Low Doses Of Antigen Research Articles

Oral Administration of Zinc Sulfate with Intramuscular Foot-and-Mouth Disease Vaccine Enhances Mucosal and Systemic Immunity

Background/Objectives: Foot-and-mouth disease (FMD) remains a significant global threat to livestock farming. Current commercial FMD vaccines present several challenges, including the risk of infection and adverse injection site reactions due to oil-based adjuvants. The complex immune environment of the gut-associated lymphoid tissue has the potential to induce broad and diverse immune responses. Therefore, we aimed to explore the potential of zinc sulfate as an oral adjuvant to enhance intestinal mucosal immunity and complement the effects of intramuscular (IM) FMD vaccination. Methods: We conducted serological analyses on mice and pigs, measuring secretory IgA (sIgA) levels and evaluating the expression of mucosal immunity-related genes in pigs. These assessments were used to investigate the systemic and mucosal immune responses induced by oral zinc sulfate administration in combination with an IM FMD vaccine. Results: This combination strategy significantly increased structural protein antibody titers and virus neutralization titers in experimental animals (mice) and target animals (pigs) across early, mid-, and long-term periods. Additionally, this approach enhanced the expression of key cytokines associated with mucosal immunity and increased sIgA levels, which are critical markers of mucosal immunity. Conclusions: Oral zinc sulfate administration may synergize with inactivated FMD vaccines, leading to sustained and enhanced long-term immune responses. This novel strategy could reduce the frequency of required vaccinations or allow for a lower antigen dose in vaccines, effectively stimulating the mucosal immune system and boosting systemic immunity. This approach has the potential to improve the overall efficacy of commercial FMD vaccines.

Systematic review of the literature about immunogenity and antibodies persistance of Tdap vaccination

Abstract Introduction In industrialized countries, routine use of pertussis vaccines has shifted the burden of pertussis disease from children to infants, adolescents and adults, leading to the necessity of booster doses. Materials and methods We prepared the review following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) with the aim of a) to describe the immunogenity of the main available vaccines for adolescents and adults b) to describe antibodies persistance after immunization with the main vaccines available in childhood and adults and, also, possible co-administration and c) to identify the gold standard for adolescent and adult immunizations. Results Of 6906 records identified, after removing duplicate records, 12 RCT were included (people aged 11-73): of these 7 studies had only 1 control group, 4 studies had 2 control group and 1 had 5 control group; moreover, of the 12 studies included only 2 regarding co-administration and all were about immunogenity. 9 out 12 studies had a Jadad score above 3 points and 10 out 12 meet the criteria of Cocrane Back Review Group Criteria List for Methodological Quality Assessment. Discussion and conclusions We found a limited number of good-quality RCTs investigating our object. The five component vaccines, although containing a lower dosage of antigen, are found to be more effective than one components vaccines for prevention. Evidences support the use of 5- components vaccines for booster sessions in adolescence and adulthood. Key messages • Although 3-component and 5-component vaccines contain a lower dose of antigen, they are more effective than 1-component vaccines in the prevention of diphtheria-tetanus and Bordetella pertussis. • The robustness of the data and the analytical tests support the use of vaccines with reduced antigen concentration for decennial booster sessions in adolescence and adulthood.

Co-formulation of the rF1V plague vaccine with depot-formulated cytokines enhances immunogenicity and efficacy to elicit protective responses against aerosol challenge in mice.

This study evaluated a depot-formulated cytokine-based adjuvant to improve the efficacy of the recombinant F1V (rF1V) plague vaccine and examined the protective response following aerosol challenge in a murine model. The results of this study showed that co-formulation of the Alhydrogel-adsorbed rF1V plague fusion vaccine with the depot-formulated cytokines recombinant human interleukin 2 (rhuIL-2) and/or recombinant murine granulocyte macrophage colony-stimulating factor (rmGM-CSF) significantly enhances immunogenicity and significant protection at lower antigen doses against a lethal aerosol challenge. These results provide additional support for the co-application of the depot-formulated IL-2 and/or GM-CSF cytokines to enhance vaccine efficacy.

Impact of the TLR4 agonist BECC438 on a novel vaccine formulation against Shigella spp.

