in nasal and lung mucosal secretions as well as specific IgG response in the serum samples of the immunized mice, whereas subcutaneous injection of the same vaccine induced specific antibody responses only in the serum samples but not in the mucosal secretions. Splenocytes isolated from mice intranasally immunized with the OVA/AS04 also proliferated and released cytokines (i.e., IL-4 and IFN-γ) after in vitro stimulation with the antigen. In the immunogenicity test, intranasal OVA/AS04 was not more effective than intranasal OVA/MPL at the dosing regimens tested. However, when compared to OVA/MPL, OVA/AS04 showed a different atomized droplet size distribution and more importantly a more favorable OVA deposition profile when atomized into a nasal cast that was 3-D printed based on the computer tomography scan of the nose of a child. It is concluded that AS04 has mucosal adjuvant activity when given intranasally. In addition, there is a reason to be optimistic about using AS04 as an adjuvant to target an antigen of interest to the right region of the nasal cavity in humans for immune response induction.

The Age of Cyclic Dinucleotide Vaccine Adjuvants

As prophylactic vaccine adjuvants for infectious diseases, cyclic dinucleotides (CDNs) induce safe, potent, long-lasting humoral and cellular memory responses in the systemic and mucosal compartments. As therapeutic cancer vaccine adjuvants, CDNs induce potent anti-tumor immunity, including cytotoxic T cells and NK cells activation that achieve durable regression in multiple mouse models of tumors. Clinical trials are ongoing to fulfill the promise of CDNs (ClinicalTrials.gov: NCT02675439, NCT03010176, NCT03172936, and NCT03937141). However, in October 2018, the first clinical data with Merck's CDN MK-1454 showed zero activity as a monotherapy in patients with solid tumors or lymphomas (NCT03010176). Lately, the clinical trial from Aduro's CDN ADU-S100 monotherapy was also disappointing (NCT03172936). The emerging hurdle in CDN vaccine development calls for a timely re-evaluation of our understanding on CDN vaccine adjuvants. Here, we review the status of CDN vaccine adjuvant research, including their superior adjuvant activities, in vivo mode of action, and confounding factors that affect their efficacy in humans. Lastly, we discuss the strategies to overcome the hurdle and advance promising CDN adjuvants in humans.

Ndumnego O, Ellis C, Buys A, Beyer W, van Heerden H. Immunogenicity of Non-Living Anthrax Vaccine Candidates in Cattle and Protective Efficacy of Immune Sera in A/J Mouse Model Compared to the Sterne Live Spore Vaccine

The Sterne live spore vaccine (SLSV, Bacillus anthracis strain 34F2) is the veterinary vaccine of choice against anthrax though contra-indicated for use with antimicrobials. However, the use of non-living anthrax vaccine (NLAV) candidates can overcome the SLSV limitation. In this study, cattle were vaccinated with either of the NLAV (purified recombinant PA (PrPA) or crude rPA (CrPA) and formaldehyde-inactivated spores (FIS of B. anthracis strain 34F2) and emulsigen-D^®/alhydrogel^® adjuvants) or SLSV. The immunogenicity of the NLAV and SLSV was assessed and the protective efficacies evaluated using a passive immunization mouse model. Polyclonal IgG (including the IgG1 subset) and IgM responses increased significantly across all vaccination groups after the first vaccination. Individual IgG subsets titres peaked significantly with all vaccines used after the second vaccination at week 5 and remained significant at week 12 when compared to week 0. The toxin neutralization (TNA) titres of the NLAV vaccinated cattle groups showed similar trends to those observed with the ELISA titres, except that the former were lower, but still significant, when compared to week 0. The opsonophagocytic assay indicated good antibody opsonizing responses with 75% (PrPA+FIS), 66% (CrPA+FIS) and 80% (SLSV) phagocytosis following spores opsonization. In the passive protection test, A/J mice transfused with purified IgG from cattle vaccinated with PrPA+FIS+Emulsigen-D^®/Alhydrogel^® and SLSV had 73% and 75% protection from challenge with B. anthracis strain 34F2 spores, respectively, whereas IgG from cattle vaccinated with CrPA+FIS+Emulsigen-D^®/Alhydrogel^® offered insignificant protection of 20%. There was no difference in protective immune response in cattle vaccinated twice with either the PrPA+FIS or SLSV. Moreover, PrPA+FIS did not show any residual side effects in vaccinated cattle. These results suggest that the immunogenicity and protective efficacy induced by the NLAV (PrPA+FIS) in the cattle and passive mouse protection test, respectively, are comparable to that induced by the standard SLSV.

