Michael Hess

University of Veterinary Medicine in Vienna, Wien, Vienna, Austria

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Publications (130)257.61 Total impact

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    ABSTRACT: SUMMARY This study was performed to investigate the prevalence and to characterize the genetic diversity of Histomonas meleagridis isolates in chickens in southern Vietnam. A total of 194 chickens, randomly selected from 18 backyard and 18 commercial flocks, were screened for H. meleagridis infection using both macroscopic diagnosis and an 18S rRNA gene-based PCR method. Overall, 12.9% of birds, representing 19 flocks, showed gross lesions typical for histomonosis whereas 25.3% of the birds from 29 flocks were positive by PCR assay. Following initial diagnostic approaches, H. meleagridis-positive samples were further analyzed by sequencing three different genomic loci; the 18S rRNA, alpha-actinin1, and rpb1. Thirteen samples from 12 flocks were genetically identified as H. meleagridis, demonstrating a flock and sample prevalence of 33.3% and 6.7%, respectively. There was no significant difference in prevalence between different farm types, age groups, and seasonality. Genetic analysis demonstrated minor heterogeneity of Vietnamese isolates with 99% homology to H. meleagridis sequences from the database. This is the first survey of the prevalence and genetic characterization of H. meleagridis in chickens in Vietnam.
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    ABSTRACT: The progression of Gallibacterium anatis infection in immunosuppressed versus immunocompetent chickens was investigated. Before experimental infection, birds were treated with corticosterone for general immunosuppression, or 5-fluorouracil, cyclosporine-A, cyclophosphamide for depletion of specific leukocyte populations. Necropsy and sampling were performed at 0, 3, 7, 10 and 28 days post infection. The used drugs did not cause selected depletion of B cells, T cells, heterophils and monocytes/macrophages, as determined by quantification of leukocytes in blood and lymphoid organs using different technologies. Bacterial re-isolation and counts of colony forming units (CFU) showed that G. anatis colonization pattern in various organs, and the numbers of bacteria in trachea were not affected by immunosuppression. However, the treatments acutely increased CFU counts derived from the spleen, which demonstrates that chemically induced immunosuppression intensifies systemic multiplication of G. anatis in chickens. Copyright © 2015 Elsevier B.V. All rights reserved.
    Veterinary Immunology and Immunopathology 05/2015; 166(1-2). DOI:10.1016/j.vetimm.2015.05.001 · 1.75 Impact Factor
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    ABSTRACT: Although a high number of chickens carry Campylobacter jejuni, the mechanistic action of colonization in the intestine is still poorly understood. The current study was therefore designed to investigate the effects of C. jejuni on glucose uptake, amino acids availability in digesta, and intracellular calcium [Ca(2+)]i signaling in the intestines of broiler chickens. For this, we compared: control birds (n = 60) and C. jejuni-infected birds (n = 60; infected orally with 1 × 10(8) CFU of C. jejuni NCTC 12744 at 14 days of age). Our results showed that glucose uptake was reduced due to C. jejuni infection in isolated jejunal, but not in cecal mucosa at 14 days postinfection (dpi). The decrease in intestinal glucose absorption coincided with a decrease in body weight gain during the 2-week post-infectious period. A reduction in the amount of the amino acids (serine, proline, valine, leucine, phenylalanine, arginine, histidine, and lysine) in ileal digesta of the infected birds at 2 and/or 7 dpi was found, indicating that Campylobacter utilizes amino acids as a carbon source for their multiplication. Applying the cell-permeable Ca(2+) indicator Fluo-4 and two-photon microscopy, we revealed that [Ca(2+)]i was increased in the jejunal and cecal mucosa of infected birds. The muscarinic agonist carbachol induced an increase in [Ca(2+)]i in jejunum and cecum mucosa of control chickens, a response absent in the mucosa of infected chickens, demonstrating that the modulation of [Ca(2+)]i by Campylobacter might be involved in facilitating the necessary cytoskeletal rearrangements that occur during the bacterial invasion of epithelial cells. In conclusion, this study demonstrates the multifaceted interactions of C. jejuni with the gastrointestinal mucosa of broiler chickens. For the first time, it could be shown that a Campylobacter infection could interfere with intracellular Ca(2+) signaling and nutrient absorption in the small intestine with consequences on intestinal function, performance, and Campylobacter colonization. Altogether, these findings indicate that Campylobacter is not entirely a commensal and can be recognized as an important factor contributing to an impaired chicken gut health.
