Adjuvant Cholera Toxin Research Articles

Induction of long-term immunity against respiratory syncytial virus glycoprotein by an osmotic polymeric nanocarrier

Respiratory syncytial virus (RSV) is one of the most common causes of viral deaths in infants worldwide, yet no effective vaccines are available. Here, we report an osmotically active polysaccharide-based polysorbitol transporter (PST) prepared from sorbitol diacrylate and low-molecular-weight polyethylenimine (PEI) showing a potent, yet safe, adjuvant activity and acting as an effective delivery tool for RSV glycoprotein (RGp) antigen. PST showed no toxicity in vitro or in vivo, unlike PEI and the well-known experimental mucosal adjuvant cholera toxin (CT). PST formed nano-sized complexes with RGp by simple mixing, without affecting antigenic stability. The complexes exhibited negative surface charges that made them highly efficient in the selective activation of phagocytic cells and enhancement of phagocytic uptake. This resulted in an improved cytokine production and in the significant augmentation of RGp-specific antibody production, which persisted for over 200days. Interestingly, PST/RGp enhanced phagocytic uptake owing to the osmotic property of PST and its negative zeta potential, suggesting that PST could selectively stimulate phagocytic cells, thereby facilitating a long-lived antigen-specific immune response, which was presumably further enhanced by the polysaccharide properties of PST.

Cutaneous or Respiratory Exposures to Peanut Allergens in Mice and Their Impacts on Subsequent Oral Exposure

Background: Recent data suggested that non-gastrointestinal exposure can lead to sensitisation to food allergens. We thus assessed the immune impact of respiratory or cutaneous exposure to peanut proteins on non-altered epithelium and investigated the effect of such pre-exposure on subsequent oral administration of peanut. Methods: BALB/cJ mice were exposed to purified Ara h 1 or to a non-defatted roasted peanut extract (PE) by simple deposit of allergens solutions on non-altered skin or in the nostrils. Exposures were performed 6 times at weekly intervals. Pre-exposed mice then received intra-gastric administrations of PE alone or in the presence of the Th2 mucosal adjuvant cholera toxin (CT). The specific humoral and cellular immune response was assessed throughout the protocol. Results: Both cutaneous and respiratory exposures led to the production of specific IgG1. Local and systemic IL-5 and IL-13 production were also evidenced, demonstrating activation of specific Th2 cells. This effect was dose-dependent and most efficient via the respiratory route. Moreover, these pre-exposures led to the production of specific IgE antibodies after gavage with PE, whatever the presence of CT. Conclusions: Cutaneous or respiratory exposures to peanut induce Th2 priming in mice. Moreover, pre-exposures promote further sensitisation via the oral route without the use of CT; this proposes a new adjuvant-free experimental model of sensitisation to food that may reflect a realistic exposure pattern in infants. These results also suggest that non-gastrointestinal peanut exposure should be minimised in high-risk infants, even those with non-altered skin, to potentially reduce allergic sensitisation to this major food allergen.

Combined vaccination of subcutaneous BCG and intranasal HBHA with cholera toxin enhances early protective immunity against pulmonary M. tuberculosis infection (VAC7P.972)

Abstract Effect of Mycobacterium bovis bacille de Calmette et Guérin (BCG) vaccine on preventing adult pulmonary tuberculosis has been reported to be limited. Therefore, development of a novel effective vaccination strategy against pulmonary tuberculosis has become an international research priority. We have previously reported that intranasal administration of a recombinant mycobacterial Ag, heparin-binding heamagglutinin adhesin (HBHA), combined with mucosal adjuvant cholera toxin (CT) into mice enhanced Th1-type immune response and suppressed extrapulmonary bacterial dissemination after M. tuberculosis (Mtb) infection in the lung. Here, we further report effects of the mucosal HBHA+CT vaccine on murine experimental pulmonary Mtb infection. Combination of subcutaneous BCG priming vaccine followed by the mucosal HBHA+CT vaccine as a booster significantly enhanced protective immunity against pulmonary Mtb infection on day 14. The combination of subcutaneous BCG and the mucosal HBHA+CT vaccine was more effective than the BCG vaccine alone in induction of the early protective immunity. Further, the mucosal HBHA+CT vaccine enhanced not only IFN-γ but also IL-17A production by HBHA-specific T cells in the lung after pulmonary Mtb infection. The results indicate that the combination of BCG priming vaccine and mucosal HBHA+CT boosting vaccine might be a good candidate for a new vaccine strategy against pulmonary tuberculosis.

