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Bacillus cereus is a ubiquitous soil bacterium responsible for two types of food-associated gastrointestinal diseases. While the emetic type, a food intoxication, manifests in nausea and vomiting, food infections with enteropathogenic strains cause diarrhea and abdominal pain. Causative toxins are the cyclic dodecadepsipeptide cereulide, and the proteinaceous enterotoxins hemolysin BL (Hbl), nonhemolytic enterotoxin (Nhe) and cytotoxin K (CytK), respectively. This review covers the current knowledge on distribution and genetic organization of the toxin genes, as well as mechanisms of enterotoxin gene regulation and toxin secretion. In this context, the exceptionally high variability of toxin production between single strains is highlighted. In addition, the mode of action of the pore-forming enterotoxins and their effect on target cells is described in detail. The main focus of this review are the two tripartite enterotoxin complexes Hbl and Nhe, but the latest findings on cereulide and CytK are also presented, as well as methods for toxin detection, and the contribution of further putative virulence factors to the diarrheal disease.
Richard Dietrich; Nadja Jessberger; Monika Ehling-Schulz; Erwin Märtlbauer; Per Granum. The Food Poisoning Toxins of Bacillus cereus. Toxins 2021, 13, 98 .
AMA StyleRichard Dietrich, Nadja Jessberger, Monika Ehling-Schulz, Erwin Märtlbauer, Per Granum. The Food Poisoning Toxins of Bacillus cereus. Toxins. 2021; 13 (2):98.
Chicago/Turabian StyleRichard Dietrich; Nadja Jessberger; Monika Ehling-Schulz; Erwin Märtlbauer; Per Granum. 2021. "The Food Poisoning Toxins of Bacillus cereus." Toxins 13, no. 2: 98.
The ubiquitous soil bacterium Bacillus cereus presents major challenges to food safety. It is responsible for two types of food poisoning, the emetic form due to food intoxication and the diarrheal form emerging from food infections with enteropathogenic strains, also known as toxico-infections, which are the subject of this review. The diarrheal type of food poisoning emerges after production of enterotoxins by viable bacteria in the human intestine. Basically, the manifestation of the disease is, however, the result of a multifactorial process, including B. cereus prevalence and survival in different foods, survival of the stomach passage, spore germination, motility, adhesion, and finally enterotoxin production in the intestine. Moreover, all of these processes are influenced by the consumed foodstuffs as well as the intestinal microbiota which have, therefore, to be considered for a reliable prediction of the hazardous potential of contaminated foods. Current knowledge regarding these single aspects is summarized in this review aiming for risk-oriented diagnostics for enteropathogenic B. cereus.
Nadja Jessberger; Richard Dietrich; Per Granum; Erwin Märtlbauer. The Bacillus cereus Food Infection as Multifactorial Process. Toxins 2020, 12, 701 .
AMA StyleNadja Jessberger, Richard Dietrich, Per Granum, Erwin Märtlbauer. The Bacillus cereus Food Infection as Multifactorial Process. Toxins. 2020; 12 (11):701.
Chicago/Turabian StyleNadja Jessberger; Richard Dietrich; Per Granum; Erwin Märtlbauer. 2020. "The Bacillus cereus Food Infection as Multifactorial Process." Toxins 12, no. 11: 701.
Bacillus cereus Hemolysin BL is a tripartite toxin responsible for a diarrheal type of food poisoning. Open questions remain regarding its mode of action, including the extent to which complex formation prior to cell binding contributes to pore-forming activity, how these complexes are composed, and the properties of the pores formed in the target cell membrane. Distinct complexes of up to 600 kDa were found on native gels, whose structure and size were primarily defined by Hbl B. Hbl L1 and L2 were also identified in these complexes using Western blotting and an LC-MS approach. LC-MS also revealed that many other proteins secreted by B. cereus exist in complexes. Further, a decrease of toxic activity at temperatures ≥60 °C was shown, which was unexpectedly restored at higher temperatures. This could be attributed to a release of Hbl B monomers from tight complexation, resulting in enhanced cell binding. In contrast, Hbl L1 was rather susceptible to heat, while heat treatment of Hbl L2 seemed not to be crucial. Furthermore, Hbl-induced pores had a rather small single-channel conductance of around 200 pS and a probable channel diameter of at least 1 nm on planar lipid bilayers. These were highly instable and had a limited lifetime, and were also slightly cation-selective. Altogether, this study provides astonishing new insights into the complex mechanism of Hbl pore formation, as well as the properties of the pores.