    Applied Microbiology and Biotechnology 04/2015; 99(15). DOI:10.1007/s00253-015-6543-z · 3.81 Impact Factor
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    ABSTRACT: In the present study the effects of dietary gizzard stimulation on the development and severity of adenoviral gizzard erosion (AGE) were investigated. For this purpose, specific-pathogen-free broilers were divided into six groups, investigating the influence of an oat containing diet with higher fibre content, a whole wheat containing diet and a control diet of nearly identical composition, but containing ground wheat. For each feed administered, one group of birds was experimentally infected on the 10th day of age by the oral route with virulent fowl adenovirus serotype 1 (FAdV-1), recently proven to induce gizzard erosions, while the respective negative control groups remained uninfected. Experimental feed was administered from 2 days post infection (dpi) onwards. No significant differences on gizzard health or in weight gain could be detected between uninfected control groups or between FAdV-1 infected groups that received different experimental feed. However, independent of the supplied diet, a significantly reduced weight gain was noticed from 7dpi onwards in FAdV-1 infected broilers compared to uninfected birds that received the same diet. Macroscopically, discolouration and erosion of the koilin layer and inflammation of the gizzard mucosa were observed in all FAdV-1 infected groups. Histologically, necrosis, degeneration of gizzard epithelial cells and multiple basophilic intranuclear inclusion bodies were observed. In summary, after experimental infection with FAdV-1 development of gizzard erosion in chickens was not influenced by the feeding regimes investigated. Therefore, it is unlikely that dietary gizzard stimulation influences the outcome of AGE in vertically infected broilers.
    Avian Pathology 03/2015; 44(3):1-25. DOI:10.1080/03079457.2015.1028886 · 2.04 Impact Factor
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    Michael Hess · Dieter Liebhart · Ivana Bilic · Petra Ganas
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    ABSTRACT: The protozoan flagellate Histomonas meleagridis is the etiological agent of histomonosis, first described in 1893. It is a fastidious disease in turkeys, with pathological lesions in the caeca and liver, sometimes with high mortality. In chickens the disease is less fatal and lesions are often confined to the caeca. The disease was well controlled by applying nitroimidazoles and nitrofurans for therapy or prophylaxis. Since their introduction into the market in the middle of the previous century, research nearly ceased as outbreaks of histomonosis occurred only very rarely. With the ban of these drugs in the last two decades in North America, the European Union and elsewhere, in combination with the changes in animal husbandry, the disease re-emerged. Consequently, research programs were set up in various places focusing on different features of the parasite and the disease. For the first time studies were performed to elucidate the molecular repertoire of the parasite. In addition, research has been started to investigate the parasite's interaction with its host. New diagnostic methods and tools were developed and tested with samples obtained from field outbreaks or experimental infections. Some of these studies aimed to clarify the introduction of the protozoan parasite into a flock and the transmission between birds. Finally, a strong focus was placed on research concentrated on the development of new treatment and prophylactic strategies, urgently needed to combat the disease. This review aims to summarize recent research activities and place them into context with older literature. Copyright © 2014 Elsevier B.V. All rights reserved.