Oral immunization with recombinantLactococcus lactisdelivering a multi-epitope antigen CTB-UE attenuatesHelicobacter pyloriinfection in mice

Urease is an essential virulence factor and colonization factor for Helicobacter pylori (H. pylori) and is considered as an excellent vaccine candidate antigen. However, conventional technologies for preparing an injectable vaccine require purification of the antigenic protein and preparation of an adjuvant. Lactococcus lactis NZ9000 (L. lactis) could serve as an antigen-delivering vehicle for the development of edible vaccine. In previous study, we constructed a multi-epitope vaccine, designated CTB-UE, which is composed of the mucosal adjuvant cholera toxin B subunit (CTB), three Th cell epitopes and two B-cell epitopes from urease subunits. To develop a novel type of oral vaccine against H. pylori, genetically modified L. lactis strains were established to secrete this epitope vaccine extracellularly in this study. Oral prophylactic immunization with recombinant L. lactis significantly elicited humoral anti-urease antibody responses (P < 0.001) and reduced the gastric colonization of H. pylori from 7.14 ± 0.95 to 4.68 ± 0.98 log10 CFU g(-1) stomach. This L. lactis oral vaccine offers a promising vaccine candidate for the control of H. pylori infection.

Serotype-independent protection against pneumococcal infections elicited by intranasal immunization with ethanol-killed pneumococcal strain, SPY1

The 23-valent polysaccharide vaccine and the 7-valent pneumococcal conjugate vaccine are licensed vaccines that protect against pneumococcal infections worldwide. However, the incidence of pneumococcal diseases remains high in low-income countries. Whole-cell vaccines with high safety and strong immunogenicity may be a favorable choice. We previously obtained a capsule-deficient Streptococcus pneumoniae mutant named SPY1 derived from strain D39. As an attenuated live pneumococcal vaccine, intranasal immunization with SPY1 elicits broad serotype-independent protection against pneumococcal infection. In this study, for safety consideration, we inactivated SPY1 with 70% ethanol and intranasally immunized BALB/c mice with killed SPY1 plus cholera toxin adjuvant for four times. Results showed that intranasal immunization with inactivated SPY1 induced strong humoral and cellular immune responses. Intranasal immunization with inactivated SPY1 plus cholera toxin adjuvant elicited effective serotype-independent protection against the colonization of pneumococcal strains 19F and 4 as well as lethal infection of pneumococcal serotypes 2, 3, 14, and 6B. The protection rates provided by inactivated SPY1 against lethal pneumococcal infection were comparable to those of currently used polysaccharide vaccines. In addition, vaccine-specific B-cell and T-cell immune responses mediated the protection elicited by SPY1. In conclusion, the 70% ethanol-inactivated pneumococcal whole-cell vaccine SPY1 is a potentially safe and less complex vaccine strategy that offers broad protection against S. pneumoniae.

P22 – Set‐up and validation of a mouse model for food‐allergy induced atopic dermatitis

Atopic dermatitis (AD) is a complex disorder characterized by flares of red and itchy skin. Infants with AD often also suffer from food allergy. Both ingestion of and skin contact with the antigen can exacerbate the AD. The affected skin is characterized by oedema formation and shows typical Th2 responses by increased levels of IL-4 and IL-13, but not IFN-γ. Furthermore, there is an influx of eosinophils and CD4+ cells. The CD4+ cells are previously described to originate from the gut mucosa where they developed upon oral sensitization to the food allergen. From both specific oligosaccharides and TLR ligands, it is clinically demonstrated that it can affect the development of AD, by skewing the immune response away from an allergic phenotype. In this study, a mouse model to study the effect of dietary compounds on the development and treatment of food allergy-induced AD will be set-up. For this model, BALB/c mice are orally sensitized with ovalbumin (OVA; generally used to induce hen’s egg allergy) plus cholera toxin adjuvant once a week, for 5 consecutive weeks. One week after the last sensitization, the mouse skin will be challenged with OVA on tape-stripped back skin. This is repeated 3 days later, and again 4 days later, the mice are sacrificed. Outcome parameters as skin thickness, inflammatory cell influx and skin mucosal cytokine levels will be studied. Following development of the AD model the effect of dietary intenvention with a combination of specific OS and TLR ligands will be evaluated on the different outcome parameters.

