Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Immunomodulating effects of food compounds : a study using the THP-1 cell line
    Chanput, W. - \ 2012
    Wageningen University. Promotor(en): Harry Wichers; Huub Savelkoul; Jurriaan Mes. - [S.l.] : s.n. - ISBN 9789461734006 - 183
    immuundeficiëntie - immunotherapie - niet-specifieke immunostimulatie - voedingsmiddelen - bèta-glucaan - lipopolysacchariden - immunological deficiency - immunotherapy - nonspecific immunostimulation - foods - beta-glucan - lipopolysaccharides

    THP-1 is a human leukaemia monocytic cell line from the peripheral blood of a 1 year old human male. After exposure to phorbol-12-myristate-13-acetate (PMA), THP-1 cells in monocyte state start to adhere to culture plates and alter their morphology with an indication for differentiation into macrophages. In this thesis, the THP-1 cell line was used in both monocyte and macrophage state. The results obtained during this in vitro study show that THP-1 gene expression can be modulated by specific food compounds such as β-glucans, pectin, polyphenols and fungal immunomodulatory proteins (FIPs) in both activation and resting stage. In activation stage, these cells have been activated by LPS to mimic an inflammatory situation, while in resting stage, PMAdifferentiated THP-1 macrophages without LPS challenged was used. The polarizing ability of the THP-1 cell line into either classically activated M1 or alternatively activated M2 macrophages was examined using stimuli applied in vivo. Based on the expression of M1 and M2 marker genes, THP- 1 macrophages could be successfully polarized into both M1 and M2 stage. Thereby, they can be used as a new macrophage polarizing model to estimate the polarizing/switching ability of test compounds. The integration of results from this thesis with a review of recent publications leads to the conclusion that THP-1 cells present unique characteristics as a model to investigate/estimate immunomodulating effects of food-derived compounds in both activated and resting situations.

    Therapeutic brain cancer targeting by gene therapy and immunomodulation : a translational study
    Stathopoulos, A. - \ 2012
    Wageningen University. Promotor(en): Virgil Schijns; Huub Savelkoul, co-promotor(en): F.A. Hofman. - S.l. : s.n. - ISBN 9789461733634 - 192
    hersenen - hersenkanker - gentherapie - immunotherapie - immunologie - geneeskunde - brain - brain cancer - gene therapy - immunotherapy - immunology - medicine

    The hypothesis pertinent to this thesis is that glioma tumours can be therapeutically targeted by gene and/or immunotherapy in order to eliminate or delay tumour recurrence leading to significant morbidity and mortality. In our gene therapeutic approach, described in Chapter 2, we observed that chronic expression of the C-terminal fusion of IsK with EGFP (enhanced green fluorescent protein) led to cell death of more than 50% of transfected U87-MG human astrocytoma cells as early as 2 days after transfection. Our results are consistent with activation of apoptotic pathways following IsK-mediated increase in K+ efflux. However, we abandoned the gene therapy approach because of the more attractive immunotherapeutic intervention strategies for of brain tumours, which is currently emerging as a highly potential clinical option as reviewed in Chapter 3. Interestingly, as described in Chapter 4, we found a strong therapeutic antitumour efficacy for the innate immune response modifier Resiquimod, even as a stand-alone treatment, eventually leading to immunological memory against secondary tumour challenges. In parallel, we observed that cyclophosphamide treatment, although effective as chemotherapeutic agent, may be deleterious to maintenance of long-term antitumour immune memory. Our data also demonstrates that immunotherapeutic parenteral treatment of established glioma tumours by Resiquimod, as defined in the protocol, significantly improves anti-brain tumour immunity in a way that leads to immune memory, which is superior to cyclophosphamide treatment alone. Our studies have thereby identified a promising novel antitumour immunotherapy which may lead to clinical benefit. In Chapter 5, we describe our finding that, in multiple rat glioma models, a certain composition of antigens derived from syngeneic tumour cells and their lysates when therapeutically co-administered with allogeneic cells and their lysates is able to confer anti-tumour immune responses and tumour regression. For the syngeneic C6 model in SD rats therapeutic injections of allogeneic cells alone were sufficient to trigger tumour regression. This immunization approach may prove useful as a postsurgery adjuvant therapy in future cancer treatment protocols, or even as a stand-alone therapeutic tumour vaccination. In another syngeneic rat glioma model, described in Chapter 6, we found that for regression of CNS-1 glioma tumours in Lewis rats specific innate immune response stimulating substances were required as immunological adjuvants. In our hands BCG and IL-2, the Toll-Like receptor (TLR) 7/8 activator Resiquimod, and the cytokine granulocyte-macrophage colony stimulating factor (GM-CSF), showed potent activity. Finally, as described in Chapter 7, we demonstrate that our prototype therapeutic vaccine, when co-delivered in a specific regimen together with the cytokine GM-CSF as immunological adjuvant, is able to arrest progression of glioma tumour growth, when therapeutically administered following low-dose cyclophosphamide. GM-CSF is an attractive vaccine adjuvant because of its proven immune modulatory effects and low toxicity profile. The safe pharmacological use of GM-CSF in patients is well-established, which makes it feasible for clinical use. The use of GM-CSF has been included in the first clinical studies that have been approved for an Investigational New Drug application (IND) for Single patient use in the U.S..

    Allergenicity in food allergy : influence of food processing and immunomodulation by lactic acid bacteria
    Vissers, Y.M. - \ 2011
    Wageningen University. Promotor(en): Harry Wichers; Huub Savelkoul, co-promotor(en): E.N.C. Mills. - [S.l.] : S.n. - ISBN 9789085859161 - 226
    voedselallergieën - voedselverwerking - immunotherapie - aardnoten - melkzuurbacteriën - food allergies - food processing - immunotherapy - groundnuts - lactic acid bacteria


    Allergic diseases such as allergic rhinitis, allergic asthma, atopic eczema and food allergy have become an increasing health problem world-wide, affecting between 20-30% of the total population. Peanut allergy (prevalence ~1%) is a common and persistent food allergy accounting for severe allergic reactions. Peanuts are often consumed after thermal processing (e.g. boiling, roasting) which can alter the protein structure and change its immunoreactivity and allergenicity. In vitro diagnostic testing, however, is generally performed using the native, unprocessed protein and more knowledge on the effect of processing on allergens is necessary to improve these diagnostic procedures. In addition, rationally designed processing could also lead to reduction of the allergen content in certain products and therefore be an effective food technological approach in allergy management. Another approach in allergy management is the use of immunomodulating foods, such as probiotics. There are indications that probiotics, e.g. specific lactic acid bacteria, could be beneficial for many conditions, including different clinical expressions of allergy.
    Chapter 1 gives an overview of several aspects of allergy with a focus on food allergy. Firstly the basic mechanism and the involved immune cells are discussed, after which the prevalence of food allergy in the context of the EuroPrevall project is described. Different food allergens are discussed with an emphasis on the allergens from peanut and different methods are described to assess the potential allergenicity of proteins under widely used processing conditions, including heating and the Maillard reaction. Lastly, different methods to prevent or treat allergies are discussed with a special emphasis on immunomodulation by lactic acid bacteria. This introduction chapter is concluded with the research aim and thesis outline.