Cumulative inactivated vaccine exposure and allergy development among children: a birth cohort from Japan

Background

Adjuvants used in inactivated vaccines often upregulate type 2 immunity, which is dominant in allergic diseases. We hypothesised that cumulative adjuvant exposure in infancy may influence the development of allergies later in life by changing the balance of type 1/type 2 immunity. We examined the relationship between immunisation with different vaccine types and later allergic disease development.

Methods

We obtained information regarding vaccinations and allergic diseases through questionnaires that were used in The Japan Environment and Children’s Study (JECS), which is a nationwide, multicentre, prospective birth cohort study that included 103,099 pregnant women and their children. We examined potential associations between the initial vaccination before 6 months of age and symptoms related to allergies at 12 months of age.

Results

Our statistical analyses included 56,277 children. Physician-diagnosed asthma was associated with receiving three (aOR 1.395, 95% CI 1.028–1.893) or four to five different inactivated vaccines (aOR 1.544, 95% CI 1.149–2.075), compared with children who received only one inactivated vaccine. Similar results were found for two questionnaire-based symptoms, i.e. wheeze (aOR 1.238, 95% CI 1.094–1.401; three vaccines vs. a single vaccine) and eczema (aOR 1.144, 95% CI 1.007–1.299; four or five vaccines vs. a single vaccine).

Conclusions

Our results, which should be cautiously interpreted, suggest that the prevalence of asthma, wheeze and eczema among children at 12 months of age might be related to the amount of inactivated vaccine exposure before 6 months of age. Future work should assess if this association is due to cumulative adjuvant exposure. Despite this possible association, we strongly support the global vaccination strategy and recommend that immunisations continue.

Trial registration

UMIN000030786.

Nitric Oxide Production and Fc Receptor-Mediated Phagocytosis as Functional Readouts of Macrophage Activity upon Stimulation with Inactivated Poultry Vaccines In Vitro

Vaccine batches must pass routine quality control to confirm that their ability to induce protection against disease is consistent with batches of proven efficacy from development studies. For poultry vaccines, these tests are often performed in laboratory chickens by vaccination-challenge trials or serological assays. The aim of this study was to investigate innate immune responses against inactivated poultry vaccines and identify candidate immune parameters for in vitro quality tests as alternatives for animal-based quality tests. For this purpose, we set up assays to measure nitric oxide production and phagocytosis by the macrophage-like cell line HD11, upon stimulation with inactivated poultry vaccines for infectious bronchitis virus (IBV), Newcastle disease virus (NDV), and egg drop syndrome virus (EDSV). In both assays, macrophages became activated after stimulation with various toll-like receptor agonists. Inactivated poultry vaccines stimulated HD11 cells to produce nitric oxide due to the presence of mineral oil adjuvant. Moreover, inactivated poultry vaccines were found to enhance Fc receptor-mediated phagocytosis due to the presence of allantoic fluid in the vaccine antigen preparations. We showed that inactivated poultry vaccines stimulated nitric oxide production and Fc receptor-mediated phagocytosis by chicken macrophages. Similar to antigen quantification methods, the cell-based assays described here can be used for future assessment of vaccine batch-to-batch consistency. The ability of the assays to determine the immunopotentiating properties of inactivated poultry vaccines provides an additional step in the replacement of current in vivo batch-release quality tests.

