R Ducatelle

Ghent University, Gand, Flanders, Belgium

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Publications (523)1152.28 Total impact

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    ABSTRACT: Background and AimProbiotics might offer an attractive alternative for standard antibiotic therapy to treat Clostridium difficile infections. We specifically selected a Bacillus amyloliquefaciens strain for its high in vitro antibacterial activity against C. difficile and tested its efficacy to prevent CDI in a mouse model.MethodsB. amyloliquefaciens supernatant was tested against a large collection C. difficile strains using an agar well diffusion test. B. amyloliquefaciens was orally administered to C57BL/6 mice in which CDI was induced using C. difficile VPI 10463 and its effect was compared with control mice receiving no treatment and mice receiving Saccharomyces boulardii. Mice were followed up daily for signs of disease including weight loss. At necropsy, the colon was collected and subjected to histopathological analysis. C. difficile toxin A/B levels and colon weight/length and colon/body weight ratios were calculated.ResultsB. amyloliquefaciens supernatant was able to inhibit the growth of all C. difficile strains. Results of the in vivo trial indicated a significant weight loss for untreated and S. boulardii treated mice as compared to B. amyloliquefaciens treated mice. C. difficile toxin A and B levels were significantly higher for untreated and S. boulardii treated mice than B. amyloliquefaciens treated mice. A significantly lower degree of colon damage was detected for B. amyloliquefaciens treated mice as compared to untreated and S. boulardii treated mice, based on histopathological analysis, colon weight/length and colon/body weight ratios.Conclusion Administration of B. amyloliquefaciens was successful in preventing CDI in a mouse model.
    Journal of Gastroenterology and Hepatology 03/2015; 30(8). DOI:10.1111/jgh.12957 · 3.50 Impact Factor
  • M. Oosterlinck · A. Grebert · I. Gielen · L. Bosseler · R. Ducatelle · F. Gasthuys ·
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    ABSTRACT: Multiple congenital ocular anomalies syndrome consists of several abnormalities mainly localised to the anterior segment of the eye. This condition, comprising iridal or ciliary cysts with or without iridal hypoplasia, an excessively protruding cornea (‘cornea globosa’), miotic pupils, retinal dysplasia, cataract, and other lesions, has been reported in several breeds and is strongly related to the silver coat colour, as a result of a dominant mutant allele at the PMEL17 locus. This report describes the macroscopic, ultrasonographic, histological and magnetic resonance imaging findings of the ocular abnormalities in a Comtois mare with multiple congenital ocular anomalies syndrome.
    02/2015; 27(5). DOI:10.1111/eve.12293

  • Journal of Comparative Pathology 01/2015; 152(1):91. DOI:10.1016/j.jcpa.2014.10.201 · 1.14 Impact Factor

  • Journal of Comparative Pathology 01/2015; 152(1):58-59. DOI:10.1016/j.jcpa.2014.10.071 · 1.14 Impact Factor
  • T. Hellebuyck · F. Pasmans · R. Ducatelle · V. Saey · L. Bosseler · A. Martel ·

    Journal of Comparative Pathology 01/2015; 152(1):90. DOI:10.1016/j.jcpa.2014.10.197 · 1.14 Impact Factor
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    ABSTRACT: Stocking density is a management factor which has critical implications for the poultry industry. The aim of the present study was to investigate the effect of high stocking density as a predisposing factor in an experimental model of necrotic enteritis in broiler chicks. The experimental challenge model included an oral inoculation with 10-fold dose of attenuated anticoccidial vaccine and multiple oral inoculations with a specific strain of Clostridium perfringens. Two hundred and forty as hatched day-old broiler chicks were randomly allocated to four treatment groups according to the following experimental design: group N, with normal stocking density (15 birds/m(2)) and no challenge, group D, with high stocking density (30 birds/m(2)) and no challenge, group P, with normal stocking density and positive challenge and group DP, with high stocking density and positive challenge. From each bird, the intestine, gizzard and liver were collected and scored for gross lesions. The intestinal digesta was collected for pH and viscosity determination. One caecum from each bird was taken for microbiological analysis. The statistical analysis and evaluation of the experimental data revealed significant interaction effects between "stocking density" and "challenge", regarding gross lesion scores in intestine and liver, pH values in jejunum, ileum and caeca as well as C. perfringens counts in the caeca (P ≤ 0.05). High stocking density in challenged birds increased the gross lesion score in intestine (P ≤ 0.05), contrary to unchallenged birds. It can be concluded that high stocking density affects unfavorably the welfare and gut health of broiler chicks, predisposes to necrotic enteritis in a subclinical experimental model and increases further its importance as management factor for the poultry industry.