    Section 1: Influence of processing on allergenicity of proteins
    In our first study, described in Chapter 2, Ara h 2/6 was purified from raw peanut and heated in solution (boiling) in the presence or absence of glucose. Ara h 2 and 6 were also purified from roasted peanuts for comparison. Structural changes, the capacity to induce cell proliferation and cytokine production, and IgE-binding and IgE cross-linking capacity were evaluated. Although no effect of processing on T-cell reactivity was observed, heat-induced denaturation reduced the IgE-binding and cross-linking capacity. Interestingly, the soluble fraction of the Ara h 2/6 isolated from roasted peanuts retained the conformation and allergenic activity of the native protein.
    In Chapter 3 similar methods were used to assess the effect of heating and glycation on Ara h 1. Heating in solution, irrespective of their level of glycation, resulted in formation of aggregates having reduced IgE-binding and cross-linking capacity, while T-cell reactivity was retained. The soluble fraction of Ara h 1 isolated from roasted peanuts appeared to be highly denatured, formed more globular and smaller aggregates, and showed no evidence of glycation. However, these smaller aggregates retained IgE-binding capacity, unlike the aggregates formed after heating and glycating purified Ara h 1. These results could account for observed differences between boiled and roasted peanuts and suggest that other modifications than the Maillard reaction affect the allergenicity of Ara h 1.
    As peanuts are often consumed after roasting, the wet-thermal processing procedures, employed in the two previous described studies, were related to the effect of thermal treatment and Maillard reaction under low moisture conditions, which is described in Chapter 4. The extensive heating at low moisture resulted in hydrolysis of both Ara h 1 and Ara h 2/6. However, in contrast to Ara h 2/6, soluble Ara h 1 formed large aggregates. Thermally treated Ara h 2/6 had both a lower IgE-binding and degranulation capacity compared to the native form, and the presence of glucose during heating partly counteracted both the decrease in IgE-binding and degranulation capacity. The IgE-binding capacity of Ara h 1 was also decreased; however, the basophil degranulation capacity increased significantly. This demonstrates the importance of including degranulation assays in addition to IgE-binding assays, when assessing allergenic potency of allergens. In addition, we here propose a role for large aggregates in the increased IgE-cross-linking capacity of individual allergens.
    Chapter 5 describes the effect of glycation on the immunoreactivity and basophil degranulation capacity of Cor a 11, the 7S globulin from hazelnut (and thus a homologue of Ara h 1). Three processing methods (heating at low moisture content at 37, 60 and 145°C) resulted in proteins with increasing degrees of glycation. Glycation at 37°C did not influence the specific IgG or IgE binding, while both were decreased after heating at 60°C and 145°C. However, heating at 145°C in the absence or presence of glucose resulting in the formation of aggregated structures, increased the basophil degranulation capacity of Cor a 11 using sera high in Cor a 11 specific IgE, but not when using sera from peanut allergic patients low in Cor a 11 specific IgE. Therefore, this study besides showing the importance of the use of a combination of tests also indicated the importance of using well-characterized sera as a source of IgE.
    In Chapter 6 we focused on the clinical features of all our clinically well-defined peanut allergic patients of which immune cells and sera were used for the previously described studies. In addition, soy allergic patients were included and an extensive IgE profile was determined for all patients. Gly m 4 (Bet v 1 homologue from soy) sensitization was suggested to be an important indicator of severe soy allergy in the soy allergic patients, while in peanut allergic patients sensitization to allergens from soy and pea extract nor Gly m 5 and 6 was found to have a good diagnostic specificity. This is likely due to the presence of clinically non-relevant cross-reactivity between peanut-specific IgE and homologues soy and pea components.

    Section 2: Immunomodulation by Lactobacillus strains
    In the first in vitro study, described in Chapter 7, initially 51 Lactobacillus strains were screened of which 8 were selected and tested for their immunomodulating effects on peripheral blood mononuclear cells (PBMC) of healthy donors. All tested Lactobacillus strains were capable of inducing the production of IL-1β, IL-10, IFN-γ and TNF-α. Clear strain-specific effects were observed with L. plantarum strains showing significantly higher induction capacity of IFN-γ, IL-12 and TNF-α compared with L. acidophilus strains. We therefore concluded that especially L. plantarum strains are promising candidates in IgE-mediated allergy by their stimulation potential of the T-cell response toward a putative Th1 response.
    As healthy subjects, in contrast to allergic individuals, are assumed to finely regulate the Th1/Th2 balance by inducing sufficient Treg cell activity, immunomodulatory effects of six selected Lactobacillus strains were investigated on PBMC of pollen-allergic patients in Chapter 8. All strains could modulate PBMC to induce innate cytokine production and in addition, all strains had the ability to repress IL-13 production. Again a differential effect on IFN-γ and IL-12 induction was observed. In addition, one strain could extensively suppress proliferation induced by anti-CD3/anti-CD28 stimulation. Specific strains that were able to suppress the Th2 cytokine induction and induce Th1 cytokines might be beneficial for allergic patients.
    Effects found in vitro cannot directly be extrapolated to in vivo and therefore, in Chapter 9, we performed an in vivo screening including five Lactobacillus strains. Blood samples were collected before and after a 4-week intervention with probiotics from all 62 birch-pollen-allergic patients included. Four strains caused a decrease in birch-pollen-specific IgE and for one specific strain this coincided with significant decreases in IL-5 and IL-13 and an increase in IL-10 production by anti-CD3/anti-CD28 stimulated PBMC cultures and might therefore have the potential to alleviate seasonal allergy symptoms.
    The last chapter, Chapter 10, gives an overview of the most important results of this thesis and discusses the research limitations and future research perspectives. We hypothesize the role of protein aggregation in allergenicity and we elaborate on the importance of a proper stepwise approach to realize selection of a proper lactic acid strain for in vivo human testing.
    In conclusion, this thesis showed that processing effects can have profound and specific effects on the structure and the allergenicity of relevant allergens. However, to test putative effects on allergenicity, IgE-binding tests only are not sufficient and mediator release assays are important to include, particularly when testing aggregated proteins. These results might have consequences for the proper diagnosis of food allergy in daily practice. Finally, as effects of lactic acid bacteria are strain specific, a proper pre-selection of candidate strains is important to choose the most promising strains for clinical testing. In our in vivo screening, one strain, L. plantarum CBS125632, was found to be promising because of its desired immunomodulatory activity to test in a follow-up trial to reduce symptoms of birch-pollen allergy.