Shigellosis (bacillary dysentery) is a severe gastrointestinal infection with a global incidence of 90 million cases annually. Despite the severity of this disease, there is currently no licensed vaccine against shigellosis. Shigella's primary virulence factor is its type III secretion system (T3SS), which is a specialized nanomachine used to manipulate host cells. A fusion of T3SS injectisome needle tip protein IpaD and translocator protein IpaB, termed DBF, when admixed with the mucosal adjuvant double-mutant labile toxin (dmLT) from enterotoxigenic E. coli was protective using a murine pulmonary model. To facilitate the production of this platform, a recombinant protein that consisted of LTA-1, the active moiety of dmLT, and DBF were genetically fused, resulting in L-DBF, which showed improved protection against Shigella challenge. To extrapolate this protection from mice to humans, we modified the formulation to provide for a multivalent presentation with the addition of an adjuvant approved for use in human vaccines. Here, we show that L-DBF formulated (admix) with a newly developed TLR4 agonist called BECC438 (a detoxified lipid A analog identified as Bacterial Enzymatic Combinatorial Chemistry candidate #438), formulated as an oil-in-water emulsion, has a very high protective efficacy at low antigen doses against lethal Shigella challenge in our mouse model. Optimal protection was observed when this formulation was introduced at a mucosal site (intranasally). When the formulation was then evaluated for the immune response it elicits, protection appeared to correlate with high IFN-γ and IL-17 secretion from mucosal site lymphocytes.

A mouse model of food allergy permitting skin and nasal symptoms

PurposeDeveloping experimental animal models that show clinical symptoms and methods for quantitative and objective evaluation are important for understanding food allergies. Therefore, this study aimed to develop an ovalbumin (OVA)-induced mouse model of food allergy and a useful method to evaluate the symptoms of food allergy. Material/methodsMice were sensitized via intraperitoneal injection of OVA. Subsequently, local sensitization was performed once weekly by oral administration of OVA. Itching and nasal symptoms were observed after oral administration of the antigen. First, we examined the dose-dependency of the antigen. Symptoms were checked weekly. In order to confirm food allergy symptoms, the effect of histamine H1 receptor antagonist was examined. Finally, we measured antigen-specific IgE antibody levels in the serum. ResultsScratching behavior, sneezing and nasal rubbing were increased. Both itching and rhinitis symptoms increased steadily, after which, the number of symptoms remained almost constant. No difference was observed between the results of 3- and 5-week-old mice. Cetirizine inhibited these symptoms in a dose-dependent manner. In addition, antigen-specific IgE antibodies were produced in both 3- and 5-week-old mice. ConclusionsThis method may be useful for evaluating the symptoms of skin and rhinitis that could not be assessed in the conventional food allergy model and could be induced with a low dose of antigen. In particular, the developed method, which measures the number of itching and nasal symptoms, may enable quantitative, objective, and noninvasive evaluation of food allergy severity.

Safety, Reactogenicity, Immunogenicity, and Dose Selection of 10-Valent Extraintestinal Pathogenic Escherichia coli Bioconjugate Vaccine (VAC52416) in Adults Aged 60-85 Years in a Randomized, Multicenter, Interventional, First-in-Human, Phase 1/2a Study.

ExPEC10V is a bioconjugate vaccine containing O-antigen polysaccharides of 10 extraintestinal pathogenic Escherichia coli (ExPEC) serotypes. This phase 1/2a study (NCT03819049) assessed the safety, reactogenicity, and immunogenicity of ExPEC10V (VAC52416) to prevent invasive E coli disease in elderly adults. The observer-blind, active-controlled design included a 28-day screening, vaccination, 181-day follow-up, and 1-year follow-up. Participants (60-85 years of age) were randomized to ExPEC10V low dose (antigen dose range, 4-8 µg), ExPEC10V medium dose (4-16 µg), or ExPEC10V high dose (8-16 µg); 4-valent ExPEC vaccine (ExPEC4V); or 13-valent pneumococcal conjugate vaccine (PCV13). The incidence of adverse events (AEs; solicited, day 15; unsolicited, day 30; serious AEs, day 181) and immunogenicity (electrochemiluminescent-based assay [ECL] and multiplex opsonophagocytic assay [MOPA]) were assessed. Optimal ExPEC10V dose was determined from safety data through day 30 and an immunogenicity dose selection algorithm based on day 15 ECL and MOPA results. A total of 416 participants were included (median age, 64.0 years; 54.8% female). The incidences of solicited local and systemic AEs were, respectively, 44.2% and 39.4% for low-dose, 52.9% and 46.1% for medium-dose, 57.7% and 45.2% for high-dose ExPEC10V, and 74.1% and 48.1% for PCV13. Five serious AEs, not vaccine related, were reported. The ECL revealed a robust antibody response to ExPEC10V through year 1. Opsonophagocytic killing activity was detected against all but serotype O8; this lack of response against serotype O8 was linked to low assay sensitivity. Based on the totality of data, high-dose ExPEC10V was considered optimal. ExPEC10V was well tolerated and immunogenic in elderly adults against all but serotype O8.