Nadja Jessberger; Richard Dietrich; Kristina Schauer; Stefanie Schwemmer; Erwin Märtlbauer; Roland Benz. Characteristics of the Protein Complexes and Pores Formed by Bacillus cereus Hemolysin BL. Toxins 2020, 12, 672 .
AMA StyleNadja Jessberger, Richard Dietrich, Kristina Schauer, Stefanie Schwemmer, Erwin Märtlbauer, Roland Benz. Characteristics of the Protein Complexes and Pores Formed by Bacillus cereus Hemolysin BL. Toxins. 2020; 12 (11):672.
Chicago/Turabian StyleNadja Jessberger; Richard Dietrich; Kristina Schauer; Stefanie Schwemmer; Erwin Märtlbauer; Roland Benz. 2020. "Characteristics of the Protein Complexes and Pores Formed by Bacillus cereus Hemolysin BL." Toxins 12, no. 11: 672.
Modern threats of bioterrorism force the need for multiple detection of biothreat agents to determine the presence or absence of such agents in suspicious samples. Here, we present a rapid electrochemical fiveplex biochip screening assay for detection of the bioterrorism relevant low molecular weight toxins saxitoxin, microcystin-LR, T-2 toxin, roridin A and aflatoxin B1 relying on anti-idiotypic antibodies as epitope-mimicking reagents. The proposed method avoids the use of potentially harmful toxin-protein conjugates usually mandatory for competitive immunoassays. The biochip is processed and analyzed on the automated and portable detection platform pBDi within 13.4 min. The fiveplex biochip assay revealed toxin group specificity to multiple congeners. Limits of detection were 1.2 ng/mL, 1.5 ng/mL, 0.4 ng/mL, 0.5 ng/mL and 0.6 ng/mL for saxitoxin, microcystin-LR, T-2 toxin, roridin A or aflatoxin B1, respectively. The robustness of the fiveplex biochip for real samples was demonstrated by detecting saxitoxin, microcystin-LR, HT-2 toxin, roridin A and aflatoxin B1 in contaminated human blood serum without elaborate sample preparation. Recovery rates were between 52–115% covering a wide concentration range. Thus, the developed robust fiveplex biochip assay can be used on-site to quickly detect one or multiple low molecular weight toxins in a single run.
Katharina Schulz; Christopher Pöhlmann; Richard Dietrich; Erwin Märtlbauer; Thomas Elßner. An Electrochemical Fiveplex Biochip Assay Based on Anti-Idiotypic Antibodies for Fast On-Site Detection of Bioterrorism Relevant Low Molecular Weight Toxins. Toxins 2019, 11, 696 .
AMA StyleKatharina Schulz, Christopher Pöhlmann, Richard Dietrich, Erwin Märtlbauer, Thomas Elßner. An Electrochemical Fiveplex Biochip Assay Based on Anti-Idiotypic Antibodies for Fast On-Site Detection of Bioterrorism Relevant Low Molecular Weight Toxins. Toxins. 2019; 11 (12):696.
Chicago/Turabian StyleKatharina Schulz; Christopher Pöhlmann; Richard Dietrich; Erwin Märtlbauer; Thomas Elßner. 2019. "An Electrochemical Fiveplex Biochip Assay Based on Anti-Idiotypic Antibodies for Fast On-Site Detection of Bioterrorism Relevant Low Molecular Weight Toxins." Toxins 11, no. 12: 696.
A major virulence factor involved in Bacillus cereus food poisoning is the three-component enterotoxin hemolysin BL. It consists of the binding component B and the two lytic components L1 and L2. Studying its mode of action has been challenging, as natural culture supernatants additionally contain Nhe, the second three-component enterotoxin, and purification of recombinant (r) Hbl components has been difficult. In this study, we report on pore-forming, cytotoxic, cell binding and hemolytic activity of recently generated rHbl components expressed in E. coli. It is known that all three Hbl components are necessary for cytotoxicity and pore formation. Here we show that an excess of rHbl B enhances, while an excess of rHbl L1 hinders, the velocity of pore formation. Most rapid pore formation was observed with ratios L2:L1:B = 1:1:10 and 10:1:10. It was further verified that Hbl activity is due to sequential binding of the components B - L1 - L2. Accordingly, all bioassays proved that binding of Hbl B to the cell surface is the crucial step for pore formation and cytotoxic activity. Binding of Hbl B took place within minutes, while apposition of the following L1 and L2 occurred immediately. Further on, applying toxin components simultaneously, it seemed that Hbl L1 enhanced binding of B to the target cell surface. Overall, these data contribute significantly to the elucidation of the mode of action of Hbl, and suggest that its mechanism of pore formation differs substantially from that of Nhe, although both enterotoxin complexes are sequentially highly related.