Immunological features and efficacy of a multi-epitope vaccine CTB-UE against H. pylori in BALB/c mice model

Epitope vaccine is a promising option for prophylactic and therapeutic vaccination against Helicobacter pylori infection. Urease is an essential virulence factor and colonization factor for H. pylori. In this study, we constructed a multi-epitope vaccine named CTB-UE with mucosal adjuvant cholera toxin B subunit (CTB) and tandem copies of Th and B cell epitopes from H. pylori urease A and B subunits. The immunogenicity, specificity, ability to induce neutralizing antibodies against H. pylori urease, and prophylactic and therapeutic efficacy of the CTB-UE vaccine were evaluated in BALB/c mice model after purification. The experimental results indicated that CTB-UE could induce comparatively high levels of specific antibodies against native H. pylori urease, UreA, UreB, or the selected B cell epitopes UreA₁₈₃₋₂₀₃ and UreB₃₂₇₋₃₃₄ involved with the active site of urease and showed an effectively inhibitory effect on the enzymatic activity of urease. Besides, oral prophylactic or therapeutic immunization with CTB-UE significantly decreased H. pylori colonization compared with oral immunization with rUreB or PBS, and the protection was correlated with antigen-specific CD4⁺ T cells and IgG, IgA, and mucosal sIgA antibody responses. This CTB-UE vaccine may be a promising vaccine candidate for the control of H. pylori infection.

Mucosal Adjuvants for Influenza Virus-Like Particle Vaccine

To find an effective mucosal adjuvant for influenza virus-like particles (VLPs), we compared the effects of known adjuvants Alum, CpG DNA, monophosphoryl lipid A (MPL), poly IC, gardiquimod, and cholera toxin (CT). Mice that were intranasally immunized with Alum, CpG, MPL, and CT adjuvanted VLPs showed higher levels of antibodies in both sera and mucosa. Hemagglutination inhibition and virus neutralizing activities were enhanced in groups adjuvanted with Alum, MPL, or CT. Influenza virus specific long-lived cells secreting IgG and IgA antibodies were found at high levels both in bone marrow and spleen in the Alum, CpG and CT adjuvanted groups. A similar level of protection was observed among different adjuvanted groups, except the CT adjuvant that showed a higher efficacy in lowering lung viral loads after challenge. Alum and CT adjuvants differentially increased influenza VLP-mediated activation of dendritic cells and splenocytes in vitro, supporting the in vivo pattern of antibody isotypes and cytokine production. These results suggest that Alum, MPL, or CpG adjuvants, which have been tested clinically, can be developed as an effective mucosal adjuvant for influenza VLP vaccines.

Three-Dimensional Reconstruction of Murine Peyer's Patches from Immunostained Cryosections

Peyer's patches, macroscopic aggregates of lymphoid follicles present throughout the small intestines of humans and other mammals, are considered the gateway through which luminal dietary antigens and microbes are sampled by the mucosal immune system. The cellular make-up of Peyer's patch lymphoid follicles is not only complex, but highly dynamic, as there are at least four major cell types that are known to migrate in response to antigenic stimulation. In an effort to capture the complexity and dynamic nature of this specialized tissue, here we report the three-dimensional (3D) reconstruction of immunofluorescent-labeled mouse Peyer's patch cryosections. The technology that enabled the stacking and linear blending of serial cryosections was a novel macro for Fiji, the open source image-processing package based on ImageJ. By simultaneously labeling cryosections for surface markers CD45R, CD3, and CD11c, we provide a 3D image as well as quantitative measures of B-cell, T-cell, and dendritic cell populations at steady state and following exposure to the mucosal adjuvant cholera toxin.

