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Biomedical subjects

R Ducatelle

Publications and source records attributed to R Ducatelle.

At least 127 records · Page 7Linked to original sources
PubMed1995

Chlamydia psittaci in turkeys: pathogenesis of infections in avian serovars A, B and D.

At 7 days of age, 4 groups, each of twenty specific pathogen free turkeys kept in isolation units were inoculated by aerosol with the Texas Turkey strain (avian Chlamydia psittaci serovar D), strain 92/1293 (avian Chlamydia psittaci serovar D), strain 84/55 (avian Chlamydia psittaci serovar A) or strain 89/1326 (avian Chlamydia psittaci serovar B). A fifth group of 4 specific pathogen free turkeys were sham inoculated controls. At daily intervals for 10 days and then twice weekly up to 34 days post infection, one bird in each group was killed and the target tissues and cells for replication and the sequence of events of serovar A, B and D infections was examined. In these turkeys, the primary site of replication was the respiratory tract. Chlamydial replication could be detected in the respiratory tract on day 1 post inoculation (p.i.) for group A, on day 3 p.i. for group B and on day 1 to 2 p.i. for groups D1 and D2. Subsequently, there was chlamydaemia and localisation in the digestive tract, in one or more parenchymatous organs, in the pericardium and in the conjunctivae. Specific immunoperoxidase staining revealed chamydiae in these organs in epithelial cells and in monomorphonuclear cells in all infected groups. The monomorphonuclear cells were identified as macrophages by double immunofluorescence staining. Chlamydiae were present in the same tissues for serovars A and D, but could not be demonstrated in proventriculus, duodenum, pancreas, ovaries and testes for serovar B. Furthermore, the intensity of replication was similar for all serovars. However, for serovar B in comparison with the other serovars, the bacteria appeared in most tissues 1 to 6 days later and the maximal replication in these tissues occurred 3 to 4 days later.

Aerosols↗
PubMed1994

Streptococcus bovis infections in pigeons: virulence of different serotypes.

In a first experiment, the relative virulence for pigeons of 5 strains of S. bovis was assessed by experimental inoculations. Two S. bovis serotype 1 strains, one serotype 2 strain and two serotype 3 strains were examined. One of the serotype 1 strains and the serotype 2 strain were isolated from pigeons that died from septicaemia. The other strains were isolated from cloaca samples of healthy pigeons. For each strain, 10-20 pigeons were intravenously inoculated with 1 x 10(9) CFU. Morbidity after infection with the serotype 1 and 2 strains varied between 75% and 90%. Disease signs included inability to fly, lameness, emaciation, production of slimy, green droppings, polyuria and sudden death. In groups of pigeons inoculated with the serotype 3 strains, morbidity was 0% and 6%, respectively. Results demonstrate that serotype 3 strains are less virulent for pigeons than serotype 1 and 2 strains. In a second experiment, bacteriological and histological examinations were performed on organs of pigeons serially killed between 1 and 10 days after experimental inoculation with an S. bovis serotype 3 strain of low virulence. Results were compared with results of studies carried out with a highly virulent serotype 1 strain. Notwithstanding bacterial spread and replication in various organs of inoculated pigeons, clinical disease was not observed and histological lesions were scarce and of limited extent.

Animals↗
PubMed1994

An unusual outbreak of Streptococcus bovis septicaemia in racing pigeons (Columba livia).

In December 1991, an outbreak of Streptococcus bovis septicaemia occurred in a Belgian pigeon loft where 25 male and 25 female racing pigeons were housed. The main clinical signs included inability to fly and poor breeding results. None of the female pigeons and only one male pigeon was able to fly. Nine affected pigeons were necropsied. Histologically a tenosynovitis of the tendon of the deep pectoral muscle was observed in most of them and S bovis was isolated from the canalis triosseus or the shoulder joints of five of the nine pigeons. The pigeons were successfully treated with ampicillin administered in the drinking water for seven days.

Animals↗
PubMed1994

Immunity in pigeons against homologous and heterologous serotypes of Streptococcus bovis after infection.

Groups of 20, 20 and 10 pigeons were intravenously inoculated with 1 x 10(9) CFU of a Streptococcus bovis serotype 1, 2 and 3 strain, respectively. Groups which received the highly virulent serotypes 1 or 2 strains were treated with antibiotics starting from 2 days post inoculation in order to prevent the development of clinical signs. Pigeons inoculated with the low virulence S. bovis serotype 3 strain were left untreated. Another group of 10 non-inoculated pigeons was used as challenge control. Four weeks later, pigeons were challenged intravenously with S. bovis serotype 1. Morbidity after challenge infection was 19%, 36% and 70% in groups previously inoculated with serotypes 1, 2 and 3, respectively, whereas it was 100% in the control group. Results demonstrate that pigeons developed significant protective immunity to S. bovis serotype 1 septicaemia following infection with S. bovis serotype 1 and 2 strains but not after infection with the serotype 3 strain. Protection did not correlate with the presence of antibodies as detected in ELISA.