Innate Immune Response against Hepatitis C Virus: Targets for Vaccine Adjuvants

Despite successful treatments, hepatitis C virus (HCV) infections continue to be a significant world health problem. High treatment costs, the high number of undiagnosed individuals, and the difficulty to access to treatment, particularly in marginalized susceptible populations, make it improbable to achieve the global control of the virus in the absence of an effective preventive vaccine. Current vaccine development is mostly focused on weakly immunogenic subunits, such as surface glycoproteins or non-structural proteins, in the case of HCV. Adjuvants are critical components of vaccine formulations that increase immunogenic performance. As we learn more information about how adjuvants work, it is becoming clear that proper stimulation of innate immunity is crucial to achieving a successful immunization. Several hepatic cell types participate in the early innate immune response and the subsequent inflammation and activation of the adaptive response, principally hepatocytes, and antigen-presenting cells (Kupffer cells, and dendritic cells). Innate pattern recognition receptors on these cells, mainly toll-like receptors, are targets for new promising adjuvants. Moreover, complex adjuvants that stimulate different components of the innate immunity are showing encouraging results and are being incorporated in current vaccines. Recent studies on HCV-vaccine adjuvants have shown that the induction of a strong T- and B-cell immune response might be enhanced by choosing the right adjuvant.

E. coli-Produced Monophosphoryl Lipid a Significantly Enhances Protective Immunity of Pandemic H1N1 Vaccine

Emerging influenza viruses pose an extreme global risk to human health, resulting in an urgent need for effective vaccination against influenza infection. Adjuvants are vital components that can improve vaccine efficacy, yet only a few adjuvants have been licensed in human vaccines. Here, we investigate the adjuvant effects of Escherichia coli-produced monophosphoryl lipid A (MPL), named EcML, in enhancing the immunogenicity and efficacy of an influenza vaccine. Similar to MPL, EcML activated dendritic cells and enhanced the antigen processing of cells in vitro. Using ovalbumin (OVA) as a model antigen, EcML increased OVA-specific antibody production, cytotoxic T lymphocyte activity. The safety of EcML was demonstrated as being similar to that of MPL by showing not significant in vitro cell cytotoxicity but transient systemic inflammatory responses within 24 h in OVA immunized mice. Importantly, mice vaccinated with pandemic H1N1 (pH1N1) vaccine antigen, combined with EcML, were fully protected from pH1N1 virus infection by enhanced influenza-specific antibody titers, hemagglutination inhibition titers, and IFN-γ- secreting cells. Taken together, our results strongly suggest that EcML might be a promising vaccine adjuvant for preventing influenza virus infection.

The novel combinations of CTB, CpG, and aluminum hydroxide significantly enhanced the immunogenicity of clumping factor A 221-550 of Staphylococcus aureus

Here, we prepared the novel combined adjuvants, CTB as intra-molecular adjuvant, CpG and aluminum hydroxide (Alum) to strengthen the immunogenicity of clumping factor A_221-550 of Staphylococcus aureus (S. aureus). The protein-immunoactive results showed CTB-ClfA_221-550 elicited the strong immune responses to serum from mice immunized with CTB and ClfA_221-550, respectively. The mice immunized with CTB-ClfA_221-550 plus CpG and Alum adjuvant exhibited significantly stronger CD4⁺ T cell responses for IFN-γ, IL-2, IL-4, and IL-17 and displayed the higher proliferation response of splenic lymphocytes than the control groups, in addition, these mice generated the strongest humoral immune response against ClfA_221-550 among all groups. Our results also showed CTB-ClfA_221-550 plus CpG and Alum adjuvant obviously increased the survival percentage of the mice challenged by S. aureus. These data suggested that the novel combined adjuvants, CTB, CpG, and Alum, significantly enhance the immune responses triggered with ClfA_221-550, and could provide a new approach against infection of S. aureus.

ABBREVIATIONS

CTB: Cholera Toxin B; CpG: Cytosine preceding Guanosine; ODN: Oligodeoxynucleotides; Alum: Aluminum hydroxide; TRAP: Target of RNAIII-activating Protein; TLR9: Toll-like Receptor 9; TMB: 3, 3', 5, 5'-tetramethylbenzidine; mAbs: Monoclonal Antibodies; OD: Optical Densities; S. aureus: Staphylococcus aureus; ClfA: Clumping factor A; FnBPA: Fibronection-binding protein A; IsdB: Iron-regulated surface determinant B; SasA: Staphylococcus aureus Surface Protein A; GapC: Glycer-aldehyde-3-phosphate dehydrogenase-C.

