Supramolecular Hydrogels of Indole-Capped Short Peptides as Vaccine Adjuvants

Many materials as immune adjuvant are researched to help raise immnogenicity of subunit vaccines. Among them, peptide-based hydrogels are gradually coming into notice because of their application in drugs delivery, can- cer cell inhibition, vaccine adjuvants and detection of important analytes. In this work, we introduced a novel aro- matic capping group based on indole to construct short peptide-based supramolecular hydrogelators Indol-GFFY and Indol-GDFDFDY and demonstrated their potential applications as vaccine adjuvants.

Nanoparticles as a vaccine adjuvant of anti-idiotypic antibody against schistosomiasis

Background The development of new adjuvants for human use has been the focus of attention. This study’s aim is to explore the possibility of using nanoparticle Ca nanoparticles (CA) as a vaccine adjuvant of anti-idiotypic antibody NP30 against schistosomiasis and its protective mechanisms. Methods Nanoparticle CA-NP30 conjugate (CA-NP30) was fabricated. BALB/c mice were immunized actively with CA-NP30 to evaluate its effects of protective immunity on mice. The serum levels of specific IgG,IgG1 and IgG2a antibodies against NP30 and the concentrations of IFN-γ and IL-4 in supernatant of splenocytes were determined via ELISA. Results Nanoparticle CA could enhance significantly the protective immunity of NP30 against infection of Schistosoma japonicum and the worm reduction rose from 36.0% (NP30 alone) to 52.6%. The serum levels of specific IgG,IgG1 and IgG2a antibodies against NP30 increased remarkably,as compared with those of the group immunized with NP30 alone. The concentration of IFN-γ in supernatant of splenocyte was drastically elevated [the groups immunized with CA-NP30 and NP30 alone were (493.80±400.74) pg/ml and (39.03±39.58) pg/ml,respectively],but the concentration of IL-4 showed no significant difference from that of NP30 alone [(27.94±9.84) pg/ml vs (27.28±14.44) pg/ml]. Conclusions Nanoparticle CA could act as a vaccine adjuvant of anti-idiotypic antibody NP30 against schistosomiasis. The mechanism could be that CA-NP30 enhances humoral and cellular immune responses in mice.

Optimising the oil phases of aluminium hydrogel-stabilised emulsions for stable,safe and efficient vaccine adjuvant

To increase antibody secretion and dose sparing,squalene-in-water aluminium hydrogel(alun^-stabilised emulsions(ASEs)have been developed,which offer increased surface areas and cellular interactions for higher antigen loading and enhanced immune responses.Nevertheless,the squalene(oil)in previous attempts suffered from limited oxidation resistance,thus,safety and stability were compromised.From a clinical translational perspective,it is imperative to screen the optimal oils for enhanced emulsion adjuvants.Here,because of the varying oleic to linoleic acid ratio,soybean oil,peanut oil,and olive oil were utilised as oil phases in the preparation of aluminium hydrogel-stabilised squalene-in-water emulsions,which were then screened for their stability and immunogenicity.Additionally,the underlying mechanisms of oil phases and emulsion stability were unravelled,which showed that a higher oleic to linoleic acid ratio increased anti-oxidative capabilities but reduced the long-term storage stability owing to the relatively low zeta potential of the prepared droplets.As a result,compared with squalene-in-water ASEs,soybean-in-water ASEs exhibited comparable immune responses and enhanced stability.By optimising the oil phase of the emulsion adjuvants,this work may offer an alternative strategy for safe,stable,and effective emulsion adjuvants.

Lipid-Based Poly(I:C) Adjuvants Strongly Enhance the Immunogenicity of SARS-CoV-2 Receptor-Binding Domain Vaccine

