Identification of Cross-Species Marker Peptides for the Detection of Mammalian and Poultry Meat in Vegan and Vegetarian Foods

Authentication of vegan and vegetarian foods is important since these increasingly popular food items could be adulterated with cheap meat to increase profit margins. In this study, nine marker peptides for the detection of meat (several species) were identified applying liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). These marker peptides enable the crucial differentiation of beef versus milk and chicken meat versus egg, demonstrated by the investigation of 19 commercial vegetarian meat substitutes containing milk and egg. Extensive experimental testing proved the presence of the cross-species meat marker peptides in 19 food-relevant types of mammals and poultry as well as their absence in more than 136 plant-based ingredients for the production of vegan and vegetarian foods. An authentic vegan sausage matrix based on an actual retail product was produced and spiked with 5.0%, w/w meat to confirm the high signal intensities and the heat stability of the marker peptides.

Characterization and Quantification of Mal d 1 Isoallergen Profiles and Contents in Traditional and Commercial Apple Varieties by Mass Spectrometry

The apple allergy in Northern Europe is a cross-reaction to the birch pollen allergy. No correlation between the allergenicity of an apple variety and the content of the major apple allergen Mal d 1, a homologue to the Bet v 1 allergen in birch, could be found using ELISA, so far. Therefore, an impact of polyphenols and/or differences in the isoallergen profile are discussed. To allow a more detailed analysis of the Mal d 1 content and the isoallergen profile, a mass spectrometric method was applied to investigate differences in the flesh and peel of 10 traditional varieties and 10 commercial breeds. The data revealed often, but not always, lower Mal d 1 contents in traditional varieties grown in orchard meadows, which was more obvious in the flesh. Differences among the peels were less pronounced. A closer look at the individual isoallergens 1.01, 1.02, 1.03, and 1.06 reveals an increased impact of the minor isoallergens 1.03 and 1.06 on the allergenic potential, since commercial breeds like Braeburn, Santana, and Holstein Cox, which are considered to have reduced allergenic potentials, were characterized by low levels of these isoallergens.

Genome-wide deposition of 6-methyladenine in human DNA reduces the viability of HEK293 cells and directly influences gene expression

While cytosine-C5 methylation of DNA is an essential regulatory system in higher eukaryotes, the presence and relevance of 6-methyladenine (m6dA) in human cells is controversial. To study the role of m6dA in human DNA, we introduced it in human cells at a genome-wide scale at GANTC and GATC sites by expression of bacterial DNA methyltransferases and observed concomitant reductions in cell viability, in particular after global GANTC methylation. We identified several genes that are directly regulated by m6dA in a GANTC context. Upregulated genes showed m6dA-dependent reduction of H3K27me3 suggesting that the PRC2 complex is inhibited by m6dA. Genes downregulated by m6dA showed enrichment of JUN family transcription factor binding sites. JUN binds m6dA containing DNA with reduced affinity suggesting that m6dA can reduce the recruitment of JUN transcription factors to target genes. Our study documents that global introduction of m6dA in human DNA has physiological effects. Furthermore, we identified a set of target genes which are directly regulated by m6dA in human cells, and we defined two molecular pathways with opposing effects by which artificially introduced m6dA in GANTC motifs can directly control gene expression and phenotypes of human cells.

Relative quantification of pork and beef in meat products using global and species-specific peptide markers for the authentication of meat composition

We used global and species-specific peptide markers for a relative quantitative determination of pork and beef in raw and processed meat products made of the two meat species. Four groups of products were prepared (i.e., minced raw meats, sausages, raw and fried burgers) in order to represent products with different extents of food processing. In each group, the products varied in the pork/beef proportions. All products were analysed by multiple reaction monitoring mass spectrometry (MRM-MS) for the presence/concentration of pork- and beef-specific peptide markers, as well as global markers - peptides widely distributed in muscle tissue. The combined MRM-MS analysis of pork-specific peptide HPGDFGADAQGAMSK, beef-specific peptide VLGFHG and global marker LFDLR offered the most reliable validation of declared pork/beef compositions across the whole range of meat products. Our work suggests that a simultaneous analysis of global and species-specific peptide markers can be used for composition authentication in commercial pork/beef products.

New Mass Spectrometric Approach to Quantify the Major Isoallergens of the Apple Allergen Mal d 1

Patients who suffer from birch pollinosis often develop adverse reactions to the consumption of fresh apples due to the structural similarity of the allergens Bet v 1 and Mal d 1 from birch and apples, respectively. A different allergenic potential for Mal d 1 isoallergens is postulated, but approaches to quantify the Mal d 1 isoallergen-specific are missing. Therefore, a bottom-up proteomics approach was developed to quantify Mal d 1 by stable isotope dilution and microHPLC-QTOF analyses. Marker peptides for individual isoallergens (Mal d 1.01-Mal d 1.03 and Mal d 1.06), combinations thereof (Mal d 1.01 + 1.02, Mal d 1.02 + 1.06, and Mal d 1.04 + 1.05), and two global marker peptides, comprising Mal d 1.01 + 1.02 + 1.04 + 1.05 and Mal d 1.03 + 1.06 + 1.07 + 1.08 + 1.09, were identified. By the use of an extraction standard (r-Mal d 1_mut), an optimized protocol for extraction and tryptic digestion of apple proteins was developed, and the variety-specific extraction efficiency was monitored for the flesh and peel of apples. The Mal d 1 contents in flesh and peel of five commercial apple breeds and four apple varieties from orchard meadows were quantified isoallergen-specific.

Diet composition and social environment determine food consumption, phenotype and fecundity in an omnivorous insect

Nutrition is the single most important factor for individual's growth and reproduction. Consequently, the inability to reach the nutritional optimum imposes severe consequences for animal fitness. Yet, under natural conditions, organisms may face a mixture of stressors that can modulate the effects of nutritional asymmetry. For instance, stressful environments caused by intense interaction with conspecifics. Here, we subjected the house cricket Acheta domesticus to (i) either of two types of diet that have proved to affect cricket performance and (ii) simultaneously manipulated their social environment throughout their complete life cycle. We aimed to track sex-specific consequences for multiple traits during insect development throughout all life stages. Both factors affected critical life-history traits with potential population-level consequences: diet composition induced strong effects on insect development time, lifespan and fitness, while the social environment affected the number of nymphs that completed development, food consumption and whole-body lipid content. Additionally, both factors interactively determined female body mass. Our results highlight that insects may acquire and invest resources in a different manner when subjected to an intense interaction with conspecifics or when isolated. Furthermore, while only diet composition affected individual reproductive output, the social environment would determine the number of reproductive females, thus indirectly influencing population performance.

German Government Official Methods Board Points the Way Forward: Launch of a New Working Group for Mass Spectrometry for Protein Analysis to Detect Food Fraud and Food Allergens

The detection of food fraud and undeclared food allergens is one of the major challenges for competent authorities. Because adulterations are continuously adapted to the methods used to uncover them, the accomplishment of this task has become increasingly difficult over time. In recent years, various new promising methods for the detection of multiple food adulterants and multiple food allergens have been developed. Some of them utilize LC–MS to identify specific marker peptides. However, these methods have yet to be validated and standardized. For this reason, the German officials have established a working group with the objective of validating methods through multilaboratory validation studies. The experts of the working group also aim for the first time to standardize validated methods and to develop general validation criteria. This manuscript will highlight the current work of the group. For this purpose, an overview is given on the principles and applications of the new mass spectrometric methods. Moreover, requirements and the present work of other institutions regarding method validation are described.