GAD-alum immunotherapy in type 1 diabetes expands bifunctional Th1/Th2 autoreactive CD4 T cells

AIMS/HYPOTHESIS

Antigen-specific therapy aims to modify inflammatory T cell responses in type 1 diabetes and restore immune tolerance. One strategy employs GAD65 conjugated to aluminium hydroxide (GAD-alum) to take advantage of the T helper (Th)2-biasing adjuvant properties of alum and thereby regulate pathological Th1 autoimmunity. We explored the cellular and molecular mechanism of GAD-alum action in the setting of a previously reported randomised placebo-controlled clinical trial conducted by Type 1 Diabetes TrialNet.

METHODS

In the clinical trial conducted by Type 1 Diabetes TrialNet, participants were immunised with 20 μg GAD-alum (twice or three times) or alum alone and peripheral blood mononuclear cell samples were banked at baseline and post treatment. In the present study, GAD-specific T cell responses were measured in these samples and GAD-specific T cell lines and clones were generated, which were then further characterised.

RESULTS

At day 91 post immunisation, we detected GAD-specific IL-13⁺ CD4 T cell responses significantly more frequently in participants immunised with GAD-alum (71% and 94% treated twice or three times, respectively) compared with those immunised with alum alone (38%; p = 0.003 and p = 0.0002, respectively) accompanied by high secreted levels of IL-13, IL-4 and IL-5, confirming a GAD-specific, GAD-alum-induced Th2 response. Of note, GAD-specific, IL-13⁺ CD4 T cells observed after immunisation co-secreted IFN-γ, displaying a bifunctional Th1/Th2 phenotype. Single-cell transcriptome analysis identified IL13 and IFNG expression in concert with the canonical Th2 and Th1 transcription factor genes GATA3 and TBX21, respectively. T cell receptor β-chain (TCRB) CDR3 regions of GAD-specific bifunctional T cells were identified in circulating naive and central memory CD4 T cell pools of non-immunised participants with new-onset type 1 diabetes and healthy individuals, suggesting the potential for bifunctional responses to be generated de novo by GAD-alum immunisation or via expansion from an existing public repertoire.

CONCLUSIONS/INTERPRETATION

GAD-alum immunisation activates and propagates GAD-specific CD4 T cells with a distinctive bifunctional phenotype, the functional analysis of which might be important in understanding therapeutic responses.

Vaccine adjuvant activity of a TLR4-activating synthetic glycolipid by promoting autophagy

Toll-like receptors (TLRs) play crucial roles in host immune defenses. Recently, TLR-mediated autophagy is reported to promote immune responses via increasing antigen processing and presentation in antigen presenting cells. The present study examined whether the synthetic TLR4 activator (CCL-34) could induce autophagy to promote innate and adaptive immunity. In addition, the potential of CCL-34 as an immune adjuvant in vivo was also investigated. Our data using RAW264.7 cells and bone marrow-derived macrophages showed that CCL-34 induced autophagy through a TLR4-NF-κB pathway. The autophagy-related molecules (Nrf2, p62 and Beclin 1) were activated in RAW264.7 cells and bone marrow-derived macrophages under CCL-34 treatment. CCL-34-stimulated macrophages exhibited significant antigen-processing activity and induced the proliferation of antigen-specific CD4+T cells as well as the production of activated T cell-related cytokines, IL-2 and IFN-γ. Furthermore, CCL-34 immunization in mice induced infiltration of monocytes in the peritoneal cavity and elevation of antigen-specific IgG in the serum. CCL-34 treatment in vivo did not cause toxicity based on serum biochemical profiles. Notably, the antigen-specific responses induced by CCL-34 were attenuated by the autophagy inhibitor, 3-methyladenine. In summary, we demonstrated CCL-34 can induce autophagy to promote antigen-specific immune responses and act as an efficient adjuvant.