    Veterinary Parasitology 12/2014; 208(1-2). DOI:10.1016/j.vetpar.2014.12.018 · 2.55 Impact Factor
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    ABSTRACT: AimsTo evaluate the impact of diet composition on colonization dynamics of C. jejuni and on related physiological parameters in the chicken intestine.Methods and ResultsA total of 54 one day-old Ross-308 broiler chicks were randomly divided into three isocaloric and isonitrogenous dietary groups: maize-based (MB), wheat-based (WB) diet and wheat-based diet with NSP-degrading enzyme supplementation (WBES). Chickens were orally infected with 108 CFU C. jejuni on day 14 and samples (n=6) were collected on 7, 14 and 21 days post infection (DPI), respectively. Colony forming units of C. jejuni of caecum and jejunum, short chain fatty acid (SCFA) concentrations, pH values of the caecum, jejunal histomorphology and viscosity of jejunal chymus were measured. In case of WBES diet lower C. jejuni colonization 14 DPI, higher jejunal viscosity, higher total SCFA concentrations in the caecum and enhanced jejunal histomorphology were observed compared to those measured in chickens fed MB diet.Conclusions The WBES diet altered C. jejuni colonization dynamics in the chicken intestine which resulted by higher SCFA concentrations in the caecum and by the change of gut morphology.Significance and Impact of the StudyOur study proves that diet composition can modify C. jejuni colonization depending on sampling time point post infection.This article is protected by copyright. All rights reserved.
    Journal of Applied Microbiology 10/2014; 118(1). DOI:10.1111/jam.12679 · 2.39 Impact Factor
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    ABSTRACT: Pathogenesis of Gallibacterium anatis was investigated in specific pathogen-free roosters. 35-weeks old birds were infected intranasally with G. anatis whereas negative controls were left uninfected. Following infection, necropsy, bacteriological and histopathological investigations were performed in birds killed at 3, 7, 10, 28 and 38 days post infection (dpi). Additionally, semen samples were collected twice a week until five weeks post infection for quality assessment. No clinical signs and gross pathological lesions were seen throughout the experiment. Bacteriological investigation revealed that G. anatis colonized the upper respiratory tract at 3 dpi and could be isolated from testis and epididymis at 7 dpi onwards. Bacterial persistence was found until the termination of the study at 38 dpi in respiratory tract, gut and testis. Furthermore, G. anatis was isolated from semen arguing for the possibility of vertical transmission. Histopathological examination showed infiltration of mononuclear cells in epididymal tissue indicating an inflammation. Density, total motility, progressive motility and membrane integrity of sperms were significantly decreased in infected birds as compared to control chickens. Along with these findings, an increase in spermatozoa with morphological defects was observed at different time points. In conclusion, the present study provides novel data on the impact of a G. anatis infection in roosters in a natural infection model elucidating on bacterial distribution, pathological lesions as well as influences on semen quality.
    Avian Pathology 09/2014; 43(6):1-15. DOI:10.1080/03079457.2014.967176 · 2.04 Impact Factor
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    ABSTRACT: Typhlohepatitis was observed in a flock of 2500 red-legged partridges in Great Britain, characterized by the sudden deaths of 15 birds within two days. Necropsy of 5 dead birds revealed severe lesions in the caeca with thickened caecal walls, a reddened lining and bloody contents. The livers contained multiple miliary lesions and similar pathological changes were found in the spleens of some birds. Microscopic examination of intestinal contents showed the occurrence of coccidial oocysts in two partridges. Different methods for the detection of bacteria from liver and intestine samples were conducted without positive results. Histopathological examination revealed the presence of protozoan parasites in the caecum, liver and spleen of the affected birds. In situ hybridization (ISH) for the detection of trichomonads resulted in positive findings and polymerase chain reaction (PCR) confirmed the presence of Tetratrichomonas gallinarum in the lesions. Additionally, archived tissues of red-legged partridges from different flocks suffering from severe typhlohepatitis in Great Britain in 2008 and 2009 were re-investigated by ISH and PCR. Beside the sporadic occurrence of histomonosis, in most of the cases trichomonads were detected by ISH in the caecum and liver of affected birds. Furthermore, dissemination of the flagellate into the lung and bursa of Fabricius could be demonstrated. Analyses of T. gallinarum DNA obtained from the different cases resulted in homologous nucleotide sequences. Altogether, the results demonstrate the circulation of a virulent strain of T. gallinarum in reared red-legged partridges.
