Cross-reactivity of antibodies in some commercial deoxynivalenol test kits against some fusariotoxins

RNA-cleaving deoxyribozyme-linked immunosorbent assay for the ultrasensitive detection of chloramphenicol in milk

In this presented work, an artificial deoxyribozyme was employed as the substitute for horseradish peroxidase (or alkaline phosphatase) in ELISA for generating amplified signals. The feasibility of the proposed deoxyribozyme-based ELISA (DLISA) was demonstrated in the detection of a forbidden veterinary drug, chloramphenicol. And its efficiency was praised since that ultrahigh sensitivity was accomplished with a detection limit of 0.1 ng/L. The wide linear range from 0.000001 μg/mL to 1.0 μg/mL, as well as good recoveries from 86 % to 104 % in whole milk samples showed its excellent practical performances. Besides, the DLISA was worth popularizing due to the easy connection of antibody and DNAzyme through a facile functionalization process of gold nanoparticles. These advantages showed the possibility of DLISA for developing commercial kits, and the utilization of flexible DNA fluorescent probes in DLISA would inspire more work on innovations.

Comparison of two commercial methods with a UHPLC-MS/MS method for the determination of multiple mycotoxins in cereals

Immunoassay-based techniques are important on-site screening tools for the detection of mycotoxins in cereals. This study aims to evaluate the trueness, precision, repeatability and cross-reactivity of commercially available test strips, ELISA kits and UHPLC-MS/MS on analyzing zearalenone, ochratoxin A, deoxynivalenol, T-2 toxin and fumonisin B₁. The results showed that false negative rate (25.7 %-37.4 %) of all tested mycotoxins by test strips was higher than the false positive rate (0 %-31.0 %). The repeatability of ELISA kits at the declared LOD dispersed from -85.7 % to +98.4 %. ELISA kits were more accurate at 50 % of the maximum residue limit (MRL) of mycotoxins than 150 % and 200 %. All the tested deoxynivalenol/zearalenone derivatives had cross-reactivity with different level, and sample matrix could reinforce this overestimation of target mycotoxin. This study emphasized that higher-quality antibody screening and more analytical performance investigations are need to address for on-site detection of mycotoxins in the future.

Analytical Validation of a Direct Competitive ELISA for Multiple Mycotoxin Detection in Human Serum

Mycotoxin exposure in humans is primarily assessed through its occurrence in external sources, such as food commodities. Herein, we have developed a direct competitive ELISA to facilitate the detection of aflatoxin B1 (AFB1), deoxynivalenol (DON), fumonisin (FUM B1/B2), ochratoxin A (OTA), and zearalenone (ZEA) in human serum. The analytical validation of the assay followed practices endorsed by the international research community and the EU directive 96/23/EC in order to examine detection capability, recovery, and cross-reactivity. The assay demonstrated a lower limit of quantitation (LLOQ) for AFB1 [0.61 ng/mL (hereon ng/mL = ppb)], DON (19.53 ppb), FUM (4.88 ppb), OTA (19.53 ppb), and ZEA (0.15 ppb). Recovery from human serum for all mycotoxins spanned from 73% to 106%. Likewise, the specificity for monoclonal antibodies against cross-reactant mycotoxins ranged from 2% to 11%. This study compares the LLOQ and recovery values with commercial and emerging immuno-based methods for detecting mycotoxins in foodstuffs. The LLOQ values from the present study were among the lowest in commercial or emerging methods. Despite the differences in the extraction protocols and matrices, the recovery range in this study, commercial tests, and other procedures were similar for all mycotoxins. Overall, the assay detected AFB1, DON, FUM, OTA, and ZEA in human serum with excellent accuracy, precision, and specificity.

The Deoxynivalenol Challenge

This perspective examines four of the primary challenges that the mycotoxin deoxynivalenol (DON) presents to farmers, producers, and consumers. DON is one of the big five agriculturally important mycotoxins, resulting from Fusarium infection on grains, such as maize, barley, and wheat. In many countries, such as Canada, DON is the mycotoxin of principal concern because it can lead to major economic losses and stresses on food and feed security. The challenges discussed here include (1) understanding the different toxin profiles of Fusarium graminearum chemotypes/genotypes and the fate of these toxins upon interaction with the host crop, (2) the need for rapid analytical tests to measure DON and any masked or modified toxins in food and feed products, (3) DON exposure assessments in human populations to ensure health and safety, and (4) how contaminated food and feed products can be managed throughout the supply chain system. Despite decades of research, we are continuously learning new knowledge about DON and how best to manage it; however, there is still much work to be done. DON poses a very complex challenge that is being further exacerbated by climate change, evolving fungal populations, and the increased need for global food security.