Background The outbreak of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has greatly threatened public health.Recent studies have revealed that the spike receptor-binding domain(RBD)of SARS-CoV-2 is a potent target for vaccine development.However,adjuvants are usually required to strengthen the immunogenicity of recombinant antigens.Different types of adjuvants can elicit different immune responses.Methods We developed an RBD recombinant protein vaccine with a polyriboinosinic acid–polyribocytidylic acid[poly(I:C)]adjuvant to evoke a strong immune response.The delivery of poly(I:C)was optimized in two steps.First,poly(I:C)was complexed with a cationic polymer,poly-l-lysine(PLL),to form poly(I:C)–PLL,a polyplex core.Thereafter,it was loaded into five different lipid shells(group II,III-1,2-distearoyl-sn-glycero-3-phosphocholine[DSPC],III-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine[DOPE],IV-DOPE,and IV-DSPC).We performed an enzyme-linked immunosorbent assay and enzyme-linked immunosorbent spot assay to compare the ability of the five lipopolyplex adjuvants to enhance the immunogenicity of the SARS-CoV-2 RBD protein,including humoral and cellular immune responses.Finally,the adjuvant with the highest immunogenicity was selected to verify the protective immunity of the vaccine through animal challenge experiments.Results Recombinant RBD protein has low immunogenicity.The different adjuvants we developed enhanced the immunogenicity of the RBD protein in different ways.Among the lipopolyplexes,those containing DOPE(III-DOPE and IV-DOPE)elicited RBD-specific immunoglobulin G antibody responses,and adjuvants with four components elicited better RBD-specific immunoglobulin G antibody responses than those containing three components(P<0.05).The IC50 and IC90 titers indicated that the IV-DOPE lipopolyplex had the greatest neutralization ability,with IC50 titers of 1/117,490.Furthermore,in the challenge study,IV-DOPE lipopolyplex protected mice from SARS-CoV-2 infection.On the fourth day after infection,the average animal body weights were reduced by 18.56%(24.164±0.665 g vs.19.678±0.455 g)and 0.06%(24.249±0.683 g vs.24.235±0.681 g)in the MOCK and vaccine groups,respectively.In addition,the relative expression of viral RNA in the vaccinated group was significantly lower than that in the MOCK group(P<0.05).Interstitial inflammatory cell infiltration was observed in the MOCK group,whereas no obvious damage was observed in the vaccinated group.Conclusions The IV-DOPE–adjuvanted SARS-CoV-2 recombinant RBD protein vaccine efficiently protected mice from SARS-CoV-2 in the animal challenge study.Therefore,IV-DOPE is considered an exceptional adjuvant for SARS-CoV-2 recombinant RBD protein-based vaccines and has the potential to be further developed into a SARS-CoV-2 recombinant RBD protein-based vaccine.

Enhancing the immune response and tumor suppression effect of antitumor vaccines adjuvanted with non-nucleotide small molecule STING agonist

Vaccine adjuvants have been widely used to enhance the immunogenicity of the antigens and elicit long-lasting immune response.However,only few vaccine adjuvants have been approved by the FDA for human use so far.Therefore,there is still an urgent need to develop novel adjuvants for the potential applications in clinical trials.Herein,non-nucleotide small molecule STING agonist di ABZI was employed to construct glycopeptide antigen based vaccines for the first time.Immunological evaluation indicated di ABZI not only enhanced the production of antibodies and T cell immune responses,but also inhibited tumor growth in tumor-bearing mice in glycopeptide-based subunit vaccines.These results indicated that di-ABZI demonstrates a high potential as adjuvant for the development of cancer vaccines.

A polymeric co-assembly of subunit vaccine with polyoxometalates induces enhanced immune responses

Long-lasting protective immune responses are expected following vaccination.However,most vaccines alone are inability to evoke an efficient protection.The combinatory administration of adjuvants with vaccines is critical for generating the enhanced immune responses.Herein,with biocompatible poly(4-vinylpyridine)(P4VP)as template,2.5 nm iron/molybdenum oxide cluster,{Mo_(72)Fe_(30)},is applied as an adjuvant to co-assemble with antigens of Mycobacterium bovis via hydrogen bonding at molecular scale.Molecular scale integration of the antigens and{Mo_(72)Fe_(30)}and their full exposure to body fluid media contribute to the augmentation of both humoral and cellular immune responses of the vaccines after inoculation in mice.Anti-inflammatory factor IL-10 gradually increases after 2 weeks followed by a final back to normal level by the 5th week.The balance between proinflammatory cytokines and anti-inflammatory factors suggests that immune system can be activated in the early stage of infection by the antigens carried by the supra-particles and secrete acute inflammatory factors for host defense and anti-inflammatory factors for immune protection.