    Avian Pathology 08/2014; 43(5):1-17. DOI:10.1080/03079457.2014.959435 · 2.04 Impact Factor
  • Surya Paudel · Dieter Liebhart · Michael Hess · Claudia Hess
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    ABSTRACT: Abstract Pathogenicity of Gallibacterium anatis was studied in specific pathogen free layers in a controlled environment applying the intranasal route for experimental infection. At 30 weeks, 37 hens were infected with 0.4 ml of 1.53 × 10(8) CFU/ml suspension of G. anatis strain 07990 whereas the equal numbers of hens were left uninfected for control. Following experimental infection, clinical symptoms, number and weight of the eggs were recorded daily until five weeks post infection. Besides, three birds from each group were killed at 3, 7, 10, 28 and 38 days post infection (dpi) for necropsy and sampling for bacteriological and histopathological examinations. Additionally, necropsy examination was performed on all remaining birds at 38 dpi. G. anatis infection was found to have immediate and severe effect on egg production showing early and persistent colonization in respiratory and reproductive organs as well as in the gut of infected layers. In birds killed at various time points G. anatis infection caused focal necrosis in the liver (1/37), folliculitis (2/37), pericarditis (3/37), haemorrhagic follicles (2/37), ruptured follicles (20/37), yolk in the body cavity (2/37) and egg peritonitis (1/37). The inflammation of the ovaries could be further confirmed by histopathological examination. Recovery of G. anatis from yolk at 10 dpi indicates the potential of vertical transmission. Altogether, lesions reflect typical findings of G. anatis infection reported in natural cases. Thus for the first time, lesions and the consecutive disease caused by G. anatis infection has been experimentally reproduced in a natural infection model.
    Avian Pathology 08/2014; 43(5):1-21. DOI:10.1080/03079457.2014.955782 · 2.04 Impact Factor
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    ABSTRACT: Complete genomes of the first isolates of pigeon adenovirus 1 (PiAdV-1) and Muscovy duck adenovirus (duck adenovirus 2, DAdV-2) were sequenced. The PiAdV-1 genome is 45,480bp long, and has a gene organization most similar to turkey adenovirus 1. Near the left end of the genome, it lacks ORF0, ORF1A, ORF1B and ORF1C, and possesses ORF52, whereas six novel genes were found near the right end. The DAdV-2 genome is 43,734bp long, and has a gene organization similar to that of goose adenovirus 4 (GoAdV-4). It lacks ORF51, ORF1C and ORF54, and possesses ORF55A and five other novel genes. PiAdV-1 and DAdV-2 genomes contain two and one fiber genes, respectively. Genome organization, G+C content, molecular phylogeny and host type confirm the need to establish two novel species (Pigeon aviadenovirus A and Duck aviadenovirus B) within the genus Aviadenovirus. Phylogenetic data show that DAdV-2 is most closely related to GoAdV-4.
    Virology 06/2014; 462-463C:107-114. DOI:10.1016/j.virol.2014.04.033 · 3.28 Impact Factor
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    ABSTRACT: Gizzard erosion in broilers due to an infection with virulent fowl adenovirus serotype 1 (FAdV-1) is an emerging disease. Although experimental studies were performed, a possible prevention strategy was not reported so far. The present study was set up to determine (i) a possible influence of birds' age at time of inoculation on the pathogenicity of a European FAdV-1 field strain (PA7127), (ii) the virulence of a apathogenic FAdV-1 strain (CELO), and (iii) its capability to protect SPF broilers from adenoviral gizzard erosion caused by the field virus. Oral infection of birds with PA7127 at 1-, 10- and 21-days of life, resulted in reduced weight gain compared to non-infected birds, with significance for birds infected at day-old. Independent of the birds' age at time of inoculation, clinical signs appearing approximately one week after challenge coincided with gizzard lesions. Birds infected exclusively with CELO at the first day of life did not show any clinical signs or pathological changes in the gizzard, confirming the apathogenicity of this European FAdV-1. A similar result was obtained for birds orally infected at the first day of life with CELO and challenged three weeks later with the pathogenic PA7127 strain. Therefore, complete protection of adenoviral gizzard erosion in broilers by vaccination of day-old birds could be demonstrated for the first time, although virus excretion was detected post challenge. Establishment of an amplification refractory mutation system quantitative PCR (ARMS-qPCR) facilitated the identification of the FAdV-1 strain and presence of challenges virus was confirmed in one sample.
