A novel approach to produce phage single domain antibody fragments for the detection of gluten in foods

Electrochemical tracking of gluten in marketed foods by using a recombinant antibody fragment based-platform

The only treatment to effectively manage celiac disease is the avoidance of gluten containing foods. Therefore, and given its high prevalence, it is of utmost importance to have reliable and efficient methods for the detection of gluten to ensure the well-being and quality of life of celiacs. This work presents the development of an electrochemical immunoplatform exhibiting many practical advantages including simplicity, reduced cost and high sensitivity for the screening of gluten-containing products. The methodology exploited the unique features offered by a recombinant antibody fragment with high affinity towards gliadin together with the use of magnetic microcarriers (MμCs) as scaffolds for the implementation of an indirect competitive immunoassay. Using amperometric transduction on disposable electrodes and the horseradish peroxidase/hydrogen peroxide/hydroquinone system, a dynamic range between 7.3 and 1982 ng mL-1 was obtained for gliadin standards, with a limit of detection of 1.4 ng mL-1. The developed immunoplatform was successfully employed for the analysis of a variety of processed foodstuffs, demonstrating the ability to discriminate between gluten-free and gluten-containing foods according to the legislated threshold (20 mg kg-1 of gluten). The agreement with the results provided by the R5-based ELISA and qPCR methods confirmed the suitability of the bioplatform as a competitive tool in terms of assay time (results in just 60 min after gliadin extraction) sensitivity and applicability, even at the point of need.

Screening of specific binding peptide for β-lactoglobulin using phage display technology

β-lactoglobulin (β-Lg) is a major food allergen, there is an urgent need to develop a rapid method for detecting β-Lg in order to avoid contact or ingestion by allergic patients. Peptide aptamers have high affinity, specificity, and stability, and have broad prospects in the field of rapid detection. Using β-Lg as the target, this study screened 11 peptides (P1-11) from a phage display library. Using molecular docking technology to predict binding energy and binding mode of proteins and peptides. Select the peptides with the best binding ability to β-Lg (P5, P7, P8) through ELISA. Combining them with whey protein, casein, and bovine serum protein, it was found that P7 has the best specificity for β-Lg, with an inhibition rate of 87.99%. Verified by molecular dynamics that P7 binds well with β-Lg. Therefore, this peptide can be used for the recognition of β-Lg, becoming a new recognition element for detecting β-Lg.

Developing recombinant antibodies by phage display technology to neutralize viral infectious diseases

The use of recombinant antibodies developed through phage display technology offers a promising approach for combating viral infectious diseases. By specifically targeting antigens on viral surfaces, these antibodies have the potential to reduce the severity of infections or even prevent them altogether. With the emergence of new and more virulent strains of viruses, it is crucial to develop innovative methods to counteract them. Phage display technology has proven successful in generating recombinant antibodies capable of targeting specific viral antigens, thereby providing a powerful tool to fight viral infections. In this mini-review article, we examine the development of these antibodies using phage display technology, and discuss the associated challenges and opportunities in developing novel treatments for viral infectious diseases. Furthermore, we provide an overview of phage display technology. As these methods continue to evolve and improve, novel and sophisticated tools based on phage display and peptide display systems are constantly emerging, offering exciting prospects for solving scientific, medical, and technological problems related to viral infectious diseases in the near future.

Lable-free aptamer portable colorimetric smartphone for gliadin detection in food

For individuals with celiac disease (CD), the current clinical therapy option available is a lifelong gluten-free diet. Therefore, it is essential to swiftly and efficiently detect gluten in foods. A colorimetric sensor has been developed, which operates by regulating the aggregation and dispersion state of AuNPs induced by high concentration NaCl through the specific binding of gliadin and aptamer, thereby achieving rapid detection of gliadin in flour. It is found that the sensor exhibits good linearity in the concentration range of 0.67-10 μM and the LOD (3σ/S) is 12 nM. And it can accurately distinguish various types of free-gliadin samples, with a spiked recovery rate of 85%-122.3%. To make the detection process more convenient, the colorimetric results of the biosensor were translated into RGB color-gamut parameters by a smartphone color-picking program for further analysis. Gliadin can still be accurately quantified with the established smartphone platform, and a correlation coefficient of 0.988 was found. The proposed portable smartphone aptamer colorimetric sensing device has achieved satisfactory results in the rapid detection of gliadin in food.