Mass Spectrometry-Based Untargeted Proteomics for the Assessment of Food Authenticity: The Case of Farmed Versus Wild-Type Salmon

Background: Omics technologies have been widely applied in different fields, among which, proteomics is gaining increasing interest for its application to the authenticity of food products. MS, typically coupled with LC, represents a key technique for proteomics-related studies dedicated to fish and other seafood products by using a bottom-up approach. Objective and Methods: In this paper, the optimization of an untargeted proteomics-based method using LC separation and MS detection relying on a quadrupole time-of-flight mass spectrometer is described and applied to the analysis of Canadian farmed and wild-type salmon, followed by statistical analysis based on principal component (PC) analysis. Results and Conclusions: This untargeted approach, using a data-independent acquisition MS scheme, demonstrated the ability to effectively discriminate salmon belonging to the two classes. Furthermore, selected peptides showing high loadings on PC1 could represent potential candidate peptide markers able to discriminate farmed from wild-type salmon samples in the future.

Mass Spectrometry-Based Untargeted Proteomics for the Assessment of Food Authenticity: The Case of Farmed Versus Wild-Type Salmon

Background: Omics technologies have been widely applied in different fields, among which, proteomics is gaining increasing interest for its application to the authenticity of food products. MS, typically coupled with LC, represents a key technique for proteomics-related studies dedicated to fish and other seafood products by using a bottom-up approach. Objective and Methods: In this paper, the optimization of an untargeted proteomics-based method using LC separation and MS detection relying on a quadrupole time-of-flight mass spectrometer is described and applied to the analysis of Canadian farmed and wild-type salmon, followed by statistical analysis based on principal component (PC) analysis. Results and Conclusions: This untargeted approach, using a data-independent acquisition MS scheme, demonstrated the ability to effectively discriminate salmon belonging to the two classes. Furthermore, selected peptides showing high loadings on PC1 could represent potential candidate peptide markers able to discriminate farmed from wild-type salmon samples in the future.

German Government Official Methods Board Points the Way Forward: Launch of a New Working Group for Mass Spectrometry for Protein Analysis to Detect Food Fraud and Food Allergens

The detection of food fraud and undeclared food allergens is one of the major challenges for competent authorities. Because adulterations are continuously adapted to the methods used to uncover them, the accomplishment of this task has become increasingly difficult over time. In recent years, various new promising methods for the detection of multiple food adulterants and multiple food allergens have been developed. Some of them utilize LC-MS to identify specific marker peptides. However, these methods have yet to be validated and standardized. For this reason, the German officials have established a working group with the objective of validating methods through multilaboratory validation studies. The experts of the working group also aim for the first time to standardize validated methods and to develop general validation criteria. This manuscript will highlight the current work of the group. For this purpose, an overview is given on the principles and applications of the new mass spectrometric methods. Moreover, requirements and the present work of other institutions regarding method validation are described.

Determination of food allergens by LC-MS: Impacts of sample preparation, food matrix, and thermal processing on peptide detectability and quantification

Food allergies are a growing worldwide concern and the contamination of products with food allergens represents a significant health risk to allergic consumers. With the introduction of reference doses, quantitative methods are needed for the monitoring of allergen levels, and the potential of LC-MS/MS is of hugely growing interest. In this study, we demonstrate that relevant food matrices (bakery products and chocolates) and thermal food processing substantially influence the quantification of 18 marker peptides from various nut and peanut allergens via targeted proteomics. In addition, we characterize the individual release kinetics of marker peptides and provide examples for metastable marker peptide candidates. Matrix recovery rates overall ranged between 15 and 250% with the observed variation being linked to the individual peptide structure as well as to specific matrix interferences. In contrast, thermal processing considerably influences the detectability of allergens on the protein level as different marker peptides from the identical parent allergen are similarly affected, leading to a loss in signal of up to 83% in extreme cases after a 45-min simulated baking. Provided data are finally used for evaluation of different calibrators as well as the overall potential and challenges of LC-MS for the absolute quantification of food allergens. SIGNIFICANCE: With the scientific discussion moving towards a risk-based management of food allergens, including the establishment of threshold doses, robust methods for the absolute quantification of allergens in food samples are urgently needed. Because the currently used antibody- and DNA-based technologies show severe limitations in terms of specificity and reproducibility, LC-MS has emerged as a promising alternative. Its application to absolute quantification, however, first requires an understanding of the various impacts that affect quantification results, including different food matrices, sample preparation, and thermal processing of foodstuffs. Knowledge of these factors, which are assessed as part of a comprehensive survey in this study, is also an important prerequisite to evaluate means of calibration for an LC-MS-based quantification of food allergens.

Characterization and Detection of Food Allergens Using High-Resolution Mass Spectrometry: Current Status and Future Perspective

Allergic reactions to food are among the major food safety concerns in industrialized countries, and it is estimated that approximately 5% of the population suffers from immunoglobulin-E-mediated food allergy. High-resolution mass spectrometry has become one of the most important techniques for the molecular characterization of allergens, including structural modification, degradation in the gastrointestinal environment, or identification of suitable marker peptides for the development of novel analytical approaches, in the past decade. This perspective aims to briefly summarize the current situation and discuss future developments.

Novel Approaches for the MS-Based Detection of Food Allergens: High Resolution, MS³, and Beyond

The prevalence of allergic reactions to food is believed to be increasing in industrialized countries worldwide. One of the major tasks in risk management is, therefore, the analytical surveillance of allergen contamination in food and targeted proteomics using MS, which is of hugely growing interest due to its specificity and sensitivity and the possibility to analyze multiple allergens in parallel. Though approximately 200 different foods have been described as having the potential to elicit allergic reactions, current regional labeling requirements are focused on the 5-14 priority allergens that elicit the vast majority of severe reactions or that pose a risk as hidden allergens in food production. MS-based detection methods have been published for the majority of priority allergens, and this review provides an overview of the different methodological approaches, namely multiple-reaction monitoring-, high-resolution MS-, and triple-stage MS-based methods. In addition, requirements for the identification and validation of specific marker peptides and the influence of thermal processing and structural heterogeneity of allergens are discussed.

Gastrointestinal digestion of hazelnut allergens on molecular level: Elucidation of degradation kinetics and resistant immunoactive peptides using mass spectrometry

SCOPE

Allergy to hazelnut seeds ranks among the most prevalent food allergies in Europe. The aim of this study was to elucidate the gastrointestinal digestion of hazelnut allergens on molecular level.

