Safety and immunogenicity of monovalent H7N9 influenza vaccine with AS03 adjuvant given sequentially or simultaneously with a seasonal influenza vaccine: A randomized clinical trial.

BACKGROUND: Influenza A/H7N9 viruses have pandemic potential. METHODS: We conducted an open-label, randomized, controlled trial of AS03-adjuvanted 2017 inactivated influenza A/H7N9 vaccine (H7N9 IIV) in healthy adults. Group 1 received H7N9 IIV and seasonal quadrivalent influenza vaccine (IIV4) simultaneously, followed by H7N9 IIV three weeks later. Group 2 received IIV4 alone and then two doses of H7N9 IIV at three-week intervals. Group 3 received one dose of IIV4. We used hemagglutination inhibition (HAI) and microneutralization (MN) assays to measure geometric mean titers and seroprotection (≥1:40 titer) to vaccine strains and monitored for safety. RESULTS: Among 149 subjects, seroprotection by HAI three weeks after H7N9 IIV dose 2 was 51% (95 %CI 37%-65%) for Group 1 and 40% (95 %CI 25%-56%) for Group 2. Seroprotection by MN at the same timepoint was 84% (95 %CI 72%-93%) for Group 1 and 74% (95 %CI 60%-86%) for Group 2. By 180 days after H7N9 IIV dose 2, seroprotection by HAI or MN was low for Groups 1 and 2. Responses measured by HAI and MN against each IIV4 strain three weeks after IIV4 vaccination were similar in all groups. Solicited local and systemic reactions were similar after a single vaccination, while those receiving simultaneous H7N9 and IIV4 had slightly more reactogenicity. There were no serious adverse events or medically-attended adverse events related to study product receipt. CONCLUSIONS: Adjuvanted H7N9 IIV was modestly immunogenic whether administered simultaneously or sequentially with IIV4, though responses declined by 180 days. IIV4 was immunogenic regardless of schedule. CLINICAL TRIALS REGISTRATION: NCT03318315.

Fighting the SARS-CoV-2 pandemic requires a global approach to understanding the heterogeneity of vaccine responses.

Host genetic and environmental factors including age, biological sex, diet, geographical location, microbiome composition and metabolites converge to influence innate and adaptive immune responses to vaccines. Failure to understand and account for these factors when investigating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine efficacy may impair the development of the next generation of vaccines. Most studies aimed at identifying mechanisms of vaccine-mediated immune protection have focused on adaptive immune responses. It is well established, however, that mobilization of the innate immune response is essential to the development of effective cellular and humoral immunity. A comprehensive understanding of the innate immune response and environmental factors that contribute to the development of broad and durable cellular and humoral immune responses to SARS-CoV-2 and other vaccines requires a holistic and unbiased approach. Along with optimization of the immunogen and vectors, the development of adjuvants based on our evolving understanding of how the innate immune system shapes vaccine responses will be essential. Defining the innate immune mechanisms underlying the establishment of long-lived plasma cells and memory T cells could lead to a universal vaccine for coronaviruses, a key biomedical priority.

Superoxide Dismutase Prevents SARS-CoV-2-Induced Plasma Cell Apoptosis and Stabilizes Specific Antibody Induction.

The infection of coronavirus disease (COVID-19) seriously threatens human life. It is urgent to generate effective and safe specific antibodies (Abs) against the pathogenic elements of COVID-19. Mice were immunized with SARS-CoV-2 spike protein antigens: S ectodomain-1 (CoV, in short) mixed in Alum adjuvant for 2 times and boosted with CoV weekly for 6 times. A portion of mice were treated with Maotai liquor (MTL, in short) or/and heat stress (HS) together with CoV boosting. We observed that the anti-CoV Ab was successfully induced in mice that received the CoV/Alum immunization for 2 times. However, upon boosting with CoV, the CoV Ab production diminished progressively; spleen CoV Ab-producing plasma cell counts reduced, in which substantial CoV-specific Ab-producing plasma cells (sPC) were apoptotic. Apparent oxidative stress signs were observed in sPCs; the results were reproduced by exposing sPCs to CoV in the culture. The presence of MTL or/and HS prevented the CoV-induced oxidative stress in sPCs and promoted and stabilized the CoV Ab production in mice in re-exposure to CoV. In summary, CoV/Alum immunization can successfully induce CoV Ab production in mice that declines upon reexposure to CoV. Concurrent administration of MTL/HS stabilizes and promotes the CoV Ab production in mice.