    Avian Pathology 01/2015; 44(2):1-31. DOI:10.1080/03079457.2014.1000820 · 1.64 Impact Factor
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    ABSTRACT: Aspergillus fumigatus is a ubiquitous airborne pathogen. Saprophytic growth in the presence of environmental mycotoxins might affect its fitness and virulence. T-2 toxin (T-2) is a trichothecene mycotoxin produced by Fusarium spp. in various substrates. This study aimed to evaluate the effects of T-2 on the fitness of A. fumigatus in vitro and its virulence in experimentally inoculated chickens. We cultured A. fumigatus on agar media containing T-2, and examined the changes in viability, morphology, growth rate, proteome expression, and susceptibility to antimycotics and oxidative stress of this fungus. Results showed that exposure to 1000 ng/ml T-2 in the substrate did not reduce the viability of A. fumigatus, but its growth was inhibited, with wrinkling and depigmentation of the colonies. Proteomic analysis revealed 21 upregulated proteins and 33 downregulated proteins, including those involved in stress response, pathogenesis, metabolism, transcription. The proteome seems to have shifted to enhance the glycolysis, catabolism of lipids, and amino acid conversion. Assays on fungal susceptibility to antimycotics and oxidative stress showed that T-2 exposure did not affect the minimal inhibitory concentrations of amphotericin B, itraconazole, voriconazole and terbinafine against A. fumigatus, but increased the susceptibility of A. fumigatus to H2O2 and menadione. Experimental inoculation of chickens with A. fumigatus showed that exposure of A. fumigatus to T-2 significantly exacerbated aspergillosis in chickens exposed to dietary T-2. In conclusion, A. fumigatus is capable of surviving and growing on substrates containing levels of T-2 up to 1000 ng/ml. Growth in presence of T-2 induces a stress response in A. fumigatus, which is associated with exacerbation of aspergillosis in vivo.
    World Mycotoxin Journal 01/2015; 1(-1):1-11. DOI:10.3920/WMJ2014.1765 · 2.16 Impact Factor
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    W De Cort · F Haesebrouck · R Ducatelle · F van Immerseel ·
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    ABSTRACT: Consumption of contaminated poultry meat is still an important cause of Salmonella infections in humans. Colonization inhibition (CI) occurs when a live Salmonella strain is administered to chickens and subsequently protects against challenge with another Salmonella strain belonging to the same serotype. A Salmonella Enteritidis hilAssrAfliG deletion mutant has previously been proven to reduce colonization and shedding of a wild-type Salmonella Enteritidis strain in newly hatched broilers after experimental infection. In this study, we compared two administration routes for this strain. Administering the Salmonella Enteritidis ΔhilAssrAfliG strain through drinking water on the first day of life resulted in decreased fecal shedding and cecal colonization of a wild-type Salmonella Enteritidis challenge strain administered 24 h later using a seeder-bird model. When administering the CI strain by coarse spray on newly hatched broiler chicks, an even more pronounced reduction of cecal colonization was observed, and fecal shedding of the Salmonella Enteritidis challenge strain ceased during the course of the experiment. These data suggest that administering a Salmonella Enteritidis ΔhilAssrAfliG strain to newly hatched chicks using a coarse spray is a useful and effective method that reduces colonization and shedding of a wild-type Salmonella Enteritidis strain after early challenge. © 2014 Poultry Science Association Inc.