METHODS AND RESULTS

Hazelnut flour was digested in vitro following the Infogest consensus model. For six allergenic proteins, the time-dependent course of digestion was monitored by SDS-PAGE and HPLC-MS/MS, and degradation products were characterized by a bottom-up proteomics approach. Depending on the molecular structure, a specific biochemical fate was observed for each allergen, and degradation kinetics were traced back to the peptide level. 1183 peptides were characterized, including 130 peptides that carry known IgE-binding epitopes and may represent sensitizers for hazelnut allergy. The kinetics of peptide formation and degradation were determined by label-free quantification and follow a complex multi-stage mechanism.

CONCLUSION

We present a comprehensive survey on the gastrointestinal digestion of a relevant allergenic food on level of the peptidome, including the first systematic characterization and quantification of degradation products. This provides information on the differential resistance of plant food allergens and their structural elements undergoing digestion and forms the basis for a deeper understanding of the molecular principles responsible for sensitization to food allergy.

Structural Characterization of the Allergenic 2S Albumin Cor a 14: Comparing Proteoform Patterns across Hazelnut Cultivars

The hazelnut allergen Cor a 14 belongs to the 2S albumins, a family of heterodimeric seed storage proteins exhibiting a high degree of structural diversity. Given its relevance as an allergen and the potential to elicit severe reactions, elucidation of the sequence heterogeneity of naturally occurring Cor a 14 is essential for the development of reliable diagnostics and risk evaluation. We therefore performed a comprehensive survey on the proteoforms of Cor a 14 and determined their quantitative distribution in three different hazelnut cultivars by a combinatory HPLC-HRMS approach including bottom-up and intact mass analysis. Compared with the Cor a 14 prototype sequence, we identified three sequence polymorphisms, two of the small and one of the large subunit, and elucidated their specific pairing on the protein level. Furthermore, we located a pronounced microheterogeneity on the protein termini and, for the first time, provide data on varying proteoform patterns between different cultivars of an allergenic seed. Together, these data present the basis for a more detailed investigation on the allergenicity of Cor a 14 in different cultivars and constitute, to be best of our knowledge, the largest set of proteoforms so far reported for a 2S albumin.

6th International Symposium on Molecular Allergology (ISMA)

ORAL ABSTRACTS

Symposium 1: Biochemistry, structure and environment of the allergen: what makes a protein an allergen?

O1 Two cell-membrane peptidases carrying galactose-alpha-1,3-galactose are implicated in delayed anaphylactic reactions upon pork kidney ingestion in patients with IgE-antibodies to alpha-Gal

Christiane Hilger, Kyra Swiontek, Jörg Fischer, François Hentges, Christiane Lehners, Martine Morisset, Bernadette Eberlein, Tilo Biedermann, Markus Ollert

O2 Structure solution of Pla l 1 suggests similar folding of Ole e 1-like family members but distinct immunological properties

Sabrina Wildner, Teresa Stemeseder, Regina Freier, Peter Briza, Roland Lang, Eva Batanero, Mayte Villalba, Jonas Lidholm, Thomas Hawranek, Fatima Ferreira, Hans Brandstetter, Gabriele Gadermaier

Symposium 2: New allergen molecules in the spotlight

O3 Identification of the cysteine protease Amb a 11 as a novel major allergen from short ragweed (Ambrosia artemisiifolia)

Philippe Moingeon, Rachel Groeme, Julien Bouley, Véronique Bordas, Maxime Le Mignon, Laetitia Bussières, Aurélie Lautrette, Laurent Mascarell, Vincent Lombardi, Véronique Baron-Bodo, Henri Chabre, Thierry Batard, Emmanuel Nony

O4 Production and characterization of polybia paulista recombinant antigen 5: a valuable diagnostic tool

Karine Marafigo De Amicis, Alexandra Sayuri Watanabe, Daniele Danella Figo, José Roberto Aparecido Dos Santos-Pinto, Mario Sergio Palma, Fabio Fernandes Morato Castro, Jorge Kalil, Therese Wohlschlager, Peter Briza, Sabrina Wildner, Fatima Ferreira-Briza, Gabriele Gadermaier, Keity Souza Santos

Symposium 3: Progress in molecular and cellular diagnosis

O5 Basophil activation test with recombinant Pru p 3; identifying genuine peach allergic patients

Margaretha Faber, Athina Van Gasse, Vito Sabato, Margo M. Hagendorens, Chris H. Bridts, Luc S. De Clerck, Araceli Diaz Perales, Didier Ebo

O6 Nanofluidic technology enables rapid, near-patient quantification of allergen-specific IgE

Petra Zavadakova, Aurélie Buchwalder, Fabien Rebeaud, Iwan Märki

Symposium 4: Relevance of molecular diagnostics for intervention and treatment

O7 Longitudinal analysis of Bet v 1-specific epitope repertoires during birch pollen immunotherapy

Barbara Gepp, Nina Lengger, Christian Möbs, Wolfgang Pfützner, Christian Radauer, Barbara Bohle

O8 A natural CCD-free tool: is polistes sp. venom suitable for polybia paulista diagnosis and therapy?

Karine Marafigo De Amicis, Alexandra Sayuri Watanabe, Clovis Eduardo Galvao, Daniele Danella Figo, Jose Roberto Aparecido Santos-Pinto, Mario Sergio Palma, Fabio Fernandes Morato Castro, Jorge Kalil, Fatima Ferreira, Gabriele Gadermaier, Keity Souza Santos

Symposium 5: The advent of molecular allergology in epidemiology

O9 Peanut oleosins: from identification to diagnostic testing

Christian Schwager, Skadi Kull, Frauke Schocker, Jochen Behrends, Wolf-Meinhard Becker, Uta Jappe

O10 Endotypes of oral allergy syndrome in childhood: a molecular diagnostic approach

Carla Mastrorilli, Salvatore Tripodi, Carlo Caffarelli, Riccardo Asero, Arianna Dondi, Giampaolo Ricci, Carlotta Povesi Dascola, Elisabetta Calamelli, Andrea Di Rienzo Businco, Annamaria Bianchi, Tullio Frediani, Carmen Verga, Iride Dello Iacono, Diego Peroni, Giuseppe Pingitore, Roberto Bernardini, Paolo Maria Matricardi

Symposium 6: Molecular AIT: which approaches will make it to market?

O11 Mbc4: an innovative molecule to tackle birch pollen and concomitant food allergies

Heidi Hofer, Claudia Asam, Michael Hauser, Peter Briza, Martin Himly, Christof Ebner, Fatima Ferreira

O12 Challenges and solutions associated with the production of recombinant Bet v 1 allergen as a therapeutic protein

Emmanuel Nony, Maxime Le Mignon, Pierrick Lemoine, Karine Jain, Kathy Abiteboul, Monica Arvidsson, Sabina Rak, Philippe Moingeon

Clinical Cases: Breakthroughs and headaches from CRD: interactive session

CC1 Anaphylaxis caused by lipid transfer proteins: a complex clinical pattern syndrome

Inês Mota, Filipe Benito Garcia, Angela Gaspar, Cristina Arêde, Susana Piedade, Graça Sampaio, Graça Pires, Luís Miguel Borrego, Cristina Santa-Marta, Mário Morais-Almeida

CC2 IgE sensitization profile in a patient with asteraceae pollen-exotic fruits association

Florin-Dan Popescu, Mariana Vieru, Florin-Adrian Secureanu

CC3 Food-dependent: exercise induced anaphylaxis. Which component to blame?