Nanoformulated Single-Stranded RNA-Based Adjuvant with a Coordinative Amphiphile as an Effective Stabilizer: Inducing Humoral Immune Response by Activation of Antigen-Presenting Cells

As agonists of TLR7/8, single-stranded RNAs (ssRNAs) are safe and promising adjuvants that do not cause off-target effects or innate immune overactivation. However, low stability prevents them from mounting sufficient immune responses. This study evaluates the adjuvant effects of ssRNA derived from the cricket paralysis virus intergenic region internal ribosome entry site, formulated as nanoparticles with a coordinative amphiphile, containing a zinc/dipicolylamine complex moiety as a coordinative phosphate binder, as a stabilizer for RNA-based adjuvants. The nanoformulated ssRNA adjuvant was resistant to enzymatic degradation in vitro and in vivo, and that with a coordinative amphiphile bearing an oleyl group (CA-O) was approximately 100 nm, promoted effective recognition, and improved activation of antigen-presenting cells, leading to better induction of neutralizing antibodies following single immunization. Hence, CA-O may increase the efficacy of ssRNA-based adjuvants, proving useful to meet the urgent need for vaccines during pathogen outbreaks.

The CTA1-DD adjuvant strongly potentiates follicular dendritic cell function and germinal center formation, which results in improved neonatal immunization

Vaccination of neonates and young infants is hampered by the relative immaturity of their immune systems and the lack of safe and efficacious vaccine adjuvants. Immaturity of the follicular dendritic cells (FDCs), in particular, appears to play a critical role for the inability to stimulate immune responses. Using the CD21mT/mG mouse model we found that at 7 days of life, FDCs exhibited a mature phenotype only in the Peyer´s patches (PP), but our unique adjuvant, CTA1-DD, effectively matured FDCs also in peripheral lymph nodes following systemic, as well as mucosal immunizations. This was a direct effect of complement receptor 2-binding to the FDC and a CTA1-enzyme-dependent enhancing effect on gene transcription, among which CR2, IL-6, ICAM-1, IL-1β, and CXCL13 encoding genes were upregulated. This way we achieved FDC maturation, increased germinal center B-cell- and Tfh responses, and enhanced specific antibody levels close to adult magnitudes. Oral priming immunization of neonates against influenza infection with CTA1-3M2e-DD effectively promoted anti-M2e-immunity and significantly reduced morbidity against a live virus challenge infection. To the best of our knowledge, this is the first study to demonstrate direct effects of an adjuvant on FDC gene transcriptional functions and the subsequent enhancement of neonatal immune responses.

Influenza NG-34 T cell conserved epitope adjuvanted with CAF01 as a possible influenza vaccine candidate

Conserved epitopes are targets commonly researched to be part of universal vaccine candidates against influenza viruses (IV). These conserved epitopes need to be cross-protecting against distinct IV subtypes and to have a strong immunogenic potential. Nevertheless, subunit vaccines generally require a strong adjuvant to enhance their immunological effects. Herewith, we compare four different adjuvants differing in their immunological signatures that may enhance efficacy of a conserved hemagglutinin (HA)-epitope from IV, the NG-34, to define the most efficient combination of antigen/adjuvant to combat IV infections. Soluble NG-34 was mixed with adjuvants like aluminium hydroxide (AH) and AddaVax, known to induce Th2 and humoral responses; CAF01 which displays a biased Th1/Th17 profile and Diluvac Forte which augments the humoral response. Combinations were tested in different groups of mice which were subjected to immunological analyses. CAF01 + NG-34 induced a complete immune response with the highest IgG1, IgG2c titers and percentages of activated CD4 T cell promoting IFN-γ, IL-2 and TNF-α producing cells. Furthermore, in NG-34 stimulated mice splenocytes, cytokine levels of IFN-γ, IL-1β, IL-6, IL-10, IL-17 and TNF-α were also the highest in the CAF01 + NG-34 mouse group. This complete induced immune response covering the humoral and the cellular arms of the adaptive immunity promoted by CAF01 + NG-34 group suggests that CAF01 could be a good candidate as an adjuvant to combine with NG-34 for an efficacious vaccine against IV. However, more studies performed in IV hosts as well as studies with a challenge model are further required.