    Veterinary Microbiology 05/2014; 172(1-2). DOI:10.1016/j.vetmic.2014.05.020 · 2.73 Impact Factor
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    ABSTRACT: In a prospective longitudinal study a broiler breeder flock and its progeny were monitored for the presence of avian hepatitis E virus (HEV) RNA and antibodies. The flock was part of a multiple age farm where the presence of avian HEV with clinical symptoms (increased mortality and decreased egg production) was demonstrated in several previous production cycles. Samples were taken twice at the rearing site and several times at the production site from broiler breeders including roosters and day-old chicks. The samples were investigated by conventional and real-time RT-PCR, enzyme linked immunosorbent assay (ELISA) and histological methods. At all time points samples from the hens were positive for avian HEV RNA. The birds did not show any clinical signs, even though histopathological lesions in liver and spleen of non-specific aetiology could be demonstrated. A significant increase in number of positive birds and viral load was seen in week 45, in accordance with an increase in antibody titres. In comparison, roosters investigated in week 62 tested negative by RT-PCR and ELISA. Avian HEV RNA was also detected in day-old chicks hatched from eggs laid in week 25, indicating vertical transmission. All partial helicase and capsid sequences retrieved within this study clustered together and were identical to previous sequences obtained from the same multiple age farm. It is concluded that avian HEV persisted on the farm over years and circulated between the rearing and the production site without causing any clinical signs although high viral loads in the adult hens were observed.
    Avian Pathology 05/2014; 43(4):1-26. DOI:10.1080/03079457.2014.924616 · 2.04 Impact Factor
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    ABSTRACT: In the present study a well characterized strain collection (n=33) of Avibacterium species was investigated by MALDI-TOF MS. The robustness of the currently available reference database (Bruker Biotyper 3.0) was tested to determine the degree of identification of these strains. Reproducible signal patterns were obtained from all strains. However, identification of most strains was only possible at genus level. Furthermore, two strains could not be identified by this method. Based on their protein spectra profiles a MALDI MSP dendrogram was created to determine their relationship. Most of the strains were closely related e.g. 26 strains formed cluster 1 including the type strains of Avibacterium volantium, Avibacterium gallinarum, Avibacterium endocarditidis and Avibacterium avium. While, Avibacterium paragallinarum biovars 1 and 2 formed cluster 2 and finally, strain 55000 remained on its own. The present MALDI-TOF MS results confirm recent findings that only certain isolates of Av. paragallinarum represent a well-defined species within the genus Avibacterium, making a taxonomic revision essential. To improve identification of Avibacterium at species level by MALDI-TOF MS relevant reference strains were included in the newly created database and results were presented. In conclusion, Av. paragallinarum can be identified by MALDI/Biotyper and not the other species of the genus.