Nadja Jessberger; Richard Dietrich; Stefanie Schwemmer; Franziska Tausch; Valerie Schwenk; Andrea Didier; Erwin Märtlbauer. Binding to The Target Cell Surface Is The Crucial Step in Pore Formation of Hemolysin BL from Bacillus cereus. Toxins 2019, 11, 281 .
AMA StyleNadja Jessberger, Richard Dietrich, Stefanie Schwemmer, Franziska Tausch, Valerie Schwenk, Andrea Didier, Erwin Märtlbauer. Binding to The Target Cell Surface Is The Crucial Step in Pore Formation of Hemolysin BL from Bacillus cereus. Toxins. 2019; 11 (5):281.
Chicago/Turabian StyleNadja Jessberger; Richard Dietrich; Stefanie Schwemmer; Franziska Tausch; Valerie Schwenk; Andrea Didier; Erwin Märtlbauer. 2019. "Binding to The Target Cell Surface Is The Crucial Step in Pore Formation of Hemolysin BL from Bacillus cereus." Toxins 11, no. 5: 281.
TheBacillus(B.)cereusgroup is genetically highly homogenous and consists of nine recognized species which are present worldwide.B. cereussensu stricto play an important role in food-borne diseases by producing different toxins. Yet, only a small percentage ofB. cereusstrains are able to produce the heat stable depsipeptide cereulide, the causative agent of emetic food poisonings. To minimize the entry of emeticB. cereusinto the food chain, food business operators are dependent on efficient and reliable methods enabling the differentiation between emetic and non-emetic strains. Currently, only time-consuming cell bioassays, molecular methods and tandem mass spectrometry are available for this purpose. Thus, the aim of the present study was to establish a fast and reliable method for the differentiation between emetic and non-emetic strains by MALDI-TOF MS. Selected isolates/strains of theB. cereusgroup (total n=110, i.e. emetic n=45, non-emetic n=65) were cultured on sheep blood agar for 48h.Subsequently, the cultures were directly analyzed by MALDI-TOF MS without prior extraction steps (direct smear method). The samples were measured in linear positive ionization mode in the mass range ofm/z800 - 1,800 Da. Using ClinProTools 3.0 statistical software and flex analyst, a differentiation between emetic and non-emetic isolates was possible with a rate of correct identification of 99.1 % by means of the evaluation of two specific biomarkers (m/z1171 and 1187 Da).ImportanceBacillus(B.)cereusplays an important role in food-borne diseases due to the production of different toxins, e.g. the heat stable depsipeptide cereulide. Only a small number ofB. cereusstrains are able to produce this toxin, the causative agent of emetic food poisonings. To minimize the entry of emeticB. cereusinto the food chain, food business operators require efficient and reliable methods enabling the differentiation between emetic and non-emetic strains. The aim of the present study was to develop a fast and reliable method for the differentiation between emetic and non-emetic strains by MALDI-TOF MS. A differentiation between emetic and non-emetic isolates was possible with a rate of correct identification of 99.1 % by means of the evaluation of two specific biomarkers (m/z1171 and 1187 Da).
Sebastian Ulrich; Christoph Gottschalk; Richard Dietrich; Erwin Märtlbauer; Manfred Gareis. Identification of cereulide producingBacillus cereusby MALDI-TOF MS. 2018, 324756 .
AMA StyleSebastian Ulrich, Christoph Gottschalk, Richard Dietrich, Erwin Märtlbauer, Manfred Gareis. Identification of cereulide producingBacillus cereusby MALDI-TOF MS. . 2018; ():324756.
Chicago/Turabian StyleSebastian Ulrich; Christoph Gottschalk; Richard Dietrich; Erwin Märtlbauer; Manfred Gareis. 2018. "Identification of cereulide producingBacillus cereusby MALDI-TOF MS." , no. : 324756.