Inflammasomes as Targets for Adjuvants

Inflammasomes are an essential part of the innate immune system. They are necessary for the development of a healthy immune response against infectious diseases. Inflammasome activation leads to the secretion of pro-inflammatory cytokines such as IL-1β and IL-18, which stimulate the adaptive immune system. Inflammasomes activators can be used as adjuvants to provide and maintain the strength of the immune response. This review is focused on the mechanisms of action and the effects of adjuvants on inflammasomes. The therapeutic and prophylaxis significance of inflammasomes in infectious diseases is also discussed.

Evaluation of glycoprotein E subunit and live attenuated varicella-zoster virus vaccines formulated with a single-strand RNA-based adjuvant

Introduction

Varicella‐zoster virus (VZV), a human alphaherpesvirus 3, elicits both chickenpox and shingles and/or postherpetic neuralgia. A live attenuated vaccine (LAV) and glycoprotein E (gE) subunit vaccine were developed to prevent VZV‐induced diseases. We recently reported that single‐strand RNA (ssRNA) based on the intergenic region of the internal ribosome entry site of cricket paralysis virus (CrPV) is an effective adjuvant for protein‐based and virus‐like particle‐based vaccines. Here, Chinese hamster ovary expression system and an LAV from Oka/SK strains.

Methods

We appraised the adjuvant effect of the same CrPV ssRNA encoding the gE gene formulated in the two vaccines using VZV‐primed C57BL/6 mice and guinea pigs. Humoral immunity and cell‐mediated immunity were assessed by enzyme‐linked immunosorbent assay (ELISA) and ELISPOT in gE subunit vaccine and by ELISA and fluorescent antibody to membrane antigen in LAV.

Results

The gE subunit vaccine‐induced gE‐specific antibodies and CD4⁺ T‐cell responses (indicated by interferon‐γ [IFN‐γ] and interleukin‐2 secretion) in the ssRNA‐based adjuvant containing the VZV gE gene. Therefore, an ssRNA adjuvant combined with gE antigen can trigger the innate immune response and induce an adaptive immune response to ultimately activate humoral and cell‐mediated responses. VZV LAV could also induce VZV‐specific antibodies and IFN‐γ stimulated by LAV, whereas the effect of ssRNA as a vaccine adjuvant could not be confirmed. However, the ssRNA adjuvant increased VZV‐specific neutralizing antibody response.

Conclusions

Taken together, these results highlight that the gE subunit vaccine and LAV developed in this study can be functional VZV vaccines, and ssRNAs appear to function better as adjuvants in a subunit vaccine than in an LAV.

Chitosan and chitosan nanoparticles as adjuvant in local Rift Valley Fever inactivated vaccine

The present study aimed to improve the potency of inactivated Rift Valley Fever Virus (RVFV) vaccine using chitosan (CS) or chitosan nanoparticles (CNP) as adjuvants. Chitosan nanoparticles were prepared by ionic gelation method. Rift Valley Fever Virus (RVFV) inactivated antigen was loaded on CS and CNP to form two vaccine formulations, RVFV-chitosan nanoparticles based vaccine (RVFV-CNP) and RVFV chitosan based vaccine (RVFV-CS). Five groups of mice were used in this study, each group was injected with one of the following: phosphate buffer saline (group1 G1), RVFV-CNP (G2), (RVF-CS) (G3), RVFV-Alum based vaccine (RVFV-Alum) (G4) and adjuvant free RVFV inactivated antigen (RVFV-Ag) (G5). The immunization was performed twice with 2 weeks interval. The results showed that, RVFV-CNP vaccine enhanced strongly the phagocytic activity of peritoneal macrophage (PM), neutralization antibodies titer against RVFV and IgG values against RVFV nucleoprotein than other vaccine formulations did. In addition, the RVFV-CNP and RVF-CS vaccines upregulate the gene expression of IL-2, IFN-γ (which promote cell mediated immunity) and IL-4 (which promote humeral immunity), while RVFV-Alum vaccine upregulate the gene expression of IL-4 only. These findings indicated that CS and CNP were comparable to the alum as adjuvant in efficacy but superior to it in inducing cell-mediated immune response and might be a candidate adjuvant for inactivated RVFV vaccine.