Interactive proteogenomic exploration of response to Fusarium head blight in oat varieties with different resistance

Fusarium species are cereal pathogens that cause the Fusarium Head Blight (FHB) disease. FHB can reduce yield, cause mycotoxin accumulation in the grain and reduce germination efficiency of the harvested seeds. Understanding the biochemical interactions between the host plants and the pathogen is crucial for controlling the disease and for the development of cultivars with improved tolerance to FHB. Here, we studied morphological and proteomic differences between the susceptible oat variety Belinda and the more resistant variety Argamak using variety-specific transcriptome assemblies as references. Measurements of deoxynivalenol toxin levels confirmed the partial resistance in Argamak and the susceptibility in Belinda. To jointly investigate the proteomics- and sequence data, we developed an RShiny-based interface for interactive exploration of the dataset using univariate and multivariate statistics. When applying this interface to the dataset, quantitative protein differences between Belinda and Argamak were detected, and eighteen peptides were found uniquely in Argamak during infection, among them several lipoxygenases. Such proteins can be developed as markers for Fusarium resistance breeding. In conclusion, this study provides the first proteogenomic insight on molecular Fusarium-oat interactions at both morphological and molecular levels and the data are openly available through an interactive interface for further inspection. SIGNIFICANCE: Fusarium head blight causes widespread damage to crops, and chronic and acute toxicity to human and livestock due to the accumulation of toxins during infection. In the present study, two oat varieties with differing resistance were challenged with Fusarium to understand the disease better, and studied both at morphological and molecular levels, identifying proteins which could play a role in the defense mechanism. Furthermore, a proteogenomics approach allows joint profiling of expression and sequence level differences to identify potentially functionally differing mutations. Here such analysis is made openly available through an interactive interface which allows other scientists to draw further findings from the data. This study may both serve as a basis for understanding oat disease response and developing breeding markers for Fusarium resistant oat and future proteogenomic studies using the interactive approach described.

TRI Genotyping and Chemotyping: A Balance of Power

Fusarium is among the top 10 most economically important plant pathogens in the world. Trichothecenes are the principal mycotoxins produced as secondary metabolites by select species of Fusarium and cause acute and chronic toxicity in animals and humans upon exposure either through consumption and/or contact. There are over 100 trichothecene metabolites and they can occur in a wide range of commodities that form food and feed products. This review discusses strategies to mitigate the risk of mycotoxin production and exposure by examining the Fusarium-trichothecene model. Fundamental to mitigation of risk is knowing the identity of the pathogen. As such, a comparison of current, recommended molecular approaches for sequence-based identification of Fusaria is presented, followed by an analysis of the rationale and methods of trichothecene (TRI) genotyping and chemotyping. This type of information confirms the source and nature of risk. While both are powerful tools for informing regulatory decisions, an assessment of the causes of incongruence between TRI genotyping and chemotyping data must be made. Reconciliation of this discordance will map the way forward in terms of optimization of molecular approaches, which includes data validation and sharing in the form of accessible repositories of genomic data and browsers for querying such data.

Cost-Effective Sampling and Analysis for Mycotoxins in a Cereal Batch

The presence of hazards (e.g., contaminants, pathogens) in food/feed, water, plants, or animals can lead to major economic losses related to human and animal health or the rejection of batches of food or feed. Monitoring these hazards is important but can lead to high costs. This study aimed to find the most cost-effective sampling and analysis (S&A) plan in the cases of the mycotoxins deoxynivalenol (DON) in a wheat batch and aflatoxins (AFB₁ ) in a maize batch. An optimization model was constructed, maximizing the number of correct decisions for accepting/rejecting a batch of cereals, with a budget as major constraint. The decision variables were the choice of the analytical method: instrumental method (e.g., liquid chromatography combined with mass-spectrometry (LC-MS/MS)), enzyme-linked-immuno-assay (ELISA), or lateral flow devices (LFD), the number of incremental samples collected from the batch, and the number of aliquots analyzed. S&A plans using ELISA showed to be slightly more cost effective than S&A plans using the other two analytical methods. However, for DON in wheat, the difference between the optimal S&A plans using the three different analytical methods was minimal. For AFB₁ in maize, the cost effectiveness of the S&A plan using instrumental methods or ELISA were comparable whereas the S&A plan considering onsite detection with LFDs was least cost effective. In case of nonofficial controls, which do not have to follow official regulations for sampling and analysis, onsite detection with ELISA for both AFB₁ in maize and DON in wheat, or with LFDs for DON in wheat, could provide cost-effective alternatives.

