A Novel Targeted RIG-I Receptor 5'Triphosphate Double Strain RNA-Based Adjuvant Significantly Improves the Immunogenicity of the SARS-CoV-2 Delta-Omicron Chimeric RBD-Dimer Recombinant Protein Vaccine.

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.

Yeast oral vaccines against infectious diseases.

Vaccines that are delivered orally have several advantages over their counterparts that are administered via injection. Despite the advantages of oral delivery, however, approved oral vaccines are currently limited either to diseases that affect the gastrointestinal tract or to pathogens that have a crucial life cycle stage in the gut. Moreover, all of the approved oral vaccines for these diseases involve live-attenuated or inactivated pathogens. This mini-review summarizes the potential and challenges of yeast oral vaccine delivery systems for animal and human infectious diseases. These delivery systems utilize whole yeast recombinant cells that are consumed orally to transport candidate antigens to the immune system of the gut. This review begins with a discussion of the challenges associated with oral administration of vaccines and the distinct benefits offered by whole yeast delivery systems over other delivery systems. It then surveys the emerging yeast oral vaccines that have been developed over the past decade to combat animal and human diseases. In recent years, several candidate vaccines have emerged that can elicit the necessary immune response to provide significant protection against challenge by pathogen. They serve as proof of principle to show that yeast oral vaccines hold much promise.

INVESTIGATING ANTIGENIC FEATURES OF THE SARS-CoV-2 ISOLATED IN RUSSIAN FEDERATION IN 2021-2022 BY HYPERIMMUNE MOUSE SERUM NEUTRALISATION.

Introduction. The rapid spread of a new coronavirus infection among populations in many countries worldwide has contributed to the genetic evolution of the virus, resulting in the emergence of multiple genetic variants of the SARSCoV-2 coronavirus. Mutations in the viral genome can affect the ability of the virus to bypass the immune system and complicate development of diagnostic and prophylactic drugs. Data on the neutralizing activity of the sera obtained against previously circulating genetic variants of the virus in relation to current SARS-CoV-2 strains may serve as a scientific basis for the selection of the antigens in vaccine development. The aim of this work was to study cross-reactivity of SARSCoV-2 coronavirus strains belonging to different genetic variants, which were isolated in the territory of the Russian Federation during 2020-2022 in the neutralization reaction using mouse hyperimmune sera. Materials and methods. Ten strains of SARS-CoV-2 coronavirus belonging to different genetic variants were used (three non-VOC strains, alpha, beta, gamma, delta, delta+AY, omicron 1 and omicron 2). The hCoV-19/Australia/VIC01/2020 strain (Wuhan) was included in the study as a prototypical variant. BALBc mice were immunized with inactivated concentrated antigen mixed with a 1:1 adjuvant, which was a virus-like immunostimulatory complex based on Quillaja saponaria (Quillaja saponaria). The antibody titer was determined in the neutralization reaction. Results. Essential decrease of neutralizing ability of antibodies specific to non-vOC genetic variants of SARS-CoV-2 coronavirus was revealed against beta VOC and to a lesser degree against alpha and gamma VOC variants. The differences in the neutralizing activity level of antibodies for alpha and beta VOC variants are not significant among themselves, and with gamma VOC variants - there are no significant differences. Neutralizing ability of antibodies specific to delta VOC against alpha and beta VOC variants decreased 4-fold. Neutralizing activity of sera obtained to omicron 1 and 2 variants in relation to the prototype coronavirus variant was reduced 18-fold, to the gamma variant - 12-fold, to delta variants - more than 30-fold;for other variants it was even lower. Conclusions. The results obtained testify to the presence of cross-reactivity between strains of coronavirus belonging to genetic lines Wuhan, alpha, beta, gamma;it is weaker for delta variants. Mutations in the genome of VOC omicron variants led to a significant decrease in antigenic cross-links with earlier genetic variants of the coronavirus. These findings explain the low efficacy of vaccines based on the Wuhan strain, synthetic immunogens, and recombinant proteins based on it against omicron VOC variants, which have caused a rise in morbidity since early 2022, as well as cases of re-infection of humans with new genetic variants of the coronavirus.Copyright © 2023 Saint Petersburg Pasteur Institute. All rights reserved.