    Avian Pathology 05/2014; 43(3):1-18. DOI:10.1080/03079457.2014.916038 · 2.04 Impact Factor
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    ABSTRACT: The gastrointestinal tract represents the first barrier against pathogens. However, the interaction of Campylobacter with intestinal epithelial cells and its effects on the intestinal function of chickens are poorly studied. Therefore, the goal of the present study was to characterize the effects of C. jejuni oral infection on the mRNA expression of nutrient transporters in the intestine. Newly hatched specific pathogen-free (SPF) chickens were orally infected with C. jejuni (NCTC 12744; 1×10(8)CFU/bird) at 14 days of age. Quantitative RT-PCR analyses at 14 days-post infection (dpi) revealed that the relative gene expression of the sodium/glucose cotransporter (SGLT-1) and the peptide transporter (PepT-1) was down-regulated (P<0.05) in all investigated segments (duodenum, jejunum and cecum) of Campylobacter-infected birds, while the facilitated glucose transporter (GLUT-2) was down-regulated (P<0.05) in jejunal and cecal tissues only. Furthermore, down-regulation (P<0.05) of the cationic amino acid transporter (CAT-2) and the excitatory amino acid transporter (EAAT-3) was seen in the jejunum, and down-regulation (P<0.05) of the l-type amino acid transporter (y(+)LAT-2) was noticed in the duodenum of infected birds. The decreased expression of intestinal nutrient transporters coincided with a decrease (P<0.05) in body weight and body weight gain during a 2-week post infection period. For the first time, it can be concluded that nutrient transporter expression is compromised in the small and large intestine of Campylobacter-infected birds with negative consequences on growth performance. Furthermore, the down-regulation of mRNA expression of glucose and amino acid transporters may result in accumulation of nutrients in the intestinal lumen, which may favor C. jejuni replication and colonization.
    Veterinary Microbiology 04/2014; 172(1-2). DOI:10.1016/j.vetmic.2014.04.001 · 2.73 Impact Factor
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    ABSTRACT: Histomonas meleagridis is the aetiological agent of histomonosis or "blackhead disease". Histomonosis is of special importance today, because there is no effective treatment to prevent its occurrence with considerable losses for the poultry industry. Despite its importance only a few molecular studies have yet been performed to investigate the degree of genetic diversity between different isolates of this parasite. In the present study a collection of well defined samples, previously shown positive for the DNA of H. meleagridis, was used to investigate genetic relatedness of the parasite. Samples originated from 25 turkey flocks collected in France between 2007 and 2010. Additionally, diagnostic samples, collected at our Clinic in Vienna, from different European countries and Azerbaijan, during 2010 to 2013 were included in the analyses. For the analysis three different genetic loci were analyzed: 18S rRNA, α-actinin1 and rpb1 genes. To amplify partial sequences of α-actinin1 and rpb1 genes, primers specifically targeting H. meleagridis were designed. Following PCR, the sequences of 18S rRNA, α-actinin1 and rpb1 loci were analyzed. Phylogenetic analyses demonstrated separation of H. meleagridis isolates in two different clusters. The majority of isolates grouped within the cluster 1 and originated from different European countries. The cluster 2 was rare and predominantly found in samples originating from France. Considering that the genetic variability of clusters can be seen as two distinct genetic types we propose the term genotype instead of cluster.
    PLoS ONE 03/2014; 9(3):e92438. DOI:10.1371/journal.pone.0092438 · 3.23 Impact Factor
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    ABSTRACT: Escherichia coli (E. coli) infections are very widespread in poultry. However, little is known about the interaction between the intestinal epithelium and E. coli in chickens. Therefore, the effects of avian non-pathogenic and avian pathogenic Escherichia coli (APEC) on the intestinal function of broiler chickens were investigated by measuring the electrogenic ion transport across the isolated jejunal mucosa. In addition, the intestinal epithelial responses to cholera toxin, histamine and carbamoylcholine (carbachol) were evaluated following an E. coli exposure. Jejunal tissues from 5-week-old broilers were exposed to 6×108 CFU/mL of either avian non-pathogenic E. coli IMT11322 (Ont:H16) or avian pathogenic E. coli IMT4529 (O24:H4) in Ussing chambers and electrophysiological variables were monitored for 1 h. After incubation with E. coli for 1 h, either cholera toxin (1 mg/L), histamine (100 μM) or carbachol (100 μM) were added to the incubation medium. Both strains of avian E. coli (non-pathogenic and pathogenic) reduced epithelial ion conductance (Gt) and short-circuit current (Isc). The decrease in ion conductance after exposure to avian pathogenic E. coli was, at least, partly reversed by the histamine or carbachol treatment. Serosal histamine application produced no significant changes in the Isc in any tissues. Only the uninfected control tissues responded significantly to carbachol with an increase of Isc, while the response to carbachol was blunted to non-significant values in infected tissues. Together, these data may explain why chickens rarely respond to intestinal infections with overt secretory diarrhea. Instead, the immediate response to intestinal E. coli infections appears to be a tightening of the epithelial barrier.