    Immunomodulation by diet : individual differences in sensitivity in layer hens
    Adriaansen-Tennekes, R. - \ 2009
    Wageningen University. Promotor(en): Huub Savelkoul; Bas Kemp, co-promotor(en): Henk Parmentier. - [S.l. : S.n. - ISBN 9789085855064 - 223
    hennen - pluimvee - immunomodulatoren - immunotherapie - pluimveevoeding - lijnen - hens - poultry - immunomodulators - immunotherapy - poultry feeding - lines
    Enhancing relevant immunity of production animals to achieve more
    robust animals is receiving more and more attention. Several epidemics have
    hit production animals recently and with devastating consequences, but enhancing
    diseases resistance increasingly provides new opportunities. Furthermore,
    welfare and health of production animals is becoming a more and
    more consumer driven topic. Several routes are being used to approach the
    possibility of enhancing immunity such as selective breeding, enriched and
    altered housing conditions, vaccination programs, diet supplementation with
    immune stimulating components, and other management procedures. Disease
    susceptibility has been shown to be related to stress reactivity, which in turn
    is related to differences in HPA axis reactivity. Interestingly, independent of
    selection criteria used, the extremes of various selection procedures result in
    a recurrent dichotomy in HPA axis reactivity, either being hyperresponsive
    or hyporesponsive to stress. Animals with a hyperresponsive HPA axis show
    greater environmental sensitivity, while the hyporeactive animals are more
    intrinsically regulated. Often, research on immunomodulation is performed
    with compromised animals and/or exaggerated supplementation of dietary
    components in one generation of animals, but epigenetics by definition seems
    to be the mechanism for mothers to prepare their offspring for the environment
    they will be born into. Enhancing immunity through normal diet in uncompromised
    animals is rarely investigated, let alone over generations. In this
    thesis the aim was to induce immunomodulation through diet in selection lines
    of chicken that have previously been selected on their antibody response to
    sheep red blood cells over two generations of chicken. First, potential HPA
    axis differences were examined in these selection lines to establish their environmental
    sensitivity, whereafter immunomodulation through normal diet
    was investigated in humoral and cellular parameters of immunity. As humoral
    immunocompentence was not easily modulated, an immune trigger was
    used to detect potential differences in humoral reactivity. The selection lines
    showed differential sensitivity to immunomodulation by diet in both generations,
    suggesting that adaptation to environmental factors may be a line-specific
    (genetically based) process, with differential neuroendocrine regulation.
    Most interestingly, the second generation showed effects of the diets in all the
    selection lines, albeit in different manners. It is concluded that normal diet can
    cause immunomodulation, mainly in animals with hyper HPA axis reactivity,
    and that introducing such practices may be more beneficial when mothers are
    treated, as all offspring showed immunomodulation, irrespective of selection line. While genetic background and/or epigenetic processes on neuroendocrine
    and immune regulation of the individual form the framework wherein individual
    immunomodulation by diet can take place, environmental conditions
    determine if the modulation is beneficial or not.
    A multidisciplinary study of allergy : mouse models, immune modulation and lifestyle
    Jeurink, P.V. - \ 2008
    Wageningen University. Promotor(en): Huub Savelkoul; Gerrit Antonides, co-promotor(en): Johan van Ophem; Harry Wichers. - S.l. : S.n. - ISBN 9789085049616 - 275
    allergieën - immunotherapie - levensstijl - diermodellen - antigenen - t cellen - cytokinen - immuniteitsreactie - immuniteit - immunologie - allergies - immunotherapy - lifestyle - animal models - antigens - t lymphocytes - cytokines - immune response - immunity - immunology
    Allergic diseases affect a substantial part of the global population. Although extensive studies have elucidated the allergic mechanism, no conclusive answer has yet been found that will prevent the onset of an allergic disease. Literature suggests that no single factor like a gene mutation, environmental factor or lifestyle component can be hold accountable for the allergic cascade. Therefore, the main goal of this research project was to use a multidiscipli¬nary approach to allergies, by combining information on the genetic components, lifestyles and in vivo and in vitro assessment of the immune cells involved in allergy.
    The accomplishment of this multidisciplinary goal required knowledge on the genetic factors involved in the immunopathology of allergic diseases, but also immunological and cell biological knowledge. In addition, we investigated the influence of environmental factors on the allergic response which also required knowledge on sociology and economics to assess involved lifestyle factors. Within the multidisciplinary research areas, allergic responses are studied at multiple levels. For example, the genetic differences can be studied by means of mice with different genetic backgrounds (BALB/c, STS/A, C57BL/6) or in knock-out (CD4 or CD8 knock-out) or transgenic (IL-5 transgenic) mice. These differences in the genetic background on their turn have an effect on the expression of the allergic disease characteristics. Examples of the assessed allergic characteristics comprise antigen-presentation by specialized antigen-presenting cells, the presence of T helper 2 cells, the involvement of Th2 produced cytokines like IL-4 and IL-5, and the isotype switching of B cells towards allergen-specific IgE. Alterations of the allergic characteristics were studied by the use of in vitro cultures of human peripheral blood mononuclear cells (PBMC) that display all above mentioned characteristics when they are properly isolated, cryopreserved and cultured. These alterations were elicited by the use of heat-treatment of allergens or the exposure to fungal derived proteins or polysaccharides. Taken together, these different levels within the allergic individual can on their turn be influenced by environmental and nutritional factors. To study this, lifestyle factors have been assessed by the use of a personalized internet-based questionnaire and these data were thereafter linked to allergen-specific immunoglobulin levels. To further stress the importance of multilevel research within a multidisciplinary study, a more detailed description of the separate chapters within this thesis are combined with their major results, and finalized with future perspectives.
    From phage display to plant expression: Fulfilling prerequisites for chicken oral immunotherapy against coccidiosis
    Wieland, W.H. - \ 2004
    Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): Arjen Schots; D.V. Orzaéz Calatayud. - Wageningen : S.n. - ISBN 9789085040736 - 132
    kippen - coccidiose - immunotherapie - iga - antilichamen - transgene planten - biotechnologie - immunisatie - immuniteit - immunologie - fowls - coccidiosis - immunotherapy - iga - antibodies - transgenic plants - biotechnology - immunization - immunity - immunology
    The frequency and spectrum of infections with pathogens harbouring resistance to antibiotics and other drugs has dramatically increased over the last years. One of the main causes is the extensive use of antibiotics and other drugs in human and veterinary medicine. Parasites, such as Eimeria causing coccidiosis in chicken and pathogenic bacteria like Salmonellae and Campylobacter are examples of pathogens that acquired resistance. Furthermore, continuous use of drugs in diets of animals kept for human consumption increases the risk of residues in food, that possibly affect human health. These drawbacks of antimicrobial drugs have led to a demand for alternative treatments. In this thesis an alternative approach for prevention of coccidiosis in chicken is described, based on immune intervention by passively administered, plant produced, secretory IgA.As a first step, Eimeria binding IgA fragments were selected using the phage display technique. The phage display system was adapted to be used for the display of chicken Fab fragments. A newly constructed vector, named pChick3, allows straightforward cloning of chicken variable antibody domains in frame with the constant domains of the chicken light chain and the first constant domain of the IgA heavy chain. In a following step, new plant expression vectors were designed and constructed. Ten antibodies, selected from the chicken phage antibody library were then transferred to this vector system and subsequently expressed in planta as full size IgA. Upon expression of the ten selected anti- Eimeria antibodies, differences up to 500-fold in yield were observed. Several factors on translational or protein level could cause the observed differences: e.g. processing, stability, assembly and silencing. Two were tested (silencing, chain compatibility i.e. assembly) and both have an influence on the levels of expression. An explanation may be found in the combination of several factors. These observations lead to the conclusion that an extra in planta selection step is inevitable for successful integration of phage display and plant expression systems. Finally, the structure of the chicken polymeric immunoglobulin receptor was elucidated. In a fashion similar to its mammalian counterpart, this receptor transports IgA to the gut lumen forming secretory IgA. This complex is highly stable, and IgA is protected against degradation by proteases or pH-fluctuation, which makes secretory IgA the most suitable form for passive immunization. Interestingly, the chicken SC comprises only four immunoglobulin-like domains compared to five found in mammals. Thus, an integrated system for both selection and expression of immunoglobulins was developed and with the final achievement of the production of Eimeria -specific secretory IgA in plants, the prerequisites for chicken passive immune therapy were fulfilled.
    Besmettelijke dierziekten: geintegreerd aanpakken
    Hanekamp, W. ; Snoep, J. - \ 1998
    Praktijkonderzoek Rundvee, Schapen en Paarden. Praktijkonderzoek 11 (1998)4. - ISSN 1386-8470 - p. 25 - 29.
    diergeneeskunde - melkvee - melkveehouderij - infectieziekten - vaccinatie - immunisatie - immunotherapie - vaccins - preventieve geneeskunde - ziektepreventie - preventie - diergezondheid - hygiëne - ziekteoverdracht - dieren - zoönosen - veterinary science - dairy cattle - dairy farming - infectious diseases - vaccination - immunization - immunotherapy - vaccines - preventive medicine - disease prevention - prevention - animal health - hygiene - disease transmission - animals - zoonoses
    Omdat het dier de belangrijkste besmettingsbron is, is aankoop van vee een grote risicofactor en dienen mensen die veel in contact komen met dieren bedrijfskleding aan te trekken.
    Immunological aspects of oral vaccination in fish
    Joosten, P.H.M. - \ 1997
    Agricultural University. Promotor(en): W.B. van Muiswinkel; J.H.W.M. Rombout. - S.l. : Joosten - ISBN 9789054856986 - 134
    vissen - diergeneeskunde - vaccinatie - immunisatie - immunotherapie - vaccins - geneesmiddelen - farmacologie - toedieningswijzen - reticulo-endotheliaal systeem - antilichamen - immunoglobulinen - immunologische technieken - elisa - immunochemie - fishes - veterinary science - vaccination - immunization - immunotherapy - vaccines - drugs - pharmacology - application methods - reticuloendothelial system - antibodies - immunoglobulins - immunological techniques - elisa - immunochemistry

    In this thesis immunological consequences of oral vaccination in fish have been described. The efficacy of oral vaccination can be increased by protection of the antigen against degradation in the foregut, in order to reach the hindgut in sufficient quantities for uptake and subsequent activation of the mucosal and systemic immune system. Using a specific monoclonal antibody, in addition to mucosal B cells, a distinct mucosal T cell population was demonstrated, which may play an important role in local immunity. Furthermore, two approaches to protect antigens against digestive degradation are described: bioencapsulation and microencapsulation. For the first approach antigen is encapsulated in living food, and subsequently fed to juvenile carp and seabream. In carp, oral vaccination at 2 and 4 weeks old resulted in immunological tolerance. However, in older carp (8 weeks old) and seabream (8 and 10 weeks old), immunological memory was induced. It can be concluded that oral vaccination with bioencapsulated bacterial antigens is effective for oral vaccination of juvenile fish, when applied at the right age. For microencapsulation an alginate microparticle system was studied, which may be more suitable for vaccination of older fish. The supernatant appeared to be the most immunogenic fraction of a bacterin, which is taken up in the hindgut and evokes best memory formation. This fraction was encapsulated in alginate microparticles and fed to adult carp and trout. Different microparticle preparations, with respect to release time and antigen concentration, were needed for immunological memory formation in each fish species. Therefore, oral vaccination with bacterial antigens in alginate microparticles can be effective. Oral tolerance against protein antigens was demonstrated in animals fed with ferritin or recombinant VHS G protein. However, the immune response to ovalbumin appeared to be carp strain dependent. A carp strain that produced specific antibodies after injection with OVA was selected and repeated feeding of OVA, prior to injection, resulted in increased antibody titres in serum. Oral tolerance induction in fish therefore appeared to depend on the protein and possibly also on genetic factors.