Rosa Anita Rodrigues Fernandes, Isabel Carrapatoso, Raquel Gomes, Celso Pereira, Ana Todo-Bom

CC4 Anaphylaxis to intravenous iron preparations in a patient that tolerates oral administration

María Cecilia Martín Fernández De Basoa, Javier Barrios Regio, Juan De Castro Cordova, Antón Fernández Ferreiro

CC5 IgE sensitization pattern in an adult patient with oral allergy syndrome to peanuts and pollinosis from southern Romania

Florin-Dan Popescu, Mariana Vieru, Florin-Adrian Secureanu

CC6 Evidence of specific IgE to plant-derived cross-reactive carbohydrate determinant in a patient with delayed anaphylaxis to red meat

Mariana Vieru, Florin-Dan Popescu, Florin-Adrian Secureanu

POSTER PRESENTATIONS

Poster Session 1: Molecular allergology and epidemiology

P1 Atopic children produce stronger and more frequent IgG responses than non-atopic children: longitudinal data from the German MAS birth cohort

Olympia Tsilochristou, Serena Perna, Alina Schwarz, Alexander Rohrbach, Antonio Cappella, Laura Hatzler, Carl-Peter Bauer, Ute Hoffmann, Johannes Forster, Fred Zepp, Antje Schuster, Raffael D’amelio, Ulrich Wahn, Thomas Keil, Susanne Lau, Paolo Maria Matricardi

P2 The IgG sensitization profiles against 112 allergenic components support the absence of a protective role of IgG in allergic individuals, outside of the context of SIT

Pol André Apoil, Claire Mailhol, Anne Broué-Chabbert, Agnès Juchet, Alain Didier, Elodie Carrer, Thomas Lanot, Antoine Blancher

P3 The immune response against the timothy grass pollen allergen Phl p 5 in non-allergic humans

Almedina Kurtaj, Christoph Hillebrand, Gerda Fichtinger, Martin Danzer, Christian Gabriel, Theresa Thalhamer, Sandra Scheiblhofer, Josef Thalhamer, Richard Weiss

P4 Analyzing the cross-reactivity profile of the major ragweed allergen Amb a 1

Martin Wolf, Michael Hauser, Ulrike Pichler, Teresa Twaroch, Gabriele Gadermaier, Christof Ebner, Hidenori Yokoi, Toshiro Takai, Alain Didierlaurent, Adriano Mari, Peter Briza, Heidrun Behrendt, Angela Neubauer, Frank Stolz, Fátima Ferreira, Michael Wallner

P5 LTP (Pru p 3) sensitisation in skin prick test: which means in clinical practice?

Sara Carvalho, Tatiana Lourenço, Joana Cosme, Fátima Cabral Duarte, Amélia Spínola Santos, Ana Célia Costa, Manuel Pereira Barbosa

P6 IgE profiles, allergen exposure and lifestyle of 501 Austrian pupils: investigation of influences on the development of allergic sensitizations

Teresa Stemeseder, Eva Klinglmayr, Bettina Schweidler, Lisa Lueftenegger, Stephanie Moser, Patrick Doppler, Roland Lang, Martin Himly, Gertie J. Oostingh, Arne Bathke, Joerg Zumbach, Thomas Hawranek, Gabriele Gadermaier

P7 Molecular profiles of sensitization to perennial inhalant allergens in a middle European region

Petr Panzner, Martina Vachova, Tomas Vlas, Marek Maly

P8 Evolution of the IgE response to house dust mite allergen molecules in childhood

Daniela Posa, Serena Perna, Stephanie Hofmaier, Laura Hatzler, Alexander Rohrbach, Carl-Peter Bauer, Ute Hoffmann, Johannes Forster, Fred Zepp, Antje Schuster, Philippe Stock, Ulrich Wahn, Linus Grabenhenrich, Thomas Keil, Susanne Lau, Kuan-Wei Chen, Yvonne Resch, Susanne Vrtala, Rudolf Valenta, Paolo Maria Matricardi

P9 Tropomyosin (Pen a1): to include or not to include in skin prick testing?

Joana Cosme, Sara Carvalho, Tatiana Lourenço, Amélia Spínola Santos, Manuel Pereira Barbosa

Immunoallergy Department - Hospital de Santa Maria – Centro Hospitalar Lisboa Norte, Lisbon, Portugal, Lisbon, Portugal; Immunoallergy Department - Hospital de Santa Maria – Centro Hospitalar Lisboa Norte, Lisbon, Portugal; Faculdade de Medicina de Lisboa, Lisbon, Portugal

P10 Component-resolved IgE profiles in Georgian patients

Tamar Abramidze, Nino Lomidze, Maia Gotua

P11 Cross reactivity between food and pollen allergens in Lithuania according to spIgE evaluation

Austeja Dapkeviciute, Ruta Einikyte, Jolita Norkuniene, Laima Skrickiene, Asta Miskiniene, Violeta Kvedariene

P12 Distribution of inhalant allergy in the population of Lithuania

Ruta Einikyte, Austeja Dapkeviciute, Jolita Norkuniene, Laima Skrickiene, Asta Miskiniene, Violeta Kvedariene

Poster Session 2: Allergen molecules: identification, characterization, structure and function

P13 Interference of antigen 5-based cross-reactivity in the diagnosis of hymenoptera venom allergy

Maximilian Schiener, Bernadette Eberlein, Carmen Moreno-Aguilar, Gunilla Pietsch, Mareike Mc Intyre, Lea Schwarze, Dennis Rußkamp, Tilo Biedermann, Edzard Spillner, Ulf Darsow, Carsten Schmidt-Weber, Markus Ollert, Simon Blank

P14 IgE cross-reactivity between European Hymenoptera and Asian hornet (Vespa velutina) venom allergens

Cyril Longé, Andrea Brazdova, Jean-Louis Brunet, Claire Schwartz, Bruno Girodet, François Lavaud, Joelle Birnbaum, Nhân Pham Thi, Magalie Duchateau, Julia Chamot-Rooke, Laurence Guilloux, Marie-Ange Selva, Rémy Couderc, Hélène Sénéchal, Jean-Pierre Sutra, Pascal Poncet

P15 Carbohydrate composition of house dust mite extracts and major group 1 and group 2 allergens

Steffen Augustin, Linda Pump, Martin Wald, Thomas Eichhorn, Frank Fischer, Christoph Willers

P16 Specificity of monoclonal antibodies against cross-reactive carbohydrate determinants

Michaela Miehe, Melanie Plum, Sara Wolf, Frederic Jabs, Tim Raiber, Frank Bantleon, Henning Seismann, Thilo Jakob, Edzard Spillner

P17 Red meat allergic patients have a selective IgE response to the a-Gal glycan

Danijela Apostolovic, Anh Thu Tran, Sara Sanchez-Vidaurre, Tanja Cirkovic Velickovic, Maria Starkhammar, Carl Hamsten, Marianne Van Hage