Cross-reactivity of commercial and non-commercial deoxynivalenol-antibodies to emerging trichothecenes and common deoxynivalenol-derivatives

Immunoassay based techniques are an important and fast option for the detection and quantification of mycotoxins. They are frequently used as on-site screening tools in grain elevators, storage and production facilities. However, accurate quantification may be hampered by the co-recognition of structurally related metabolites by the used antibodies. Therefore, it is crucial to assess their cross-reactivity to avoid misinterpretation of the results. Several immunoassays for the determination of deoxynivalenol (DON) are commercially available. Recently, novel trichothecene mycotoxins with structures similar to DON, the NX-toxins (NX-2, NX-3 and NX-4), were discovered, which can potentially co-occur with DON in cereals. So far, no data about the cross-reactivity of those toxins with DON-antibodies are available. The aim of this study was to assess the cross-reactivities of NX-toxins and some other DON-related metabolites with DON-antibodies in buffer solutions. Six commercially available enzyme-linked immunosorbent assays (ELISAs) and two previously developed DON-antibodies (Mab#1 and Mab#22) were tested. Cross-reactivity with NX-metabolites was not observed for any of the ELISA-kits nor Mab#22, whereas Mab#1 reacted moderately against NX-3 and NX-4 (cross-reactivity based on a molar basis of 14 and 30%, respectively). Modifications at position C-3 (3-acetyl-DON and DON-3-glucoside) led to moderate or high cross-reactivity with Mab#22 and the commercial ELISA-kits, whereas these compounds were not recognised by Mab#1. Similar to NX-metabolites, 15-acetyl-DON interacted only weakly with Mab#22 and the commercial ELISA-kits, but strongly with Mab#1. The results demonstrate the importance of proper antibody characterisation. If NX-metabolites prove to be widely distributed and reach significant levels, the development of specific antibodies targeting these novel metabolites might become necessary.

Use of enzyme-linked immunosorbent assay to screen for aflatoxins, ochratoxin A, and deoxynivalenol in dry pet foods

The objective of this study was to perform a market survey on dry pet foods using enzyme-linked immunosorbent assay (ELISA) to detect total aflatoxins (AFs), ochratoxin A (OTA), and deoxynivalenol (DON). Pet food products (n = 58) marketed for dogs, cats, birds, and rabbits were tested in duplicate with ELISA, and results above the limit of quantitation were confirmed using liquid chromatography tandem mass spectrometry (LC-MS/MS). OTA was detected in one product (rabbit food) and AFs were detected in two products (one dog treat and one bird treat). In contrast, DON was detected in the majority (74%) of products tested. Bird and rabbit products were the most affected by DON, with levels above 0.5 μg/g in 50 and 80% of samples, respectively. One rabbit sample tested positive for both OTA and DON. Overall, the findings of this study revealed a low incidence of AFs and OTA in commercial pet food. Although DON was detected in numerous products, the levels were well below those associated with acute toxic effects.

Bioinspired recognition elements for mycotoxin sensors

Mycotoxins are low molecular weight molecules produced as secondary metabolites by filamentous fungi that can be found as natural contaminants in many foods and feeds. These toxins have been shown to have adverse effects on both human and animal health, and are the cause of significant economic losses worldwide. Sensors for mycotoxin analysis have traditionally applied elements of biological origin for the selective recognition purposes. However, since the 1970s there has been an exponential growth in the use of genetically engineered or synthetic biomimetic recognition elements that allow some of the limitations associated with the use of natural receptors for the analyses of these toxins to be circumvented. This review provides an overview of recent advances in the application of bioinspired recognition elements, including recombinant antibodies, peptides, aptamers, and molecularly imprinted polymers, to the development of sensors for mycotoxins based on different transduction elements. Graphical abstract Novel analytical methods based on bioinspired recognition elements, such as recombinant antibodies, peptides, aptamers, and molecularly imprinted polymers, can improve the detection of mycotoxins and provide better tools than their natural counterparts to ensure food safety.