How B cells drive T-cell responses: A key role for cross-presentation of antibody-targeted antigens.

In this review we discuss an underexposed mechanism in the adaptive immune system where B cell and T cell immunity collaborate. The main function of B cell immunity is the generation of antibodies which are well known for their high affinity and antigen-specificity. Antibodies can bind antigens in soluble form making so-called immune complexes (ICs) or can opsonize antigen-exposing cells or particles for degradation. This leads to well-known effector mechanisms complement activation, antibody-dependent cytotoxicity and phagocytosis. What is less realized is that antibodies can play an important role in the targeting of antigen to dendritic cells (DCs) and thereby can drive T cell immunity. Here we summarize the studies that described this highly efficient process of antibody-mediated antigen uptake in DCs in vitro and in vivo. Only very low doses of antigen can be captured by circulating antibodies and subsequently trapped by DCs in vivo. We studied the handling of these ICs by DCs in subcellular detail. Upon immune complex engulfment DCs can sustain MHC class I and II antigen presentation for many days. Cell biological analysis showed that this function is causally related to intracellular antigen-storage compartments which are functional endolysosomal organelles present in DCs. We speculate that this function is immunologically very important as DCs require time to migrate from the site of infection to the draining lymph nodes to activate T cells. The implications of these findings and the consequences for the immune system, immunotherapy with tumor-specific antibodies and novel vaccination strategies are discussed.

Early IgE production is associated with accumulation of CD11b+ classical dendritic cells and CD11b+CD11c- macrophages in subcutaneous adipose tissue

In view of increased incidence of IgE-mediated diseases in Russia and worldwide, the efforts of various research groups are focused on studying the mechanisms that trigger the process of switching B-lymphocytes to IgE synthesis upon human exposure to harmless allergens, including the role of various antigen-presenting cells (APCs) in this process. However, the role of distinct APCs upon long-term penetration of low antigen doses via the tissue barriers, is yet poorly understood, as well as specific features of these events upon entrance of the antigen through the subcutaneous adipose tissue which contains tissueassociated lymphoid clusters (TALC).The aim of this work was to determine the relationship between the local accumulation of various APCs in the subcutaneous adipose tissue and development of early IgE production in a clinically relevant experimental model of allergy with long-term administration of low allergen doses. In this experimental model, specific IgE synthesis is induced, with minimal concomitant IgG production, thus mimicking the situation observed in patients with clinically sound allergies. BALB/c mice were immunized for 4 weeks subcutaneously in the withers area or intraperitoneally with low (100 ng) or high (10 μg) doses of the model allergen (ovalbumin). Blood samples were taken weekly from mice for ELISA testing, to determine the production of specific antibodies. Provocation tests were performed with high dose of the allergen, and adipose tissue samples were taken from the site of antigen injection for flow cytometric assays, in order to evaluate the contents of various APC subpopulations. Specific IgE production was induced mainly by subcutaneous injection of the antigen at low doses (100 ng) into the area of withers. When using this experimental regimen, we observed accumulation of classical CD11b+ cells in adipose tissue at the withers site, but not in the peritoneal adipose tissue, in absence of CD11b- classical, inflammatory or plasmacytoid, dendritic cells. These findings coincided in time with increased production of specific IgE on days +14 to +21. Accumulation of CD11b+CD11c- macrophages and their CD206+ M2 subpopulations at early terms (days +7 and +21) was also observed only after subcutaneous injection of the antigen into the withers area. The high-dose antigen injection (10 μg) which mediated IgG1 production to greater extent than production of IgE, led to earlier accumulation of CD11b+ classical dendritic cells (on day 7th), and to the absence of macrophage accumulation at later stages (day 21th). Thus, the early start of specific IgE production upon low-dose injection of the antigen into the subcutaneous adipose tissue may be associated with its presentation by CD11b+ classical dendritic cells in the presence of CD11b+CD11c- macrophages.

A novel built-in adjuvant metallothionein-3 aids protein antigens to induce rapid, robust, and durable immune responses.