[Aluminium adjuvant exposure through vaccines in France in 2018]

OBJECTIVES

Aluminum-containing vaccine adjuvants stimulate an adequate immune response to vaccination. The safety and rapid elimination of these molecules, a guarantee of their safe use for several decades, have been challenged by a growing number of studies over the last 20 years. Evaluation of exposure to aluminum adjuvants of an individual is thus essential. The current review answers the following questions: what is the exposure of aluminum adjuvants of an individual vaccinated in France? What are the factors of variation?

METHODS

To evaluate the immunization exposure to aluminum for a vaccinee in France, we used the 2018 vaccination schedule and the Social Security database for vaccines reimbursed that year. French mandatory and recommended vaccines for an individual who does not travel abroad and has no particular professional obligations have been taken into account.

RESULTS

Our results show that an individual following the vaccination requirements and recommendations of 2018 receives between 2545 and 7735μg of Al³⁺ during his lifetime, and at least 50% before the age of 1year. Exposure varies with age, weight, sex, and choice of administered vaccines.

CONCLUSION

Vaccines with higher doses of aluminum are mainly injected at the beginning of life. Women receive a proportionately larger dose than men. The most reimbursed vaccines are often those with the highest amount of aluminum salts.

ASIA syndrome and endocrine autoimmune disorders

An adjuvant is an immunological or pharmacological substance or group of substances that can be added to a given agent to enhance its effect in terms of efficacy, effectiveness and potency. Different mechanisms have been hypothesized underlying the action of the adjuvant, including boosting immune (innate and adaptive) response: this generally results in sparing the necessary amount of the agent and can potentially reduce the frequency of the needed number of therapeutic interventions. Adjuvants can be commonly found in vaccines, immunization products, mineral oils, cosmetics, silicone breast implants and other therapeutic/medical devices, being usually safe and effective. However, in a fraction of genetically susceptible and predisposed subjects, the administration of adjuvants may lead to the insurgence of serious side-effects, called "autoimmune/inflammatory syndrome by adjuvants" (ASIA) or Shoenfeld's syndrome. The present review is aimed at focusing on the "endocrine pebbles" of the mosaic of autoimmunity and of the ASIA syndrome, collecting together 54 cases of sub-acute thyroiditis, 2 cases of Hashimoto's thyroiditis, 11 cases of primary ovarian failure/primary ovarian insufficiency, 13 cases of autoimmune diabetes type 1, and 1 case of autoimmune adrenal gland insufficiency occurred after exposure to adjuvants.

Vaccines for Herpes Simplex: Recent Progress Driven by Viral and Adjuvant Immunology

Herpes simplex viruses (HSV) types 1 and 2 are ubiquitous. They both cause genital herpes, occasionally severe disease in the immunocompromised, and facilitate much HIV acquisition globally. Despite more than 60 years of research, there is no licensed prophylactic HSV vaccine and some doubt as to whether this can be achieved. Nevertheless, a previous HSV vaccine candidate did have partial success in preventing genital herpes and HSV acquisition and another immunotherapeutic candidate reduced viral shedding and recurrent lesions, inspiring further research. However, the entry pathway of HSV into the anogenital mucosa and the subsequent cascade of immune responses need further elucidation so that these responses could be mimicked or improved by a vaccine, to prevent viral entry and colonization of the neuronal ganglia. For an effective novel vaccine against genital herpes the choice of antigen and adjuvant may be critical. The incorporation of adjuvants of the vaccine candidates in the past, may account for their partial efficacy. It is likely that they can be improved by understanding the mechanisms of immune responses elicited by different adjuvants and comparing these to natural immune responses. Here we review the history of vaccines for HSV, those in development and compare them to successful vaccines for chicken pox or herpes zoster. We also review what is known of the natural immune control of herpes lesions, via interacting innate immunity and CD4 and CD8 T cells and the lessons they provide for development of new, more effective vaccines.