P18 Specificity of non-specific lipid transfer proteins and influence of the ligands on their three-dimensional structure

Pawel Dubiela, Piotr Humeniuk, Sabine Pfeifer, Merima Bublin, Tomasz Borowski, Karin Hoffmann-Sommergruber

P19 Real-time PCR analysis of Pru av 1 and Pru av 3 allergens

Martie C.M. Verschuren, Shanna Bastiaan-Net, Defien Depoortere, Kay Foetisch, Stephan Scheurer, Harry J Wichers, Theo Noij

P20 Specificity of anti-Pru av 1 antibodies for the detection of Pru av 1 isoallergens

Martie C.M. Verschuren, Shanna Bastiaan-Net, Nikki M.E. Van Uden, Karel Vandenberghe, Kay Foetisch, Stephan Scheurer, Harry J. Wichers H.J., Theo H.M. Noij

P21 Enhancing recombinant production yield of Bet v 1 through codon usage harmonization

Anargyros Roulias, Maria Alejandra Parigiani, Heidi Hofer, Claudia Asam, Christof Ebner, Fátima Ferreira

P22 Structural and dynamic insights into the world of PR-10 allergens

Linda Ahammer, Sarina Grutsch, Martin Tollinger

Poster Session 3: Allergen molecules: identification, characterization, structure and function

P23 Purification of polcalcin from different pollen allergenic sources by antibody-affinity chromatography

Raquel Moya, Mª Angeles López-Matas, Raquel Reyes, Jerónimo Carnés

P24 Variations of wheat allergens in cultivars measured through a targeted quantitative mass spectrometry approach

Colette Larré, Hélène Rogniaux, Roberta Lupi, Sandra Denery-Papini

P25 Art v 1, Amb a 4 and Par h 1 defensin-like proteins share similar structural features but distinct immunological and allergenic properties

Isabel Maria Pablos, Stephanie Eichhorn, Yoan Machado, Peter Briza, Christof Ebner, Jung-Won Park, Alain Didierlaurent, Naveen Arora, Stefan Vieths, Gabriele Gadermaier, Fatima Ferreira

P26 Homogeneity or diversity of IgE-binding proteins in wheat dependant exercise induced anaphylaxis?

Sandra Denery-Papini, Charlene Tanaka, Florence Pineau, Roberta Lupi, Martine Drouet, Etienne Beaudouin, Martine Morisset, Susan Altenbach

P27 Deciphering the role of disulfide bonds and of repetitive epitopes in immunoglobulin E binding to wheat gliadins

Sandra Denery-Papini, Hamza Mameri, Chantal Brossard, Roberta Lupi, Florence Pineau, Jean Charles Gaudin, Denise Anne Moneret-Vautrin, Etienne Beaudouin, Evelyne Paty, Martine Drouet, Olivier Tranquet, Colette Larré

P28 Assessment of the allergenicity of soluble fractions from bread and durum wheats genotypes

Roberta Lupi, Stefania Masci, Olivier Tranquet, Denise-Anne Moneret-Vautrin, Sandra Denery-Papini, Colette Larré

P29 Isolation and characterization of Ara h 12 and Ara h 13: defensins, a novel class of peanut allergens

Skadi Kull, Arnd Petersen, Marisa Böttger, Sandra Rennert, Wolf-Meinhard Becker, Susanne Krause, Martin Ernst, Thomas Gutsmann, Johann Bauer, Buko Lindner, Uta Jappe

P30 Allergenicity attributes of different peanut market types

Stef Koppelman, Shyamali Jayasena, Dion Luykx, Erik Schepens, Danijela Apostolovic, Govardus De Jong, Tom Isleib, Julie Nordlee, Joe Baumert, Steve Taylor, Soheila Maleki

P31 The impact of peanut lipids on Ara h 1-induced immune responses in monocytes-derived dendritic cells

Chiara Palladino, Barbara Gepp, Sofía Sirvent, Alba Angelina, Merima Bublin, Christian Radauer, Nina Lengger, Thomas Eiwegger, Oscar Palomares, Heimo Breiteneder

P32 Compared allergenicity of native and thermally aggregated ovalbumin as large agglomerated particles

Mathilde Claude, Roberta Lupi, Grégory Bouchaud, Marie Bodinier, Chantal Brossard, Sandra Denery-Papini

P33 Simulation of the gastrointestinal digestion of the hazelnut allergens Cor a 9 and Cor a 11 by an in-vitro model and characterisation of peptidic products including epitopes by HPLC-MS/MS

Robin Korte, Julia Bräcker, Jens Brockmeyer

P34 Analysis of distribution of rice allergens in brown rice grain and allergenicity of the products containing rice bran

Rie Satoh, Reiko Teshima

Poster Session 4: Molecular approaches in AIT

P35 Production of a recombinant hypoallergenic variant of the major peanut allergen Ara h 2 for allergen-specific immunotherapy

Angelika Tscheppe, Dieter Palmberger, Merima Bublin, Christian Radauer, Chiara Palladino, Barbara Gepp, Nina Lengger, Reingard Grabherr, Heimo Breiteneder

P36 Mutagenesis of amino acids critical for calcium-binding leads to the generation of a hypoallergenic Phl p 7 variant

Marianne Raith, Linda Sonnleitner, Doris Zach, Konrad Woroszylo, Margit Focke-Tejkl, Herbert Wank, Thorsten Graf, Annette Kuehn, Ines Swoboda

P37 Are birch pollen allergen immunotherapy induced blocking antibodies protective for cross-reactive allergens?

Claudia Asam, Sara Huber, Heidi Hofer, Roland Lang, Thomas Hawranek, Fátima Ferreira, Michael Wallner

P38 High success of 58 subcutaneous immunotherapy for pets allergy in a polyallergic cohort of patients: a component resolved individually adapted treatment (CRIAT)

Fabienne Gay-Crosier

P39 Neutrophils are potential antigen presenting cells in IgE- mediated allergy

Dominika Polak, Birgit Nagl, Claudia Kitzmüller, Barbara Bohle

P40 Characterization of allergen-specific CD8+ T cells in type I allergy

Nazanin Samadi, Claudia Kitzmüller, Rene Geyeregger, Barbara Bohle, Beatrice Jahn-Schmid

Poster Session 5: Molecular and cellular diagnostic tests

P41 Nanofluidic-based biosensors allow quantification of total circulating IgE from a drop of blood in 5 minutes

Aurélie Buchwalder, Ariel Gomez, Fabien Rebeaud, Iwan Märki

P42 Allergen microarray for the analysis of serum IgE binding profile and allergenic activity

Jaana Haka, Liisa Hattara, Marika Heikkinen, Merja H Niemi, Juha Rouvinen, Petri Saviranta, Pekka Mattila, Kristiina Takkinen, Marja-Leena Laukkanen

P43 Generation of a well-characterized panel of periplaneta americana allergens for component resolved diagnosis

Stephanie Eichhorn, Isabel Pablos, Bianca Kastner, Bettina Schweidler, Sabrina Wildner, Peter Briza, Jung-Won Park, Naveen Arora, Stefan Vieths, Gabriele Gadermaier, Fatima Ferreira

P44 Improved diagnostic sensitivity of recombinant Api m 1 and Ves v 5 in diagnosis of Hymenoptera venom allergy

Mira Silar, Julij Selb, Rok Kogovsek, Mitja Kosnik, Peter Korosec

P45 Added value of biomarkers of primary sensitization and cross-reactivity in patients with hymenoptera venom allergy

Leticia Pestana, Alcinda Campos Melo, Ana Mendes, Maria Elisa Pedro, Manuel Pereira Barbosa, Maria Conceição Pereira Santos

P46 Cosensitization to Alt a 1 and Act d 2: more than a fortuitous association?