Adjuvants are crucial components of vaccines that can enhance and modulate antigen-specific immune responses. Herein, we reported for the first time that human metallothionein-3 (MT3), a low molecular weight cysteine-rich metal-binding protein, was a novel promising adjuvant candidate that could help protein antigens to induce rapid, effective, and durable antigen-specific immune responses. In the present study, MT3 was fused to outer membrane protein 19 (Omp19) of Brucella abortus (MT3-Omp19, MO) and C fragment heavy chain (Hc) of tetanus neurotoxin (MT3-Hc, MH), respectively. The results showed that MT3 as a built-in adjuvant increased the Omp19- or Hc-specific antibody responses by 100-1000 folds in seven days after primary immunization. Compared to other commercially available adjuvants, MT3 could stimulate earlier (4 days after primary injection) and stronger (10-100 folds) antibody response with lower antigen dose, and its adjuvanticity relied on fusion to antigen. Although the mechanism was not clear yet, the fusion protein MO was observed to directly activate DCs, promote germinal center formation and improve the speed of Ig class switching. Interestingly, our subsequent study found that other members of the mammalian MT family (human MT1 or murine MT3 for examples) also had potential adjuvant effects, but their effects were lower than human MT3. Overall, this study explored a new function of human MT3 as a novel built-in adjuvant, which may have important clinical application potential in vaccine development against global pandemics.

Early IgE Production Is Linked with Extrafollicular B- and T-Cell Activation in Low-Dose Allergy Model.

Despite its paramount importance, the predominant association of early IgE production with harmless antigens, via germinal-center B- and T-cell subpopulations or extrafollicular activation, remains unresolved. The aim of this work was to clarify whether the reinforced IgE production following the subcutaneous immunization of BALB/c mice with low antigen doses in withers adipose tissue might be linked with intensified extrafollicular or germinal-center responses. The mice were immunized three times a week for 4 weeks in the withers region, which is enriched in subcutaneous fat and tissue-associated B cells, with high and low OVA doses and via the intraperitoneal route for comparison. During long-term immunization with both low and high antigen doses in the withers region, but not via the intraperitoneal route, we observed a significant accumulation of B220-CD1d-CD5-CD19+ B-2 extrafollicular plasmablasts in the subcutaneous fat and regional lymph nodes but not in the intraperitoneal fat. Only low antigen doses induced a significant accumulation of CXCR4+ CXCR5- CD4+ extrafollicular T helpers in the withers adipose tissue but not in the regional lymph nodes or abdominal fat. Only in subcutaneous fat was there a combination of extrafollicular helper accumulation. In conclusion, extrafollicular B- and T-cell activation are necessary for early IgE class switching.

The Role of HnRNPA1 in T Cell-Mediated Gut Tolerance

Abstract Our previous research showed that Akt phosphorylation of the RNA-binding protein, (RBP) heterogeneous nuclear ribonucleoprotein (hnRNP) A1, is dependent on TCR signal strength, and occurs under conditions of induced T regulatory (Treg) cell differentiation. We have shown hnRNPA1 is required for optimal Treg differentiation by performing knockdown experiments, and our present research is focused on identifying a role for Akt phosphorylation in hnRNPA1 function. HnRNPA1 is phosphorylated by Akt at S199 and our lab has generated a new mutant mouse model, hnRNPA1-S199A (mA1), in which hnRNPA1 will no longer be Akt-phosphhorylated. Our initial characterization of mA1 mouse model failed to reveal major abnormalities in immune cells populations at steady state except for changes in the Treg proportion in the mesenteric lymph nodes. To investigate the effect of the mA1 on the development of oral tolerance we used an adoptive transfer model in which OT-II mA1 or OT-II WT naïve T cells were transferred into congenic strains and then the mice were given OVA food. Results indicate that mA1 OT-II T cells have a proliferation defect in vivo and we also observed a significant reduction in the induction of OVA-specific Treg in the mA1 T cells. Similar results were obtained when adoptively transferred OT-II mA1 T cells were challenged with limiting doses of specific peptide, given iv. RNASeq analysis of the transferred mA1 and WT T cells is being performed. These results suggest that Akt phosphorylation of hnRNPA1 is necessary for T cell response to low dose antigen and Treg induction in vivo. Our studies identify a new mechanism by which RBP influence T cell proliferation and Treg differentiation which has implications for tolerance to food antigens in the gut. Supported by NIH (F31-AI152320-02) NIH (R01-AI125513-03)

