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Background: Understanding the discrepancy between IgE sensitization and allergic reactions to peanut could facilitate diagnosis and lead to novel means of treating peanut allergy. Objective: To identify differences in IgE and IgG4 binding to peanut peptides between peanut‐allergic (PA) and peanut‐sensitized but tolerant (PS) children. Methods: PA (n = 56), PS (n = 42) and nonsensitized nonallergic (NA, n = 10) patients were studied. Synthetic overlapping 15‐mer peptides of peanut allergens (Ara h 1‐11) were spotted onto microarray slides, and patients' samples were tested for IgE and IgG4 binding using immunofluorescence. IgE and IgG4 levels to selected peptides were quantified using ImmunoCAP. Diagnostic model comparisons were performed using likelihood‐ratio tests between each specified nominal logistic regression models. Results: Seven peptides on Ara h 1, Ara h 2, and Ara h 3 were bound more by IgE of PA compared to PS patients on the microarray. IgE binding to one peptide on Ara h 5 and IgG4 binding to one Ara h 9 peptide were greater in PS than in PA patients. Using ImmunoCAP, IgE to the Ara h 2 peptides enhanced the diagnostic accuracy of Ara h 2‐specific IgE. Ratios of IgG4/IgE to 4 out of the 7 peptides were higher in PS than in PA subjects. Conclusions: Ara h 2 peptide‐specific IgE added diagnostic value to Ara h 2‐specific IgE. Ability of peptide‐specific IgG4 to surmount their IgE counterpart seems to be important in established peanut tolerance. [ABSTRACT FROM AUTHOR]

Peanut allergy has garnered significant attention because of the high sensitization rate, increase in allergy, and severity of the reaction. Sufficiently reliable therapies and efficient mitigating techniques to combat peanut allergy are still lacking. Current management relies on avoiding peanuts and nuts and seeds with homologous proteins, although adverse events mostly occur with accidental ingestion. There is a need for hypoallergenic peanut products to protect sensitized individuals and perhaps serve as immunotherapeutic products. Alongside traditional practices of thermal and chemical treatment, novel processing approaches such as high‐pressure processing, pulsed ultraviolet light, high‐intensity ultrasound, irradiation, and pulsed electric field have been performed toward reducing the immunoreactivity of peanut. Covalent and noncovalent chemical modifications to proteins also have the tendency to alter peanut allergenicity. Enzymatic hydrolysis seems to be the most advantageous technique in diminishing the allergenic potential of peanut. Furthermore, the combined processing approach (hurdle technologies) such as enzymatic hydrolysis followed by, or in conjunction with, roasting, high pressure and heat, ultrasound with enzymatic treatment, or germination have shown a significant reduction of peanut immunoreactivity and may emerge as useful techniques in reducing the allergenicity of peanut and other foods. This study represents our current knowledge about the alterations in allergenic properties of peanut via different processing mechanisms as well as evaluating its future potential, geographical based data on increasing sensitization, clinical relevance, eliciting dose, and current management of peanut allergy. Furthermore, the molecular characteristics and clinical relevance of peanut allergens have been discussed. [ABSTRACT FROM AUTHOR]

Peanut allergy is an IgE-mediated adverse reaction to a subset of proteins found in peanuts. Immunotherapy aims to desensitize allergic patients through repeated and escalating exposures for several months to years using extracts or flours. The complex mix of proteins and variability between preparations complicates immunotherapy studies. Moreover, peanut immunotherapy is associated with frequent negative side effects and patients are often at risk of allergic reactions once immunotherapy is discontinued. Allergen-specific approaches using recombinant proteins are an attractive alternative because they allow more precise dosing and the opportunity to engineer proteins with improved safety profiles. We tested whether Ara h 1 and Ara h 2, two major peanut allergens, could be produced using chloroplast of the unicellular eukaryotic alga, Chlamydomonas reinhardtii. C. reinhardtii is novel host for producing allergens that is genetically tractable, inexpensive and easy to grow, and is able to produce more complex proteins than bacterial hosts. Compared to the native proteins, algal-produced Ara h 1 core domain and Ara h 2 have a reduced affinity for IgE from peanut-allergic patients. We further found that immunotherapy using algal-produced Ara h 1 core domain confers protection from peanut-induced anaphylaxis in a murine model of peanut allergy. [ABSTRACT FROM AUTHOR]

Peanuts are one of the most allergenic foods and are widespread in western food products. Therefore, there has been intense research into the allergic nature of the proteins involved. Ara h 3 is one of three immunodominant allergenic proteins. It is a 60-kDa protein, which forms following cleavage of the preprotein and association of the resultant 40- and 20-kDa subunits. The large subunit has been shown to harbour most of the reactive epitopes and has the protein fold likely responsible for its trypsin inhibitor activity. In this work, we have developed a method for the high-level expression and purification of recombinant Ara h 3 40-kDa subunit. Specific antibodies have been produced and applied to the secondary and tertiary screens of hundreds of peanut cultivars. Several of these cultivars were identified that have significantly reduced accumulation of Ara h 3. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus produces a wide array of virulence factors and causes a correspondingly diverse array of infections. Production of these virulence factors is under the control of a complex network of global regulatory elements, one of which is sarA. sarA encodes a DNA binding protein that is considered to function as a transcription factor capable of acting as either a repressor or an activator. Using competitive ELISA assays, we demonstrate that SarA is present at approximately 50 000 copies per cell, which is not characteristic of classical transcription factors. We also demonstrate that SarA is present at all stages of growth in vitro and is capable of binding DNA with high affinity but that its binding affinity and pattern of shifted complexes in electrophoretic mobility shift assays is responsive to the redox state. We also show that SarA binds to the bacteriophage lambda (λ) attachment site, attL, producing SarA-DNA complexes similar to intasomes, which consist of bacteriophage lambda integrase, Escherichia coli integration host factor and attL DNA. In addition, SarA stimulates intramolecular excision recombination in the absence of λ excisionase, a DNA binding accessory protein. Taken together, these data suggest that SarA may function as an architectural accessory protein. [ABSTRACT FROM AUTHOR]