    Computer simulation to support policy-making in Aujeszky's disease control
    Buijtels, J.A.A.M. - \ 1997
    Agricultural University. Promotor(en): A.A. Dijkhuizen; R.B.M. Huirne; M.C.M. de Jong. - S.l. : Buijtels - ISBN 9789054856528 - 187
    ziekte van marek - ziekte van aujeszky - varkens - diergeneeskunde - vaccinatie - immunisatie - immunotherapie - vaccins - investering - kosten-batenanalyse - economische evaluatie - computersimulatie - simulatie - simulatiemodellen - dynamisch programmeren - markov-processen - economie - gebruikswaarde - economische impact - nederland - marek's disease - aujeszky's disease - pigs - veterinary science - vaccination - immunization - immunotherapy - vaccines - investment - cost benefit analysis - economic evaluation - computer simulation - simulation - simulation models - dynamic programming - markov processes - economics - use value - economic impact - netherlands

    Aujeszky's disease is a contagious viral disease that affects the central nervous system of pigs. Several eradication programs or measures are available, each of them providing different results. Determining the preferred strategy is to a large extent a matter of economic consideration.

    Under the EU rules, countries or regions that are Aujeszky-free can ban imports of breeding animals carrying antibodies of the disease; movements to Aujeszky-free areas from other areas of both breeding and rearing pigs are subject to strict conditions and controls, which differ depending on whether or not the area of origin has an EU-approved eradication program. If important import destinations achieve disease-free status, exporting countries that have failed to eradicate the disease will be severely penalized. Therefore, sterner demands are to be expected considering control and eradication of Aujeszky's disease in the Netherlands in the future. To meet these demands, the objective of this study was to develop a computer simulation environment in which "what-if' scenarios can be performed to explore the epidemiological and economic effects of different Aujeszky's disease control programs. The model can be used to support the choice of the optimal eradication program under various conditions, in particular from an epidemiological and economic point of view.

    First, a flexible economic framework to evaluate Aujeszky's disease eradication programs was developed, and illustrated with an example (Chapter 2). The framework has four elements: changes in percentage of infectious herds, changes in product quantities, changes in product prices and economic integration. Each of these elements is defined as a separate module in the simulation model and has its own input and output data, depending on the control strategy under consideration. With these elements all epidemiological and economic aspects of the disease can be monitored over time.

    In an illustrative example, probability distributions of the number of infectious herds corresponding to each control strategy were compared and the optimal strategy was chosen, according to the risk attitude of the decision maker. The framework can be considered a standardized approach in comparing and selecting animal health control strategies by integrating technical and economic data and principles.

    To obtain epidemiological information with respect to the control of Aujeszky's disease virus, an epidemiological state-transition simulation model was constructed to evaluate the spread of the virus (Chapter 3). In the model, the population of herds in the Netherlands is subdivided into four herd types: great-grandparent stock+multiplier, rearing, farrowing and fattening. Every time step, each herd is in one of 32 states per herd type. The states are based on (1) the reproduction ratio R ind , which is the number of individuals infected by one infectious individual, (2) the prevalence for each value of R ind and (3) the expected number of infectious animals in an infectious herd within each prevalence range of the herds. The different values Of R ind are based as much as possible on field data and experiments, where different vaccination strategies were applied.

    The transition matrix with the probabilities of every possible transition from one state to another was calculated on a weekly base. With this matrix the distribution of herds over states from week to week was derived. To include the non-linearity of the transmission process, the transmission probabilities from non-infectious to either non-infectious or infectious were developed such that they depend on the state vector itself The fraction of herds that becomes infectious equals one minus the fraction of herds that has not been infected by the virus emitted by infectious herds.

    Calculations revealed that infection in the Dutch pig population would not disappear without vaccination, nor with a vaccination scheme in which sows were vaccinated less than 3 times per year and fattening pigs once per cycle (Chapter 4). The infection, however, would be eradicated within 2 to 3 years, if sows were vaccinated 3 or 4 times per year and fattening pigs twice per cycle. The outcome turned out to be sensitive to the impact of other than animal contacts on the number of new effective virus introductions per time unit.

    The structure of the production pyramid and herd density in the affected regions were other important factors which influenced the course of infection. To examine the impact of these factors the total number of herds in the Netherlands were further subdivided into four regions (North, East, West-Middle, South).

    Outcomes showed that the percentage of infectious herds in equilibrium was highest for rearing herds (76.3%) and lowest for great-grandparent stock+multiplier herds (20.0%) if no vaccination was done. The herd type "fattening" had more impact on the effectivity of the different vaccination strategies than the herd type "farrowing". This difference is becoming less if more intensive vaccination strategies are applied. Besides the difference in herd type, also herd density and the percentage of non-vaccinated herds were an important factor in the eradication process.

    After simulating these epidemiological characteristics of Aujeszky's disease virus, market outcomes and pig producers' returns were simulated under different scenarios with respect to closure of export markets for live piglets and fattened pigs (Chapter 5). If the Netherlands fails to eradicate Aujeszky's disease before its trading partners in these markets, live piglet exports would be banned, reducing industry revenue and export earnings by about 9% and 10% respectively in the medium term. If exports of live fattened pigs are also banned, the reductions are 26 and 32% respectively. The piglet-producing sector would be more
    severely affected than the fattening sector. The model also showed that, if export markets for carcasses were also to close for an unspecified food safety reason, capacity of the industry would fall over 50%.

    Lastly four control strategies to eradicate Aujeszky's disease virus in the Netherlands were compared epidemiologically and economically (Chapter 6). Vaccination decreased the number of cases per production loss. The decrease was largest if vaccination strategy changed from "no vaccination" to the less intensive vaccination. Extra vaccinations under more intensive vaccination strategies, however, still had impact. The attendant costs were highest per dead animal (especially for gilts) and per abortion. Growth delay of gilts and piglets turned out to be of minor importance.

    The sales distribution on the piglet markets (import, export and on the domestic markets) was particularly influenced by vaccination, but the decreases in revenues were only less than 4.3%. The only exception was the number of piglets and live animals that were imported into the Netherlands, which decreased by more than 15% and about 9% respectively. The accompanying revenues from piglets and fattened pigs were highest if "no vaccination" was done. Compared with the revenue in this strategy, this difference is greatest on the piglet market, as the decrease in revenue was about 3.6%, while the decrease was about 0.55% on the market of fattened pigs.

    According to the resulting present values over a period of 10 years, "no vaccination" is economically the best solution only if no trade restrictions are to be expected. Economically speaking, however, the most intensive vaccination strategy should be applied, if an export ban of two years on live animals to, for instance, Germany is expected within 10 years after the start of the vaccination strategy. A prolonged export ban makes this strategy even more favourable. From an economic point of view intermediate vaccination strategies are never preferred.