Risks to human and animal health related to the presence of deoxynivalenol and its acetylated and modified forms in food and feed

Deoxynivalenol (DON) is a mycotoxin primarily produced by Fusarium fungi, occurring predominantly in cereal grains. Following the request of the European Commission, the CONTAM Panel assessed the risk to animal and human health related to DON, 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON) and DON-3-glucoside in food and feed. A total of 27,537, 13,892, 7,270 and 2,266 analytical data for DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside, respectively, in food, feed and unprocessed grains collected from 2007 to 2014 were used. For human exposure, grains and grain-based products were main sources, whereas in farm and companion animals, cereal grains, cereal by-products and forage maize contributed most. DON is rapidly absorbed, distributed, and excreted. Since 3-Ac-DON and 15-Ac-DON are largely deacetylated and DON-3-glucoside cleaved in the intestines the same toxic effects as DON can be expected. The TDI of 1 μg/kg bw per day, that was established for DON based on reduced body weight gain in mice, was therefore used as a group-TDI for the sum of DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside. In order to assess acute human health risk, epidemiological data from mycotoxicoses were assessed and a group-ARfD of 8 μg/kg bw per eating occasion was calculated. Estimates of acute dietary exposures were below this dose and did not raise a health concern in humans. The estimated mean chronic dietary exposure was above the group-TDI in infants, toddlers and other children, and at high exposure also in adolescents and adults, indicating a potential health concern. Based on estimated mean dietary concentrations in ruminants, poultry, rabbits, dogs and cats, most farmed fish species and horses, adverse effects are not expected. At the high dietary concentrations, there is a potential risk for chronic adverse effects in pigs and fish and for acute adverse effects in cats and farmed mink.

Analytical techniques for deoxynivalenol detection and quantification in wheat destined for the manufacture of commercial products

The concern regarding toxicity from the presence of deoxynivalenol (DON) in wheat that affects both economy and public health leads to the need to find appropriate detection methods for determining the degree of DON contamination in terms of the equipment available and the speed required for obtaining the incidence. The objective of this study was to compare the performance of two alternative analytical techniques for DON quantification for use in the food industry with a reference technique. Samples of wheat and the commercial by-products were analysed by high-performance liquid chromatography (HPLC) with an ultraviolet detector as the reference method and the results compared with those obtained from a rapid lateral-flow immunochromatographic device (Reveal Q+) and of a Fourier-transform-infrared (FTIR) spectroscopy technique. Pearson’s correlation coefficient between the HPLC and Reveal-Q+ data (0.45), although significant (P<0.0003), was lower than that obtained between HPLC and the FTIR method (0.94, P<0.0001). Both methods were considered efficient in quantifying DON levels in wheat-flour samples. This study was aimed at assisting the producers in choosing an appropriate tool for the purpose of analysis and upon consideration of the available equipment.

Group detection of DON and its modified forms by an ELISA kit

Deoxynivalenol (DON) and its modified forms (3-, and 15-acetyl-DON, DON-3-glucoside) are commonly analysed by chromatographic methods. Indeed, coupled with proper extraction and clean-up, LC-MS represents the best approach for multi-mycotoxin measurements. On the other hand, immunochemistry-based methods are possibly able to detect a family of structurally related compounds, although the determination of single contributions is not possible so far. However, ELISA methods often lead to an apparent overestimation of the mycotoxins content because modified forms and matrix components can potentially cross-react with the antibodies (designed for the parent toxin). Several data about the possible cross-reactivity of commercial DON-detecting ELISA kit are reported in the literature so far. Data are commonly obtained in buffer solutions or in matrix-matched solutions, but comparison of a set of naturally incurred samples has never been reported. In the present work the accuracy of a commercial DON-detecting ELISA kit was evaluated on naturally incurred soft wheat (n = 15) and maize (n = 15), taking into account the matrix effect. Recovery was calculated considering the DON concentration found by LC-MS/MS and the total DON concentration, expressed as the sum of DON and its modified forms found by LC-MS/MS. The obtained data clearly show that, when 3-modified forms of DON occur in the sample, the ELISA kit does actually detect them, thus returning an apparent overestimation if only DON content is considered. When the ELISA recovery is calculated on the total DON content, the accuracy of the analysis increases and the variability decreases. According to our data, the ELISA kit seems to be a promising group detection tool for the accurate evaluation of DON and its modified forms, expressed as sum of DON, DON-3Glc and 3Ac-DON, for soft wheat and maize samples.