Production and Characterization of Novel Fabs Generated from Different Phage Display Libraries as Probes for Immunoassays for Gluten Detection in Food

Gluten is the main fraction of wheat proteins. It is widely used in the food industry because of the properties that are generated in the dough, but it is also able to trigger diseases like allergies, autoimmunity processes (such as celiac disease), and intolerances in sensitized persons. The most effective therapy for these diseases is the total avoidance of gluten in the diet because it not only prevents damage but also enhances tissue healing. To ensure the absence of gluten in food products labeled as gluten-free, accurate detection systems, like immunoassays, are required. In this work, four recombinant Fab antibody fragments, selected by phage display technology, were produced and tested for specificity and accuracy against gluten in experimental flour mixtures and commercial food products. A high-affinity probe (Fab-C) was identified and characterized. An indirect ELISA test was developed based on Fab-C that complied with the legal detection limits and could be applied in the assessment of gluten-free diets.

Development of a new recombinant antibody, selected by phage-display technology from a celiac patient library, for detection of gluten in foods

Gluten, a group of ethanol-soluble proteins present in the endosperm of cereals, is extensively used in the food industry due to its ability to improve dough properties. However, gluten is also associated with a range of gluten-related diseases (GRDs), such as wheat allergies, celiac disease, and gluten intolerance. The recommended treatment for GRDs patients is a gluten-free diet. To monitor adherence to this diet, it is necessary to develop gluten-detection systems in food products. Among the available methods, immunodetection systems are the most popular due to their simplicity, reproducibility, and accuracy. The aim of this study was to generate novel high-affinity antibodies against gluten to be used as the primary reactant in an enzyme-linked immunosorbent assay (ELISA) test. These antibodies were developed by constructing an immune library from mRNA obtained from two celiac patients with a high humoral response to gluten-related proteins. The resulting library (composed by 1.1x107) was subjected to selection against gliadin using phage display technology. Following several rounds of selection, the Fab-C was selected, and demonstrated good functionality in ELISA tests, presenting a limit of detection of 15 mg/kg for detection of gluten in spiked mixtures and food products. The methodology can discriminate gluten-free products according to the current legislation.

Using casein and gluten protein fractions to obtain functional ingredients

Today, the food industry widely uses both animal and plant proteins. Animal proteins have a balanced amino acid composition, while plant proteins have more pronounced functional properties. However, both types of proteins can act as allergens, which limits their practical application. Therefore, we aimed to select optimal conditions for obtaining hypoallergenic mixtures based on casein hydrolysates and gluten proteins, which have good functional properties and a balanced amino acid composition. We used wheat flour (Makfa, Russia) with 12.6% of crude protein and 69.4% of starch, as well as rennet casein (Atletic Food, Russia) with 90% of protein. The methods included the Lowry method, the Anson method, Laemmli electrophoresis, ion-exchange chromatography, and the enzyme-linked immunosorbent assay. Protex 6L was an optimal enzyme preparation for the hydrolysis of gliadin, while chymotrypsin was optimal for the hydrolysis of glutenin and casein. The optimal amount for all the enzymes was 40 units/g of substrate. We analyzed the effect of casein, glutenin, and gliadin enzymolysis time on the functional properties of the hydrolysates and found that the latter had relatively low water- and fat-holding capacities. The highest foaming capacity was observed in gliadin hydrolysates, while the highest emulsifying capacity was registered in casein and glutenin hydrolysates. Further, protein enzymolysis significantly decreased allergenicity, so the hydrolysates can be used to obtain functional additives for hypoallergenic products. Finally, the mixtures of casein hydrolysate and gliadin or glutenin hydrolysates had a balanced amino acid composition and a high amino acid score. Also, they retained high emulsifying and foaming capacities. The study proved the need for mixtures based on wheat protein and casein hydrolysates, which have good functional properties and hypoallergenicity.

Construction of a Fab Library Merging Chains from Semisynthetic and Immune Origin, Suitable for Developing New Tools for Gluten Immunodetection in Food

The observed increase in the prevalence of gluten-related disorders has prompted the development of novel immunological systems for gluten detection in foodstuff. The innovation on these methods relies on the generation of new antibodies, which might alternatively be obtained by molecular evolution methods such as phage display. This work presents a novel approach for the generation of a Fab library by merging semi-synthetic heavy chains built-up from a pre-existent recombinant antibody fragment (dAb8E) with an immune light chain set derived from celiac donors. From the initial phage population (107 candidates) and after three rounds of selection and amplification, four different clones were isolated for further characterization. The phage Fab8E-4 presented the best features to be applied in an indirect ELISA for the detection of gluten in foods, resulting in improved specificity and sensitivity.