Animals↗
PubMed1994

Prevalence of Streptococcus bovis in racing pigeons.

The prevalence of S. bovis in the intestinal tract of healthy racing pigeons was determined. Crop and cloaca swab samples obtained from 810 pigeons from 14 different lofts and from 122 pigeons that were presented for routine health control were examined for the presence of S. bovis. Pooled faecal samples were also obtained from pigeons in 82 different pigeon lofts. S. bovis was isolated from crop or cloaca samples of approximately 40% of pigeons of all ages by direct culture and from 80% of the pooled faecal samples by enrichment culture. In a longitudinal study, crop and cloaca samples were collected every 3 months from pigeons in seven different pigeon lofts. The prevalence of S. bovis in these pigeons ranged from 0 to 100%. The carriage rate was not related to the season or to the age of the pigeons. The prevalence of S. bovis in organ lesions of pigeons examined at necropsy was investigated over a 35-month period. S. bovis was isolated from 10% of the birds examined. The incidence of S. bovis septicaemia was significantly higher in January to August than in September to December. It was concluded that S. bovis is an opportunistic pathogenic agent in pigeons.

Animals↗
PubMed1994

Comparison of the Salmonella-Tek ELISA to culture methods for detection of Salmonella enteritidis in litter and cloacal swabs of poultry.

An enzyme-linked immunosorbent assay (ELISA), using the Salmonella-Tek ELISA test system, was compared with bacteriological isolation for detection of Salmonella enteritidis phage type 4 in litter and cloacal swabs of poultry. Before ELISA, samples were enriched in tetrathionate broth for 18-24 h or in tetrathionate broth (18-24 h), followed by M-broth/novobiocine (4-6 h). The bacteriological isolation procedure included incubation in buffered peptone water and inoculation on modified semisolid Rappaport-Vassiliadis. For detection of S. enteritidis in litter samples, ELISA was more sensitive than bacteriological examination. For cloacal swabs, both techniques were equally sensitive. The two enrichment procedures gave no significant differences in ELISA results. It was concluded that the Salmonella-Tek ELISA test might be a promising test for detection of Salmonella infected poultry flocks, providing that further studies are performed to determine the cut-off value for litter and cloacal swabs of commercial flocks.

Animals↗
PubMed1994

In vivo association of Actinobacillus pleuropneumoniae serotype 2 with the respiratory epithelium of pigs.

The ability of an Actinobacillus pleuropneumoniae serotype 2 strain to associate in vivo with the epithelium of the porcine respiratory tract was investigated in a sequential study after intranasal inoculation of hysterectomy-derived and colostrum-deprived pigs. At 30 min postinoculation more than 95% of the bacteria present in the lungs were intimately associated with the epithelium of the alveoli or the cilia of the terminal bronchioli, as observed by light and electron microscopy. At 90 and 180 min postinoculation multiple focal early inflammatory lesions in which histologically different, more or less concentric zones could be distinguished were observed. In the center of these pneumonic areas bacteria were associated with infiltrated cells and exudate. In the zone surrounding the center, approximately 95% of the bacteria were lying with their longest side in close apposition to the epithelial cells of alveoli and the cilia of the terminal bronchioli. Bacteria were only sporadically associated with the cilia or the epithelium of the bronchi and trachea. Bacteria were not observed in tonsils or conchae. In view of the findings presented here, we propose the hypothesis that adherence of the A. pleuropneumoniae serotype 2 strain to epithelial cells of the lower respiratory tract constitutes an important initial step in pathogenesis.

Actinobacillus pleuropneumoniae↗
PubMed1994

Evaluation of five immunoassays for detection of Chlamydia psittaci in cloacal and conjunctival specimens from turkeys.