    Poultry Science 12/2014; 94(1). DOI:10.3382/ps/peu018 · 1.67 Impact Factor
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    ABSTRACT: Devrieseasis caused by Devriesea agamarum is a highly prevalent disease in captive desert lizards, resulting in severe dermatitis and in some cases mass mortality. In this study, we assessed the contribution of autovaccination to devrieseasis control by evaluating the capacity of 5 different formalin-inactivated D. agamarum vaccines to induce a humoral immune response in bearded dragons (Pogona vitticeps). Each vaccine contained one of the following adjuvants: CpG, incomplete Freund's, Ribi, aluminium hydroxide, or curdlan. Lizards were administrated one of the vaccines through subcutaneous injection and booster vaccination was given 3 weeks after primo-vaccination. An indirect ELISA was developed and used to monitor lizard serological responses. Localized adverse effects following subcutaneous immunization were observed in all but the Ribi adjuvanted vaccine group. Following homologous experimental challenge, the incomplete Freund's as well as the Ribi vaccine were observed to confer protection in bearded dragons against the development of D. agamarum associated septicemia but not against dermatitis. Subsequently, two-dimensional gelelectrophoresis followed by immunoblotting and mass spectrometry was conducted with serum obtained from 3 lizards that showed seroconversion after immunisation with the Ribi vaccine. Fructose-bisphosphate aldolase and aldo-keto reductase of D. agamarum reacted with serum from the latter lizards. Based on the demonstrated seroconversion and partial protection against D. agamarum associated disease following the use of formalin-inactivated vaccines as well as the identification of target antigens in Ribi vaccinated bearded dragons, this study provides promising information towards the development of a vaccination strategy to control devrieseasis in captive lizard collections.
    PLoS ONE 12/2014; 9(12):e113084. DOI:10.1371/journal.pone.0113084 · 3.23 Impact Factor
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    ABSTRACT: Background Helicobacter (H.) suis causes gastritis and decreased weight gain in pigs. It is also the most prevalent non-Helicobacter pylori Helicobacter species in humans with gastric disease. H. suis is extremely fastidious, and so far, biphasic culture conditions were essential for isolation and culture, making it impossible to obtain single colonies. Hence, cultures obtained from an individual animal may contain multiple H. suis strains, which is undesirable for experiments aiming for instance at investigating H. suis strain differences.Materials and Methods Pure cultures of H. suis were established by growing bacteria as colonies on 1% brucella agar plates, followed by purification and enrichment by biphasic subculture. Characteristics of these single colony-derived strains were compared with those of their parent strains using multilocus sequence typing (MLST) and by studying bacterium–host interactions using a gastric epithelial cell line and Mongolian gerbil model.ResultsThe purification/enrichment procedure required a nonstop culture of several weeks. For 4 of 17 H. suis strains, MLST revealed differences between parental and single colony-derived strains. For three of four single colony-derived strains tested, the cell death-inducing capacity was higher than for the parental strain. One single colony-derived strain lost its capacity to colonize Mongolian gerbils. For the four other strains tested, colonization capacity and histopathologic changes were similar to what has been described when using strains with only a history of limited biphasic culture.ConclusionsA method was developed to obtain single colony-derived H. suis strains, but this procedure may affect the bacterial genotype and phenotype.
    Helicobacter 12/2014; 20(3). DOI:10.1111/hel.12192 · 4.11 Impact Factor
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    ABSTRACT: Diagnosis of chronic progressive lymphoedema (CPL) in draught horses, including the Belgian Draught Horse, is mainly based on clinical evaluation of typical lower limb lesions. A deficient perilymphatic elastic support, caused by a pathological elastin degradation in skin and subcutis, has been suggested as a contributing factor for CPL. Elastin degradation products induce the generation of anti-elastin Ab (AEAb), detectable in horse serum by ELISA. For a clinically healthy group of draught horses, a significantly lower average AEAb-level than 3 clinically affected groups (mild, moderate and severe symptoms) was demonstrated previously. To improve CPL-diagnosis, we evaluated the AEAb-ELISA as an in vitro diagnostic aid in individual horses. Test reproducibility was assessed, performing assays independently in 2 laboratories on a total of 345 horses. Possible factors associated with AEAb-levels (age, gender, pregnancy, test lab and date of blood collection) were analyzed using a mixed statistical model. Results were reproducible in both laboratories. AEAb-levels in moderately and severely affected horses were significantly higher than in healthy horses. Nevertheless, this was only demonstrated in barren mares, and, there was a very large overlap between the clinical groups. Consequently, even when a high AEAb cut-off was handled to obtain a reasonable specificity of 90%, a very low sensitivity (21%) of AEAb for CPL-diagnosis was obtained. Results on the present sample demonstrate that the described ELISA procedure is of no use as a diagnostic test for CPL in individual horses. Copyright © 2014 Elsevier B.V. All rights reserved.