How does a celiac iceberg really float? The relationship between celiac disease and gluten

Celiac disease (CD) is an autoimmune intestinal disease caused by intolerance of genetically susceptible individuals after intake of gluten-containing grains (including wheat, barley, etc.) and their products. Currently, CD, with "iceberg" characteristics, affects a large population and is distributed over a wide range of individuals. This present review summarizes the latest research progress on the relationship between CD and gluten. Furthermore, the structure and function of gluten peptides related to CD, gluten detection methods, the effects of processing on gluten and gluten-free diets are emphatically reviewed. In addition, the current limitations in CD research are also discussed. The present work facilitates a comprehensive understanding of CD as well as gluten, which can provide a theoretical reference for future research.

From Polyclonal Sera to Recombinant Antibodies: A Review of Immunological Detection of Gluten in Foodstuff

Gluten is the ethanol-soluble protein fraction of cereal endosperms like wheat, rye, and barley. It is widely used in the food industry because of the physical-chemical properties it gives to dough. Nevertheless, there are some gluten-related diseases that are presenting increasing prevalences, e.g., celiac disease, for which a strict gluten-free diet is the best treatment. Due to this situation, gluten labeling legislation has been developed in several countries around the world. This article reviews the gluten immune detection systems that have been applied to comply with such regulations. These systems have followed the development of antibody biotechnology, which comprise three major methodologies: polyclonal antibodies, monoclonal antibodies (mAbs) derived from hybridoma cells (some examples are 401.21, R5, G12, and α-20 antibodies), and the most recent methodology of recombinant antibodies. Initially, the main objective was the consecution of new high-affinity antibodies, resulting in low detection and quantification limits that are mainly achieved with the R5 mAb (the gold standard for gluten detection). Increasing knowledge about the causes of gluten-related diseases has increased the complexity of research in this field, with current efforts not only focusing on the development of more specific and sensitive systems for gluten but also the detection of protein motifs related to pathogenicity. New tools based on recombinant antibodies will provide adequate safety and traceability methodologies to meet the increasing market demand for gluten-free products.

Production of a Recombinant Single-Domain Antibody for Gluten Detection in Foods Using the Pichia pastoris Expression System

The detection of gluten in foodstuffs has become a growing concern in food allergen management as a result of the high ratio of population sensitive to the main gluten-containing cereals. In this study, a promising single-domain antibody previously isolated by phage display (dAb8E) was produced in Pichia pastoris resulting in high levels of the antibody fragment expression (330 mg/L). The purified dAb8E was proved to specifically bind to gluten proteins from wheat, barley and rye, exhibiting no cross reaction to other heterologous species. The dynamic range of the sandwich enzyme-linked immunosorbent assay (ELISA) covered 0.1 to 10 µg/mL of gliadin, reaching a limit of detection of 0.12 µg/mL. When experimental binary mixtures of the target cereals were analyzed, the limit of detection was 0.13 mg/g, which would theoretically correspond to gluten concentrations of approximately 13 mg/kg. Finally, thirty commercially available food products were analyzed by means of the developed assay to further confirm the applicability of the dAb8E for gluten determination. The proposed methodology enabled the generation of a new gluten-specific nanobody which could be used to guarantee the appropriate labelling of gluten-free foods.

Truncated aptamers as selective receptors in a gluten sensor supporting direct measurement in a deep eutectic solvent

Enzyme-linked immunosorbent assays are currently the most popular methods to quantify gluten in foods. Unfortunately, the antibodies used as specific receptors in such methods are not compatible with the usual solvents for the extraction of gluten proteins. In consequence, commercial tests require a high dilution of the sample after the extraction, increasing the limit of quantification and decreasing convenience. In this work, we have rationally truncated an aptamer capable of recognizing gliadin in a deep eutectic solvent (DES). The truncated aptamer is a 19-nucleotides-long DNA that minimizes self-hybridization, allowing the development of an electrochemical sandwich-based sensor for the quantification of gluten in the DES ethaline. The sensor incorporates two identical biotin-labeled truncated aptamers, one of which is immobilized on a carbon screen-printed electrode and the other reports the binding of gliadin after incubation in streptavidin-peroxidase. This sensor can detect gliadin in DES, with a dynamic range between 1 and 100 μg/L and an intra-assay coefficient of variation of 11%. This analytical performance allows the quantification of 20 μg of gluten/kg of food when 1 g of food is extracted with 10 mL of ethaline. We demonstrate the ability of this method to achieve the measurement of gluten in food samples, after the extraction with pure ethaline. The assay is useful for the analysis of residual gluten levels in foods, thus facilitating the evaluation of any potential health risk associated with the consumption of such food by people with celiac disease or other gluten-related disorders.