The Duration of Chlamydia muridarum Genital Tract Infection and Associated Chronic Pathological Changes Are Reduced in IL-17 Knockout Mice but Protection Is Not Increased Further by Immunization

IL-17 is believed to be important for protection against extracellular pathogens, where clearance is dependent on neutrophil recruitment and local activation of epithelial cell defences. However, the role of IL-17 in protection against intracellular pathogens such as Chlamydia is less clear. We have compared (i) the course of natural genital tract C. muridarum infection, (ii) the development of oviduct pathology and (iii) the development of vaccine-induced immunity against infection in wild type (WT) BALB/c and IL-17 knockout mice (IL-17-/-) to determine if IL-17-mediated immunity is implicated in the development of infection-induced pathology and/or protection. Both the magnitude and duration of genital infection was significantly reduced in IL-17-/- mice compared to BALB/c. Similarly, hydrosalpinx was also greatly reduced in IL-17-/- mice and this correlated with reduced neutrophil and macrophage infiltration of oviduct tissues. Matrix metalloproteinase (MMP) 9 and MMP2 were increased in WT oviducts compared to IL-17-/- animals at day 7 post-infection. In contrast, oviducts from IL-17-/- mice contained higher MMP9 and MMP2 at day 21. Infection also elicited higher levels of Chlamydia -neutralizing antibody in serum of IL-17-/- mice than WT mice. Following intranasal immunization with C. muridarum Major Outer Membrane Protein (MOMP) and cholera toxin plus CpG adjuvants, significantly higher levels of chlamydial MOMP-specific IgG and IgA were found in serum and vaginal washes of IL-17-/- mice. T cell proliferation and IFNγ production by splenocytes was greater in WT animals following in vitro re-stimulation, however vaccination was only effective at reducing infection in WT, not IL-17-/- mice. Intranasal or transcutaneous immunization protected WT but not IL-17-/- mice against hydrosalpinx development. Our data show that in the absence of IL-17, the severity of C. muridarum genital infection and associated oviduct pathology are significantly attenuated, however neither infection or pathology can be reduced further by vaccination protocols that effectively protect WT mice.

Direct interaction between cholera toxin and dendritic cells is required for oral adjuvant activity

Cholera toxin (CT) binds to GM1-ganglioside receptors present on all nucleated cells. Despite this, it is a very potent mucosal adjuvant that has a dramatic impact on immune cells, as well as nerve and epithelial cells, causing diarrhea. This fact has hampered our understanding of whether the adjuvanticity of CT is direct or indirect, as cells that bind CT may or may not be involved in its adjuvant function. The mucosal barrier is maintained by tight junctions between epithelial cells but dendritic cells (DCs) can protrude luminal dendrites. Here we investigated which cells are involved in the immune augmenting effect of CT. We explored oral immunizations with ovalbumin (OVA) and CT in bone marrow chimeric mice deficient in GM1-ganglioside in defined cellular subsets. We found that chimeric mice lacking GM1 in nonhematopoietic cells, including epithelial cells, mounted an unaltered intestinal IgA response. In contrast, chimeric mice lacking GM1-expressing hematopoietic cells in general, or specifically GM1-expressing conventional DCs (cDCs), largely failed to elicit anti-OVA adaptive immune responses. Therefore, the adjuvanticity of CT does not require epithelial activation, but is directly dependent on the binding of CT to gut cDCs via GM1-ganglioside. These results could have important implications for the generation of novel oral adjuvants.