Role of toll-like receptors in the pathogenesis of COVID-19: Current and future perspectives

The coronavirus disease 2019 (COVID-19) pandemic underlines a persistent threat of respiratory tract infectious diseases and warrants preparedness for a rapid response. At present, COVID-19 has had a serious social impact and imposed a heavy global burden on public health. The exact pathogenesis of COVID-19 has not been fully elucidated. Since the outbreak of COVID-19, a renewed attention has been brought to Toll-like receptors (TLRs). Available data and new findings have demonstrated that the interaction of human TLRs and SARS-CoV-2 is a vital mediator of COVID-19 immunopathogenesis. TLRs such as TLR2, 4, 7 and 8 are potentially important in viral combat and activation of immunity in patients with COVID-19. Therapeutics targeting TLRs are currently considered promising options against the pandemic. A number of TLR-targeting immunotherapeutics are now being investigated in preclinical studies and different phases of clinical trials. In addition, innovative vaccines based on TLRs under development could be a promising approach for building a new generation of vaccines to solve the current challenges. In this review, we summarize recent progress in the role of TLRs in COVID-19, focusing the new candidate drugs targeting TLRs, the current technology and potential paths forward for employing TLR agonists as vaccine adjuvants.Copyright © 2023 The Scandinavian Foundation for Immunology.

Subacute Thyroiditis Following Vaccination with COVID-19 mRNA Vaccine

Introduction: Subacute thyroiditis is a self-limiting post-viral inflammatory disorder occurring in 3 phases (hyper-, hypo-, and euthyroidism) Post-vaccine thyroiditis has also been reported, but is rare. Case Description: A 36-year-old Emirati female presented to our clinic with generalized fatigue, mild to moderate vague neck pain, intermittent palpitations, and loss of appetite 2 weeks after receiving her first dose of Pfizer-BioNTech mRNA vaccine against COVID-19. Clinical examination findings and laboratory test results were consistent with subacute thyroiditis. Patient is a mother of 5 healthy children, youngest is breast-fed infant (11 months old). There was no history suggestive of postpartum thyroiditis and no family history of thyroid dysfunction. Physical examination at initial visit showed mild tachycardia, and a normal blood pressure. She weighed 66 kg. Thyroid function tests revealed a suppressed TSH of 0.011 muIU/mL, high Free T4 of >100 pmol/l), and Free T3 FT3 of 29.6 pmol/L. Both TSH receptor antibodies, and Thyroid antibodies (TPO) were negative. Thyroid scintigraphy showed decreased uptake in both lobes. Thyroid ultrasound showed hypoechoic heterogeneous echotexture of the thyroid gland with vascular conglomerate and micro-calcification, along with normal sized reactive lymph nodes at sternal angle. Symptoms aggravated through the next week;patient dropped 3kg of her body weight and her palpitations increased, with a recorded resting heart rate between 120-130 beats/min. TSH decreased to 0.001muIU/mL while FT4 remained high, with an improvement to 90 pmol/L. Subsequently, the patient started to regain weight. Palpitations improved within a month. She developed a biochemically hypothyroid picture followed by clinical and biochemical euthyroidism after one more month. Second dose of the vaccine was uneventful. Last evaluation was 10 months later;TSH, FT3 and FT4 were all in normal range, acute-phase reactants were completely normal and in complete remission. Discussion(s): The exact mechanism for post-vaccination subacute thyroiditis remains unknown, vaccine adjuvants may induce diverse autoimmune and inflammatory reaction. Subacute thyroiditis has rarely been reported with other COVID-19 vaccines contains no Polyethylene glycol (PEG). A possible cross-reactivity between thyroid cell antigens and spike protein of the coronavirus produced by mRNA vaccines might be responsible. Further research is needed to investigate the incidence of subacute thyroiditis in COVID-19 pandemic days.Copyright © 2023