Safety, immunogenicity, and protection provided by unadjuvanted and adjuvanted formulations of a recombinant plant-derived virus-like particle vaccine candidate for COVID-19 in nonhuman primates.

Although antivirals are important tools to control severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, effective vaccines are essential to control the current coronavirus disease 2019 (COVID-19) pandemic. Plant-derived virus-like particle (VLP) vaccine candidates have previously demonstrated immunogenicity and efficacy against influenza. Here, we report the immunogenicity and protection induced in rhesus macaques by intramuscular injections of a VLP bearing a SARS-CoV-2 spike protein (CoVLP) vaccine candidate formulated with or without Adjuvant System 03 (AS03) or cytidine-phospho-guanosine (CpG) 1018. Although a single dose of the unadjuvanted CoVLP vaccine candidate stimulated humoral and cell-mediated immune responses, booster immunization (at 28 days after priming) and adjuvant administration significantly improved both responses, with higher immunogenicity and protection provided by the AS03-adjuvanted CoVLP. Fifteen micrograms of CoVLP adjuvanted with AS03 induced a polyfunctional interleukin-2 (IL-2)-driven response and IL-4 expression in CD4 T cells. Animals were challenged by multiple routes (i.e., intratracheal, intranasal, and ocular) with a total viral dose of 106 plaque-forming units of SARS-CoV-2. Lower viral replication in nasal swabs and bronchoalveolar lavage fluid (BALF) as well as fewer SARS-CoV-2-infected cells and immune cell infiltrates in the lungs concomitant with reduced levels of proinflammatory cytokines and chemotactic factors in the BALF were observed in animals immunized with the CoVLP adjuvanted with AS03. No clinical, pathologic, or virologic evidence of vaccine-associated enhanced disease was observed in vaccinated animals. The CoVLP adjuvanted with AS03 was therefore selected for vaccine development and clinical trials.

Immunogenicity and safety of the human papillomavirus vaccine in young survivors of cancer in the USA: a single-arm, open-label, phase 2, non-inferiority trial.

BACKGROUND: Young survivors of cancer are at increased risk for cancers that are related to human papillomavirus (HPV), primarily caused by oncogenic HPV types 16 and 18. We aimed to examine the immunogenicity and safety of the three-dose series of HPV vaccine in young survivors of cancer. METHODS: We conducted an investigator-initiated, phase 2, single-arm, open-label, non-inferiority trial at five National Cancer Institute-designated comprehensive cancer centres in the USA. Eligible participants were survivors of cancer who were HPV vaccine-naive, were aged 9-26 years, in remission, and had completed cancer therapy between 1 and 5 years previously. Participants received three intramuscular doses of either quadrivalent HPV vaccine (HPV4; enrolments on or before March 1, 2016) or nonavalent HPV vaccine (HPV9; enrolments after March 1, 2016) over 6 months (on day 1, at month 2, and at month 6). We also obtained data from published clinical trials assessing safety and immunogenicity of HPV4 and HPV9 in 9-26-year-olds from the general population, as a comparator group. The primary endpoint was antibody response against HPV types 16 and 18 at month 7 in the per-protocol population. A response was deemed non-inferior if the lower bound of the multiplicity-adjusted 95% CI was greater than 0·5 for the ratio of anti-HPV-16 and anti-HPV-18 geometric mean titres (GMTs) in survivors of cancer versus the general population. Responses were examined separately in male and female participants by age group (ie, 9-15 years and 16-26 years). Safety was assessed in all participants who received at least one vaccine dose and for whom safety data were available. This study is registered with ClinicalTrials.gov, NCT01492582. This trial is now completed. FINDINGS: Between Feb 18, 2013, and June 22, 2018, we enrolled 453 survivors of cancer, of whom 436 received one or more vaccine doses: 203 (47%) participants had survived leukaemia, 185 (42%) were female, and 280 (64%) were non-Hispanic white. Mean age at first dose was 15·6 years (SD 4·6). 378 (83%) of 453 participants had evaluable immunogenicity data; main reasons for exclusion from per-protocol analysis were to loss to follow-up, patient reasons, and medical reasons. Data were also obtained from 26 486 general population controls. The ratio of mean GMT for anti-HPV types 16 and 18 in survivors of cancer versus the general population was more than 1 for all subgroups (ie, aged 9-15 years, aged 16-26 years, male, and female groups) in both vaccine cohorts (ranging from 1·64 [95% CI 1·12-2·18] for anti-HPV type 16 in female participants aged 9-15 years who received HPV9, to 4·77 [2·48-7·18] for anti-HPV type 18 in male participants aged 16-26 years who received HPV4). Non-inferiority criteria were met within each age and sex subgroup, except against HPV type 18 in female participants aged 16-26 years receiving HPV9 (4·30 [0·00-9·05]). Adverse events were reported by 237 (54%) of 435 participants; injection site pain was most common (174 [40%] participants). One serious adverse event (ie, erythema nodosum) was possibly related to vaccine (HPV9; 16-26 year female cohort). INTERPRETATION: Immunogenicity and safety of HPV vaccine three-dose series in survivors of cancer is similar to that in the general population, providing evidence for use in this clinically vulnerable population. FUNDING: US National Cancer Institute, Merck, Sharp & Dohme, and American Lebanese Syrian Associated Charities.