Five commercially available immunoassays were evaluated for the detection of Chlamydia psittaci in cloacal and conjunctival swabs from industrially raised turkeys: IMAGEN (DAKO Diagnostics, Ely, Cambridgeshire, United Kingdom), Chlamydia CEL-VET IF (Cellabs, Brookvale, Australia), IDEIA (DAKO Diagnostics), CELISA (Cellabs), and CLEARVIEW (Unipath, Bedford, United Kingdom). Results were compared with isolation in Buffalo Green Monkey cells as a reference method. For the conjunctival samples, the sensitivities of the IMAGEN test, the Chlamydia CEL-VET IF test, the IDEIA, the CELISA, and the CLEARVIEW test were found to be 100, 66, 0, 0, and 0%, respectively, as compared to the reference test. Also for the conjunctival samples, the specificities of the IMAGEN test, the Chlamydia CEL-VET IF test, and the IDEIA were found to be 100, 11, and 92.8%, respectively. For the cloacal specimens, the sensitivities of the IMAGEN test, the Chlamydia CEL-VET IF test, the IDEIA, the CELISA, and the CLEARVIEW test were found to be 100, 93.3, 26.6, 0, and 53.3%, respectively. Also for the cloacal specimens, the specificities of the IMAGEN test, the Chlamydia CEL-VET IF test, the IDEIA, and the CLEARVIEW test were found to be 92, 12, 100, and 88%, respectively. The IMAGEN test was the most sensitive and specific direct chlamydia antigen detection test for cloacal and conjunctival samples from turkeys.

Animals↗
PubMed1993

Primary pathogenicity of an European isolate of Chlamydia psittaci from turkey poults.

Chlamydia psittaci was isolated as the sole pathogenic agent from a severe outbreak of respiratory disease in a commercial broiler turkey farm in the Netherlands. The mortality rate in the flocks was 65%. Clinical signs included conjunctivitis, swelling of the sinus infraorbitalis and sneezing. Cloacal excretion of chlamydia was demonstrated in twelve out of fifteen birds examined by a direct immunofluorescence test. In all the fifteen birds antibodies against Chlamydia psittaci were detected in the sera by a competitive ELISA. At necropsy sinusitis, rhinitis, airsacculitis, pneumonia, pericarditis and enlargement of the liver and spleen were found. Chlamydiae were demonstrated in the sinus material of all and in conjunctival smears of eight of the fifteen examined birds. Chlamydiae were isolated from all the examined birds after one to three passages on Buffalo Green Monkey (BGM) cell cultures using samples taken from lung, liver and spleen. No other pathogens were isolated. The chlamydia isolate was typed using a panel of serovar-specific monoclonal antibodies in a micro-immunofluorescence test. The isolate belonged to the avian Chlamydia psittaci serovar D. Experimental inoculation with this isolate of 7-day-old specific pathogen free (SPF) turkeys resulted in severe clinical signs, with mortality and extensive pathological lesions, similar to those seen in turkeys from the examined broiler turkey farm. From the data it was concluded that this Chlamydia psittaci isolate can cause severe disease in turkeys.

Animals↗
PubMed1993

Prevalence of antibodies to Streptococcus bovis serotype 1 in racing pigeons.

Indirect ELISA techniques for the detection of antibodies to S. bovis serotypes 1, 2 and 3 in pigeon plasma were developed. Whole formaldehyde-inactivated bacteria were used as coating antigens. Bound antibodies were detected with peroxidase-conjugated rabbit anti-pigeon serum and OPD and H2O2 as chromogen and substrate, respectively. ELISA was used to determine the prevalence of antibodies to S. bovis serotype 1 in healthy Belgian racing pigeons. Antibodies were demonstrated in 83 (= 37%) of 225 samples tested. Results indicate that pigeons may build up plasma antibodies in the absence of clinical signs resembling septicaemia.

Animals↗
PubMed1993

Serotyping of European isolates of Chlamydia psittaci from poultry and other birds.

A panel of five serovar-specific monoclonal antibodies which distinguish the five known avian serovars of Chlamydia psittaci was used to serotype 45 European avian Chlamydia psittaci isolates. Chlamydial antigen was grown in Buffalo green monkey (BGM) cells or in embryonated chicken eggs and was then inoculated into BGM cells. Serotyping was performed in an indirect immunofluorescence test. The 45 European isolates included 22 isolates from the order Psittaciformes, 9 isolates from the order Columbiformes, 6 isolates from the order Galliformes, 5 isolates from the order Passeriformes, and 3 isolates from the order Anseriformes. All of these were successfully serotyped. No additional serovars were found. One isolate from a duck and two isolates from psittacine birds gave positive immunofluorescences with two monoclonal antibodies considered to be specific for two different serovars. These three isolates were cloned by an agar overlay method. Serotyping of the clones demonstrated that the duck and one psittacine bird each were infected with two different serovars. After cloning, one isolate from a psittacine bird reacted only with serovar A. From these results it was concluded that this serotyping system allows the classification of all isolates tested so far. The results show that similar serovars are prevalent in avian species in Europe and the United States. The results also indicate that birds from a certain order are more susceptible to a distinct serovar. The use of a panel of serovar-specific monoclonal antibodies in the immunofluorescence test provides a reliable method for serotyping avian isolates. Monoclonal antibodies to new avian isolate serovars can easily be added to the panel, which makes the system useful for epidemiological studies.