Transcutaneous immunization of healthy volunteers with an attenuated Listeria monocytogenes vaccine strain and cholera toxin adjuvant

BackgroundAttenuated Listeria monocytogenes vaccine strains have been administered intravenously (Le et al. [1], Maciag et al. [2]) and orally (Angelakopoulos et al. [3], Johnson et al. [4]) to humans. Here, one was given transcutaneously with cholera toxin adjuvant. MethodsEight healthy volunteers were studied (5 active, 3 placebo). Safety was assessed by physical exam and labs. Systemic immunological responses were measured by ELISA and IFN-gamma ELISpot. Results4/5 active volunteers had cellular responses to listerial antigens. 5/5 active volunteers showed humoral responses to cholera toxin. ConclusionsAn attenuated L. monocytogenes vector was safely administered transcutaneously. Topical administration appeared at least as immunogenic as previously studied oral delivery.

Pan-Shigella Surface Protein antigen 1 as potential cross-protective antigen for Shigella vaccine development. (P4286)

Abstract Shigellosis is a disease characterized by the destruction of the colonic epithelium in humans and one of the most severe diarrheal diseases, especially in children under 5 years of age in developing countries. We have identified several protein antigens that are shared by different shigella serotypes and species. Among these, one antigen, PSSP-1, induces cross-protection against experimental shigellosis induced by different species and serotypes. PSSP-1-induced protection requires (i) a mucosal route of administration; and (ii) the co-administration of a mucosal adjuvant (cholera toxin, mutant thermolabile enterotoxin (dmLT). When PSSP-1was formulated with dmLT, an adjuvant that has undergone human clinical testing, it induced cross-protection against S. flexneri 2a, 3a, 5a, 6, S. boydii and importantly also S. dysenteriae 1. While intradermally administered PSSP-1 adjuvanted with dmLT induced strong serum antibody responses, it failed to induce protection in the mouse lung pneumonia model (consisting of administering Shigella intranasally). In contrast, intranasal PSSP-1 + dmLT elicited efficient local (lung) and peripheral (spleen) antibody responses and regional and systemic IL-17 and IFNγ production. Interestingly, patients with recent onset shigellosis showed variable but significant antibody responses to most conserved Shigella protein antigens but not to PSSP-1. Although the above results are promising, these will have to be validated in humans.

The Mucosal Adjuvant Cholera Toxin B Instructs Non-Mucosal Dendritic Cells to Promote IgA Production Via Retinoic Acid and TGF-β

It is currently unknown how mucosal adjuvants cause induction of secretory immunoglobulin A (IgA), and how T cell-dependent (TD) or -independent (TI) pathways might be involved. Mucosal dendritic cells (DCs) are the primary antigen presenting cells driving TI IgA synthesis, by producing a proliferation-inducing ligand (APRIL), B cell activating factor (BAFF), Retinoic Acid (RA), TGF-β or nitric oxide (NO). We hypothesized that the mucosal adjuvant Cholera Toxin subunit B (CTB) could imprint non-mucosal DCs to induce IgA synthesis, and studied the mechanism of its induction. In vitro, CTB-treated bone marrow derived DCs primed for IgA production by B cells without the help of T cells, yet required co-signaling by different Toll-like receptor (TLR) ligands acting via the MyD88 pathway. CTB-DC induced IgA production was blocked in vitro or in vivo when RA receptor antagonist, TGF-β signaling inhibitor or neutralizing anti-TGF-β was added, demonstrating the involvement of RA and TGF-β in promoting IgA responses. There was no major involvement for BAFF, APRIL or NO. This study highlights that synergism between CTB and MyD88-dependent TLR signals selectively imprints a TI IgA-inducing capacity in non-mucosal DCs, explaining how CTB acts as an IgA promoting adjuvant.

A Double Mutant Heat-Labile Toxin from Escherichia coli, LT(R192G/L211A), Is an Effective Mucosal Adjuvant for Vaccination against Helicobacter pylori Infection