Thyroiditis Post COVID-19 mRNA Booster Dose Vaccination

Introduction: SARS-CoV-2 vaccines have been associated with thyroid dysfunction including thyroiditis and Graves' disease. We report a patient who developed thyrotoxicosis secondary to thyroiditis after COVID-19 mRNA booster dose vaccination. Case Description: A 74-year-old man with no known personal or family history of thyroid disorders went to his primary care physician with symptoms of palpitations. Of note, he had the first booster (third dose) of the Pfizer/BioNTech vaccine about 1 week before. He did not recall any similar symptoms after the first two doses of the same vaccine. There were no other symptoms of thyrotoxicosis such as hand tremors, weight loss or mood change. There was no family history of thyroid disorders. He was not on any medications such as amiodarone and was not taking any herbal supplements. He did not have any symptoms of upper respiratory tract infection. There was no neck pain. Physical examination was unremarkable with no goiter or thyroid eye manifestations. Thyroid function: free T4 elevated at 46.7 pmol/L (11.5-22.7) and TSH suppressed at 0.01 mIU/L (0.5-4.5). Thyroid stimulating immunoglobulin was positive at 200% (50-179). He was initially started on carbimazole 15mg daily. However, the patient became rapidly hypothyroid despite dose reduction and subsequent discontinuation of carbimazole with free T4 of 8 pmol/L and TSH of 36.4 mIU/L. An ultrasound of the thyroid gland showed vascularity with no discrete nodules. No thyroid uptake scan was done. The diagnosis was revised to thyroiditis post vaccination. Hypothyroidism persisted despite discontinuation of carbimazole before recovery 8 months later. Patient was well and did not require any thyroxine supplementation. Discussion(s): It is postulated that COVID-19 vaccines triggered thyroiditis via an autoimmune inflammatory syndrome caused by the vaccine adjuvants. A high index of suspicion is necessary and a thyroid uptake scan may be useful in making the diagnosis. Thyroiditis is a self-limiting condition and recognising it is important as no specific thyroid treatment is necessary in most patients. Patients should not be deterred from subsequent vaccination as COVID-19 infection has higher mortality risk than thyroiditis.Copyright © 2023

A feasibility study on a digital device, SAT-008, as an influenza vaccine adjuvant

Background: Viral infections such as influenza and COVID-19 pose a serious threat to human health, which increases the demand for a new approach to enhance the host immunity. Previous studies showed that exercise activities could enhance the anti-viral neutralizing antibody titers after vaccination. We developed a novel digital device, SAT-008, as a mobile application based on an algorithm to regulate physical activity which are related to boosting innate and adaptive immune systems against virus. SAT-008 aimed to improve the activity of immune cells and the immune response in the body, which can be induced by software -designed -intensity levels of daily physical activities. Method(s): A randomized, open-label, and controlled study was conducted for 13 weeks (Oct 20 to Jan 21). A total of 42 healthy adults aged 24 to 46 years were recruited for this study and 32 among them served for analysis. Subjects were administered a single-dose quadrivalent influenza vaccine. The control group maintained daily life without using SAT-008, while the experimental group used SAT-008 during the study. Result(s): Compared to the control group, the experimental group showed a significant increase in neutralizing antibody titers of antigen subtype B Yamagata lineage after 4 weeks of vaccination and antigen subtype B Victoria lineage after 12 weeks of vaccination (P < 0.05), whereas the controls did not reach a significant level in any antibody titer. In the case of type 'A' influenza, there was no significant difference in neutralizing antibody titers between control and experimental groups. Stimulated NK cells of subjects in the control group decreased significantly between 4 weeks and 12 weeks after the vaccination (P < 0.05) while the subjects in the experimental group slightly increase the NK activity between 4 weeks and 12 weeks after the vaccination, however, there was no significance. The interaction effect was observed between control and experimental groups at weeks 4 and 12 by subsequent analysis (P < 0.05). Conclusion(s): We conclude that a novel approach using the digital device may play an important role to enhance the host immune system to act as a vaccine adjuvant against viral diseases such as influenza.

Similarities and differences of chemical compositions and physical and functional properties of adjuvant system 01 and army liposome formulation with QS21.

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.