    Veterinary Immunology and Immunopathology 11/2014; 163(1-2). DOI:10.1016/j.vetimm.2014.11.004 · 1.54 Impact Factor
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    Dataset: Martel.SM

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    ABSTRACT: Emerging infectious diseases are reducing biodiversity on a global scale. Recently, the emergence of the chytrid fungus Batrachochytrium salamandrivorans resulted in rapid declines in populations of European fire salamanders. Here, we screened more than 5000 amphibians from across four continents and combined experimental assessment of pathogenicity with phylogenetic methods to estimate the threat that this infection poses to amphibian diversity. Results show that B. salamandrivorans is restricted to, but highly pathogenic for, salamanders and newts (Urodela). The pathogen likely originated and remained in coexistence with a clade of salamander hosts for millions of years in Asia. As a result of globalization and lack of biosecurity, it has recently been introduced into naïve European amphibian populations, where it is currently causing biodiversity loss.
    Science 10/2014; 346:209-6210. · 33.61 Impact Factor
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    R Ducatelle · V Eeckhaut · F Haesebrouck · F Van Immerseel ·
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    ABSTRACT: Dysbiosis or dysbacteriosis is defined as a shift in the intestinal microbiota composition resulting in an imbalance between beneficial and harmful bacteria. Since the ban on the use of growth-promoting antibiotics in animal feed in the EU, dysbiosis has emerged as a major problem in intensive animal production. Prebiotics and probiotics are currently under investigation as possible alternatives to growth-promoting antibiotics, as their mode of action is thought to be based largely on a modulation of the composition and function of the intestinal microbiota. In this review, we analyse the currently available data from both animal and human nutrition that document the potential and limitations of prebiotics and probiotics for the control of dysbiosis. An impressive number of empirical feeding trials have been carried out in healthy animals, yielding sometimes contradictory results. More in-depth studies have revealed the complexity of the interactions taking place in the lower intestinal tract, thus illustrating that pre- and probiotics cannot be a simple replacement for growth-promoting antibiotics. Although there are indications that the strategic use of pre- and probiotics can provide major benefits, there is still a lack of basic knowledge on the delicate interactions between the microbiota, the host and the feed components, which hampers the widespread use of these valuable feed additives.
    animal 10/2014; 9(1):1-6. DOI:10.1017/S1751731114002584 · 1.84 Impact Factor
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    ABSTRACT: Salmonella enterica serovar Enteritidis has developed the potential to contaminate table eggs internally, by colonization of the chicken reproductive tract and internalization in the forming egg. The serotype Enteritidis has developed mechanisms to colonize the chicken oviduct more successfully than other serotypes. Until now, the strategies exploited by Salmonella Enteritidis to do so have remained largely unknown. For that reason, a microarray-based transposon library screen was used to identify genes that are essential for the persistence of Salmonella Enteritidis inside primary chicken oviduct gland cells in vitro and inside the reproductive tract in vivo. A total of 81 genes with a potential role in persistence in both the oviduct cells and the oviduct tissue were identified. Major groups of importance include the Salmonella pathogenicity islands 1 and 2, genes involved in stress responses, cell wall, and lipopolysaccharide structure, and the region-of-difference genomic islands 9, 21, and 40.
    Applied and Environmental Microbiology 10/2014; 80(24). DOI:10.1128/AEM.02867-14 · 3.67 Impact Factor
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    ABSTRACT: Emerging infectious diseases are reducing biodiversity on a global scale. Recently, the emergence of the chytrid fungus Batrachochytrium salamandrivorans resulted in rapid declines in populations of European fire salamanders. Here, we screened more than 5000 amphibians from across four continents and combined experimental assessment of pathogenicity with phylogenetic methods to estimate the threat that this infection poses to amphibian diversity. Results show that B. salamandrivorans is restricted to, but highly pathogenic for, salamanders and newts (Urodela). The pathogen likely originated and remained in coexistence with a clade of salamander hosts for millions of years in Asia. As a result of globalization and lack of biosecurity, it has recently been introduced into naïve European amphibian populations, where it is currently causing biodiversity loss.