Helicobacter pylori infection in the stomach is a common cause of peptic ulcer disease and is a strong risk factor for the development of gastric adenocarcinoma, yet no effective vaccine against H. pylori infection is available to date. In mice, mucosal vaccination with H. pylori antigens when given together with cholera toxin (CT) adjuvant, but not without adjuvant, can induce protective immune responses against H. pylori infection. However, the toxicity of CT precludes its use as a mucosal adjuvant in humans. We evaluated a recently developed, essentially nontoxic double mutant Escherichia coli heat-labile toxin, LT(R192G/L211A) (dmLT), as a mucosal adjuvant in an experimental H. pylori vaccine and compared it to CT in promoting immune responses and protection against H. pylori infection in mice. Immunization via the sublingual or intragastric route with H. pylori lysate antigens and dmLT resulted in a significant decrease in bacterial load after challenge compared to that in unimmunized infection controls and to the same extent as when using CT as an adjuvant. Cellular immune responses in the sublingually immunized mice known to correlate with protection were also fully comparable when using dmLT and CT as adjuvants, resulting in enhanced in vitro proliferative and cytokine responses from spleen and mesenteric lymph node cells to H. pylori antigens. Our results suggest that dmLT is an attractive adjuvant for inclusion in a mucosal vaccine against H. pylori infection.

Subcutaneous or Oral Immunization of Mice with &lt;i&gt;Lactococcus lactis&lt;/i&gt; Expressing F4 Fimbrial Adhesin FaeG

Enterotoxigenic Escherichia coli (ETEC) is one of the most common causes of diarrhea in neonatal and postweaning piglets. Fimbrial adhesion of ETEC has been considered an important colonization factor with antigenicity. To safely and effectively deliver the F4 (K88) fimbrial adhesin FaeG to the immune system, we have previously constructed the secretory expression vector pNZ8112-faeG, and FaeG was produced in cytoplasmic form in Lactococcus lactis. In this work, BALB/c mice were immunized with recombinant L. lactis to further determine the immunogenicity of recombinant FaeG (rFaeG) via the subcutaneous or oral route. Subcutaneous immunization in mice with recombinant L. lactis induced a significant increase in the F4-specific serum IgG titer and the number of antibody-secreting cells (ASCs) in the spleen. Oral immunization of mice with recombinant L. lactis induced mucosal and systemic F4-specific immune responses and increased the number of ASCs in the spleen, mesenteric lymph nodes and Peyer's patches. High-dose (2.8 × 10(11) CFU) recombinant strains and adjuvant cholera toxin B subunit enhanced specific mucosal immune responses. The results suggest the feasibility of delivering rFaeG expressed in L. lactis to the immune system in order to induce an F4-specific immune response.

Dietary Resveratrol Prevents the Development of Food Allergy in Mice

BackgroundResveratrol is a bioactive polyphenol enriched in red wine that exhibits many beneficial health effects via multiple mechanisms. However, it is unclear whether resveratrol is beneficial for the prevention of food allergy. This study investigated whether resveratrol inhibited the development of food allergy by using a mouse model of the disease.Methodology/Principal FindingsMice fed standard diet or standard diet plus resveratrol were sensitized by intragastric administration of ovalbumin (OVA) and mucosal adjuvant cholera toxin (CT). Several manifestations of food allergy were then compared between the mice. The effects of resveratrol on T cells or dendritic cells were also examined by using splenocytes from OVA-specific T cell-receptor (TCR) transgenic DO11.10 mice or mouse bone marrow-derived dendritic cells (BMDCs) in vitro. We found that mice fed resveratrol showed reduced OVA-specific serum IgE production, anaphylactic reaction, and OVA-induced IL-13 and IFN-ã production from the mesenteric lymph nodes (MLNs) and spleens in comparison to the control mice, following oral sensitization with OVA plus CT. In addition, resveratrol inhibited OVA plus CT-induced IL-4, IL-13, and IFN-ã production in splenocytes from DO11.10 mice associated with inhibition of GATA-3 and T-bet expression. Furthermore, resveratrol suppressed the OVA plus CT-induced CD25 expression and IL-2 production in DO11.10 mice-splenocytes in association with decreases in CD80 and CD86 expression levels. Finally, resveratrol suppressed CT-induced cAMP elevation in association with decreases in CD80 and CD86 expression levels in BMDCs.Conclusions/SignificanceIngestion of resveratrol prevented the development of a food allergy model in mice. Given the in vitro findings, resveratrol might do so by inhibiting DC maturation and subsequent early T cell activation and differentiation via downregulation of CT-induced cAMP activation in mice. These results suggest that resveratrol may have potential for prophylaxis against food allergy.