Enhancing adoptive CD8 T cell therapy by systemic delivery of tumor associated antigens

Adoptive T-cell transfer (ACT) offers a curative therapeutic option for subsets of melanoma and hematological cancer patients. To increase response rates and broaden the applicability of ACT, it is necessary to improve the post-infusion performance of the transferred T cells. The design of improved treatment strategies includes transfer of cells with a less differentiated phenotype. Such T cell subsets have high proliferative potential but require stimulatory signals in vivo to differentiate into tumor-reactive effector T cells. Thus, combination strategies are needed to support the therapeutic implementation of less differentiated T cells. Here we show that systemic delivery of tumor-associated antigens (TAAs) facilitates in vivo priming and expansion of previously non-activated T cells and enhance the cytotoxicity of activated T cells. To achieve this in vivo priming, we use flexible delivery vehicles of TAAs and a TLR7/8 agonist. Contrasting subcutaneous delivery systems, these vehicles accumulate TAAs in the spleen, thereby achieving close proximity to both cross-presenting dendritic cells and transferred T cells, resulting in robust T-cell expansion and anti-tumor reactivity. This TAA delivery platform offers a strategy to safely potentiate the post-infusion performance of T cells using low doses of antigen and TLR7/8 agonist, and thereby enhance the effect of ACT.

Ex vivo dendritic cell-based (DC) vaccine pulsed with a low dose of liposomal antigen and CpG-ODN improved PD-1 blockade immunotherapy

Lack of pre-existing tumor infiltrated T cells resulting in resistance to programmed cell death protein 1 (PD-1) blockade therapies can be solved by combining with anti-cancer vaccines and CpG-ODN in increasing T cell expansion and infiltration. Therefore, we prepared an ex vivo dendritic cell-based (DC) vaccine pulsed with a low dose of either liposomal or non-liposomal gp100 antigen (2.8 µg) plus CpG-ODN (800 ng) formulations and evaluated its anti-tumor activity in combination with anti-PD-1 therapy. Our results showed a combination of liposomal peptide plus CpG-ODN pulsed DC with anti-PD-1 antibody was more efficacious, as evidenced by a significant increase in Teff/Treg TILs with a marked fourfold elevation of IFN-γ expression level in the tumor site of treated mice which reversed resistance to PD-1 blockade in a CD8 T cell-dependent manner. Furthermore, this combination also led to a remarkable tumor remission and prolonged survival rate in melanoma-bearing mice compared to non-liposomal peptide plus CpG-ODN or single-treated liposomal peptide formulations. Our results provide essential insights to devise combining regimens to improve the efficacy of immune checkpoint blockers even by a low dose of peptide and CpG-ODN.

Immunologic mechanisms of seasonal influenza vaccination administered by microneedle patch from a randomized phase I trial

In a phase 1 randomized, single-center clinical trial, inactivated influenza virus vaccine delivered through dissolvable microneedle patches (MNPs) was found to be safe and immunogenic. Here, we compare the humoral and cellular immunologic responses in a subset of participants receiving influenza vaccination by MNP to the intramuscular (IM) route of administration. We collected serum, plasma, and peripheral blood mononuclear cells in 22 participants up to 180 days post-vaccination. Hemagglutination inhibition (HAI) titers and antibody avidity were similar after MNP and IM vaccination, even though MNP vaccination used a lower antigen dose. MNPs generated higher neuraminidase inhibition (NAI) titers for all three influenza virus vaccine strains tested and triggered a larger percentage of circulating T follicular helper cells (CD4 + CXCR5 + CXCR3 + ICOS + PD-1+) compared to the IM route. Our study indicates that inactivated influenza virus vaccination by MNP produces humoral and cellular immune response that are similar or greater than IM vaccination.