Metalloimmunology: The metal ion-controlled immunity

Metals are essential components in all forms of life required for the function of nearly half of all enzymes and are critically involved in virtually all fundamental biological processes. Especially, the transition metals iron (Fe), zinc (Zn), manganese (Mn), nickel (Ni), copper (Cu) and cobalt (Co) are crucial micronutrients known to play vital roles in metabolism as well due to their unique redox properties. Metals carry out three major functions within metalloproteins: to provide structural support, to serve as enzymatic cofactors, and to mediate electron transportation. Metal ions are also involved in the immune system from metal allergies to nutritional immunity. Within the past decade, much attention has been drawn to the roles of metal ions in the immune system, since increasing evidence has mounted to suggest that metals are critically implicated in regulating both the innate immune sensing of and the host defense against invading pathogens. The importance of ions in immunity is also evidenced by the identification of various immunodeficiencies in patients with mutations in ion channels and transporters. In addition, cancer immunotherapy has recently been conclusively demonstrated to be effective and important for future tumor treatment, although only a small percentage of cancer patients respond to immunotherapy because of inadequate immune activation. Importantly, metal ion-activated immunotherapy is becoming an effective and potential way in tumor therapy for better clinical application. Nevertheless, we are still in a primary stage of discovering the diverse immunological functions of ions and mechanistically understanding the roles of these ions in immune regulation. This review summarizes recent advances in the understanding of metal-controlled immunity. Particular emphasis is put on the mechanisms of innate immune stimulation and T cell activation by the essential metal ions like calcium (Ca²⁺), zinc (Zn²⁺), manganese (Mn²⁺), iron (Fe²⁺/Fe³⁺), and potassium (K⁺), followed by a few unessential metals, in order to draw a general diagram of metalloimmunology.

Gold Nanoparticles Coimmobilized with Small Molecule Toll-Like Receptor 7 Ligand and α-Mannose as Adjuvants

Adjuvants enhance the immune response during vaccination. Among FDA-approved adjuvants, aluminum salts are most commonly used in vaccines. Although aluminum salts enhance humoral immunity, they show a limited effect for cell-mediated immune responses. Thus, further development of adjuvants that induce T-cell-mediated immune response is needed. Toll-like receptors (TLRs) recognizing specific pathogen-associated molecular patterns activate innate immunity, which is crucial to shape adaptive immunity. Using TLR ligands as novel adjuvants in vaccines has therefore attracted substantial attention. Among them a small molecule TLR7 ligand, imiquimod, has been approved for clinical use, but its use is restricted to local administration due to unwanted adverse side effects when used systematically. Since TLR7 is mainly located in the endosomal compartment of immune cells, efficient transport of the ligand into the cells is important for improving the potency of the TLR7 ligand. In this study we examined gold nanoparticles (GNPs) immobilized with α-mannose as carriers for a TLR7 ligand to target immune cells. The small molecule synthetic TLR7 ligand, 2-methoxyethoxy-8-oxo-9-(4-carboxy benzyl)adenine (1V209), and α-mannose were coimmobilized via linker molecules consisting of thioctic acid on the GNP surface (1V209-αMan-GNPs). The in vitro cytokine production activity of 1V209-αMan-GNPs was higher than that of the unconjugated 1V209 derivative in mouse bone marrow-derived dendritic cells and in human peripheral blood mononuclear cells. In the in vivo immunization study, 1V209-αMan-GNPs induced significantly higher titers of IgG2c antibody specific to ovalbumin as an antigen than did unconjugated 1V209, and splenomegaly and weight loss were not observed. These results indicate that 1V209-αMan-GNPs could be useful as safe and effective adjuvants for development of vaccines against infectious diseases and cancer.