Françoise Bienvenu, Claire Goursaud, Lorna Garnier, Sandrine Jacquenet, Michaël Degaud, Sébastien Viel, Annick Barre, Pierre Rougé, Jacques Bienvenu, Joana Vitte

P47 Molecular diagnosis for peanut allergy: ALFA method performs as well as established methods for Ara h 1, Ara h 2, Ara h 6, Ara h 9 and CCD

Amel Bensalah, Isabelle Cleach, Laurent Mousseau, Chantal Agabriel, Valérie Liabeuf, Joëlle Birnbaum, Jean-Louis Mège, Joana Vitte

P48 Evaluation of a food challenge service in relation to specific IgE to molecular components in children with suspected peanut allergy

James Gardner, Minal Gandhi, Harsha Kariyawasam, Giuseppina Rotiroti

P49 Component resolved diagnosis in cereal allergy

Isabel Carrapatoso, Celso Pereira, Frederico Regateiro, Emília Faria, Ana Todo-Bom

Poster Session 6: Molecular diagnosis in prevention and therapy

P50 Pretreatment molecular sensitizations determine the sIgG4 induction during the updosing of SCIT and may be useful to identify clinically relevant additional sensitizations

Johannes Martin Schmid, Ronald Dahl, Hans Juergen Hoffmann

P51 Usefulness of recombinant latex allergens in immunotherapy’s decision and follow-up

Inês Mota, Filipe Benito Garcia, Angela Gaspar, Mário Morais-Almeida

P52 Omega-5-gliadin in the diagnosis of wheat-dependent anaphylaxis induced by ibuprofen but not by exercise

Joana Cosme, Letícia Pestana, Amélia Spínola Santos, Manuel Pereira Barbosa

P53 Food dependent exercise-induced anaphylaxis: a component-resolved and in vitro depletion approach to access IgE cross-reactivity

Diana Silva, Teresa Vieira, Ana Maria Pereira, André Moreira, Luís Delgado

P54 Olive pollen allergens: what are we missing?

Sara Prates, Cátia Alves, Elena Finelli, Paula Leiria Pinto

P55 Purified Alt a 1 extract in Alternaria alternata allergy diagnosis

Bárbara Kong Cardoso, Cíntia Cruz, Filipa Semedo, Elza Tomaz, Filipe Inácio

P56 Use of specific IgE Bos d8 (casein) to aid early introduction of dietary baked milk in children with cows’ milk allergy

James Gardner, Santanu Maity, Giuseppina Rotiroti, Minal Gandhi

P57 Molecular characterisation and immunoreactivity of a peanut ingredient for use in oral food challenges

Ivona Baricevic-Jones, Justin T. Marsh, Phil E. Johnson, Anuradha Balasundaram, Anya-May Hope, Aafke Taekema, Angela Simpson, Aida Semic-Jusufagic, E.N. Clare Mills

P58 Specific IgE to recombinant allergens of hazelnut and oral food challenge in children

Gourdon Dubois Nelly, Sellam Laetitia, Pereira Bruno, Michaud Elodie, Messaoudi Khaled, Evrard Bertrand, Fauquert Jean-Luc

Poster session 7/8: miscellaneous

P59 What defines a protein as an allergen? A discussion of sources and sufficiency

Richard E. Goodman

P60 Cat allergy: relationship between clinical and molecular diagnostic

María Cecilia Martín Fernández De Basoa, Antón Fernández Ferreiro, Elena Rodríguez Plata

P61 Anaphylaxis to rabbit: the cat came in last

Luis Amaral, Borja Bartolomé, Alice Coimbra, Jose L Placido

P62 Dog allergy: relationship between clinical and molecular diagnostic

María Cecilia Martín Fernández De Basoa, Antón Fernández Ferreiro, Elena Rodríguez Plata

P63 Correlation of serum timothy grass-pollen specific IgE levels determined by two immunoblot test systems

Mariana Vieru, Florin-Dan Popescu, Florin-Adrian Secureanu, Carmen Saviana Ganea

P64 Development of oral food challenge formulations for diagnosis of fish allergy using powdered fish ingredients

Carol Ann Costello, Ivona Baricevic-Jones, Martin Sorensen, Clare Mills, Adrian Rogers, Aage Otherhals

P65 Fish and peanut allergens interact with plasma membranes of intestinal and bronchial epithelial cells and induce differential gene expression of cytokines and chemokines

Tanja Kalic, Isabella Ellinger, Chiara Palladino, Barbara Gepp, Eva Waltl, Verena Niederberger-Leppin, Heimo Breiteneder

P66 Interleukin 4 affects fat tissue metabolism and expression of pro-inflammatory factors in isolated rat adipocytes

Dawid Szczepankiewicz, Ewa Pruszynska-Oszmalek, Marek Skrzypski, Krzysztof W. Nowak, Aleksandra Szczepankiewicz

P67 Ozone induced airway hyperreactivity in PD-L2−/− mice model

Gwang-Cheon Jang

P68 Thymic stromal lymphopoietin (TSLP) and its receptor as targets for the development of anti-inflammatory inhibitory agents

Iva Markovic, Andreas Borowski, Tina Vetter, Andreas Wohlmann, Michael Kuepper, Karlheinz Friedrich

P69 The mononuclear phagocyte system in experimentally-induced allergic rhinitis

Ibon Eguiluz Gracia, Anthony Bosco, Ralph Dollner, Guro Reinholt Melum, Anya C Jones, Maria Lexberg, Patrick G Holt, Espen Sønderaal Bækkevold, Frode Lars Jahnsen

P70 Expression of histamine metabolizing enzymes is increased in allergic children

Aleksandra Szczepankiewicz, Paulina Sobkowiak, Marta Rachel, Beata Narozna, Dorota Jenerowicz, Witold Swiatowy, Anna Breborowicz

P71 Modifying the glycosylation of human IgE towards oligomannosidic structures does not affect its biological activity

Melanie Plum, Sara Wolf, Frank Bantleon, Henning Seismann, Frederic Jabs, Michaela Miehe, Thilo Jakob, Edzard Spillner

P72 Flying Labs: an educational initiative to transfer allergy research into high-school settings

Michael Wallner, Heidi Hofer, Fatima Ferreira, Reinhard Nestelbacher

P73 Clinical significance of antihistamines and Kujin, an anti-allergic Kampo medicine

Hiroyuki Fukui

New High-Performance Liquid Chromatography Coupled Mass Spectrometry Method for the Detection of Lobster and Shrimp Allergens in Food Samples via Multiple Reaction Monitoring and Multiple Reaction Monitoring Cubed

Crustacean shellfish allergy ranks among the most frequent and severe food allergies for adults, demanding rugged and sensitive analytical routine methods. The objective of this study was therefore to develop a mass spectrometric approach for the detection of contamination with shrimp and lobster, two economically important types of crustaceans, in complex food matrices. Following a biomarker approach, we identified proteotypic peptides and developed a multiple reaction monitoring (MRM) method allowing for the identification and differentiation of shrimp and lobster in the food matrix at concentrations down to 0.1%. To further enhance sensitivity, we employed the MRM-cubed (MRM(3)) mode, which allowed us to detect crustaceans down to concentrations of 25 μg/g (crustacean/food, 0.0025%). We hereby present the first mass spectrometric method for the detection of shrimp and lobster in food matrices.