Lettuce Plants Expressing High Levels of Factor VIII Antigen in the Chloroplast for Oral Tolerance in Hemophilia a

Inhibitor formation is a serious complication in factor VIII (FVIII) replacement therapy for the X-linked bleeding disorder hemophilia A and occurs in 20-30% of patients. No prophylactic tolerance protocols exist. In previous proof-of-principle work, we demonstrated oral tolerance induction to FVIII in hemophilia A mice using frozen tobacco leaf cells expressing the heavy chain (HC) and C2 domain of human B domain-deleted (BDD) FVIII (Blood 124:1659-68, 2014). This approach is based on expression of heterologous proteins in the chloroplasts of green leaves and natural bioencapsulation provided by plant cell wall, so that the antigen is protected until its release in the small intestine. The antigens are expressed as fusions with the transmucosal carrier CTB proteins for effective targeting of the gut epithelium and translocation to the immune system. However, significant hurdles toward clinical feasibility remained that we now successfully addressed. Until now, methods to express large human proteins in chloroplasts of edible crop plants did not exist. Building on our recently established gene transfer technology for lettuce chloroplasts and identification of powerful posttranscriptional regulatory elements, we focused on the development of chloroplast genomics tools (e.g. bioinformatics tools for codon optimization and assays that identify sites of ribosome stalling), which ultimately allowed us to express high levels of FVIII antigen in edible crop plants that are suitable for clinical application. Remarkably, codon-optimization improved expression of FVIII heavy chain (HC) and light chain (LC) by15- to 42-fold. Hence, the entire BDD-FVIII sequence can be orally delivered, thereby covering the entire patient population regardless of individual CD4+ T cell epitope usage. A clinical grade manufacturing process is in place, and lyophilization of leaf cells generates material that is stable at ambient temperature for at least 2 years. Testing in hemophilia A mice showed effectiveness of low FVIII antigen doses upon delivery of lyophilized lettuce cells. Repeated oral gavage (twice/week for 2 months) of a mixture of CTB-HC and CTB-C2 suppressed subsequent inhibitor formation against intravenous FVIII (1IU, once/ week for 4 weeks) in hemophilia A mice as well as the original tobacco material, using very low doses of 0.15-0.5 ug/antigen/mouse. When using CTB-HC/CTB-LC combination, a dose of 1.5 ug was most optimal and suppressed inhibitor titers by ~1 log (avg. 4.7 BU/ml vs 44 BU/ml in controls; 50% of tolerized mice had 0-3 BU/ml, while 86% of controls developed 6-126 BU/ml, n=12-14, P <0.05). Translational oral tolerance studies in humans would benefit from cellular biomarkers. Our prior studies showed induction of two subsets of Treg that suppress antibody formation against FVIII, namely CD4+CD25+FoxP3+ Treg and LAP+CD4+CD25-FoxP3- Treg. The latter stain positive on the cell surface for LAP (latency-associated peptide) because of overexpression of TGF-b. Although we found increases in the frequencies of LAP+CD4+CD25-FoxP3- Treg in peripheral blood, a statistical significance was not always observed when compared to the blood of control mice that received intravenous FVIII but not oral tolerance. However, we found significant and consistent increases in the frequencies of circulating LAP-expressing CD4+CD25+FoxP3+ Treg in tolerized mice, suggesting that LAP may be a suitable cellular biomarker for plant-based oral tolerance induction. In conclusion, clinical candidates for oral tolerance to FVIII are now available in form of lettuce plants expressing immunogenic domains or the entire antigen. DisclosuresHerzog:Novo Nordisk: Research Funding; Applied Genetic Technologies Corporation: Consultancy; Spark Therapeutics: Patents & Royalties. Daniell:Novo Nordisk: Research Funding.

Safety and immunogenicity of SARS-CoV-2 recombinant protein vaccine formulations in healthy adults: interim results of a randomised, placebo-controlled, phase 1–2, dose-ranging study