Animals↗
PubMed1993

Susceptibility of hares and rabbits to a Belgian isolate of European brown hare syndrome virus.

Signs and pathologic changes of European brown hare syndrome (EBHS) were reproduced in four hares (Lepus europaeus) after experimental inoculation of a liver suspension from hares from Belgium, which naturally died of EBHS. Virus particles were demonstrated by electron microscopy in the liver of an experimentally infected hare. They were spherical with a diameter of 28 to 30 nm. After density gradient centrifugation, virus particles were detected in the density zone of 1.34 g/ml. Based on immunoelectron microscopy with a convalescent serum, we identified the virus as the cause of EBHS. Clinical signs were not produced in three seronegative domestic rabbits after subcutaneous inoculation of the EBHS virus. Although low levels of antibodies against EBHS virus were found in the serum of these three rabbits 4 weeks after the inoculation of EBHS virus, the rabbits were not protected when challenged with viral hemorrhagic disease (VHD) virus. The different pathogenicity of the Belgian EBHS and VHD virus isolates in rabbits and the lack of protection in rabbits with circulating EBHS virus antibodies against a challenge with VHD virus indicates that both Belgian virus isolates form two different virus populations.

Animals↗
PubMed1992

Diagnosis of avian chlamydiosis: specificity of the modified Giménez staining on smears and comparison of the sensitivity of isolation in eggs and three different cell cultures.

For the diagnosis of chlamydiosis in dead and live birds different methods were compared for their sensitivity and specificity. The specificity of the modified Giménez staining and the direct immunofluorescence (DIF) test for direct demonstration of Chlamydia psittaci in organ, cloacal and/or conjunctival smears was examined. The sensitivity of the isolation of Chlamydia psittaci in 6 days embryonated specific pathogen free (SPF) chicken eggs, Buffalo Green Monkey (BGM) cell line, McCoy cell line and Vero cell line was compared. On smears, the direct immunofluorescence test was more specific than the modified Giménez staining. The concordance between the results of both detection methods was 80%. The BGM cell culture was the most sensitive artificial host for isolation of Chlamydia psittaci, followed by the embryonated eggs, the Vero cell line and the McCoy cell line. The concordance between the results of isolation in BGM cell culture and eggs was 96.5%, while it was 86% between the results of isolation in BGM cell culture and Vero cell culture and only 65.5% between the results of isolation in BGM cell culture and McCoy cell culture. For dead bird species, chlamydiosis could be diagnosed more often using DIF on smears than with isolation. The concordance between the results of the DIF on smears and isolation followed by DIF was 91%.

Animals↗
PubMed1992

Biochemical and antigenic properties of Streptococcus bovis isolated from pigeons.

Biochemical and serological properties of 60 strains of Streptococcus bovis isolated from healthy pigeons and from pigeons that died from S. bovis septicemia were determined. On the basis of the hemolysis of bovine erythrocytes, the production of polysaccharides on saccharose-containing media, and the fermentation of mannitol, inulin, trehalose, and L-arabinose, the isolates were classified in five biotypes and two subbiotypes. Slide agglutination and microagglutination tests using monospecific rabbit antisera allowed the classification of all isolates in five serotypes.

Animals↗
PubMed1991

Protective effects of vaccines against experimental salmonellosis in racing pigeons.

Five inactivated and one attenuated vaccine produced for the prevention of salmonellosis in pigeons were compared in an experimental challenge model. The birds were vaccinated according to the recommendations of the manufacturers and they were infected by gavage with a Salmonella typhimurium (var copenhagen) pigeon strain. The challenged control animals showed severe weight loss, excessive water intake over a prolonged period, and excreted large numbers of salmonellae. None of the vaccines fully protected the pigeons, and only an inactivated oil adjuvant vaccine was able to reduce the severity of the clinical signs significantly. Mortality was low and tended to increase with the severity of the clinical signs. These results do not justify the preventive use of salmonella vaccination in pigeons. Nevertheless, the oil adjuvant vaccine may help in the effective cleaning of lofts after an outbreak of salmonellosis.

Animals↗