Comprehensive peptide marker identification for the detection of multiple nut allergens using a non-targeted LC-HRMS multi-method

Food allergies have emerged as a global problem over the last few decades; therefore, reliable and sensitive analytical methods to ensure food safety for allergic consumers are required. The application of mass spectrometry is of growing interest in this field and several procedures based on low resolution tandem mass spectrometry using single tryptic peptides as analytical targets have recently been described. However, a comprehensive survey of marker peptides for the development of multi-methods is still missing, as is a consensus guide to marker identification. In this study, we therefore report a consistent approach to the development of liquid chromatography-mass spectrometry (LC-MS) multi-screening methods for the detection of allergens in food matrices. Proteotypic peptides were identified by a shotgun proteomics approach and verified through a thorough investigation of specificity and sensitivity. On the basis of this procedure, we identified 44 suitable tryptic marker peptides from six allergenic nut species and developed the first analytical LC-MS method for the detection of trace nut contaminations in processed foods using high resolution mass spectrometry (HRMS). The analysis of spiked matrix samples gave limits of detection (LODs) below 10 μg/g for several nuts; these LODs are comparable with routinely used methods such as ELISA and PCR. Notably, the HRMS approach can be used in an untargeted fashion to identify multiple allergens also retrospectively. In conclusion, we present here the so far largest consensus set of analytical markers from nut allergens and to the best of our knowledge the first multi-allergen method based on LC-HRMS.

Simple, Rapid, and Selective Isolation of 2S Albumins from Allergenic Seeds and Nuts

The 2S albumins belong to the group of seed storage proteins present in different seeds and nuts. Due to their pronounced allergenic potential, which is often associated with severe allergic reactions, this protein family is of special interest in the field of allergen research. Here we present a simple, rapid, and selective method for the purification of 2S albumins directly from allergenic seeds and nuts. We systematically optimized the parameters "buffer system", "extraction temperature", "buffer molarity", and "pH " and were able to achieve 2S albumin purities of about 99% without further purification and demonstrate transferability of this method to nine different allergenic food matrices. Compared to conventional isolation routines, significant reduction of hands-on time and required laboratory equipment is achieved, but nonetheless higher protein yields are obtained. The presented method allows for the rapid purification of different 2S albumins including the corresponding isoforms from natural material.

Structural and functional characterization of cleavage and inactivation of human serine protease inhibitors by the bacterial SPATE protease EspPα from enterohemorrhagic E. coli

EspPα and EspI are serine protease autotransporters found in enterohemorrhagic Escherichia coli. They both belong to the SPATE autotransporter family and are believed to contribute to pathogenicity via proteolytic cleavage and inactivation of different key host proteins during infection. Here, we describe the specific cleavage and functional inactivation of serine protease inhibitors (serpins) by EspPα and compare this activity with the related SPATE EspI. Serpins are structurally related proteins that regulate vital protease cascades, such as blood coagulation and inflammatory host response. For the rapid determination of serpin cleavage sites, we applied direct MALDI-TOF-MS or ESI-FTMS analysis of coincubations of serpins and SPATE proteases and confirmed observed cleavage positions using in-gel-digest of SDS-PAGE-separated degradation products. Activities of both serpin and SPATE protease were assessed in a newly developed photometrical assay using chromogenic peptide substrates. EspPα cleaved the serpins α1-protease inhibitor (α1-PI), α1-antichymotrypsin, angiotensinogen, and α2-antiplasmin. Serpin cleavage led to loss of inhibitory function as demonstrated for α1-PI while EspPα activity was not affected. Notably, EspPα showed pronounced specificity and cleaved procoagulatory serpins such as α2-antiplasmin while the anticoagulatory antithrombin III was not affected. Together with recently published research, this underlines the interference of EspPα with hemostasis or inflammatory responses during infection, while the observed interaction of EspI with serpins is likely to be not physiologically relevant. EspPα-mediated serpin cleavage occurred always in flexible loops, indicating that this structural motif might be required for substrate recognition.

Meat authentication: a new HPLC-MS/MS based method for the fast and sensitive detection of horse and pork in highly processed food

Fraudulent blending of food products with meat from undeclared species is a problem on a global scale, as exemplified by the European horse meat scandal in 2013. Routinely used methods such as ELISA and PCR can suffer from limited sensitivity or specificity when processed food samples are analyzed. In this study, we have developed an optimized method for the detection of horse and pork in different processed food matrices using MRM and MRM(3) detection of species-specific tryptic marker peptides. Identified marker peptides were sufficiently stable to resist thermal processing of different meat products and thus allow the sensitive and specific detection of pork or horse in processed food down to 0.24% in a beef matrix system. In addition, we were able to establish a rapid 2-min extraction protocol for the efficient protein extraction from processed food using high molar urea and thiourea buffers. Together, we present here the specific and sensitive detection of horse and pork meat in different processed food matrices using MRM-based detection of marker peptides. Notably, prefractionation of proteins using 2D-PAGE or off-gel fractionation is not necessary. The presented method is therefore easily applicable in analytical routine laboratories without dedicated proteomics background.

New sensitive high-performance liquid chromatography-tandem mass spectrometry method for the detection of horse and pork in halal beef

The accidental or fraudulent blending of meat from different species is a highly relevant aspect for food product quality control, especially for consumers with ethical concerns against species, such as horse or pork. In this study, we present a sensitive mass spectrometrical approach for the detection of trace contaminations of horse meat and pork and demonstrate the specificity of the identified biomarker peptides against chicken, lamb, and beef. Biomarker peptides were identified by a shotgun proteomic approach using tryptic digests of protein extracts and were verified by the analysis of 21 different meat samples from the 5 species included in this study. For the most sensitive peptides, a multiple reaction monitoring (MRM) method was developed that allows for the detection of 0.55% horse or pork in a beef matrix. To enhance sensitivity, we applied MRM(3) experiments and were able to detect down to 0.13% pork contamination in beef. To the best of our knowledge, we present here the first rapid and sensitive mass spectrometrical method for the detection of horse and pork by use of MRM and MRM(3).