Antineoplastic treatment class modulates COVID-19 mRNA-BNT162b2 vaccine immunogenicity in cancer patients: a secondary analysis of the prospective Vax-On study.

BACKGROUND: Preliminary analysis from the Vax-On study did not find a correlation between cancer treatment type and antibody response to COVID-19 vaccination. We carried out a secondary subgroup analysis to verify the effects of comprehensive cancer treatment classification on vaccine immunogenicity. METHODS: The Vax-On study prospectively enrolled patients who started a two-dose messenger RNA-BNT162b2 vaccine schedule from 9 March 2021 to 12 April 2021 (timepoint-1). Those on active treatment within the previous 28 days accounted for the exposed cases. Patients who had discontinued such treatment by at least 28 days or received intravesical therapy represented the control cases. Quantification of immunoglobulin G (IgG) antibodies against the receptor binding domain of the S1 subunit of the SARS-CoV-2 spike protein was carried out before the second dose (timepoint-2) and 8 weeks thereafter (timepoint-3). Seroconversion response was defined at ≥50 arbitrary units/ml IgG titer. Classification of antineoplastic agents was based on their pharmacodynamic properties. RESULTS: Three hundred and sixty-six patients were enrolled (86 and 260 as control and exposed cases, respectively). Univariate analysis revealed a significantly lower IgG titer after both doses of vaccine in subgroups treated with tyrosine kinase inhibitors (TKIs), multiple cytotoxic agents, alkylating agents, and topoisomerase inhibitors. At timepoint-3, seroconversion response was significantly impaired in the topoisomerase inhibitors and mechanistic target of rapamycin (mTOR) inhibitors subgroups. After multivariate testing, treatment with alkylating agents and TKIs was significantly associated with a reduced change in IgG titer at timepoint-2. Treatment with mTOR inhibitors resulted in a similar interaction at each timepoint. Cyclin-dependent kinase 4/6 inhibitor treatment was independently correlated with an incremental variation in IgG titer at timepoint-3. Specific subgroups (TKIs, antimetabolites, alkylating agents, and multiple-agent chemotherapy) predicted lack of seroconversion at timepoint-2, but their effect was not retained at timepoint-3. Eastern Cooperative Oncology Group performance status 2, immunosuppressive corticosteroid dosing, and granulocyte colony-stimulating factor use were independently linked to lower IgG titer after either dose of vaccine. CONCLUSIONS: Drugs interfering with DNA synthesis, multiple-agent cytotoxic chemotherapy, TKIs, mTOR and cyclin-dependent kinase 4/6 inhibitors differentially modulate humoral response to messenger RNA-BNT162b2 vaccine.

Screening HLA-A-restricted T cell epitopes of SARS-CoV-2 and the induction of CD8+ T cell responses in HLA-A transgenic mice.