Haemolysin BL is an important virulence factor regarding the diarrheal type of food poisoning caused by Bacillus cereus. However, the pathogenic importance of this three-component enterotoxin is difficult to access, as nearly all natural B. cereus culture supernatants additionally contain the highly cytotoxic Nhe, the second three-component toxin involved in the aetiology of B. cereus-induced food-borne diseases. To better address the toxic properties of the Hbl complex, a system for overexpression and purification of functional, cytotoxic, recombinant (r)Hbl components L2, L1 and B from E. coli was established and an nheABC deletion mutant was constructed from B. cereus reference strain F837/76. Furthermore, 35 hybridoma cell lines producing monoclonal antibodies (mAbs) against Hbl L2, L1 and B were generated. While mAbs 1H9 and 1D8 neutralized Hbl toxicity and thus, represent important tools for future investigations of the mode-of-action of Hbl on the target cell surface, mAb 1D7, in contrast, even enhanced Hbl toxicity by supporting the binding of Hbl B to the cell surface. By using the specific mAbs in Dot blots, indirect and hybrid sandwich enzyme immuno assays (EIAs), complex formation between Hbl L1 and B, as well as L1 and L2 in solution could be shown for the first time. Surface plasmon resonance experiments with the rHbl components confirmed these results with KD values of 4.7 × 10−7 M and 1.5 × 10−7 M, respectively. These findings together with the newly created tools lay the foundation for the detailed elucidation of the molecular mode-of-action of the highly complex three-component Hbl toxin.
Franziska Tausch; Richard Dietrich; Kristina Schauer; Robert Janowski; Dierk Niessing; Erwin Märtlbauer; Nadja Jessberger. Evidence for Complex Formation of the Bacillus cereus Haemolysin BL Components in Solution. Toxins 2017, 9, 288 .
AMA StyleFranziska Tausch, Richard Dietrich, Kristina Schauer, Robert Janowski, Dierk Niessing, Erwin Märtlbauer, Nadja Jessberger. Evidence for Complex Formation of the Bacillus cereus Haemolysin BL Components in Solution. Toxins. 2017; 9 (9):288.
Chicago/Turabian StyleFranziska Tausch; Richard Dietrich; Kristina Schauer; Robert Janowski; Dierk Niessing; Erwin Märtlbauer; Nadja Jessberger. 2017. "Evidence for Complex Formation of the Bacillus cereus Haemolysin BL Components in Solution." Toxins 9, no. 9: 288.
Marine toxins, such as saxitoxin and domoic acid are associated with algae blooms and can bioaccumulate in shell fish which present both health and economic concerns. The ability to detect the presence of toxin is paramount for the administration of the correct supportive care in case of intoxication; environmental monitoring to detect the presence of toxin is also important for prevention of intoxication. Immunoassays are one tool that has successfully been applied to the detection of marine toxins. Herein, we had the variable regions of two saxitoxin binding monoclonal antibodies sequenced and used the information to produce recombinant constructs that consist of linked heavy and light variable domains that make up the binding domains of the antibodies (scFv). Recombinantly produced binding elements such as scFv provide an alternative to traditional antibodies and serve to “preserve” monoclonal antibodies as they can be easily recreated from their sequence data. In this paper, we combined the anti-saxitoxin scFv developed here with a previously developed anti-domoic acid scFv and demonstrated their utility in a microsphere-based competitive immunoassay format. In addition to detection in buffer, we demonstrated equivalent sensitivity in oyster and scallop matrices. The potential for multiplexed detection using scFvs in this immunoassay format is demonstrated.
Lisa C. Shriver-Lake; Jinny L. Liu; P. Audrey Brozozog Lee; Ellen R. Goldman; Richard Dietrich; Erwin Märtlbauer; George P. Anderson. Integrating scFv into xMAP Assays for the Detection of Marine Toxins. Toxins 2016, 8, 346 .
AMA StyleLisa C. Shriver-Lake, Jinny L. Liu, P. Audrey Brozozog Lee, Ellen R. Goldman, Richard Dietrich, Erwin Märtlbauer, George P. Anderson. Integrating scFv into xMAP Assays for the Detection of Marine Toxins. Toxins. 2016; 8 (11):346.