Autoimmune reactions associated with various types of sars-cov- 2 vaccines among rheumatic disease patients: a case series

Background: Vaccinations are of paramount importance in eradicating various diseases. Currently, there have been numerous reports on the development of new-onset autoimmune phenomena and disease flares following COVID-19 vaccination. The etiology and vaccine trigger mechanism of autoimmune disease still remains unclear. Molecular mimicry, by-stander activation and role of vaccine adjuvants are the main pathogenic mechanisms linked to an autoimmune phenomenon. However, vaccines as inducers of an autoimmunity is still an arguable subject. Case: We report a case series of six patients who developed new onset autoimmune reaction and disease flares following SARS-COV 2 vaccine. The patients received viral vector vaccine, inactivated vaccine and mRNA vaccine who developed symptoms in an average of 7-28 days following inoculation. A 27 year old male, previously healthy developed new onset of clinical amyopathic dermatomyositis after a week of 1st and 2nd dose of a viral vector vaccine. Two patients with systemic lupus erythematous developed severe cutaneous, hematologic and renal flare 14 and 28 days following vaccination. Two rheumatoid arthritis patients in long remission, developed atypical arthritis and disease flares after 10 and 14 days of inactivated and mRNA vaccine inoculation. One patient with spondylarthritis in remission experienced disease flare 7 days following inactivated SARS-COV- 2 vaccination. The patient age ranges from 19-72 years old of whom two are males and four are females. The management was individualized which includes oral corticosteroid and disease modifying anti-rheumatic drugs which showed improvement of symptoms. Conclusion: Development of an autoimmune reaction following SARS-COV 2 vaccination is of scientific and public importance. Vaccination might potentially trigger an autoimmune disease, however further investigations need to be established. The causative link between vaccination and autoimmunity needs to be studied. Susceptibility to a vaccine-induced autoimmunity might be triggered by the individual's genetic predisposition and several pathomechanisms.

Enhanced immune effect of CpG 7909/alum adjuvant to the inactivated vaccine of SARS-CoV-2

Objective: To evaluate the immunogenicity effect of CpG 7909 and Alum adjuvant to inactivated SARS-CoV-2 vaccine. Method(s): Mice were immunized with inactivated SARS-CoV-2 vaccines prepared with CpG 7909 and/or Alum adjuvant by intramuscular injection for 0 and 21 days. To evaluate the immunogenicity of inactivated SARS-CoV-2 vaccines with different adjuvants, serum samples were collected on Day 14, 28, 35 and 42 after immunization to detect the neutralizing antibody titers by microneutralization assay. Spleen samples were collected on Day 42 after immunization to detect the cellular immunity by flow cytometry and ELISPOT. Result(s): Compared with the inactivated SARS-CoV-2 vaccines adjuvanted with CpG 7909 or Alum only, the combination of CpG 7909 and Alum adjuvant significantly increased neutralizing antibody titers in mice and showed great cross-neutralization activity against the Delta variant. It also significantly induced the activation of specific IL-4, IFN-gamma and GCB cells. Conclusion(s): The combination of CpG 7909 and Alum adjuvant synergistically enhanced the humoral and cellular immune responses induced by inactivated SARS-CoV-2 vaccine and showed great cross-neutralization activity against the Delta variant. Copyright © 2022, Chinese Journal of New Drugs Co. Ltd. All right reserved.

Thyroid myopathy after receiving COVID-19 Vaccine

Introduction: There have been few reported cases of post-vaccination thyroiditis and Grave's disease. Here, we present a unique case of post vaccination thyroiditis associated with thyrotoxic myopathy after COVID-19 vaccination. Case Description: A 39-year-old man with no significant past medical history presented to the ED complaining of diffuse muscle pain, joint pain and stiffness for 2 days. He was unable to stand without support. On examination, he had normal deep tendon reflexes but decreased power on the right arm and leg. Admission labs revealed TSH of 0.008 (0.55- 4.7 uIU/mL), Free T4 2.49 (0.89 - 1.76 ng/dl) and FT3 7.4 (2.3-4.2 ng/dl), low potassium of 3.0 L (3.6 - 5.1 mmol/L) and normal CPK 135 (49 – 397 IU/L). MRI of the brain and cervical spine did not show any pathology. Muscle weakness was assessed to be from hypokalemia related to thyrotoxicosis. After potassium replacement, his symptoms improved but did not resolve completely. He was discharged home on methimazole and propranolol. During out-patient follow up 2 months later, his TFTs did not improve (FT4 2.90 ng/dl and TSH of 0.008 uIU/mL) with persistent muscle weakness and muscle aches despite normal potassium of 4.4 (3.6 - 5.1 mmol/L). TSI and TPO antibodies came back negative. Thyroid uptake and scan revealed decreased 4-hour (3.4%) and 24-hour (4%) uptake. Additional history revealed that he received his second dose of COVID-19 vaccine 6 days prior to onset of symptoms. At this point, a diagnosis of post COVID vaccination thyrotoxic myopathy was made. Methimazole was stopped and he was treated with a tapering dose of prednisone. His symptoms resolved completely with normalization of TFTs after a month (Free T4 1.28 ng/dl, TSH 2.993 uIU/mL). Discussion: Autoimmune thyroid disease including thyroiditis and Grave‘s disease have been reported after receiving COVID-19 vaccine. One of the mechanisms for this complication is thought to be autoimmune/inflammatory syndrome induced by vaccine adjuvants. This case illustrates the importance of keeping broad differentials in mind in patients who recently received COVID-19 vaccine especially as the pandemic persists and more people are being vaccinated.