Since severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-specific T cells have been found to play essential roles in host immune protection and pathology in patients with coronavirus disease 2019 (COVID-19), this study focused on the functional validation of T cell epitopes and the development of vaccines that induce specific T cell responses. A total of 120 CD8+ T cell epitopes from the E, M, N, S, and RdRp proteins were functionally validated. Among these, 110, 15, 6, 14, and 12 epitopes were highly homologous with SARS-CoV, OC43, NL63, HKU1, and 229E, respectively; in addition, four epitopes from the S protein displayed one amino acid that was distinct from the current SARS-CoV-2 variants. Then, 31 epitopes restricted by the HLA-A2 molecule were used to generate peptide cocktail vaccines in combination with Poly(I:C), R848 or poly (lactic-co-glycolic acid) nanoparticles, and these vaccines elicited robust and specific CD8+ T cell responses in HLA-A2/DR1 transgenic mice as well as wild-type mice. In contrast to previous research, this study established a modified DC-peptide-PBL cell coculture system using healthy donor PBMCs to validate the in silico predicted epitopes, provided an epitope library restricted by nine of the most prevalent HLA-A allotypes covering broad Asian populations, and identified the HLA-A restrictions of these validated epitopes using competitive peptide binding experiments with HMy2.CIR cell lines expressing the indicated HLA-A allotype, which initially confirmed the in vivo feasibility of 9- or 10-mer peptide cocktail vaccines against SARS-CoV-2. These data will facilitate the design and development of vaccines that induce antiviral CD8+ T cell responses in COVID-19 patients.

Altering the Immunogenicity of Hemagglutinin Immunogens by Hyperglycosylation and Disulfide Stabilization.

Influenza virus alters glycosylation patterns on its surface exposed glycoproteins to evade host adaptive immune responses. The viral hemagglutinin (HA), in particular the H3 subtype, has increased its overall surface glycosylation since its introduction in 1968. We previously showed that modulating predicted N-linked glycosylation sites on H3 A/Hong Kong/1/1968 HA identified a conserved epitope at the HA interface. This epitope is occluded on the native HA trimer but is likely exposed during HA "breathing" on the virion surface. Antibodies directed to this site are protective via an ADCC-mediated mechanism. This glycan engineering strategy made an otherwise subdominant epitope dominant in the murine model. Here, we asked whether cysteine stabilization of the hyperglycosylated HA trimer could reverse this immunodominance by preventing access to the interface epitope and focus responses to the HA receptor binding site (RBS). While analysis of serum responses from immunized mice did not show a redirection to the RBS, cysteine stabilization did result in an overall reduction in immunogenicity of the interface epitope. Thus, glycan engineering and cysteine stabilization are two strategies that can be used together to alter immunodominance patterns to HA. These results add to rational immunogen design approaches used to manipulate immune responses for the development of next-generation influenza vaccines.

Investigating barriers to the protective efficacy provided by rotavirus vaccines in African infants.

Julie Bines discusses an accompanying study by Sheila Isanaka and colleagues on nutrient supplementation and immune responses to rotavirus vaccination.

Immunogenicity of an oral rotavirus vaccine administered with prenatal nutritional support in Niger: A cluster randomized clinical trial.

BACKGROUND: Nutritional status may play a role in infant immune development. To identify potential boosters of immunogenicity in low-income countries where oral vaccine efficacy is low, we tested the effect of prenatal nutritional supplementation on immune response to 3 doses of a live oral rotavirus vaccine. METHODS AND FINDINGS: We nested a cluster randomized trial within a double-blind, placebo-controlled randomized efficacy trial to assess the effect of 3 prenatal nutritional supplements (lipid-based nutrient supplement [LNS], multiple micronutrient supplement [MMS], or iron-folic acid [IFA]) on infant immune response (n = 53 villages and 1,525 infants with valid serology results: 794 in the vaccine group and 731 in the placebo group). From September 2015 to February 2017, participating women received prenatal nutrient supplement during pregnancy. Eligible infants were then randomized to receive 3 doses of an oral rotavirus vaccine or placebo at 6-8 weeks of age (mean age: 6.3 weeks, 50% female). Infant sera (pre-Dose 1 and 28 days post-Dose 3) were analyzed for anti-rotavirus immunoglobulin A (IgA) using enzyme-linked immunosorbent assay (ELISA). The primary immunogenicity end point, seroconversion defined as ≥3-fold increase in IgA, was compared in vaccinated infants among the 3 supplement groups and between vaccine/placebo groups using mixed model analysis of variance procedures. Seroconversion did not differ by supplementation group (41.1% (94/229) with LNS vs. 39.1% (102/261) with multiple micronutrients (MMN) vs. 38.8% (118/304) with IFA, p = 0.91). Overall, 39.6% (n = 314/794) of infants who received vaccine seroconverted, compared to 29.0% (n = 212/731) of infants who received placebo (relative risk [RR]: 1.36; 95% confidence interval [CI]: 1.18, 1.57, p < 0.001). This study was conducted in a high rotavirus transmission setting. Study limitations include the absence of an immune correlate of protection for rotavirus vaccines, with the implications of using serum anti-rotavirus IgA for the assessment of immunogenicity and efficacy in low-income countries unclear. CONCLUSIONS: This study showed no effect of the type of prenatal nutrient supplementation on immune response in this setting. Immune response varied depending on previous exposure to rotavirus, suggesting that alternative delivery modalities and schedules may be considered to improve vaccine performance in high transmission settings. TRIAL REGISTRATION: ClinicalTrials.gov NCT02145000.