IL-7Rα and L-selectin, but not CD103 or CD34, are required for murine peanut-induced anaphylaxis

BackgroundAllergy to peanuts results in severe anaphylactic responses in affected individuals, and has dramatic effects on society and public policy. Despite the health impacts of peanut-induced anaphylaxis (PIA), relatively little is known about immune mechanisms underlying the disease. Using a mouse model of PIA, we evaluated mice with deletions in four distinct immune molecules (IL7Rα, L-selectin, CD34, CD103), for perturbed responses.MethodsPIA was induced by intragastric sensitization with peanut antigen and cholera toxin adjuvant, followed by intraperitoneal challenge with crude peanut extract (CPE). Disease outcome was assessed by monitoring body temperature, clinical symptoms, and serum histamine levels. Resistant mice were evaluated for total and antigen specific serum IgE, as well as susceptibility to passive systemic anaphylaxis.ResultsPIA responses were dramatically reduced in IL7Rα−/− and L-selectin−/− mice, despite normal peanut-specific IgE production and susceptibility to passive systemic anaphylaxis. In contrast, CD34−/− and CD103−/− mice exhibited robust PIA responses, indistinguishable from wild type controls.ConclusionsLoss of L-selectin or IL7Rα function is sufficient to impair PIA, while CD34 or CD103 ablation has no effect on disease severity. More broadly, our findings suggest that future food allergy interventions should focus on disrupting sensitization to food allergens and limiting antigen-specific late-phase responses. Conversely, therapies targeting immune cell migration following antigen challenge are unlikely to have significant benefits, particularly considering the rapid kinetics of PIA.

Prophylactic and therapeutic efficacy of the epitope vaccine CTB-UA against Helicobacter pylori infection in a BALB/c mice model

Epitope vaccine based on the enzyme urease of Helicobacter pylori is a promising option for prophylactic and therapeutic vaccination against H. pylori infection. In our previous study, the epitope vaccine CTB-UA, which was composed of the mucosal adjuvant cholera toxin B subunit (CTB) and an epitope (UreA₁₈₃₋₂₀₃) from the H. pylori urease A subunit (UreA) was constructed. This particular vaccine was shown to have good immunogenicity and immunoreactivity and could induce specific neutralizing antibodies, which exhibited effectively inhibitory effects on the enzymatic activity of H. pylori urease. In this study, the prophylactic and therapeutic efficacy of the epitope vaccine CTB-UA was evaluated in a BALB/c mice model. The experimental results indicated that oral prophylactic or therapeutic immunization with CTB-UA significantly decreased H. pylori colonization compared with oral immunization with PBS. The results also revealed that the protection was correlated with antigen-specific IgG, IgA, and mucosal secretory IgA antibody responses. CTB-UA may be a promising vaccine candidate for the control of H. pylori infection.

Loss of Sialic Acid Binding Domain Redirects Protein σ1 to Enhance M Cell-Directed Vaccination

Ovalbumin (OVA) genetically fused to protein sigma 1 (pσ1) results in tolerance to both OVA and pσ1. Pσ1 binds in a multi-step fashion, involving both protein- and carbohydrate-based receptors. To assess the relative pσ1 components responsible for inducing tolerance and the importance of its sialic binding domain (SABD) for immunization, modified OVA-pσ1, termed OVA-pσ1(short), was deleted of its SABD, but with its M cell targeting moiety intact, and was found to be immunostimulatory and enhanced CD4+ and CD8+ T cell proliferation. When used to nasally immunize mice given with and without cholera toxin (CT) adjuvant, elevated SIgA and serum IgG responses were induced, and OVA-pσ1(s) was more efficient for immunization than native OVA+CT. The immune antibodies (Abs) were derived from elevated Ab-forming cells in the upper respiratory tissues and submaxillary glands and were supported by mixed Th cell responses. Thus, these studies show that pσ1(s) can be fused to vaccines to effectively elicit improved SIgA responses.