The efficacy of a 2,4-diaminoquinazoline compound as an intranasal vaccine adjuvant to protect against influenza A virus infection in vivo.

Adjuvants are substances added to vaccines to enhance antigen-specific immune responses or to protect antigens from rapid elimination. As pattern recognition receptors, Toll-like receptors 7 (TLR7) and 8 (TLR8) activate the innate immune system by sensing endosomal single-stranded RNA of RNA viruses. Here, we investigated if a 2,4-diaminoquinazoline-based TLR7/8 agonist, (S)-3-((2-amino-8-fluoroquinazolin-4-yl)amino)hexan-1-ol (named compound 31), could be used as an adjuvant to enhance the serological and mucosal immunity of an inactivated influenza A virus vaccine. The compound induced the production of proinflammatory cytokines in macrophages. In a dose-response analysis, intranasal administration of 1 µg compound 31 together with an inactivated vaccine (0.5 µg) to mice not only enhanced virus-specific IgG and IgA production but also neutralized influenza A virus with statistical significance. Notably, in a virus-challenge model, the combination of the vaccine and compound 31 alleviated viral infection-mediated loss of body weight and increased survival rates by 40% compared with vaccine only-treated mice. We suggest that compound 31 is a promising lead compound for developing mucosal vaccine adjuvants to protect against respiratory RNA viruses such as influenza viruses and potentially coronaviruses.

Novel Synthetic Lipopeptides as Potential Mucosal Adjuvants Enhanced SARS-CoV-2 rRBD-Induced Immune Response.

As TLR2 agonists, several lipopeptides had been proved to be candidate vaccine adjuvants. In our previous study, lipopeptides mimicking N-terminal structures of the bacterial lipoproteins were also able to promote antigen-specific immune response. However, the structure-activity relationship of lipopeptides as TLR2 agonists is still unclear. Here, 23 synthetic lipopeptides with the same lipid moiety but different peptide sequences were synthesized, and their TLR2 activities in vitro and mucosal adjuvant effects to OVA were evaluated. LP1-14, LP1-30, LP1-34 and LP2-2 exhibited significantly lower cytotoxicity and stronger TLR2 activity compared with Pam2CSK4, the latter being one of the most potent TLR2 agonists. LP1-34 and LP2-2 assisted OVA to induce more profound specific IgG in sera or sIgA in BALF than Pam2CSK4. Furthermore, the possibility of LP1-34, LP2-2 and Pam2CSK4 as the mucosal adjuvant for the SARS-CoV-2 recombinant RBD (rRBD) was investigated. Intranasally immunized with rRBD plus either the novel lipopeptide or Pam2CSK4 significantly increased the levels of specific serum and respiratory mucosal IgG and IgA, while rRBD alone failed to induce specific immune response due to its low immunogenicity. The novel lipopeptides, especially LP2-2, significantly increased levels of rRBD-induced SARS-CoV-2 neutralizing antibody in sera, BALF and nasal wash. Finally, Support vector machine (SVM) results suggested that charged residues in lipopeptides might be beneficial to the agonist activity, while lipophilic residues might adversely affect the agonistic activity. Figuring out the relationship between peptide sequence in the lipopeptide and its TLR2 activity may lay the foundation for the rational design of novel lipopeptide adjuvant for COVID-19 vaccine.