Effect of processed aloe vera gel on immunogenicity in inactivated quadrivalent influenza vaccine and upper respiratory tract infection in healthy adults: A randomized double-blind placebo-controlled trial.

BACKGROUND: Aloe vera is a functional food with various pharmacological functions, including an immune-modulating effect. Until now, A. vera has never been studied as an adjuvant in influenza vaccine, and its effects on upper respiratory tract infection (URI) are unknown. PURPOSE: The objective of our study was to investigate the effect of processed A. vera gel (PAG) on immunogenicity of quadrivalent inactivated influenza vaccine and URI in healthy adults. STUDY DESIGN: A randomized, double-blind, placebo-controlled clinical trial was performed. METHODS: This study was conducted in 100 healthy adults at a single center from September 2017 to May 2018. Subjects were randomly divided into a PAG group (n = 50) and a placebo group (n = 50). The enrolled subjects were instructed to ingest the study drug for 8 weeks. The participants received a single dose of quadrivalent inactivated influenza vaccine after taking the study drug for the first 4 weeks of the study. The primary endpoint was seroprotection rate against at least one viral strain at 4 weeks post-vaccination. Other outcomes were seroprotection rate at 24 weeks post-vaccination, seroconversion rate, geometric mean fold increase (GMFI) at 4 and 24 weeks post-vaccination, seroprotection rate ratio and geometric mean titer ratio (GMTR) at 4 weeks post-vaccination between PAG and placebo groups, and incidence, severity, and duration of URI. RESULTS: The European Committee for proprietary medicinal products (CPMP) evaluation criteria were met at least one in the PAG and placebo groups for all strains. However, there was no significant difference in the seroprotection rate at 4 weeks post-vaccination against all strains in both PAG and placebo groups. Among secondary endpoints, the GMFI at 4 weeks post-vaccination for the A/H3N2 was significantly higher in the PAG than in placebo group. The GMTR as adjuvant effect was 1.382 (95% CI, 1.014-1.1883). Kaplan-Meier curve analysis showed a reduction in incidence of URI (p = 0.035), and a generalized estimating equation model identified a decrease in repeated URI events (odds ratio 0.57; 95% CI, 0.39-0.83; p = 0.003) in the PAG group. CONCLUSIONS: Oral intake of PAG did not show a significant increase in seroprotection rate from an immunogenicity perspective. However, it reduced the number of URI episodes. A well-designed further study is needed on the effect of PAG's antibody response against A/H3N2 in the future.

Putative Role of Vitamin D for COVID-19 Vaccination.

Severe acute respiratory syndrome coronavirus 2 is a new, highly pathogenic virus that has recently elicited a global pandemic called the 2019 coronavirus disease (COVID-19). COVID-19 is characterized by significant immune dysfunction, which is caused by strong but unregulated innate immunity with depressed adaptive immunity. Reduced and delayed responses to interferons (IFN-I/IFN-III) can increase the synthesis of proinflammatory cytokines and extensive immune cell infiltration into the airways, leading to pulmonary disease. The development of effective treatments for severe COVID-19 patients relies on our knowledge of the pathophysiological components of this imbalanced innate immune response. Strategies to address innate response factors will be essential. Significant efforts are currently underway to develop vaccines against SARS-CoV-2. COVID-19 vaccines, such as inactivated DNA, mRNA, and protein subunit vaccines, have already been applied in clinical use. Various vaccines display different levels of effectiveness, and it is important to continue to optimize and update their composition in order to increase their effectiveness. However, due to the continuous emergence of variant viruses, improving the immunity of the general public may also increase the effectiveness of the vaccines. Many observational studies have demonstrated that serum levels of vitamin D are inversely correlated with the incidence or severity of COVID-19. Extensive evidence has shown that vitamin D supplementation could be vital in mitigating the progression of COVID-19 to reduce its severity. Vitamin D defends against SARS-CoV-2 through a complex mechanism through interactions between the modulation of innate and adaptive immune reactions, ACE2 expression, and inhibition of the renin-angiotensin system (RAS). However, it remains unclear whether Vit-D also plays an important role in the effectiveness of different COVID-19 vaccines. Based on analysis of the molecular mechanism involved, we speculated that vit-D, via various immune signaling pathways, plays a complementary role in the development of vaccine efficacy.