    Science 10/2014; 346(6209):630-631. DOI:10.1126/science.1258268 · 33.61 Impact Factor
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    ABSTRACT: Inflammatory bowel disease (IBD) is a chronic inflammation of the digestive tract, characterized by dysbiosis of the intestinal microbiota. Probiotics have been suggested as a strategy to reduce active disease or extend remission. We isolated and characterized the butyrate-producing strain Butyricicoccus pullicaecorum 25-3T and identified it as a potential probiotic for patients with IBD. To evaluate the safety of 25-3T for use in humans, we conducted a standard acute oral toxicity test and a 28-day repeated oral dose toxicity test. The complete genome of B. pullicaecorum 25-3T was sequenced to search for virulence factors and antibiotic resistance determinants. The minimum inhibitory concentration (MIC) of 21 antimicrobials was determined. Results showed no adverse effects in the oral toxicity tests. B. pullicaecorum 25-3T is resistant against aminoglycosides and trimethoprim. The genome of 25-3T contains no virulence factors, one gene related to harmful metabolites and 52 sequences with high similarity to antimicrobial and toxic compound resistance genes, that did not correspond with a resistant phenotype. This first report of a safety assessment of a butyrate-producing strain from Clostridium cluster IV shows that B. pullicaecorum 25-3T is a non-pathogenic strain, but carries antibiotic resistance genes with the risk of transfer, that need further investigation.
    Food and Chemical Toxicology 10/2014; 72:129–137. DOI:10.1016/j.fct.2014.06.024 · 2.90 Impact Factor
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    ABSTRACT: Both mycotoxin contamination of feed and Clostridium perfringens-induced necrotic enteritis have an increasing global economic impact on poultry production. Especially the Fusarium mycotoxin deoxynivalenol (DON) is a common feed contaminant. This study aimed at examining the predisposing effect of DON on the development of necrotic enteritis in broiler chickens. An experimental Clostridium perfringens infection study revealed that DON, at a contamination level of 3,000 to 4,000 µg/kg feed, increased the percentage of birds with subclinical necrotic enteritis from 20±2.6% to 47±3.0% (P<0.001). DON significantly reduced the transepithelial electrical resistance in duodenal segments (P<0.001) and decreased duodenal villus height (P = 0.014) indicating intestinal barrier disruption and intestinal epithelial damage, respectively. This may lead to an increased permeability of the intestinal epithelium and decreased absorption of dietary proteins. Protein analysis of duodenal content indeed showed that DON contamination resulted in a significant increase in total protein concentration (P = 0.023). Furthermore, DON had no effect on in vitro growth, alpha toxin production and netB toxin transcription of Clostridium perfringens. In conclusion, feed contamination with DON at concentrations below the European maximum guidance level of 5,000 µg/kg feed, is a predisposing factor for the development of necrotic enteritis in broilers. These results are associated with a negative effect of DON on the intestinal barrier function and increased intestinal protein availability, which may stimulate growth and toxin production of Clostridium perfringens.