A Versatile Family 3 Glycoside Hydrolase from Bifidobacterium adolescentis Hydrolyzes β-Glucosides of the Fusarium Mycotoxins Deoxynivalenol, Nivalenol, and HT-2 Toxin in Cereal Matrices

Glycosylation plays a central role in plant defense against xenobiotics, including mycotoxins. Glucoconjugates of Fusarium toxins, such as deoxynivalenol-3-O-β-d-glucoside (DON-3G), often cooccur with their parental toxins in cereal-based food and feed. To date, only limited information exists on the occurrence of glucosylated mycotoxins and their toxicological relevance. Due to a lack of analytical standards and the requirement of high-end analytical instrumentation for their direct determination, hydrolytic cleavage of β-glucosides followed by analysis of the released parental toxins has been proposed as an indirect determination approach. This study compares the abilities of several fungal and recombinant bacterial β-glucosidases to hydrolyze the model analyte DON-3G. Furthermore, substrate specificities of two fungal and two bacterial (Lactobacillus brevis and Bifidobacterium adolescentis) glycoside hydrolase family 3 β-glucosidases were evaluated on a broader range of substrates. The purified recombinant enzyme from B. adolescentis (BaBgl) displayed high flexibility in substrate specificity and exerted the highest hydrolytic activity toward 3-O-β-d-glucosides of the trichothecenes deoxynivalenol (DON), nivalenol, and HT-2 toxin. A Km of 5.4 mM and a Vmax of 16 μmol min(-1) mg(-1) were determined with DON-3G. Due to low product inhibition (DON and glucose) and sufficient activity in several extracts of cereal matrices, this enzyme has the potential to be used for indirect analyses of trichothecene-β-glucosides in cereal samples.

Assessment of the electronic structure and properties of trichothecene toxins using density functional theory

A comprehensive quantum chemical study was carried out on 35 type A and B trichothecenes and biosynthetic precursors, including selected derivatives of deoxynivalenol and T-2 toxin. Quantum chemical properties, Natural Bond Orbital (NBO) analysis, and molecular parameters were calculated on structures geometry optimized at the B3LYP/6-311+G** level. Type B trichothecenes possessed significantly larger electrophilicity index compared to the type A trichothecenes studied. Certain hydroxyl groups of deoxynivalenol, nivalenol, and T-2 toxin exhibited considerable rotation during molecular dynamics simulations (5 ps) at the B3LYP/6-31G** level in implicit aqueous solvent. Quantitative structure activity relationship (QSAR) models were developed to evaluate toxicity and detection using genetic algorithm, principal component, and multilinear analyses. The models suggest electronegativity and several 2-dimensional topological descriptors contain important information related to trichothecene cytotoxicity, phytotoxicity, immunochemical detection, and cross-reactivity.

Proposal of a comprehensive definition of modified and other forms of mycotoxins including "masked" mycotoxins

As the term “masked mycotoxins” encompasses only conjugated mycotoxins generated by plants and no other possible forms of mycotoxins and their modifications, we hereby propose for all these forms a systematic definition consisting of four hierarchic levels. The highest level differentiates the free and unmodified forms of mycotoxins from those being matrix-associated and from those being modified in their chemical structure. The following lower levels further differentiate, in particular, “modified mycotoxins” into “biologically modified” and “chemically modified” with all variations of metabolites of the former and dividing the latter into “thermally formed” and “non-thermally formed” ones. To harmonize future scientific wording and subsequent legislation, we suggest that the term “modified mycotoxins” should be used in the future and the term “masked mycotoxins” to be kept for the fraction of biologically modified mycotoxins that were conjugated by plants.

Analysis of Fusarium toxins in grain via dust: a promising field of application for rapid test systems