Long-term humoral immunogenicity, safety and protective efficacy of inactivated vaccine against COVID-19 (CoviVac) in preclinical studies.

The unprecedented in recent history global COVID-19 pandemic urged the implementation of all existing vaccine platforms to ensure the availability of the vaccines against COVID-19 to every country in the world. Despite the multitude of high-quality papers describing clinical trials of different vaccine products, basic detailed data on general toxicity, reproductive toxicity, immunogenicity, protective efficacy and durability of immune response in animal models are scarce. Here, we developed a ß-propiolactone-inactivated whole virion vaccine CoviVac and assessed its safety, protective efficacy, immunogenicity and stability of the immune response in rodents and non-human primates. The vaccine showed no signs of acute/chronic, reproductive, embryo- and fetotoxicity, or teratogenic effects, as well as no allergenic properties in studied animal species. The vaccine induced stable and robust humoral immune response both in form of specific anti-SARS-CoV-2 IgG and NAbs in mice, Syrian hamsters, and common marmosets. The NAb levels did not decrease significantly over the course of one year. The course of two immunizations protected Syrian hamsters from severe pneumonia upon intranasal challenge with the live virus. Robustness of the vaccine manufacturing process was demonstrated as well. These data encouraged further evaluation of CoviVac in clinical trials.

Immunogenicity and Safety of AS03-adjuvanted H5N1 Influenza Vaccine in Children 6-35 Months of Age: Results From a Phase 2, Randomized, Observer-blind, Multicenter, Dose-ranging Study.

BACKGROUND: This phase 2 observer-blind, randomized, multicenter, dose-ranging study evaluated immunogenicity and safety of different formulations of an AS03-adjuvanted H5N1 influenza vaccine in children 6-35 months of age. METHODS: One hundred eighty-five children randomized into 5 groups [1.9 µg hemagglutinin (HA)/AS03B, 0.9 µg HA/AS03C, 1.9 µg HA/AS03C, 3.75 µg HA/AS03C or 3.75 µg HA/AS03D] were to receive 2 doses administered 21 days apart (primary vaccination). AS03 was classified by amount of DL-α-tocopherol, with AS03B the highest amount. One year later, all subjects were to receive unadjuvanted 3.75 µg HA as antigen challenge. Immunogenicity was assessed 21 days after primary vaccination (day 42) and 7 days after antigen challenge (day 392). Immunogenicity-fever index, based on hemagglutination inhibition and microneutralization antibody titers at day 42 and fever 7 days after each vaccination, was used to guide the selection of an acceptable formulation. RESULTS: After primary vaccination, formulations elicited strong homologous immune responses with all subjects' hemagglutination inhibition titers ≥1:40 post-vaccination. Immunogenicity-fever index based on hemagglutination inhibition and microneutralization assays showed that 1.9 µg HA/AS03B ranked the highest. Antibody levels persisted >4 times above baseline 12 months after primary vaccination with all formulations (day 385). Antibodies increased >4-fold after antigen challenge (day 392/day 385) with 1.9 µg HA/AS03B, 0.9 µg HA/AS03C and 1.9 µg HA/AS03C formulations. Overall per subject, the incidence of fever ranged from 28.6% (3.75 µg HA/AS03D) to 60.5% (1.9 µg HA/AS03B). CONCLUSIONS: All formulations were highly immunogenic and demonstrated acceptable safety profiles, with the 1.9 µg HA/AS03B providing the most favorable balance of immunogenicity versus reactogenicity for use in children 6-35 months of age.

Difluoromethylornithine (DFMO), an Inhibitor of Polyamine Biosynthesis, and Antioxidant N-Acetylcysteine Potentiate Immune Response in Mice to the Recombinant Hepatitis C Virus NS5B Protein.