    The main conclusions of this thesis are:
    - State-transition simulation proves to be an appropriate method to evaluate transmission of Aujeszky's disease virus. The epidemiological information obtained can well be used in economic evaluation of different control strategies.
    - Aujeszky's disease is only eradicated in the Netherlands if the most intensive vaccination strategy (≥3 times per year) is applied for breeding sows, and fattening pigs are vaccinated at least once per cycle.
    - If applying the most intensive vaccination strategy, it takes about 200 weeks for an average herd to become non-infectious.
    - The relative impact of other than animal contacts on the number of new virus introductions increases from 4% to 98%, if the vaccination strategy is changed from "no vaccination" to the most intensive vaccination program.
    - Subdivision of the total population into herd types and regions is important to enhance insight into transmission of infection in the pig population and to support decision making at regional level.
    - Price equilibrium models can well estimate the short-term changes in prices as well as those in the medium term. To accomplish this, it is of importance that sufficient historical data about quantities, prices and the infections occurred are available to estimate the required parameters accurately. A monthly data-set of about 10 years turned out to be sufficient.
    - Direct production losses from Aujeszky's disease virus are less than 6% of the vaccination costs when vaccination is carried out. More than 80% of these losses are caused by growth delay of fattening pigs.
    - The most intensive vaccination strategy (i.e., sows are vaccinated 3 or 4 times per year and fattening and rearing pigs twice per cycle) is economically preferred if an export ban on part of the live animals is expected during at least 2 years within 10 years after the start of the vaccination program. If this is not to be expected then "no vaccination" turns out to be the best strategy. The risk of an export ban on live animals should justify the eradication of the virus from the population.
    - For the current situation in the Netherlands it is economically preferred to start blood sampling all sows and remove the gE-positive animals instead of continuing vaccination, provided that the additional risk of new introductions of the virus is sufficiently limited.

    Effect van moment van vlekziektevaccinatie op het interval spenen-bronst
    Riel, J. van; Vesseur, P. - \ 1996
    Praktijkonderzoek varkenshouderij 10 (1996)2. - ISSN 1382-0346 - p. 5 - 5.
    erysipelothrix - vruchtbaarheid - immunisatie - immunotherapie - infectieziekten - oestrus - biggen - zeugen - vaccinatie - vaccins - diergeneeskunde - spenen - erysipelothrix - fertility - immunization - immunotherapy - infectious diseases - oestrus - piglets - sows - vaccination - vaccines - veterinary science - weaning
    In de praktijk zijn er vragen over de gevolgen van vlekziektevaccinaties voor de vruchtbaarheid. Een oriënterende studie heeft aanwijzingen opgeleverd dat enten in de eerste week van de lactatie een negatieve invloed heeft op het interval spenen-bronst.
    Een betere diergezondheid door beheersen en vrijwaren van dierziekten!
    Swinkels, H. ; Kemp, B. ; Vesseur, P. - \ 1994
    Praktijkonderzoek varkenshouderij 8 (1994)4. - ISSN 1382-0346 - p. 6 - 8.
    diergezondheid - huisvesting, dieren - ziektebestrijding - bedrijfssystemen - gezondheid - hygiëne - immunisatie - immunotherapie - varkens - screenen - vaccinatie - vaccins - diergeneeskunde - animal health - animal housing - disease control - farming systems - health - hygiene - immunization - immunotherapy - pigs - screening - vaccination - vaccines - veterinary science
    Het is echter zo dat het klant is koning principe ook van kracht is in de varkenssector. Derhalve zullen de Nederlandse varkenshouders met het oog op behoud van de huidige exportpositie moeten blijven streven naar verbetering van de kwaliteit van het eindproduct.
    Her-entingen tegen Pseudo Vogelpest (NCD) op 'Het Spelderholt'
    Voorst, A. van - \ 1993
    Praktijkonderzoek voor de Pluimveehouderij 4 (1993)3. - ISSN 0924-9087 - p. 4 - 6.
    kippen - immunisatie - immunotherapie - pseudovogelpest - pluimvee - vaccinatie - vaccins - diergeneeskunde - fowls - immunization - immunotherapy - newcastle disease - poultry - vaccination - vaccines - veterinary science
    Pseudo Vogelpest of NCD is een gevreesde virusziekte, waartegen een entverplichting geldt. Na het uitbreken van de ziekte in het zuiden van Nederland is al het volwassen pluimvee op Het Spelderholt opnieuw geënt.
    Geen effect aujeszky-enting op de technische resultaten
    Bakker, J. - \ 1991
    Praktijkonderzoek varkenshouderij 5 (1991)4. - ISSN 1382-0346 - p. 6 - 7.
    ziekte van Aujeszky - agrarische bedrijfsvoering - immunisatie - immunotherapie - arbeid (werk) - ziekte van Marek - varkens - vaccinatie - vaccins - diergeneeskunde - werkplanning - Aujeszky's disease - farm management - immunization - immunotherapy - labour - Marek's disease - pigs - vaccination - vaccines - veterinary science - work planning
    Op dit moment worden alleen gl-negatieve vaccins gebruikt. Dit om onderscheid te kunnen maken tussen de antistoffen gemaakt door het vaccin en het veldvirus, dat de ziekte van Aujeszky veroorzaakt. Het onderzoek is toen uitgevoerd op het Varkensproefbedrijf te Sterksel om de gevolgen van de vaccinatie op de technische resultaten na te gaan op een bedrijf, waarop geen verschijnselen van de ziekte van Aujeszky voorkomen. Er bleek geen effect van de vaccinatie op de technische resultaten te kunnen worden aangetoond.
    E. Coli K99 specific B-cell formation in lymphoid tissues of cattle and its significance for bovine monoclonal antibody production : some preliminary results
    Wissink, H.C.G. ; Veerhuis, R. ; Booman, P. - \ 1989
    Zeist : IVO (IVO - report B-321) - 22
    antilichamen - antigenen - rundvee - hybridoma's - immunisatie - immunotherapie - monoclonale antilichamen - vaccinatie - vaccins - diergeneeskunde - antibodies - antigens - cattle - hybridomas - immunization - immunotherapy - monoclonal antibodies - vaccination - vaccines - veterinary science
    Monoclonal antibodies in animal production : their use in diagnostics and passive immunization
    Booman, P. - \ 1989
    Agricultural University. Promotor(en): C.C. Oosterlee; E.J. Ruitenberg. - S.l. : Booman - 149
    zoötechniek - monoclonale antilichamen - hybridoma's - diergeneeskunde - vaccinatie - immunisatie - immunotherapie - vaccins - obstetrie - zwangerschap - immunologische technieken - elisa - zootechny - monoclonal antibodies - hybridomas - veterinary science - vaccination - immunization - immunotherapy - vaccines - obstetrics - pregnancy - immunological techniques - elisa
    One of the landmarks in immunology was the invention and development of monoclonal antibody-secreting hybridomas by Milstein and his coworkers. The enormous promise of monoclonal antibody technology, which became apparent soon after its discovery, may explain the unusual speed with which monoclonal antibodies have been applied to biological and medical sciences.

    In animal production monoclonal antibodies are increasingly finding application in the areas of diagnostics, passive immunization and fundamental research. In Chapter 1 of this thesis some applications of monoclonal antibodies within these areas, with emphasis on reproduction, are discussed. It has been concluded that the particular advantages of monoclonal antibodies can firstly and most easily be shown in immunodiagnosis. Once a hybridoma producing a monoclonal antibody appropriate for a particular application has been obtained, large amounts of a homogeneous and reliable reagent are available for as long as they are needed. As ingredients in test kits, monoclonal antibodies have rapidly replaced conventional polyclonal antibodies.

    An example of a typical diagnostic test in animal production in which monoclonal antibodies might be used is the milk-progesterone test for confirmation of oestrus and pregnancy diagnosis in cattle. In Chapter 2 the production and characterization of monoclonal antibodies against progesterone have been described in order to standardize an enzyme immunoassay for milk-progesterone. The antibodies differed considerably in their binding affinity for progesterone and showed distinct specificities for a variety of steroids. Results show that, although the technique of monoclonal antibody production selects antibodies specific for a single antigenic determinant, this does not always preclude the possibility of cross-reactivity. Moreover, most antibodies produced have affinities far below the corresponding conventional antisera, as has been discussed in Chapter 1. The monoclonal antibody with the highest association constant and relatively good specificity did not detect progesterone with any greater sensitivity than the conventional polyclonal sera. However, since monoclonal antibodies avoid the dependency upon animals producing high quality antisera and improve test standardization, a commercially available rapid progesterone cow-side test has been designed based on the monoclonal antibody with the best characteristics.