    PLoS ONE 03/2014; 9(3):e92156. DOI:10.1371/journal.pone.0092156 · 3.23 Impact Factor
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    ABSTRACT: Asymptomatic carriage of Campylobacter jejuni is highly prevalent in chicken flocks. Thus, we investigated whether chronic Campylobacter carriage affects chicken intestinal functions despite the absence of clinical symptoms. An experiment was carried out in which commercial chickens were orally infected with C. jejuni (1 × 10(8) CFU/bird) at 14 days of life. Changes in ion transport and barrier function were assessed by short-circuit current (Isc) and transepithelial ion conductance (Gt) in Ussing chambers. Gt increased in cecum and colon of Campylobacter-infected chicken 7 d post-infection (DPI), whereas Gt initially decreased in the jejunum at 7 DPI and increased thereafter at 14 DPI. The net charge transfer across the epithelium was reduced or tended to be reduced in all segments, as evidenced by a decreased Isc. Furthermore, the infection induced intestinal histomorphological changes, most prominently including a decrease in villus height, crypt depth and villus surface area in the jejunum at 7 DPI. Furthermore, body mass gain was decreased by Campylobacter carriage. This study demonstrates, for the first time, changes in the intestinal barrier function in Campylobacter-infected chickens and these changes were associated with a decrease in growth performance in otherwise healthy-appearing birds.
    Innate Immunity 02/2014; 21(2). DOI:10.1177/1753425914521648 · 3.27 Impact Factor
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    ABSTRACT: The immune and intestinal epithelial cells are particularly sensitive to the toxic effects of deoxynivalenol (DON). The aim of this experiment was to study the effects of DON and/or a microbial feed additive on the DNA damage of blood lymphocytes and on the level of thiobarbituric acid reactive substance (TBARS) as an indicator of lipid peroxidation and oxidative stress in broilers. A total of forty 1-d-old broiler chicks were randomly assigned to 1 of 4 dietary treatments (10 birds per group) for 5 wk. The dietary treatments were 1) basal diet; 2) basal diet contaminated with 10 mg DON/kg feed; 3) basal diet contaminated with 10 mg DON/kg feed and supplemented with 2.5 kg/ton of feed of Mycofix Select; 4) basal diet supplemented with Mycofix Select (2.5 kg/ton of feed). At the end of the feeding trial, blood were collected for measuring the level of lymphocyte DNA damage of blood and the TBARS level was measured in plasma, heart, kidney, duodenum and jejunum. The dietary exposure of DON caused a significant increase (P = 0.001) of DNA damage in blood lymphocytes (31.99±0.89%) as indicated in the tail of comet assay. Interestingly addition of Mycofix Select to DON contaminated diet decreased (P = 0.001) the DNA damage (19.82±1.75%) induced by DON. In order to clarify the involvement of lipid peroxidation in the DNA damage of DON, TBARS levels was measured. A significant increase (P = 0.001) in the level of TBARS (23±2 nmol/mg) was observed in the jejunal tissue suggesting that the lipid peroxidation might be involved in the DNA damage. The results indicate that DON is cytotoxic and genotoxic to the chicken intestinal and immune cells and the feed additive have potential ability to prevent DNA damage induced by DON.