Chicago/Turabian StyleLisa C. Shriver-Lake; Jinny L. Liu; P. Audrey Brozozog Lee; Ellen R. Goldman; Richard Dietrich; Erwin Märtlbauer; George P. Anderson. 2016. "Integrating scFv into xMAP Assays for the Detection of Marine Toxins." Toxins 8, no. 11: 346.
A polyclonal rabbit antibody-based sandwich ELISA for the rapid and specific detection of spores of Alicyclobacillus acidoterrestris was established. The reactivity of the antisera with spores was confirmed by immunofluorescence. For a thorough evaluation of the ELISA, 61 strains and isolates of Alicyclobacillus spp. were characterized regarding their guaiacol production ability and genetic variability. The ELISA was highly sensitive, the detection limits were isolate-dependent and ranged from 2.1 × 103 – 3.8 × 104 spores/mL, except for one isolate, for which a slightly lower sensitivity (5 × 105 spores/mL) was observed. Inclusivity tests revealed that the ELISA reacts with all tested A. acidoterrestris, while no cross-reactions with spores of 30 strains of Bacillus spp. and Clostridium spp. were observed. Further on, the assay applicability was tested with orange, apple (clear and unfiltered), tomato, pink grapefruit, pear, and white grape juices. Juices were inoculated with 1 or 10 spores/mL of A. acidoterrestris. After enrichment for 48 h, the established ELISA enabled the reliable and reproducible detection of contaminated samples. The enriched samples could be applied directly to the assay, underlining the robustness of the developed ELISA method.
Sophia Mast; Richard Dietrich; Andrea Didier; Erwin Märtlbauer. Development of a Polyclonal Antibody-Based Sandwich Enzyme-Linked Immunosorbent Assay for the Detection of Spores of Alicyclobacillus acidoterrestris in Various Fruit Juices. Journal of Agricultural and Food Chemistry 2016, 64, 497 -504.
AMA StyleSophia Mast, Richard Dietrich, Andrea Didier, Erwin Märtlbauer. Development of a Polyclonal Antibody-Based Sandwich Enzyme-Linked Immunosorbent Assay for the Detection of Spores of Alicyclobacillus acidoterrestris in Various Fruit Juices. Journal of Agricultural and Food Chemistry. 2016; 64 (2):497-504.
Chicago/Turabian StyleSophia Mast; Richard Dietrich; Andrea Didier; Erwin Märtlbauer. 2016. "Development of a Polyclonal Antibody-Based Sandwich Enzyme-Linked Immunosorbent Assay for the Detection of Spores of Alicyclobacillus acidoterrestris in Various Fruit Juices." Journal of Agricultural and Food Chemistry 64, no. 2: 497-504.
The ability of Bacillus cereus to cause foodborne toxicoinfections leads to increasing concerns regarding consumer protection. For the diarrhea-associated enterotoxins, the assessment of the non-hemolytic enterotoxin B (NheB) titer determined by a sandwich enzyme immunoassay (EIA) correlates best with in vitro cytotoxicity. In general, the regulation of enterotoxin expression of B. cereus is a coordinately-regulated process influenced by environmental, and probably also by host factors. As long as these factors are not completely understood, the currently-applied diagnostic procedures are based on indirect approaches to assess the potential virulence of an isolate. To date, sandwich EIA results serve as a surrogate marker to categorize isolates as either potentially low or highly toxic. Here, we report on a single amino acid exchange in the NheB sequence leading to an underestimation of the cytotoxic potential in a limited number of strains. During the screening of a large panel of B. cereus isolates, six showed uncommon features with low sandwich EIA titers despite high cytotoxicity. Sequence analysis revealed the point-mutation Glu151Asp in the potential binding region of the capture antibody. Application of this antibody also results in low titers in an indirect EIA format and shows variable detection intensities in Western-immunoblots. A commercially-available assay based on a lateral flow device detects all strains correctly as NheB producers in a qualitative manner. In conclusion, isolates showing low NheB titers should additionally be assayed in an indirect EIA or for their in vitro cytotoxicity to ensure a correct classification as either low or highly toxic.
Andrea Didier; Nadja Jeßberger; Victoria Krey; Richard Dietrich; Siegfried Scherer; Erwin Märtlbauer. The Mutation Glu151Asp in the B-Component of the Bacillus cereus Non-Hemolytic Enterotoxin (Nhe) Leads to a Diverging Reactivity in Antibody-Based Detection Systems. Toxins 2015, 7, 4655 -4667.