    Results of Chapter 2 underline the necessity to evaluate carefully the need of producing monoclonal instead of polyclonal antibodies for a given antigen, as considerable time and effort are required to obtain a monoclonal antibody with suitable properties. Preselection of antibodies on affinity and specificity in an early stage makes the monoclonal antibody technology more efficacious. In our laboratory a cocktail of related steroids was used to enable such an early selection of antibodies against either oestrone or oestrone sulphate. Testing the replacement of oestrone, coupled to horse- radish peroxidase, from the antibodies made it possible to produce high affinity monoclonal antibodies with nearly unique specificities in a relatively short time. Experiments are in progress to develop a test for pregnancy diagnosis in pigs in faecal samples based on those antibodies.

    Another application in diagnostics is the use of monoclonal antibodies against a male-specific protein, the H-Y antigen, for sexing bovine embryos before implantation. H-Y is a weak antigen and immunization with H-Y antigen in an inbred strain of mice usually results in production of low titered, low affinity antisera. Because only a low percentage of mice has a good antibody response and their sera run out quickly, monoclonal antibodies were produced (Chapter 3). Male specificity of the antibodies was tested in a variety of assays including enzyme immunoassays based on various sources of soluble H-Y and indirect immunofluorescence assays based on binding of the antibodies to H-Y antigen on the cell surface of male and female cells obtained from a number of tissues and species. Several monoclonal antibodies appeared to be positive in all assays tested, suggesting that the molecule conferring the H-Y antigenicity lacks speciesspecificity and appears to be identical for soluble and membrane-bound H-Y antigen.

    The most promising monoclonal antibodies reactive with the H-Y antigen have been evaluated for their efficiency in sexing Day 7 bovine preimplantation embryos (Chapter 4). Although in an indirect immunofluorescence assay a discrimination between male and female embryos could be made, evaluation of the staining patterns was fairly subjective because of non-specific binding of the monoclonal antibodies to the embryonic cells. After modifying the technique in order to reduce non-specific binding, the number of false positives after sexing under these conditions was greatly reduced, which suggests that the monoclonal antibodies detect a male-specific antigen. It was concluded that the occurrence of false-negative embryos might be caused by a weak expression of the H-Y antigen and/or a low affinity of the monoclonal antibody for bovine cell-surface H-Y antigen. The antibodies used in our experiments had been selected on basis of their binding to both soluble and cell-surface H-Y antigen originating from different sources. Currently, monoclonal antibodies which are selected on high affinity for protein structural determinants on bovine cell-surface H-Y antigen are being produced in order to be used in a highly discriminating sensitive fluorescence assay.

    In Chapter 1 has been discussed that it will take some time to fully realize the potential of monoclonal antibodies in the area of passive immunization or immunomodulation. The production costs are still relatively high and the reaction of the animal to the injected antibodies may limit the effects of passive immunization. Some such limitations are illustrated in the experiments in which anti- progesterone murine monoclonal antibodies were administered to cyclic pigs (Chapter 5). Intravenous injection of increasing amounts of anti- progesterone antibodies resulted in a concomitant rise in levels of antibody-bound progesterone. At the same time a significant rise in plasma concentrations of total progesterone was observed immediately after administration of higher doses of antibodies. Therefore, the net effect of progesterone binding by the antibody was relatively small and more or less independent of the quantities of antibody administered. It has been suggested that animals maintain adequate levels of free progesterone in their circulation by resorption of progesterone from a pool present in body tissues. The effects of administration of anti-progesterone antibodies on plasma levels of free progesterone are, however, not only influenced by the proposed compensating effect of resorption, but also by the possible initiation of a humoral response of the pigs to the injected antibodies. In the experiments described in Chapter 5 it is shown that a minimum dose of 32 mg anti-progesterone antibody elicited an antimouse response after the first injection, having an neutralizing effect on the anti-progesterone monoclonal antibodies administered with the second injection. When smaller quantities of antibody were used, an anti-mouse reaction was detected after the second or third injection.

    From reports concerning the therapeutic use of monoclonal antibodies in man it is known that such an immune response may be directed partially against the isotypic determinants, partially against the idiotypic determinants of the murine antibodies administered. Although anti- idiotypic responses cannot be excluded as a complicating factor, homologous antibodies might offer some advantages over their murine counterparts in terms of effectiveness for passive immunization.

    In Chapter 6 the construction of a bovine-murine heteromyeloma cell line to be used for the production of bovine monoclonal antibodies has been described. It was anticipated that a heteromyeloma would retain the superior fusion characteristics of the mouse myeloma cells and, because of the presence of bovine chromosomes, would be better able to support stable bovine antibody production than interspecies hybridomas produced by fusing mouse myeloma cells with bovine lymphocytes. First (bovine-murine) and second generation (bovine-[bovine-murine]) fusion partners were compared for fusion efficiency and the generated number of antigen- specific antibody-producing clones. In addition, the optimal time- interval between boosting and harvesting of the lymphocytes for fusion and the source of lymphocytes was studied. It could be concluded that fusion of bovine lymph node cells with the second generation heteromyelomas on Day 7 after the final booster injection resulted in the largest number of specific antibody-producing clones. Experiments with a third generation bovine-murine heteromyeloma cell line indicated that fusion efficiency could be further improved (unpublished data). Studies with anti-rotavirus and anti-pregnant mare serum gonadotrophin (PMSG) bovine monoclonal antibodies, produced with the second generation fusion partners, indicate that the heteromyeloma cell lines are very useful for the production of bovine monoclonal antibodies.

    The availability of such bovine monoclonal antibodies offers the possibility to compare the efficacy of homologous and heterologous antibodies in cattle after repeated passive immunization. The in vivo immunoneutralization of PMSG by murine and bovine monoclonal antibodies was chosen as a model for such a study (Chapter 7). Results indicate that repeated injection of murine monoclonal antibodies against PMSG (mMCA) alone did not, or only to a small degree, elicit an anti-mouse immune response. The simultaneous administration of mMCA and PMSG resulted in relatively high levels of anti-mouse antibodies after the second injection, leading to a decrease in neutralizing activity of mMCA. The results suggest that the neutralizing activity of mMCA is inhibited more by anti- idiotypic than by anti-isotypic antibodies against mMCA. After repeated administration of the bovine monoclonal antibody against PMSG (bMCA), either alone or in combination with PMSG, no anti-bMCA antibodies could be detected. In addition, no change in plasma levels of bMCA and PMSG, compared with levels after the first injection, was observed. Although it has to be confirmed by further experiments whether our findings can be generalized, the present results suggest that for repeated passive immunization in cattle homologous antibodies are to be preferred above heterologous antibodies. As far as we can see now it is necessary to evaluate carefully the need to produce homologous or heterologous antibodies, dependent on the amounts of antibody to be administered and the number of treatments.

    In conclusion, the potential of monoclonal antibodies for diagnostic use, therapy or fundamental research, discussed in Chapter 1, together with the results presented in this thesis indicate that the monoclonal antibody technology will have an important impact on the improvement of animal quality and productivity.

    Development of a vaccine for the prevention of hemorrhagic enteritis in turkeys
    Hurk, J.V.J.M. van den - \ 1988
    Agricultural University. Promotor(en): R.W. Goldbach, co-promotor(en): D. Peters. - S.l. : Van den Hurk - 134
    diergeneeskunde - kalkoenen - enteritis - gastro-enteritis - adenoviridae - virusziekten - vaccinatie - immunisatie - immunotherapie - vaccins - serologie - serologische overzichten - taxonomie - veterinary science - turkeys - enteritis - gastroenteritis - adenoviridae - viral diseases - vaccination - immunization - immunotherapy - vaccines - serology - serological surveys - taxonomy
    Hemorrhagic enteritis (HE) in turkeys is an acute infectious disease characterized by depression, intestinal bleeding, and death. HE occurs worldwide affecting 6 to 12 week-old turkeys and lasting 4 to 6 days. This economically important disease is caused by hemorrhagic enteritis virus (HEV), a turkey adenovirus which is tentatively classified as a member of the group II avian adenoviruses. Serologically related HEV strains with marked differences in pathogenicity for turkeys have been described. Until recently, only 2 vaccines were available for the prevention of HE in turkeys. Both are live virus vaccines containing avirulent HEV (HEV-A) and both elicit protective immunity in turkeys. However, since the first vaccine is a crude extract prepared from spleens of turkeys infected with HEV-A, and the second vaccine is propagated in a transformed cell line contaminated with Marek's disease virus, their safety features are questionable.