Pristine mesoporous carbon hollow spheres as safe adjuvants induce excellent Th2-biased immune response

The development of a safe and effective adjuvant that amplifies the immune response to an antigen is important for vaccine delivery. In this study, we developed pristine mesoporous carbon hollow spheres as high-capacity vaccine protein nanocarriers and safe adjuvants for boosting the immune response. Mono-dispersed invaginated mesostructured hollow carbon spheres （IMHCSs） have an average particle size of -200 nm, large pore size of 15 rim, and high pore volume of 2.85 cmB.g-1. IMHCSs exhibited a very high loading capacity （1,040 ~tg-mg-1） towards ovalbumin （OVA, a model antigen）, controlled OVA release behavior, excellent safety profile to normal cells, and high antigen delivery efficacy towards macrophages. In vivo immunization studies in mice demonstrated that OVA-loaded IMHCSs induced a 3-fold higher IgG response compared to a traditional adjuvant QuilA used in veterinary vaccine research. OVA delivered by IMHCSs induced a higher IgG1 concentration than IgG2a, indicating a T-helper 2 （Th2）-polarized response. Interferon-y and interleukin-4 concentration analysis revealed both T-helper 1 （Thl） and Th2 immune responses induced by OVA- loaded IMHCSs. IMHCSs are safer adjuvants than QuilA. Our study revealed that pure IMHCSs without further functionalization can be used as a safe adjuvant for promoting Th2-biased immune responses for vaccine delivery.

Adjuvant-attenuated symptom severity of influenza infections in vaccinated children

Background:Young children are at high risk for developing complications of influenza,as well as severe clinical presentation of disease.Vaccination provides direct protection and reduces symptom severity in breakthrough in-fections.We assessed whether adjuvanted trivalent seasonal influenza vaccine is associated with symptom severity in children who developed laboratory-confirmed influenza,as compared to children who received quadrivalent inactivated influenza.Methods:A cluster randomized controlled trial of influenza vaccines in Canadian Hutterite colonies was conducted from the 2016-2017 to the 2018-2019 influenza season.Children were vaccinated with either quadrivalent inactivated influenza vaccine(QIV),or the MF59 adjuvanted trivalent influenza vaccine(aTIV).We assessed children who developed PCR-confirmed influenza infection for symptom severity outcomes using multivariable generalized negative binomial regression.Results:Among vaccinated children,49 infections were observed across 1779 person-days.Vaccine formulation(aTIV vs QIV)was not significantly associated with composite symptom outcomes,including total number of symptoms or total duration of symptom presentation(p>0.05 for all outcomes).Receipt of aTIV vaccination was significantly associated with attenuation of fever,with an estimated 74%reduction in fever severity.In influenza A type infections,adjuvanted vaccination was significantly associated with reduced systemic symptoms(incidence rate ratios:0.16,95%confidence intervals:0.03,0.64,p=0.01).No associations were observed between vaccine formulation and symptom severity in influenza B infections.Conclusions:In vaccinated children who develop an influenza infection,vaccine formulation was associated with attenuated fever severity,leading to reduced systemic symptoms.In influenza A infections,adjuvanted vaccination was significantly associated with reduced systemic symptoms.

Manganese nanodepot augments host immune response against coronavirus

Interferon(IFN)responses are central to host defense against coronavirus and other virus infections.Manganese(Mn)is capable of inducing IFN production,but its applications are limited by nonspecific distributions and neurotoxicity.Here,we exploit chemical engineering strategy to fabricate a nanodepot of manganese(nanoMn)based on Mn2+.Compared with free Mn2+,nanoMn enhances cellular uptake and persistent release of Mn2+in a pH-sensitive manner,thus strengthening IFN response and eliciting broad-spectrum antiviral effects in vitro and in vivo.Preferentially phagocytosed by macrophages,nanoMn promotes M1 macrophage polarization and recruits monocytes into inflammatory foci,eventually augmenting antiviral immunity and ameliorating coronavirus-induced tissue damage.Besides,nanoMn can also potentiate the development of virus-specific memory T cells and host adaptive immunity through facilitating antigen presentation,suggesting its potential as a vaccine adjuvant.Pharmacokinetic and safety evaluations uncover that nanoMn treatment hardly induces neuroinflammation through limiting neuronal accumulation of manganese.Therefore,nanoMn offers a simple,safe,and robust nanoparticle-based strategy against coronavirus.