On site, mycotoxin measurements shall enable rapid decisions on the acceptance or rejection of lots. Hence, results have to be available fast, easy to get and, first of all, reliable. An innovative approach using dust samples was tested for its fitness for on-site mycotoxin analyses of grain lots and compared to current practice in grain testing. To prove correlation between mycotoxin concentrations in dust and respective concentrations in grain, regression analyses were performed. To obtain data points, dust was sieved from grain and both samples were analysed. As the contamination of the overall sample and its dust particles correlated well (wheat: R2DON=0.85, R2ZEA=0.82; rye: R2DON=0.73), contaminations in the grain were predictable from concentrations determined in respective dust particles. For on-site analysis, common lateral flow devices (LFD) were evaluated for their suitability to detect deoxynivalenol (DON) in grain dusts. On site, grain and dust samples were taken during the unloading of trucks using a customised dust-sampler. In contrast to grain samples, no additional physical sample preparation or homogenisation step was needed for dust. Instead, the sample was directly extracted and analysed for DON using LFD. By means of the regression line DON concentrations in grain were predicted from dust results and compared to concentrations directly measured in grain samples. No false negative results were observed and a contaminated grain lot (<1000 ?g/ kg DON) could be clearly identified. Evidence for reduced measurement uncertainty compared to current practice at lower total measurement costs was given. In this way, the fitness for purpose of the new approach combining rapid analyses with dust sampling for on-site mycotoxin screening was shown. The innovative high-throughput technology has the potential to improve on-site mycotoxin measurements in terms of speed, sensitivity, manageability and reliability and thus is a promising tool for enhanced industrial self-control.

Using commercial immunoassay kits for mycotoxins: ‘joys and sorrows’?

Rapid test methods are widely used for measuring mycotoxins in a variety of matrices. This review presents an overview of the current commercially available immunoassay rapid test formats. Enzyme linked immune-sorbent assay (ELISA), lateral flow tests, flow through immunoassay, fluorescent polarisation immunoassay, and immunoaffinity columns coupled with fluorometric assay are common formats in the current market. The two existing evaluation programs for commercial testing kits by United State Department of Agricultural Grain Inspection, Packers & Stockyards Administration (USDA-GIPSA) and AOAC Research Institute are introduced. The strengths and weaknesses of these test kits are discussed with regard to the application scope, variance, specificity and cross reactivity, accuracy and precision, and measurement range. Generally speaking, the current commercially available testing kits meet research and industrial needs as ‘fit-for-purpose’. Furthermore, quality assurance concerns and future perspectives are elaborated for broader application of commercial test kits in research, industry and regulatory applications. It is expected that new commercial kits based on advanced technologies such as electrochemical affinity biosensors, molecularly imprinted polymers, surface plasmon resonance, fluorescence resonance energy transfer, aptamer-based biosensors and dynamic light scattering might be available to users in the future. Meanwhile, harmonisation of testing kit evaluation, incorporation of more quality assurance into the testing kit utilisation scheme, and a larger variety of kits available at lower cost will expand the usage of testing kits for food safety testing worldwide.

Cross-reactivity of rapid immunochemical methods for mycotoxins detection towards metabolites and masked mycotoxins: the current state of knowledge

The cross-reactivity of antibodies employed within immunochemistry-based analytical methods may lead to overestimation of the results. Under certain conditions, specifically when controlling mycotoxin maximum limits serious problems can be encountered. Not only the structurally related mycotoxins, such as their masked (conjugated) forms, but also the unidentified matrix components are responsible for concentration overestimation of respective target analytes. The cross-reactivity phenomenon may also pose a risk of miss-interpretation of the proficiency tests results, when the assigned value becomes influenced by over-estimated results reported by users of immunochemical tests. In this paper, the current state of the knowledge on trueness problems associated with the rapid screening immunochemical methods have been reviewed. Special attention is focused on discussion of cross-reactivity in the ELISA tests, because this rapid test dominates the routine screening practice. However, the cross-reactions reported in lateral flow test strips, fluorescence polarisation immunoassay, or immunosensors have also been addressed.

Development and evaluation of monoclonal antibodies for the glucoside of T-2 toxin (t2-glc)

The interactions between fungi and plants can yield metabolites that are toxic in animal systems. Certain fungi are known to produce sesquiterpenoid trichothecenes, such as T-2 toxin, that are biotransformed by several mechanisms including glucosylation. The glucosylated forms have been found in grain and are of interest as potential reservoirs of T-2 toxin that are not detected by many analytical methods. Hence the glucosides of trichothecenes are often termed “masked” mycotoxins. The glucoside of T-2 toxin (T2-Glc) was linked to keyhole limpet hemocyanin and used to produce antibodies in mice. Ten monoclonal antibody (Mab)-producing hybridoma cell lines were developed. The Mabs were used in immunoassays to detect T2-Glc and T-2 toxin, with midpoints of inhibition curves (IC₅₀s) in the low ng/mL range. Most of the Mabs demonstrated good cross-reactivity to T-2 toxin, with lower recognition of HT-2 toxin. One of the clones (2-13) was further characterized with in-depth cross-reactivity and solvent tolerance studies. Results suggest Mab 2-13 will be useful for the simultaneous detection of T-2 toxin and T2-Glc.

