Michael Hess

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

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Publications (123)240.89 Total impact

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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; · 2.20 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 : journal of the W.V.P.A. 09/2014;
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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; · 1.73 Impact Factor
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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 : journal of the W.V.P.A. 08/2014;
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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. · 3.37 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;
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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; · 1.73 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; · 1.73 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; · 3.13 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; · 2.68 Impact Factor
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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; · 2.36 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; · 3.77 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 01/2014; 9(3):e92156. · 3.53 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. · 3.53 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 01/2014; 9(3):e92438. · 3.53 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 45,480 bp 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 43,734 bp 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. 01/2014; s 462–463:107–114.
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    ABSTRACT: SUMMARY In recent years, Trichomonas gallinae emerged as the causative agent of an infectious disease of passerine birds in Europe leading to epidemic mortality of especially greenfinches Chloris chloris and chaffinches Fringilla coelebs. After the appearance of finch trichomonosis in the UK and Fennoscandia, the disease spread to Central Europe. Finch trichomonosis first reached Austria and Slovenia in 2012. In the present study the genetic heterogeneity of T. gallinae isolates from incidents in Austria and Slovenia were investigated and compared with British isolates. For this purpose comparative sequence analyses of the four genomic loci ITS1-5.8S-ITS2, 18S rRNA, rpb1 and Fe-hydrogenase were performed. The results corroborate that one clonal T. gallinae strain caused the emerging infectious disease within passerine birds and that the disease is continuing to spread in Europe. The same clonal strain was also found in a columbid bird from Austria. Additionally, the present study demonstrates clearly the importance of multi-locus sequence typing for discrimination of circulating T. gallinae strains.
    Parasitology 12/2013; · 2.36 Impact Factor
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    ABSTRACT: Two separate bird trials were performed to establish a reliable route of infection for Gallibacterium anatis in chickens, comparing intranasal (i.n.) and intravenous (i.v.) applications. Additionally, three mutually divergent isolates from three geographical locations, as shown by MALDI-TOF-MS and partial rpoB gene sequence analysis, were compared. In the first trial, birds were infected with one of the selected isolates by the i.v. or i.n. route. Subsequently, birds were killed 3, 12 and 24 h post infection following i.v. infection while at 3, 7 and 10 days post infection (dpi) in the case of i.n. infection along with birds of the control group. As a result, i.n. infection showed prominent and consistent bacterial tissue distribution in different organs persisting until 10 dpi, which was a striking contrast to the i.v. infection route. Likewise, histopathology revealed mild to severe tracheal lesions following i.n. infection. The second trial was set up to confirm both the achieved results and the robustness of i.n. infection but with an extended observation period, until 28 dpi In agreement with the preceding trial, identical results for bacteriological and histopathological examinations were obtained with persistency of bacteria until 28 dpi Comparing the three different isolates from Mexico, China and Austria, the Mexican isolate showed a somewhat higher pathogenicity than the other strains. Consequently, pathogenesis of G. anatis strains was studied in chickens elucidating i.n. infection as the most reliable route characterized by a long-lasting bacteraemia, targeting the respiratory and reproductive tract.
    Avian Pathology 10/2013; · 1.73 Impact Factor
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    ABSTRACT: There are eight species established for aviadenoviruses: Fowl adenovirus A to Fowl adenovirus E, Goose adenovirus A, Falcon adenovirus A and Turkey adenovirus B. The aim of this study was to sequence and analyze the complete genomes of turkey adenovirus 4 (TAdV-4) and turkey adenovirus 5 (TAdV-5, strain 1277BT) in addition to almost two thirds of the genome of another TAdV-5 strain (strain D1648). By applying Next Generation Sequencing, the full genomes were found to be 42,940 and 43,686 bp long and the G+C content was 48.5% and 51.6% for TAdV-4 and TAdV-5, respectively. One fiber gene was identified in TAdV-4, whereas two fiber genes were found in TAdV-5. The genome organization of TAdV-4 resembled that of fowl adenovirus 5 (FAdV-5) but it had ORF1C near the left end of the genome. TAdV-4 also had five 123-bp long tandem repeats followed by five 33-bp tandem repeats, but they occur before and not after the ORF8 as in several fowl adenoviruses. The genome organization of TAdV-5 was almost the same as that of fowl adenovirus 1 (FAdV-1) but with a possible difference in the splicing pattern of ORF11 and ORF26. Phylogenetic analyses and G+C content show differences that seem to merit the establishment of two new species within the genus Aviadenovirus: Turkey adenovirus C (for TAdV-4) and Turkey adenovirus D (for TAdV-5). Our analyses suggest a common evolutionary origin of TAdV-5 and FAdV-1.
    Journal of General Virology 09/2013; · 3.13 Impact Factor
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    ABSTRACT: The efficacy of vaccinating poultry against histomonosis was demonstrated recently. In the present study, the reversion to virulence and the residual pathogenicity of an in vitro attenuated, clonal strain of Histomonas meleagridis were tested in two consecutive experiments. The European Pharmcopoeia (Ph. Eur.) monograph for testing such features for coccidiosis live vaccines in chickens has served as a guideline. In the first experiment, attenuated histomonads were used in successive infection cycles in five groups of either five chickens or turkeys, respectively. All birds were killed at 14 days post infection (d.p.i.) to record lesion scores (LS) from livers and caeca. In the second experiment, the 5times in vivo passaged histomonads were used to infect groups of 30 chickens and turkeys each, together with birds infected with virulent H. meleagridis. At three different time points 10birds/group were killed and tissues of caeca, livers and lungs were used for PCR and immunohistochemistry (IHC) to confirm the presence of parasites. In the first experiment, various lesion scores were recordable in the livers and caeca of turkeys, with the highest LS 4 noticed once in the liver. In comparison, no lesions were seen in organs from chickens. In the second experiment, only mild lesions in the caeca of both turkeys and chickens were found. Liver lesions recorded as score 1 were noticed in just one individual of each species. PCR and IHC revealed that the attenuated and backpassaged histomonads were not present in liver samples but confined to the caeca, different to virulent H. meleagridis. Overall, no clinical signs or death occurred in turkeys or chickens inoculated orally and cloacally with 10(4) backpassaged histomonads in comparison with virulent parasites. Consequently, for the first time, the stable attenuation and safety of histomonads has been demonstrated, thus providing major implications for vaccine development.
    Vaccine 09/2013; · 3.77 Impact Factor

Publication Stats

995 Citations
240.89 Total Impact Points


  • 2004–2014
    • University of Veterinary Medicine in Vienna
      • Clinic for Avian, Reptile and Fish
      Wien, Vienna, Austria
  • 2012
    • University of Copenhagen
      • Department of Veterinary Disease Biology
      Copenhagen, Capital Region, Denmark
  • 2008–2010
    • Heinrich-Heine-Universität Düsseldorf
      • Institut für Zoomorphologie, Zellbiologie und Parasitologie
      Düsseldorf, North Rhine-Westphalia, Germany
  • 2002
    • Punjab Agricultural University
      Ludhiana, Punjab, India
  • 1995–2002
    • Freie Universität Berlin
      • Institute of Poultry Diseases
      Berlin, Land Berlin, Germany
  • 1999
    • University of Santiago, Chile
      CiudadSantiago, Santiago, Chile