    HEV is unique among the adenoviruses because it is not antigenically related with the mammalian or group I avian adenoviruses. Its classification as an adenovirus is based upon common physical, chemical, morphological and structural properties. An adenovirus is composed of 240 hexons and 12 pentons, outer capsid proteins which give the virus its characteristic icosahedral shape, capsid associated proteins, and core proteins associated with the double-stranded linear DNA genome with a molecular weight of 17 - 30 x 10 6. Until recently, HEV and its structural proteins had been poorly characterized due to the lack of a suitable invitro system for virus propagation. In summary, there was a need for an improved vaccine for HE in turkeys, and the development of a such a vaccine would be facilitated by the discovery of a cell type suitable for HEV replication and by a more basic knowledge of the virus itself.

    The major goal of the research described in this dissertation was the development and testing of a safe and efficient vaccine for HE in turkeys. In order to achieve this goal, a cell culture system for virus propagation as well as methods to measure virus replication invitro and protection in immunized birds had to be developed. In addition, the knowledge of virus and viral components had to be expanded.

    The development and application of sensitive and specific enzyme-linked immunosorbent assays (ELISAs) for the quantitation of HEV antibodies in turkey sera and HEV antigen in tissue extracts is described in Chapter 2. The presence and decline of maternal antibody titers in sera of poults and seroconversion and induction of protective antibody titers in turkeys following immunization with HEV-A were determined by ELISA (Chapters 2 and 6). The ELISA for the titration of antigen was used to monitor protection in turkeys following immunization with HEV-A and challenge with virulent HEV (HEV-V) (Chapter 6). A strong antigenic relationship between HEV-A and HEV-V was measured with both ELISAs.

    The characterization of both HEV-A and HEV-V and their structural proteins, purified from spleens of infected turkeys is described in the Chapters 3 and 4. The electron microscopic data on the size (72nm) and structure of the virion and its density in CsCl (ρ= 1.34 g/cm3 ), as well as the profile of the viral polypeptides in polyacrylamide gels showing molecular weights ranging from 96,000 to 9,500, justified the classification of HEV as an adenovirus. The major structural proteins were identified as hexon, penton, penton base, fiber, IIIa, and core proteins based on their structure observed by electron microscopy and/or recognition by specific antibodies. Free hexon and penton proteins, purified by immunoaffinity chromatography using monoclonal antibodies, had identical properties as their counterparts in the virus. The hexon was an important neutralizing antigen. The penton of HEV consisted of a single fiber attached to its penton base, a feature shared with the mammalian adenoviruses and the avian egg drop syndrome 1976 virus, but not with the fowl adenoviruses which have double fibers. In contrast to the many common properties of HEV-A and HEV-V, serological differences between the fibers of and differences in electrophoretic migration between the penton bases of both strains were observed. The IIIa, proteins of HEV and human adenovirus type 2 shared a common epitope. This is the first antigenic relationship detected between avian and mammalian adenoviruses.

    The propagation of HEV-A and HEV-V in turkey blood leukocyte cells is escribed in Chapter 5. The presence of HEV in the nuclei of non- adherent as well as in adherent cells was revealed by electron microscopy and by light microscopy, using a fluorescent antibody test. The non-adherent infected cells had the characteristics of immature mononuclear leukocytes while the adherent cells had monocyte-macrophage characteristics. HEV-A could be serially passed in turkey leukokcytes at least seven times. optimum conditions for virus propagation in turkey leukocyte cultures and harvest times were determined. HEV could not be produced in chicken leukocytes.

    HEV-A, propagated in turkey leukocyte cell cultures, was tested as a vaccine to prevent HE in turkeys in experimental and field trials (Chapter 6). Immunization of turkeys with live HEV-A resulted in protection against a challenge with HEV-V as measured by the serological response and the absence of clinical disease and HEV antigen in spleens. In the field trials, 19 out of 20 flocks seroconverted within 21 days after vaccination with live HEV-A distributed in the drinking water. The overall immune response of the turkeys in these flocks was 96%. Most importantly, neither clinical nor other adverse effects caused by HEV-A vaccination were observed in any of the vaccinated turkeys in the experimental and field trials. The optimum time of the vaccination of poults was determined in relation to interference with maternal antibodies.

    Active immunisation against somatostatin increases milk yield in goats
    Garssen, G.J. ; Welling, A.M.A.W. ; Spencer, G.S.G. - \ 1986
    Zeist : I.V.O. (I.V.O.-rapport B-288) - 22
    antilichamen - endocrinologie - geiten - hormonen - immunisatie - immunoglobulinen - immunotherapie - reticulo-endotheliaal systeem - somatotropine - vaccinatie - vaccins - diergeneeskunde - antibodies - endocrinology - goats - hormones - immunization - immunoglobulins - immunotherapy - reticuloendothelial system - somatotropin - vaccination - vaccines - veterinary science
    In dit onderzoek is nagegaan wat het effect is van actieve immunisatie tegen somatostatine op de melkproduktie van de geit, door 6 geiten, halverwege de dracht geimmuniseerd met een conjugaat van somatostatine en humaan alfa-glubuline, te vergelijken met 6 andere geiten van dezelfde jaargang met een vergelijkbare melkproduktie en gewicht die alleen met globuline waren geimmuniseerd. Somatostatine, een 14 aminozuren tellend peptide, is o.a. betrokken bij de regeling van de groeihormoon-afgifte door de hypofyse, waarop het remmend werkt
    The reaction of the immune system of fish to vaccination
    Lamers, C.H.J. - \ 1985
    Landbouwhogeschool Wageningen. Promotor(en): L.P.M. Timmermans, co-promotor(en): W.B. van Muiswinkel. - s.l. : S.n. - 255
    antilichamen - cyprinidae - vissen - immunisatie - immunoglobulinen - immunotherapie - reticulo-endotheliaal systeem - vaccinatie - vaccins - diergeneeskunde - antibodies - cyprinidae - fishes - immunization - immunoglobulins - immunotherapy - reticuloendothelial system - vaccination - vaccines - veterinary science

    The studies presented in this thesis deal with the effect of bacterial antigens of Yersinia ruckeri and Aeromonashydrophila on the immune system of carp. The antigens were administered by injection or by bath treatment. The effect on the immune system was studied by measuring the numbers of antibody forming cells (AFCs), the level of serum antibody and the processing of antigen in the lymphoid organs. The antigen dose and the formation of immunological memory were taken into account. Moreover, in view of oral vaccination, a study was carried out on the uptake and transport of macromolecules through the intestinal epithelial cells.

    Y. ruckeri O-antigen was very immunogenic in carp. Both i.m. and i.p. injection of antigen and direct immersion in antigen solution evoked distinct levels of AFCs and serum antibody (Appendix paper I). The height of the response was dependent on entry route; e.g. it was clearly lower after direct immersion. Contrary to the numbers of AFCs, which showed a fast decrease after a peak at day 10, serum antibody persisted for a long time, especially at the highest antigen dose. It was suggested that a long-term presence of antigen in the lymphoid organs, as observed by immunofluorescence, might account for this feature.

    Secondary antibody responses in carp injected or bathed in Y.ruckeri O-antigen gave indications for the formation of immunological memory on the first contact with the antigen for both priming routes. Highest secondary responses were obtained in animals in which antibody levels resulting from the priming had decreased to background levels (Appendix paper II).