Prevalence, biogenesis, and functionality of the serine protease autotransporter EspP

Enterohemorrhagic E. coli (EHEC) causes severe diseases in humans worldwide. One of its virulence factors is EspP, which belongs to the serine protease autotransporters of Enterobacteriaceae (SPATE) family. In this review we recapitulate the current data on prevalence, biogenesis, structural properties and functionality. EspP has been used to investigate mechanistic details of autotransport, and recent studies indicate that this transport mechanism is not autonomous but rather dependent on additional factors. Currently, five subtypes have been identified (EspPα-EspPε), with EspPα being associated with highly virulent EHEC serotypes and isolates from patients with severe disease. EspPα has been shown to degrade major proteins of the complement cascade, namely C3 and C5 and probably interferes with hemostasis by cleavage of coagulation factor V. Furthermore, EspPα is believed to contribute to biofilm formation perhaps by polymerization to rope-like structures. Together with the proteolytic activity, EspPα might ameliorate host colonization and interfere with host response.

Enterohaemorrhagic Escherichia coli haemolysin is cleaved and inactivated by serine protease EspPα

The haemolysin from enterohaemorrhagic Escherichia coli (EHEC-Hly) and the serine protease EspPα are putative virulence factors of EHEC. We investigated the interplay between these secreted factors and demonstrate that EspPα cleaves the 107 kDa large EHEC-Hly. Degradation was observed when purified EspPα was added to a growing culture of an EHEC-Hly-expressing strain, with isolated proteins and with coexpressing strains, and was independent of the EHEC serotype. EHEC-Hly breakdown occurred as a multistage process with the formation of characteristic fragments with relative molecular masses of ∼82 kDa and/or ∼84 kDa and ∼34 kDa. The initial cleavage occurred in the N-terminal hydrophobic domain of EHEC-Hly between Leu²³⁵ and Ser²³⁶ and abolished its haemolytic activity. In a cellular infection system, the cytolytic potential of EHEC-Hly-secreting recombinant strains was abolished when EspPα was coexpressed. EHEC in contact with human intestinal epithelial cells simultaneously upregulated their EHEC-Hly and EspP indicating that both molecules might interact under physiological conditions. We propose the concept of bacterial effector molecule interference (BEMI), reflecting the concerted interplay of virulence factors. Interference between effector molecules might be an additional way to regulate virulence functions and increases the complexity of monomolecular phenotypes.

Structure and function relationship of the autotransport and proteolytic activity of EspP from Shiga toxin-producing Escherichia coli

BACKGROUND

The serine protease autotransporter EspP is a proposed virulence factor of Shiga toxin-producing Escherichia coli (STEC). We recently distinguished four EspP subtypes (EspPalpha, EspPbeta, EspPgamma, and EspPdelta), which display large differences in transport and proteolytic activities and differ widely concerning their distribution within the STEC population. The mechanisms underlying these functional variations in EspP subtypes are, however, unknown.

METHODOLOGY/PRINCIPAL FINDINGS

The structural basis of proteolytic and autotransport activity was investigated using transposon-based linker scanning mutagenesis, site-directed mutagenesis and structure-function analysis derived from homology modelling of the EspP passenger domain. Transposon mutagenesis of the passenger domain inactivated autotransport when pentapeptide linker insertions occurred in regions essential for overall correct folding or in a loop protruding from the beta-helical core. Loss of proteolytic function was limited to mutations in Domain 1 in the N-terminal third of the EspP passenger. Site-directed mutagenesis demonstrated that His(127), Asp(156) and Ser(263) in Domain 1 form the catalytic triad of EspP.

CONCLUSIONS/SIGNIFICANCE

Our data indicate that in EspP i) the correct formation of the tertiary structure of the passenger domain is essential for efficient autotransport, and ii) an elastase-like serine protease domain in the N-terminal Domain 1 is responsible for the proteolytic phenotype. Lack of stabilizing interactions of Domain 1 with the core structure of the passenger domain ablates proteolytic activity in subtypes EspPbeta and EspPdelta.

Subtypes of the plasmid-encoded serine protease EspP in Shiga toxin-producing Escherichia coli: distribution, secretion, and proteolytic activity

We investigated the prevalence, distribution, and structure of espP in Shiga toxin-producing Escherichia coli (STEC) and assessed the secretion and proteolytic activity of the encoded autotransporter protein EspP (extracellular serine protease, plasmid encoded). espP was identified in 56 of 107 different STEC serotypes. Sequencing of a 3,747-bp region of the 3,900-bp espP gene distinguished four alleles (espPalpha, espPbeta, espPgamma, and espPdelta), with 99.9%, 99.2%, 95.3%, and 95.1% homology, respectively, to espP of E. coli O157:H7 strain EDL933. The espPbeta, espPgamma, and espPdelta genes contained unique insertions and/or clustered point mutations that enabled allele-specific PCRs; these demonstrated the presence of espPalpha, espPbeta, espPgamma, and espPdelta in STEC isolates belonging to 17, 16, 15, and 8 serotypes, respectively. Among four subtypes of EspP encoded by these alleles, EspPalpha (produced by enterohemorrhagic E. coli [EHEC] O157:H7 and the major non-O157 EHEC serotypes) and EspPgamma cleaved pepsin A, human coagulation factor V, and an oligopeptide alanine-alanine-proline-leucine-para-nitroaniline, whereas EspPbeta and EspPdelta either were not secreted or were proteolytically inactive. The lack of proteolysis correlated with point mutations near the active serine protease site. We conclude that espP is widely distributed among STEC strains and displays genetic heterogeneity, which can be used for subtyping and which affects EspP activity. The presence of proteolytically active EspP in EHEC serogroups O157, O26, O111, and O145, which are bona fide human pathogens, suggests that EspP might play a role as an EHEC virulence factor.

Hemolysin from Shiga toxin-negative Escherichia coli O26 strains injures microvascular endothelium

We identified Shiga toxin gene (stx)-negative Escherichia coli O26:H11 and O26:NM (nonmotile) strains as the only pathogens in the stools of five patients with hemolytic-uremic syndrome (HUS). Because the absence of stx in E. coli associated with HUS is unusual, we examined the strains for potential virulence factors and interactions with microvascular endothelial cells which are the major targets affected during HUS. All five isolates possessed the enterohemorrhagic E. coli (EHEC)-hlyA gene encoding EHEC hemolysin (EHEC-Hly), expressed the enterohemolytic phenotype, and were cytotoxic, in dose- and time-dependent manners, to human brain microvascular endothelial cells (HBMECs). Significantly reduced cytotoxicity in an EHEC-Hly-negative spontaneous derivative of one of these strains, and a dose- and time-dependent cytotoxicity of recombinant E. coli O26 EHEC-Hly to HBMECs, suggest that the endothelial cytotoxicity of these strains was mediated by EHEC-Hly. The toxicity of EHEC-Hly to microvascular endothelial cells plausibly contributes to the virulence of the stx-negative E. coli O26 strains and to the pathogenesis of HUS.

[First clinical experience with large volume plasma exchange in malignant tumor patients]

An attempt has been made to standardize the method of large volume plasma exchange in tumor patients on the basis of an albumin-electrolyte exchange solution. Problems relating to the alteration of tumor patients' serum proteins are discussed. Three patients with malignancies successfully underwent therapeutic plasmaphereses.