From Sharks to Yeasts: Squalene in the Development of Vaccine Adjuvants.

Squalene is a natural linear triterpene that can be found in high amounts in certain fish liver oils, especially from deep-sea sharks, and to a lesser extent in a wide variety of vegeTable oils. It is currently used for numerous vaccine and drug delivery emulsions due to its stability-enhancing properties and biocompatibility. Squalene-based vaccine adjuvants, such as MF59 (Novartis), AS03 (GlaxoSmithKline Biologicals), or AF03 (Sanofi) are included in seasonal vaccines against influenza viruses and are presently being considered for inclusion in several vaccines against SARS-CoV-2 and future pandemic threats. However, harvesting sharks for this purpose raises serious ecological concerns that the exceptional demand of the pandemic has exacerbated. In this line, the use of plants to obtain phytosqualene has been seen as a more sustainable alternative, yet the lower yields and the need for huge investments in infrastructures and equipment makes this solution economically ineffective. More recently, the enormous advances in the field of synthetic biology provided innovative approaches to make squalene production more sustainable, flexible, and cheaper by using genetically modified microbes to produce pharmaceutical-grade squalene. Here, we review the biological mechanisms by which squalene-based vaccine adjuvants boost the immune response, and further compare the existing sources of squalene and their environmental impact. We propose that genetically engineered microbes are a sustainable alternative to produce squalene at industrial scale, which are likely to become the sole source of pharmaceutical-grade squalene in the foreseeable future.

Assessment of adjuvantation strategy of lipid squalene nanoparticles for enhancing the immunogenicity of a SARS-CoV-2 spike subunit protein against COVID-19.

Vaccination is regarded as the most effective intervention for controlling the coronavirus disease 2019 (COVID-19) pandemic. The objective of this study is to provide comprehensive information on lipid squalene nanoparticle (SQ@NP)-adjuvanted COVID-19 vaccines regarding modulating immune response and enhancing vaccine efficacy. After being adjuvanted with SQ@NP, the SARS-CoV-2 spike (S) subunit protein was intramuscularly (i.m.) administered to mice. Serum samples investigated by ELISA and virus neutralizing assay showed that a single-dose SQ@NP-adjuvanted S-protein vaccine can induce antigen-specific IgG and protective antibodies comparable with those induced by two doses of nonadjuvanted protein vaccine. When the mice received a boosting vaccine injection, anamnestic response was observed in the groups of adjuvanted vaccine. Furthermore, the secretion of cytokines in splenocytes, such as interferon (IFN)-γ, interleukin (IL)-5 and IL-10, was significantly enhanced after adjuvantation of S-protein vaccine with SQ@NP; however, this was not the case for the vaccine adjuvanted with conventional aluminum mineral salts. Histological examination of injection sites showed that the SQ@NP-adjuvanted vaccine was considerably well tolerated following i.m. injection in mice. These results pave the way for the performance tuning of optimal vaccine formulations against COVID-19.

Carbohydrate-containing nanoparticles as vaccine adjuvants.

Introduction: Adjuvants are essential to vaccines for immunopotentiation in the elicitation of protective immunity. However, classical and widely used aluminum-based adjuvants have limited capacity to induce cellular response. There are increasing needs for appropriate adjuvants with improved profiles for vaccine development toward emerging pathogens. Carbohydrate-containing nanoparticles (NPs) with immunomodulatory activity and particulate nanocarriers for effective antigen presentation are capable of eliciting a more balanced humoral and cellular immune response.Areas covered: We reviewed several carbohydrates with immunomodulatory properties. They include chitosan, ß-glucan, mannan, and saponins, which have been used in vaccine formulations. The mode of action, the preparation methods, characterization of these carbohydrate-containing NPs and the corresponding vaccines are presented.Expert opinion: Several carbohydrate-containing NPs have entered the clinical stage or have been used in licensed vaccines for human use. Saponin-containing NPs are being evaluated in a vaccine against SARS-CoV-2, the pathogen causing the on-going worldwide pandemic. Vaccines with carbohydrate-containing NPs are in different stages of development, from preclinical studies to late-stage clinical trials. A better understanding of the mode of action for carbohydrate-containing NPs as vaccine carriers and as immunostimulators will likely contribute to the design and development of new generation vaccines against cancer and infectious diseases.