    Upon i.m. injection of two A.hydrophila bacterins, formalin killed cells (F-A h ) and heat killed and disrupted cells (H-A h ), considerable serum antibody titers were found in carp. H-A h induced higher levels of antibody than F-A h , which in both cases persisted for more than 8 months (Appendix paper III). Whereas antigen dose clearly affected the height of the response, the peak day depended on the type of bacterin (day 14 and day 20 for all doses of H-A h and F-A h respectively). The effect of mixing the antigen with adjuvant found expression in a second increase of AFCs after a "normal" peak in the primary response, and a prolonged increase of serum antibody levels (Appendix paper VIII).

    Antisera raised against the two A.hydrophila b acterins showed different agglutinating properties (Appendix paper III). Antibody induced by F-A h was mainly directed to lipopolysaccharide (LPS), whereas with H-A h this was not the case. It was concluded that LPS is an important antigen of A. hydrophila. However, there is at least one other immunogenic component.

    Fractionated immune (anti F-A h ) and non-immune control sera were tested for immunoglobulin (Ig) by an Elisa and for agglutinating properties. It was shown that Ig was restricted to the first high molecular weight protein peak. In addition to the antibody in this peak also a non-Ig agglutinin was present in lower molecular weight fractions, probably a natural agglutinin.

    Memory formation was monitored by studying secondary responses upon a primary i.m. injection, carp developed memory to A.hydrophila bacterin (Appendix paper VI). The height of the secondary responses was directly correlated with the priming dose. Moreover, the dose of the booster injection determined the outcome of the formed memory; corresponding priming and boosting doses expressed the highest memory levels. The development of maximum memory took some months, and its presence was still demonstrable at 12 months. The low dose priming induced only a weak memory, which was limited in time.

    A single bath in A.hydrophila bacterin was not followed by the appearance of serum antibody. However, it did induce formation of memory, for a second bath resulted in clear secondary responses. This memory was maximum at 3 months after priming and was limited in time, for it was gone at 12 months. When a booster was given by i.m. injection instead of immersion, the induced memory was not expressed as a clear secondary response. This feature suggests the importance of local processes during the immune response after bath vaccination (Appendix paper V).

    In Appendix paper VI a brief morphological description is given of the spleen, head kidney and trunk kidney. An antigen localization study was carried out after i.m. injection of A.hydrophila bacterin, by means of immunofluorescence. The antigen first appeared in the splenic ellipsoids and solitary phagocytic cells of the head and trunk kidney. Later on it gradually concentrated in or near melanocentres (MMCs) in all organs studied. In the later phases antigen was only located in and around MMCs, both intracellularly and bound to cell membranes, and it remained so for a full year. No antigen could be traced in the lymphoid organs following bath immunization. The question arose if the observed processes were of immunological interest, and which were just a non-specific reaction. Therefore the fate of injected inert material (carbon) was studied for comparison (Appendix paper VII). The processing of carbon was comparable to that described for A.hydrophila antigen. However, at two points there was a difference: 1) in the spleen carbon was transported to MMCs by cells leaving the ellipsoids, whereas this was not clear for A.hydrophila antigen, which appeared near and in MMCs bound to the surface of cells; 2) carbon was only seen intracellularly. Based on these observations it was assumed that the membrane bound antigen in the MMCs had immunological relevance. To test this assumption simultaneous histological and immunological tests were carried out after injection of A. hydrophila antigen (Appendix paper VIII). In those tests it was found that extracellular bound antigen in MMCs was not observed until circulating antibody was present, which is suggestive for the antigen to be complexed by antibody. A further support for this assumption was given by the simultaneous presence of tissue bound Ig and A.hydrophila antigen in MMCs.

    The possible immunological importance of MMCs is discussed in Appendix papers VI-VIII. There are several indications for MMCs to be early phylogenetic analogues of the mammalian germinal centres.

    In Appendix paper IX a study is presented on uptake and transport of intact macromolecules in the intestinal epithelium of carp.This study was started as oral administration is an interesting vaccination method. Electronmicroscopical observations showed that two protein tracer-molecules, horse radish peroxidase (HRP) and ferritin were absorbed more extensively in the second than in the first gut segment. Moreover, HRP and ferritin were processed by the enterocytes in a different way. HRP seemed to be taken up by membrane binding and was subsequently transported to the intercellular space, where it contacted the abundant intra-epithelial leucocytes. There was no notable intracellular digestion of HRP. However, ferritin was taken up by pinocytosis and ended up in lysosome-like bodies or supranuclear vacuoles (2nd segment), where it was digested slowly. Although no ferritin was found in the intercellular space, large macrophages, with phagosomes containing ferritin, were present between the epithelial cells. Also some smaller macrophages containing ferritin, have been observed in the lamina propria and even in the spleen. These data were discussed in terms of both selective and non-selective absorption of macromolecules and the possible immunological implications. It was concluded that orally administered antigens reach intra-epithelial leucocytes, and might induce a (local) immune response. As most antigens are transmitted in the second segment, this part of the gut probably has an important immunological function.

    FINAL CONCLUSIONS

    - The humoral immune response in carp can be evoked by soluble and particulate bacterial antigens from Yersinia ruckeri and Aeromonas hydrophila.

    - The height of the humoral response and the antigen dose are directly correlated.

    - The height of the humoral response is dependent of the route of antigen administration. Injection gives higher serum antibody levels than bath vaccination.

    - The peak day of the response is not antigen dose dependent, but is influenced by the bacterin type.

    - Circulating antibody in these animals can be very persistent (e.g. 1 year). This phenomenon is due to continuous stimulation by antigen in or on macrophages (especially melano-macrophages).

    - Local processes in the skin and gills play a regulatory role in the response after bath vaccination.

    - Memory develops after both antigen injection and bathing in antigen solution.

    - The development of memory in fish takes much more time than the antibody response itself. Maximum levels are usually not reached before 3 months after the initial contact with the antigen.

    - The height of the secondary responses can be used as an indirect method for the quantification of memory. The data obtained can be used for calculating a memory factor.

    - The height of memory levels achieved and the priming antigen dose are directly correlated.

    - The expression of memory is affected by several factors, such as residual "priming" antibody at the moment of boosting, the ratio between the first and second antigen dose, and whether or not the priming and boosting routes correspond.

    - In the early phase of the response mononuclear phagocytes in the kidney and spleen are responsible for antigen handling and stimulation of immuno-competent cells. In the later phase melano-macrophage centres (MMCs) become more important for the stimulation of the response and for memory induction.

    - MMCs probably are the early phylogenetic analogous of mammalian germinal centres.

    - Epithelial cells of the second segment of the intestine are important for the initial antigen uptake. Certain antigens are not digested in the cells, but released in the intercellular space (circulation) and taken up by intestinal macrophages. It is unclear if the intestinal lymphocytes react upon these antigens.

    - Successful application of bacterial vaccines to fish is possible. Injection methods can be used for small numbers of fish. Bath methods are possible for large scale application or young animals. Oral administration is not as effective as injection or immersion, but recent data provide good prospectives for future use.

    - The best results in terms of protection can be expected when the vaccination route (e.g. bath) corresponds with the route of pathogen entry (e.g. gills and skin).

    - In tests for the determination of vaccination efficacy the same challenge route as the vaccination route should be preferred.

    - It will be an advantage when fish, after a vaccination, can develop immunological memory during a period of 2-3 months at optimal temperatures in a relatively clean environment (e.g. specific pathogen free hatcheries).

    Inentingen bij honden
    Anonymous, - \ 1975
    Wageningen : [s.n.] (Literatuurlijst / Centrum voor landbouwpublikaties en documentatie no. 3826)
    bibliografieën - honden - immunisatie - immunotherapie - vaccinatie - vaccins - diergeneeskunde - bibliographies - dogs - immunization - immunotherapy - vaccination - vaccines - veterinary science
    Immunological methods
    Veken, J.A. van der; Slogteren, D.H.M. van; Want, J.P.H. van der - \ 1962
    Berlin etc. : [s.n.] (Publicatie / Laboratorium voor bloembollenonderzoek, Lisse no. 000156) - 43
    immunologie - antigenen - plantkunde - vaccinatie - immunisatie - immunotherapie - vaccins - immunology - antigens - botany - vaccination - immunization - immunotherapy - vaccines
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