    PLoS ONE 01/2014; 9(1):e88028. DOI:10.1371/journal.pone.0088028 · 3.23 Impact Factor
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    Aziza Amin · Ivana Bilic · Dieter Liebhart · Michael Hess
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    ABSTRACT: SUMMARY Members of the family Trichomonadidae, mainly Trichomonas gallinae and Tetratrichomonas gallinarum, represent important parasites in birds with worldwide presence, since being reported in the 19th century. Especially Columbiformes, Falconiformes and Strigiformes can be severely affected by trichomonads, whereas the majority of infections in Galliformes and Anatiformes are subclinical although severe infections are occasionally reported. With the recent appearance of deadly infections in wild Passeriformes the protozoan parasite T. gallinae obtained greater attention which will be addressed in this review. Although light microscopy remains the method of choice to confirm the presence of trichomonads molecular studies were introduced in recent years, in order to characterize the parasites and to establish relationships between isolates. Isolation of trichomonads is a prerequisite for detailed in vitro and in vivo studies and different media are reported to obtain suitable material. The limited information about virulence factors will be reviewed in context with the pathogenicity of trichomonads which varies greatly, indicating certain strain heterogeneity of the parasites. Options for treatment characterized by the leading role of imidazoles whose activity is sometimes hampered by resistant parasites remains a challenge for the future. Introducing more standardized genetic studies and investigations concentrating on the host-pathogen interaction should be helpful to elucidate virulence factors which might lead to new concepts of treatment.
    Parasitology 01/2014; 141(6):1-15. DOI:10.1017/S0031182013002096 · 2.35 Impact Factor
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    ABSTRACT: Virulent fowl adenovirus (FAdV) serotype 4 strains are the etiological agents of hepatitis-hydropericardium syndrome (HHS), a highly infectious disease in chickens with severe economic impact. In the present study, three different FAdV-4 derived capsid proteins, fiber-1, fiber-2, and hexon loop-1, were expressed in a baculovirus system and tested for their capacity to induce protection in chickens. Purified recombinant proteins were administered to day-old specific pathogen-free (SPF) chickens allocated in three separate groups and challenged with virulent FAdV-4 at 21 days of life. Two additional groups served as controls, a challenge control group with mock-vaccinated but infected birds and a negative control group with PBS injection substituting both vaccination and challenge. The fiber-2 vaccinated group displayed high resistance against the adverse effects of the challenge with only one dead bird out of 28, as compared to the challenge control group where infection caused 78% mortality. A moderate protective effect resulting in 38% mortality was observed for fiber-1, whereas the hexon loop-1 vaccinated group was not effectively protected as manifested by 73% mortality. While a fiber-2 specific ELISA showed a gradual antibody increase after immunization of birds with the homologous protein, a commercial ELISA did not detect vaccination-induced antibodies in any of the groups but displayed a difference in challenge virus-directed response in protected and non-protected birds. Although immunoblotting confirmed the presence of specific antibodies in all vaccinated groups, the anti-protein sera did not exhibit neutralizing activity. Fecal excretion of challenge virus DNA was detected with a real-time PCR in the majority of tested birds until termination of the study independent of protection, indicating the prevention of clinical symptoms, but not infection, by vaccination. In conclusion, recombinant fiber-2 was identified as a protective immunogen and is proposed as an attractive candidate for a subunit vaccine to prevent hepatitis-hydropericardium syndrome in chickens.
    Vaccine 01/2014; 32(9). DOI:10.1016/j.vaccine.2013.12.056 · 3.49 Impact Factor

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2k Citations
257.61 Total Impact Points


  • 2004–2015
    • University of Veterinary Medicine in Vienna
      • • Department for Farm Animals and Veterinary Public Health
      • • Clinic for Avian, Reptile and Fish
      Wien, Vienna, Austria
  • 2010
    • Heinrich-Heine-Universität Düsseldorf
      • Institut für Zoomorphologie, Zellbiologie und Parasitologie
      Düsseldorf, North Rhine-Westphalia, Germany
  • 1995–2002
    • Freie Universität Berlin
      • Institute of Poultry Diseases
      Berlin, Land Berlin, Germany
  • 1999
    • University of Santiago, Chile
      CiudadSantiago, Santiago, Chile