Hepatitis C virus (HCV) is one of the main triggers of chronic liver disease. Despite tremendous progress in the HCV field, there is still no vaccine against this virus. Potential vaccines can be based on its recombinant proteins. To increase the humoral and, especially, cellular immune response to them, more effective adjuvants are needed. Here, we evaluated a panel of compounds as potential adjuvants using the HCV NS5B protein as an immunogen. These compounds included inhibitors of polyamine biosynthesis and urea cycle, the mTOR pathway, antioxidants, and cellular receptors. A pronounced stimulation of cell proliferation and interferon-γ (IFN-γ) secretion in response to concanavalin A was shown for antioxidant N-acetylcysteine (NAC), polyamine biosynthesis inhibitor 2-difluoromethylornithine (DFMO), and TLR9 agonist CpG ODN 1826 (CpG). Their usage during the immunization of mice with the recombinant NS5B protein significantly increased antibody titers, enhanced lymphocyte proliferation and IFN-γ production. NAC and CpG decreased relative Treg numbers; CpG increased the number of myeloid-derived suppressor cells (MDSCs), whereas neither NAC nor DFMO affected MDSC counts. NAC and DFMO suppressed NO and interleukin 10 (IL-10) production by splenocytes, while DFMO increased the levels of IL-12. This is the first evidence of immunomodulatory activity of NAC and DFMO during prophylactic immunization against infectious diseases.

Portulaca oleracea L. polysaccharides enhance the immune efficacy of dendritic cell vaccine for breast cancer.

Previous studies have reported that Portulaca oleracea L. polysaccharides (POL-P3b) is an immunoregulatory agent. However, few studies exist on POL-P3b as a novel immune adjuvant in combination with the DC vaccine for breast cancer treatment. In this work, a DC vaccine loaded with mouse 4T1 tumor cell antigen was prepared to evaluate the properties of POL-P3b in inducing the maturation and function of DC derived from mouse bone marrow, and then to investigate the effect of the DC vaccine combined with POL-P3b on breast cancer in vivo and in vitro. Morphological changes of DC were observed using scanning electron microscopy. Phenotypic and functional analyses of DC were detected by flow cytometry and allogeneic lymphocyte reaction. Cytokine levels in the DC culture supernatant were detected by ELISA. Western blotting analysis was used for the protein expression of TLR4, MyD88 and NF-κB. Apoptosis detection and protein expression of the tumor tissue were analyzed by TUNEL staining and immunohistochemistry, respectively. The security of POL-P3b was evaluated by the detection of hematological and blood biochemical indicators and pathological analysis for tissues. POL-P3b can induce DC activation and maturation, which is attributed to increasing the specific anti-tumor immune response, and the mechanism of action involved in the TLR4/MyD88/NF-κB signaling pathway. Experimental results in vivo further suggested that the administration of POL-P3b-treated antigen-primed DC achieved remarkable tumor growth inhibition through inducing apoptosis and enhancing immune responses. Moreover, the POL-P3b-treated DC vaccine was able to inhibit lung metastases. The results proved the feasibility of POL-P3b as an edible adjuvant of the DC vaccine for anti-breast cancer therapy.

Toll-like Receptor-4 (TLR4) Agonist-Based Intranasal Nanovaccine Delivery System for Inducing Systemic and Mucosal Immunity.

Eliciting a robust immune response at mucosal sites is critical in preventing the entry of mucosal pathogens such as influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This task is challenging to achieve without the inclusion of a strong and safe mucosal adjuvant. Previously, inulin acetate (InAc), a plant-based polymer, is shown to activate toll-like receptor-4 (TLR4) and elicit a robust systemic immune response as a vaccine adjuvant. This study investigates the potential of nanoparticles prepared with InAc (InAc-NPs) as an intranasal vaccine delivery system to generate both mucosal and systemic immune responses. InAc-NPs (∼250 nm in diameter) activated wild-type (WT) macrophages but failed to activate macrophages from TLR4 knockout mice or WT macrophages when pretreated with a TLR4 antagonist (lipopolysaccharide-RS (LPS-RS)), which indicates the selective nature of a InAc-based nanodelivery system as a TLR4 agonist. Intranasal immunization using antigen-loaded InAc-NPs generated ∼65-fold and 19-fold higher serum IgG1 and IgG2a titers against the antigen, respectively, as compared to PLGA-NPs as a delivery system. InAc-NPs have also stimulated the secretion of sIgA at various mucosal sites, including nasal-associated lymphoid tissues (NALTs), lungs, and intestine, and produced a strong memory response indicative of both humoral and cellular immune activation. Overall, by stimulating both systemic and mucosal immunity, InAc-NPs laid a basis for a potential intranasal delivery system for mucosal vaccination.