    PLoS ONE 09/2014; 9(9):e108775. DOI:10.1371/journal.pone.0108775 · 3.23 Impact Factor
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    ABSTRACT: A number of Helicobacter species cause gastrointestinal or hepatic disease in humans, including H. pylori, gastric non-H. pylori helicobacters from animal origin and enterohepatic Helicobacter species. Little is known on the presence of Helicobacter species in great apes, our closest living relatives and potential reservoirs of microorganisms that might emerge in humans. The aim of the present study was to investigate the presence of gastric and enterohepatic Helicobacter species in African chimpanzees and gorillas. Fresh fecal samples were collected from wild endangered chimpanzees and critically endangered western lowland gorillas from different African National Parks, as well as wild-born captive animals from primate sanctuaries. Intact Helicobacter bacteria were demonstrated in feces by fluorescence in situ hybridization. Screening using a Helicobacter genus-specific PCR revealed the presence of Helicobacter DNA in the majority of animals in all groups. Cloning and sequencing of 16S rRNA gene fragments revealed a high homology to sequences from various zoonotic enterohepatic Helicobacter species, including H. cinaedi and H. canadensis. A number of gorillas and chimpanzees also tested positive using PCR assays designed to amplify part of the ureAB gene cluster and the hsp60 gene of gastric helicobacters. Phylogenetic analysis revealed the presence of a putative novel zoonotic gastric Helicobacter taxon/species. For this species, we propose the name ‘Candidatus Helicobacter homininae’, pending isolation and further genetic characterization. The presence of several Helicobacter species not only implies a possible health threat for these endangered great apes, but also a possible zoonotic transmission of gastric and enterohepatic helicobacters from these primate reservoirs to humans.
    Veterinary Microbiology 09/2014; 174(1-2). DOI:10.1016/j.vetmic.2014.08.032 · 2.51 Impact Factor
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    ABSTRACT: Background Information on the genetic events leading to thyroid cancer in dogs is lacking.Hypothesis/Objectives Upregulation of the PI3K/Akt pathway has an important role in the tumorigenesis of thyroid carcinoma in dogs.AnimalsFifty-nine dogs with thyroid carcinoma and 10 healthy controls.Methods Quantitative RT-PCR was performed for VEGFR-1, VEGFR-2, EGFR, PIK3CA, PIK3CB, PDPK1, PTEN, AKT1, AKT2, COX-2, and CALCA. Mutation analysis was performed for known hotspots of RAS (N, K, H), PIK3CA, BRAF, RET, and for the entire coding region of PTEN.ResultsForty-three dogs (73%) had follicular cell thyroid carcinoma (FTC) and 16 dogs (27%) had medullary thyroid carcinoma (MTC). The relative mRNA expressions of VEGFR-1 (P < .001), VEGFR-2 (P = .002), PDPK1 (P < .001), AKT1 (P = .009), and AKT2 (P < .001) were increased in FTC, and those of EGFR (P < .001), VEGFR-1 (P = .036), and PIK3CA (P = .019) were increased in MTC when compared to normal thyroid glands. Mutation analysis of K-RAS identified 2 activating missense mutations, which also have been described in thyroid cancer of humans. A G12R substitution was present in 1 FTC and an E63K substitution was present in 1 MTC. No functional mutations were found in the sequenced regions of H-RAS, N-RAS, PIK3CA, BRAF, RET, and PTEN.Conclusions and Clinical ImportanceThe increased expression of several genes associated with PI3K/Akt signaling suggests the involvement of this pathway in the pathogenesis of thyroid carcinoma in dogs, warranting further research on pathway activation and gene amplification. The mutations most frequently associated with thyroid cancer in humans are rare in dogs.
    Journal of Veterinary Internal Medicine 09/2014; 28(6). DOI:10.1111/jvim.12435 · 1.88 Impact Factor

Publication Stats

8k Citations
1,152.28 Total Impact Points


  • 1981-2015
    • Ghent University
      • • Department of Pathology, Bacteriology and Avian Diseases
      • • Faculty of Veterinary Medicine
      • • Department of Pathology
      Gand, Flanders, Belgium
  • 2014
    • University of Tehran
      • Faculty of Veterinary Medicine
      Teheran, Tehrān, Iran
  • 1992-2011
    • Universitair Ziekenhuis Ghent
      Gand, Flanders, Belgium
  • 2009
    • Państwowy Instytut Weterynaryjny
      Puławy, Lublin Voivodeship, Poland
    • University of Helsinki
      • Institute of Biotechnology
      Helsinki, Southern Finland Province, Finland
  • 2007
    • University of Antwerp
      • Laboratory of Pathophysiology
      Antwerpen, Flanders, Belgium
  • 2001
    • Vrije Universiteit Brussel
      • Laboratory for Cell Genetics
      Bruxelles, Brussels Capital, Belgium
  • 1998
    • Veterinary and Agrochemical Research Centre
      Bruxelles, Brussels Capital Region, Belgium