AMA StyleAndrea Didier, Nadja Jeßberger, Victoria Krey, Richard Dietrich, Siegfried Scherer, Erwin Märtlbauer. The Mutation Glu151Asp in the B-Component of the Bacillus cereus Non-Hemolytic Enterotoxin (Nhe) Leads to a Diverging Reactivity in Antibody-Based Detection Systems. Toxins. 2015; 7 (11):4655-4667.
Chicago/Turabian StyleAndrea Didier; Nadja Jeßberger; Victoria Krey; Richard Dietrich; Siegfried Scherer; Erwin Märtlbauer. 2015. "The Mutation Glu151Asp in the B-Component of the Bacillus cereus Non-Hemolytic Enterotoxin (Nhe) Leads to a Diverging Reactivity in Antibody-Based Detection Systems." Toxins 7, no. 11: 4655-4667.
Mycophenolic acid (MPA) is frequently found, often in high concentrations, in a broad range of food and feed matrices. Apart from the well-known contamination of blue-veined cheeses caused by the use of toxinogenic Penicillium roqueforti strains for manufacturing, a broad range of other Penicillium spp. is able to produce this immunosuppressive toxin. Therefore, MPA has been proposed to be a suitable marker for Penicillium-infected food commodities. In the present work, a high-affinity monoclonal antibody (mAb) for the specific detection of MPA was developed by immunizing mice with a MPA-protein conjugate coupled by an activated ester method. Under the conditions of a direct competitive enzyme immunoassay (EIA), 50% inhibition and detection limits of MPA standard curves were 1.2 and 0.3 ng/ml, respectively. Furthermore, the mAb could be successfully employed for the production of an immunoaffinity (IA) column enabling the efficient enrichment of MPA from processed foodstuffs. By combining the IA clean-up with a polyclonal antibody-based EIA, an ultrasensitive analysis method could be established which allowed the reliable and reproducible detection of MPA in artificially contaminated tomato ketchup as a model matrix at concentrations as low as 0.1 ng/g.
Richard Dietrich; Erwin Märtlbauer. Development and application of monoclonal antibodies against the mycotoxin mycophenolic acid. Mycotoxin Research 2015, 31, 185 -190.
AMA StyleRichard Dietrich, Erwin Märtlbauer. Development and application of monoclonal antibodies against the mycotoxin mycophenolic acid. Mycotoxin Research. 2015; 31 (4):185-190.
Chicago/Turabian StyleRichard Dietrich; Erwin Märtlbauer. 2015. "Development and application of monoclonal antibodies against the mycotoxin mycophenolic acid." Mycotoxin Research 31, no. 4: 185-190.
Considering the urgent demand for rapid and accurate determination of bacterial toxins and the recent promising developments in nanotechnology and microfluidics, this review summarizes new achievements of the past five years. Firstly, bacterial toxins will be categorized according to their antibody binding properties into low and high molecular weight compounds. Secondly, the types of antibodies and new techniques for producing antibodies are discussed, including poly- and mono-clonal antibodies, single-chain variable fragments (scFv), as well as heavy-chain and recombinant antibodies. Thirdly, the use of different nanomaterials, such as gold nanoparticles (AuNPs), magnetic nanoparticles (MNPs), quantum dots (QDs) and carbon nanomaterials (graphene and carbon nanotube), for labeling antibodies and toxins or for readout techniques will be summarized. Fourthly, microscale analysis or minimized devices, for example microfluidics or lab-on-a-chip (LOC), which have attracted increasing attention in combination with immunoassays for the robust detection or point-of-care testing (POCT), will be reviewed. Finally, some new materials and analytical strategies, which might be promising for analyzing toxins in the near future, will be shortly introduced.
Kui Zhu; Richard Dietrich; Andrea Didier; Dominik Doyscher; Erwin Märtlbauer. Recent Developments in Antibody-Based Assays for the Detection of Bacterial Toxins. Toxins 2014, 6, 1325 -1348.
AMA StyleKui Zhu, Richard Dietrich, Andrea Didier, Dominik Doyscher, Erwin Märtlbauer. Recent Developments in Antibody-Based Assays for the Detection of Bacterial Toxins. Toxins. 2014; 6 (4):1325-1348.