BackgroundCoV2 preS dTM is a stabilised pre-fusion spike protein vaccine produced in a baculovirus expression system being developed against SARS-CoV-2. We present interim safety and immunogenicity results of the first-in-human study of the CoV2 preS dTM vaccine with two different adjuvant formulations.MethodsThis phase 1–2, randomised, double-blind study is being done in healthy, SARS-CoV-2-seronegative adults in ten clinical research centres in the USA. Participants were stratified by age (18–49 years and ≥50 years) and randomly assigned using an interactive response technology system with block randomisation (blocks of varying size) to receive one dose (on day 1) or two doses (on days 1 and 22) of placebo or candidate vaccine, containing low-dose (effective dose 1·3 μg) or high-dose (2·6 μg) antigen with adjuvant AF03 (Sanofi Pasteur) or AS03 (GlaxoSmithKline) or unadjuvanted high-dose antigen (18–49 years only). Primary endpoints were safety, assessed up to day 43, and immunogenicity, measured as SARS-C0V-2 neutralising antibodies (geometric mean titres), assessed on days 1, 22, and 36 serum samples. Safety was assessed according to treatment received in the safety analysis set, which included all randomly assigned participants who received at least one dose. Neutralising antibody titres were assessed in the per-protocol analysis set for immunogenicity, which included participants who received at least one dose, met all inclusion and exclusion criteria, had no protocol deviation, had negative results in the neutralisation test at baseline, and had at least one valid post-dose serology sample. This planned interim analysis reports data up to 43 days after the first vaccination; participants in the trial will be followed up for 12 months after the last study injection. This trial is registered with ClinicalTrials.gov, NCT04537208, and is ongoing.FindingsBetween Sept 3 and Sept 29, 2020, 441 individuals (299 aged 18–49 years and 142 aged ≥50 years) were randomly assigned to one of the 11 treatment groups. The interim safety analyses included 439 (>99%) of 441 randomly assigned participants (299 aged 18–49 years and 140 aged ≥50 years). Neutralising antibody titres were analysed in 326 (74%) of 441 participants (235 [79%] of 299 aged 18–49 years and 91 [64%] of 142 aged ≥50 years). There were no vaccine-related unsolicited immediate adverse events, serious adverse events, medically attended adverse events classified as severe, or adverse events of special interest. Among all study participants, solicited local and systemic reactions of any grade after two vaccine doses were reported in 81% (95% CI 61–93; 21 of 26) of participants in the low-dose plus AF03 group, 93% (84–97; 74 of 80) in the low-dose plus AS03 group, 89% (70–98; 23 of 26) in the high-dose plus AF03 group, 95% (88–99; 81 of 85) in the high-dose plus AS03 group, 29% (10–56; five of 17) in the unadjuvanted high-dose group, and 21% (8–40; six of 29) in the placebo group. A single vaccine dose did not generate neutralising antibody titres above placebo levels in any group at days 22 or 36. Among participants aged 18–49 years, neutralising antibody titres after two vaccine doses were 13·1 (95% CI 6·40–26·9) in the low-dose plus AF03 group, 20·5 (13·1–32·1) in the low-dose plus AS03 group, 43·2 (20·6–90·4) in the high-dose plus AF03 group, 75·1 (50·5–112·0) in the high-dose plus AS03 group, 5·00 (not calculated) in the unadjuvanted high-dose group, and 5·00 (not calculated) in the placebo group. Among participants aged 50 years or older, neutralising antibody titres after two vaccine doses were 8·62 (1·90–39·0) in the low-dose plus AF03 group, 12·9 (7·09–23·4) in the low-dose plus AS03 group, 12·3 (4·35–35·0) in the high-dose plus AF03 group, 52·3 (25·3–108·0) in the high-dose plus AS03 group, and 5·00 (not calculated) in the placebo group.InterpretationThe lower than expected immune responses, especially in the older age groups, and the high reactogenicity after dose two were probably due to higher than anticipated host-cell protein content and lower than planned antigen doses in the formulations tested, which was discovered during characterisation studies on the final bulk drug substance. Further development of the AS03-adjuvanted candidate vaccine will focus on identifying the optimal antigen formulation and dose.FundingSanofi Pasteur and Biomedical Advanced Research and Development Authority.

Engineering a self-navigated MnARK nanovaccine for inducing potent protective immunity against novel coronavirus.

Effective vaccines are vital to fight against the COVID-19 global pandemic. As a critical component of a subunit vaccine, the adjuvant is responsible for strengthening the antigen-induced immune responses. Here, we present a new nanovaccine that comprising the Receptor-Binding Domain (RBD) of spike protein and the manganese nanoadjuvant (MnARK), which induces humoral and cellular responses. Notably, even at a 5-fold lower antigen dose and with fewer injections, the MnARK vaccine immunized mice showed stronger neutralizing abilities against the infection of the pseudovirus (~270-fold) and live coronavirus (>8-fold) in vitro than that of Alum-adsorbed RBD vaccine (Alu-RBD). Furthermore, we found that the effective co-delivery of RBD antigen and MnARK to lymph nodes (LNs) elicited an increased cellular internalization and the activation of immune cells, including DCs, CD4+ and CD8+ T lymphocytes. Our findings highlight the importance of MnARK adjuvant in the design of novel coronavirus vaccines and provide a rationale strategy to design protective vaccines through promoting cellular internalization and the activation of immune-related pathways.

Immunogenicity and antibody persistence of diphteria-tetanus-acellular pertussis vaccination in adolescents and adults: a systematic review of the literature showed different responses to the available vaccines.