Masked mycotoxins: a review

The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non-extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders.

Evaluation of rapid test kits for quantification of deoxynivalenol in naturally contaminated oats and wheat

The aim of this study was to evaluate the performance of rapid test kits for analysis of deoxynivalenol (DON), a mycotoxin commonly found in small-grain cereals. Concentrations of DON and its acetylated derivative 3-acetyldeoxynivalenol (3-ADON) were analysed in naturally contaminated wheat (n=56) and oats (n=81) using two enzyme-linked immunosorbent assays, i.e. Ridascreen® DON (‘Standard ELISA’) and Ridascreen® FAST DON (‘Fast ELISA’), and two lateral flow devices, i.e. Rida® QUICK DON (‘Quick LFD’) and Rosa® DON (‘Rosa LFD’). Analysis by the LC-MS/MS reference method showed a median DON + 3-ADON concentration of 1,168 μg/kg (90th percentile 3,264 μg/kg) in wheat and 2,250 μg/kg (90th percentile of 9,008 μg/kg) in oats. Rosa LFD offered the best reliability, achieving detection that was stable across toxin levels in both matrices. In addition, Rosa LFD had the highest accuracy (i.e. proportion of correct results) at a DON level of 1,250 μg/kg in wheat (0.83) and 8,000 μg/kg in oats (0.96). Standard ELISA achieved the highest accuracy at a DON level of 1,750 μg/kg in oats (0.85). Detection by Quick LFD in wheat and Fast ELISA in both wheat and oats differed significantly among toxin levels (P≤0.05), with recoveries outside European Union requirements (70-120%) in some cases. The correlation with results from LC-MS/MS analysis in oats was best for Rosa LFD (R2=0.79). In wheat, however the correlation was best for Fast ELISA (R2=0.81). Rosa LFD was regarded as well-suited for on-site detection. Standard ELISA allowed simultaneous testing of several samples and achieved detection that was stable across toxin levels in both matrices, making it a useful alternative in laboratories. To our knowledge, this is the first report describing the performance of rapid test kits for detection of DON in naturally contaminated oats.

Immunochemical detection of masked mycotoxins: A short review

Mycotoxin derivatives that escape conventional analytical detection of parent (free) forms because their structure has been changed are designated masked mycotoxins. Masking phenomena are due to a defensive response of the host plant or can occur during food processing. Failure to detect masked mycotoxins will lead to a significant underestimation of the mycotoxin content of a particular sample. To date, mainly chromatographic methods were developed for masked mycotoxin determination and quantification. However, for fast screening, it is important to develop on-site methods for detection of masked and parent (free) forms. Although immunochemical methods could provide a simple and economical alternative to chromatography, their use for masked forms is only at the start of development. The key-point for antibody-based methods for masked mycotoxin determination is cross-reactivity of the specific antibody towards masked mycotoxins. If the antibody does not show meaningful affinity for masked forms, they will be latent, and the total content of this mycotoxin will be underestimated. If the antibody shows affinity for masked forms, the sum of free and masked forms will be determined. Currently, neither antibodies nor immuno-based methods were specifically developed for masked mycotoxins, but some enzyme-linked immunosorbent assay test-kits and immunoaffinity columns for mycotoxins were evaluated for their detection. This paper describes possible applications of antibody-based techniques for masked mycotoxin detection on the basis of recent literature.

Multiclass mycotoxin analysis in food, environmental and biological matrices with chromatography/mass spectrometry