Chicago/Turabian StyleKui Zhu; Richard Dietrich; Andrea Didier; Dominik Doyscher; Erwin Märtlbauer. 2014. "Recent Developments in Antibody-Based Assays for the Detection of Bacterial Toxins." Toxins 6, no. 4: 1325-1348.
A simple, efficient and rapid method for the synthesis of cephalosporin-protein conjugates was established. These conjugates were used as immunogens to produce monoclonal antibodies (mAbs) and as solid phase antigens in competitive indirect enzyme immunoassays (EIAs). With this generic approach, a novel set of monoclonal antibodies for cephalosporins was prepared, including ceftiofur and cephalexin as well as, reported here for the first time, cefoperazone, cefquinome and cephapirin. All 5 EIAs were highly sensitive, with standard curve IC(50) values of 0.7 (ceftiofur), 1.1 (cefquinome), 5.2 (cephalexin), 13.8 (cefoperazone) and 40.3 ng mL(-1) (cephapirin). Detection limits (IC(30)) ranged from 0.3 (ceftiofur mAb 1D7) to 17.2 ng mL(-1) (cephapirin mAb 2F10). Specificity studies revealed that cephalosporin-antibody binding was strongly determined by the side chain residues of the cephem nucleus. Therefore all mAbs, to some extent, recognized other beta-lactam antibiotics with similar side chain residues. Within the group of cephalosporins approved for use in veterinary medicine, however, the final EIAs were highly selective for their respective antigen, except for the ceftiofur EIA which showed cross-reactions with cefquinome. The applicability of the five assays for drug residue testing in milk was demonstrated. In each EIA the target drug could be determined in milk with high accuracy and precision at concentrations far below the European Union maximum residue limits.
Anna Bremus; Richard Dietrich; Lars Dettmar; Ewald Usleber; Erwin Märtlbauer. A broadly applicable approach to prepare monoclonal anti-cephalosporin antibodies for immunochemical residue determination in milk. Analytical and Bioanalytical Chemistry 2012, 403, 503 -515.
AMA StyleAnna Bremus, Richard Dietrich, Lars Dettmar, Ewald Usleber, Erwin Märtlbauer. A broadly applicable approach to prepare monoclonal anti-cephalosporin antibodies for immunochemical residue determination in milk. Analytical and Bioanalytical Chemistry. 2012; 403 (2):503-515.
Chicago/Turabian StyleAnna Bremus; Richard Dietrich; Lars Dettmar; Ewald Usleber; Erwin Märtlbauer. 2012. "A broadly applicable approach to prepare monoclonal anti-cephalosporin antibodies for immunochemical residue determination in milk." Analytical and Bioanalytical Chemistry 403, no. 2: 503-515.
We developed a potentiometric aflatoxin M1-immunosensor which utilizes 3-(4-hydroxyphenyl)propionic acid (p-HPPA) as electron donating compound for horseradish peroxidase (HRP; EC 1.11.1.7). The assay system consists of a polypyrrole-surface-working electrode coated with a polyclonal anti-M1 antibody (pAb–AFM1), a Ag/AgCl reference electrode and a HRP–aflatoxin B1 conjugate (HRP–AFB1 conjugate). To optimize the potentiometric measuring system p-HPPA as well as related compounds serving as electron donating compounds were compared. Also the influence of different buffer systems, varying pH and substrate concentrations on signal intensity was investigated. Our results suggest that reaction conditions that favor the formation of Pummerer's type ketones lead to an increase in signal intensity rather than formation of fluorescent dye. Comparison with commercial ready-to-use HRP electron donating compounds such as 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), o-phenylenediamine (OPD) or 3,3′,5,5′-tetramethylbenzidine (TMB) showed that only 34%, 77% and 49% of the signal intensity of p-HPPA were reached, respectively. The optimized assay had a detection limit of 40 pg mL−1 and allowed detection of 500 pg mL−1 (FDA action limit) aflatoxin M1 (AFM1) in pasteurized milk and UHT-milk containing 0.3–3.8% fat within 10 min without any sample treatment. The working range was between 250 and 2000 pg mL−1 AFM1.
Steffen Rameil; Peter Schubert; Peter Grundmann; Richard Dietrich; Erwin Märtlbauer. Use of 3-(4-hydroxyphenyl)propionic acid as electron donating compound in a potentiometric aflatoxin M1-immunosensor. Analytica Chimica Acta 2010, 661, 122 -127.