SummaryIntroductionIn industrialized countries, the routine use of Bordetella pertussis vaccines has shifted the burden of Bordetella pertussis disease from children to infants, adolescents and adults, leading to the necessity for booster doses.Materials and methodsWe prepared a review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) with the aims of: a) describing the immunogenicity of the main available vaccines for adolescents and adults; b) describing antibody persistence after immunization with the main vaccines available in childhood and adults and, also, possible co-administration; and c) identifying the gold standard for adolescent and adult immunizations.ResultsWe identified 6906 records. After removing duplicate records, we included 12 RCT (Randomized Controlled Trial) (people aged 11-73): 7 of these studies had only 1 control group, 4 had 2 control groups and 1 had 5 control groups; moreover, of the 12 studies included, only 2 regarded co-administration, while all concerned immunogenicity. Nine of the 12 studies had a Jadad score above 3 points, and 10 out of 12 met the criteria of Cochrane Back Review Group Criteria List for Methodological Quality Assessment.Discussion and conclusionWe found a limited number of good-quality RCTs investigating our object. The 5-component vaccines, although containing a lower dose of antigen, proved more effective than the 1-component vaccine. Evidence supports the use of 5-component vaccines for booster sessions in adolescence and adulthood.

Potential Cross-Reactive Immunity to SARS-CoV-2 From Common Human Pathogens and Vaccines.

The recently emerged SARS-CoV-2 causing the ongoing COVID-19 pandemic is particularly virulent in the elderly while children are largely spared. Here, we explored the potential role of cross-reactive immunity acquired from pediatric vaccinations and exposure to common human pathogens in the protection and pathology of COVID-19. To that end, we sought for peptide matches to SARS-CoV-2 (identity ≥ 80%, in at least eight residues) in the proteomes of 25 human pathogens and in vaccine antigens, and subsequently predicted their T and B cell reactivity to identify potential cross-reactive epitopes. We found that viruses subject to pediatric vaccinations do not contain cross-reactive epitopes with SARS-CoV-2, precluding that they can provide any general protection against COVID-19. Likewise, common viruses including rhinovirus, respiratory syncytial virus, influenza virus, and several herpesviruses are also poor or null sources of cross-reactive immunity to SARS-CoV-2, discarding that immunological memory against these viruses can have any general protective or pathological role in COVID-19. In contrast, we found combination vaccines for treating diphtheria, tetanus, and pertussis infectious diseases (DTP vaccine) to be significant sources of potential cross-reactive immunity to SARS-CoV-2. DTP cross-reactive epitopes with SARS-CoV-2 include numerous CD8 and CD4 T cell epitopes with broad population protection coverage and potentially neutralizing B cell epitopes in SARS-CoV-2 Spike protein. Worldwide, children receive several DTP vaccinations, including three-four doses the first year of life and one at 4–6 years of age. Moreover, a low antigenic Tdap dose is also given at ages 9–14. Thereby, children may well be protected from SARS-CoV-2 through cross-reactive immunity elicited by DTP vaccinations, supporting testing in the general population to prevent COVID-19.

Tertiary lymphoid structure related B-cell IgE isotype switching and secondary lymphoid organ linked IgE production in mouse allergy model

BackgroundNumerous data obtained by different research laboratories indicate that specific IgE production is triggered independently of specific IgG or IgA ones and so it is not linked to fully matured germinal centers formation in the secondary lymphoid organs. The aim of this study was to clarify whether specific IgE production is triggered by low antigen doses administrated in tertiary tissues enriched by lymphoid structures.MethodsOvalbumin (OVA) in different doses (100 ng to 10 μg) was administrated three times a week for 4–5 weeks intraperitoneally (i.p.) or subcutaneously (s.c.) to female BALB/c mice in the wither region which is enriched in fat-associated lymphoid clusters or in the foot pad region not containing them.ResultsOVA-specific IgE was predominantly induced by low but not high antigen doses and only after immunization into the withers. IgE isotype switching was triggered exclusively in the withers adipose tissue but not in the regional lymph nodes while mature IgE expressing cells were observed both in the withers and lymph nodes. Anti-proliferative genotoxic stress inducing drugs shifted the balance from IgG1 towards IgE production.ConclusionsTertiary lymphoid structures possess unique environment where B-cell antibody isotype switching to IgE predominantly occurs. This phenomenon is partially explained by hampered proliferation of B-cells in these structures.