Mold metabolites that can elicit deleterious effects on other organisms are classified as mycotoxins. Human exposure to mycotoxins occurs mostly through the intake of contaminated agricultural products or residues due to carry over or metabolite products in foods of animal origin such as milk and eggs, but can also occur by dermal contact and inhalation. Mycotoxins contained in moldy foods, but also in damp interiors, can cause diseases in humans and animals. Nephropathy, various types of cancer, alimentary toxic aleukia, hepatic diseases, various hemorrhagic syndromes, and immune and neurological disorders are the most common diseases that can be related to mycotoxicosis. The absence or presence of mold infestation and its propagation are seldom correlated with mycotoxin presence. Mycotoxins must be determined directly, and suitable analytical methods are necessary. Hundreds of mycotoxins have been recognized, but only for a few of them, and in a restricted number of utilities, a maximum acceptable level has been regulated by law. However, mycotoxins seldom develop alone; more often various types and/or classes form in the same substrate. The co-occurrence might render the individual mycotoxin tolerance dose irrelevant, and therefore the mere presence of multiple mycotoxins should be considered a risk factor. The advantage of chromatography/mass spectrometry (MS) is that many compounds can be determined and confirmed in one analysis. This review illustrates the state-of-the-art of mycotoxin MS-based analytical methods for multiclass, multianalyte determination in all the matrices in which they appear. A chapter is devoted to the history of the long-standing coexistence and interaction among humans, domestic animals and mycotoxicosis, and the history of the discovery of mycotoxins. Quality assurance, although this topic relates to analytical chemistry in general, has been also examined for mycotoxin analysis as a preliminary to the systematic literature excursus. Sample handling is a crucial step to devise a multiclass analytical method; so when possible, it has been treated separately for a better comparison before tackling the instrumental part of the whole analytical method. This structure has resulted sometimes in unavoidable redundancies, because it was also important to underline the interconnection. Most reviews do not deal with all the possible mycotoxin sources, including the environmental ones. The focus of this review is the analytical methods based on MS for multimycotoxin class determination. Because the final purpose to devise multimycotoxin analysis should be the assessment of the danger to health of exposition to multitoxicants of natural origin (and possibly also the interaction with anthropogenic contaminants), therefore also the analytical methods for environmental relevant mycotoxins have been thoroughly reviewed. Finally, because the best way to shed light on actual risk assessment could be the individuation of exposure biomarkers, the review covers also the scarce literature on biological fluids.

A surface plasmon resonance sensor for the detection of deoxynivalenol using a molecularly imprinted polymer

The aim of the present work was to investigate the feasibility of applying the molecular imprinting polymer technique to the detection of the mycotoxin deoxynivalenol (DON) using a surface plasmon resonance (SPR) transducer. A molecularly imprinted polypyrrole (MIPPy) film was prepared via electropolymerization of pyrrole onto a bare Au chip in the presence of a template DON molecule. Atomic force microscope SPR analysis showed that the MIPPy film was deposited homogeneously on the Au surface, with a thickness of 5 nm. The MIPPy–SPR sensor exhibited a linear response for the detection of DON in the range of 0.1–100 ng/mL (R² = 0.988). The selectivity efficiency of the MIPPy film for DON and its acetylated analogs 3-ADON and 15-ADON was 100, 19, and 44%, respectively. The limit of detection for DON with the MIPPy–SPR for a standard solution was estimated at >1 ng/mL. These results suggest that the combination of SPR sensing with a MIPPy film as a synthetic receptor can be used to detect DON.

Cross-reactivity of some commercially available deoxynivalenol (DON) and zearalenone (ZEN) immunoaffinity columns to DON- and ZEN-conjugated forms and metabolites

Seven commercially available deoxynivalenol (DON) and zearalenone (ZEN) immunoaffinity columns (IACs) were tested for cross-reactivity to conjugated forms (3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, DON-3-glucoside, DON-3-glucuronide, ZEN-glucosides, ZEN-glucuronide) and metabolites (de-epoxydeoxynivalenol, α-zearalenol, β-zearalenol) and nivalenol (NIV), using a semi-quantitative multi-mycotoxin ultra-performance liquid chromatography-tandem mass spectrometry method. The DON IACs showed cross-reactivity for nearly all DON derivatives tested. The ZEN IACs showed limited cross-reactivity to some of the ZEN derivatives. The IACs were evaluated for their potential use as sample clean-up for mycotoxins in serum.

Imaging surface plasmon resonance for multiplex microassay sensing of mycotoxins

A prototype imaging surface plasmon resonance-based multiplex microimmunoassay for mycotoxins is described. A microarray of mycotoxin-protein conjugates was fabricated using a continuous flow microspotter device. A competitive inhibition immunoassay format was developed for the simultaneous detection of deoxynivalenol (DON) and zearalenone (ZEN), using a single sensor chip. Initial in-house validation showed limits of detection of 21 and 17 ng/mL for DON and 16 and 10 ng/mL for ZEN in extracts, which corresponds to 84 and 68 μg/kg for DON and 64 and 40 μg/kg for ZEN in maize and wheat samples, respectively. Finally, the results were critically compared with data obtained from liquid chromatography-mass spectrometry confirmatory analysis method and found to be in good agreement. The described multiplex immunoassay for the rapid screening of several mycotoxins meets European Union regulatory limits and represents a robust platform for mycotoxin analysis in food and feed samples.