ß-glucans: wide-spectrum immune-balancing food-supplement-based enteric (ß-WIFE) vaccine adjuvant approach to COVID-19.

Conventional vaccines to combat COVID-19 through different approaches are at various stages of development. The complexity of COVID-19 such as the potential mutations of the virus leading to antigenic drift and the uncertainty on the duration of the immunity induced by the vaccine have hampered the efforts to control the COVID-19 pandemic. Thus, we suggest an alternative interim treatment strategy based on biological response modifier glucans such as the Aureobasidium pullulans AFO-202-derived ß-glucan, which has been reported to induce trained immunity, akin to that induced by the Bacille Calmette-Guérin vaccine, by epigenetic modifications at the central level in the bone marrow. These ß-glucans act as pathogen-associated molecular patterns, activating mucosal immunity by binding with specific pathogen recognition receptors such as dectin-1 and inducing both the adaptive and innate immunity by reaching distant lymphoid organs. ß-Glucans have also been used as immune adjuvants for vaccines such as the influenza vaccine. Therefore, until a conventional vaccine is widely available, an orally consumable vaccine adjuvant that acts like biosimilars, termed as the wide-spectrum immune-balancing food-supplement-based enteric (ß-WIFE) vaccine adjuvant approach, with well-reported safety is worth in-depth investigation and can be considered for a clinical trial.

Strategies for Vaccination: Conventional Vaccine Approaches Versus New-Generation Strategies in Combination with Adjuvants.

The current COVID-19 pandemic, caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), has raised significant economic, social, and psychological concerns. The rapid spread of the virus, coupled with the absence of vaccines and antiviral treatments for SARS-CoV-2, has galvanized a major global endeavor to develop effective vaccines. Within a matter of just a few months of the initial outbreak, research teams worldwide, adopting a range of different strategies, embarked on a quest to develop effective vaccine that could be effectively used to suppress this virulent pathogen. In this review, we describe conventional approaches to vaccine development, including strategies employing proteins, peptides, and attenuated or inactivated pathogens in combination with adjuvants (including genetic adjuvants). We also present details of the novel strategies that were adopted by different research groups to successfully transfer recombinantly expressed antigens while using viral vectors (adenoviral and retroviral) and non-viral delivery systems, and how recently developed methods have been applied in order to produce vaccines that are based on mRNA, self-amplifying RNA (saRNA), and trans-amplifying RNA (taRNA). Moreover, we discuss the methods that are being used to enhance mRNA stability and protein production, the advantages and disadvantages of different methods, and the challenges that are encountered during the development of effective vaccines.

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. Electronic Supplementary Material: Supplementary material (RNA-seq data analysis, IFN and ISGs examination, in vitro viral infection, flow cytometry, ICP-MS, DHE staining, and detection of inflammatory factors) is available in the online version of this article at 10.1007/s12274-020-3243-5.

Particulate Alum via Pickering Emulsion for an Enhanced COVID-19 Vaccine Adjuvant.

For rapid response against the prevailing COVID-19 (coronavirus disease 19), it is a global imperative to exploit the immunogenicity of existing formulations for safe and efficient vaccines. As the most accessible adjuvant, aluminum hydroxide (alum) is still the sole employed adjuvant in most countries. However, alum tends to attach on the membrane rather than entering the dendritic cells (DCs), leading to the absence of intracellular transfer and process of the antigens, and thus limits T-cell-mediated immunity. To address this, alum is packed on the squalene/water interphase is packed, forming an alum-stabilized Pickering emulsion (PAPE). "Inheriting" from alum and squalene, PAPE demonstrates a good biosafety profile. Intriguingly, with the dense array of alum on the oil/water interphase, PAPE not only adsorbs large quantities of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) antigens, but also harbors a higher affinity for DC uptake, which provokes the uptake and cross-presentation of the delivered antigens. Compared with alum-treated groups, more than six times higher antigen-specific antibody titer and three-fold more IFN-γ-secreting T cells are induced, indicating the potent humoral and cellular immune activations. Collectively, the data suggest that PAPE may provide potential insights toward a safe and efficient adjuvant platform for the enhanced COVID-19 vaccinations.