AMA StyleSteffen Rameil, Peter Schubert, Peter Grundmann, Richard Dietrich, Erwin Märtlbauer. Use of 3-(4-hydroxyphenyl)propionic acid as electron donating compound in a potentiometric aflatoxin M1-immunosensor. Analytica Chimica Acta. 2010; 661 (1):122-127.
Chicago/Turabian StyleSteffen Rameil; Peter Schubert; Peter Grundmann; Richard Dietrich; Erwin Märtlbauer. 2010. "Use of 3-(4-hydroxyphenyl)propionic acid as electron donating compound in a potentiometric aflatoxin M1-immunosensor." Analytica Chimica Acta 661, no. 1: 122-127.
The nonhemolytic enterotoxin (Nhe) is one of the two three-component enterotoxins which are responsible for diarrheal food poisoning syndrome caused by Bacillus cereus . To facilitate the detection of this toxin, consisting of the subunits NheA, NheB, and NheC, a complete set of high-affinity antibodies against each of the three components was established and characterized. A rabbit antiserum specific for the C-terminal part (15 amino acids) of NheC was produced using a respective synthetic peptide coupled to a protein carrier for immunization. Using purified B. cereus exoprotein preparations as immunogens, one monoclonal antibody against NheA and several antibodies against NheB were obtained. No cross-reactivity with other proteins produced by different strains of B. cereus was observed. Antibodies against the NheB component were able to neutralize the cytotoxic activity (up to 98%) of Nhe. Based on indirect enzyme immunoassays, the antibodies developed in this study were successfully used in the characterization of the enterotoxic activity of several B. cereus strains. For the first time, it could be shown that strains carrying the nhe genes usually express the complete set of the three components, including NheC. However, the amount of toxin produced varies considerably between the different strains.
Richard Dietrich; Maximilian Moravek; Christine Bürk; Per Einar Granum; Erwin Märtlbauer. Production and Characterization of Antibodies against Each of the Three Subunits of the Bacillus cereus Nonhemolytic Enterotoxin Complex. Applied and Environmental Microbiology 2005, 71, 8214 -8220.
AMA StyleRichard Dietrich, Maximilian Moravek, Christine Bürk, Per Einar Granum, Erwin Märtlbauer. Production and Characterization of Antibodies against Each of the Three Subunits of the Bacillus cereus Nonhemolytic Enterotoxin Complex. Applied and Environmental Microbiology. 2005; 71 (12):8214-8220.
Chicago/Turabian StyleRichard Dietrich; Maximilian Moravek; Christine Bürk; Per Einar Granum; Erwin Märtlbauer. 2005. "Production and Characterization of Antibodies against Each of the Three Subunits of the Bacillus cereus Nonhemolytic Enterotoxin Complex." Applied and Environmental Microbiology 71, no. 12: 8214-8220.
Hybridomas producing monoclonal antibodies against aflatoxin M1, ochratoxin A, zearalenone, T‐2 toxin, diacetoxyscirpenol, 3‐acetyl‐deoxynivalenol, fusarenon X, and roridin A were developed after immunization of BALB/c mice and fusion of the splenocytes with myeloma cells. The antibodies were characterized in terms of immunoglobulin subclass, sensitivity, and specificity. The use of these antibodies in competitive enzyme immunoassays, either as microtiter plate assays or membrane‐based quick tests, as well as for the production of immunoaffinity columns is described. The advantages and disadvantages of monoclonal antibodies compared to polyclonal antisera for the improvement of mycotoxin analysis are discussed.
Richard Dietrich; Elisabeth Schneider; Ewald Usleber; Erwin Märtlbauer. Use of monoclonal antibodies for the analysis of mycotoxins. Natural Toxins 1995, 3, 288 -293.
AMA StyleRichard Dietrich, Elisabeth Schneider, Ewald Usleber, Erwin Märtlbauer. Use of monoclonal antibodies for the analysis of mycotoxins. Natural Toxins. 1995; 3 (4):288-293.
Chicago/Turabian StyleRichard Dietrich; Elisabeth Schneider; Ewald Usleber; Erwin Märtlbauer. 1995. "Use of monoclonal antibodies for the analysis of mycotoxins." Natural Toxins 3, no. 4: 288-293.