The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Richard Ducatelle - One of the best experts on this subject based on the ideXlab platform.
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Salmonella gallinarum field isolates from laying hens are related to the vaccine strain sg9r
Vaccine, 2013Co-Authors: F Van Immerseel, David J Studholme, Venessa Eeckhaut, Marc Heyndrickx, Jeroen Dewulf, I Dewaele, S Van Hoorebeke, Freddy Haesebrouck, H Van Meirhaeghe, Richard DucatelleAbstract:a b s t r a c t Salmonella enterica subspecies enterica serotype gallinarum can cause severe systemic disease in chick- ens and a live Salmonella gallinarum 9R vaccine (SG9R) has been used widely to control disease. Using whole-genome sequencing we found point mutations in the pyruvate dehydrogenase (aceE) and/or lipopolysaccharide 1,2-glucosyltransferase (rfaJ) genes that likely explain the attenuation of the SG9R vac- cine strain. Molecular typing using Pulsed Field Gel Electrophoresis and Multiple-Locus Variable number of tandem repeat Analysis showed that strains isolated from different layer flocks in multiple countries and the SG9R vaccine strain were similar. The genome of one Salmonella gallinarum field strain, isolated from a flock with a mortality peak and selected on the basis of identical PFGE and MLVA patterns with SG9R, was sequenced. We found 9 non-silent single-nucleotide differences distinguishing the field strain from the SG9R vaccine strain. Our data show that a Salmonella gallinarum field strain isolated from lay- ing hens is almost identical to the SG9R vaccine. Mutations in the aceE and rfaJ genes could explain the reversion to a more virulent phenotype. Our results highlight the importance of using well defined gene
A. Berchieri - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of regions of difference between the Salmonella gallinarum biovar gallinarum and the Salmonella gallinarum biovar pullorum genomes
Infection Genetics and Evolution, 2015Co-Authors: Diego Felipe Alves Batista, Paul Barrow, Oliveiro Caetano De Freitas Neto, Marcos T Oliveira, A M Almeida, Antonio Sergio Ferraudo, A. BerchieriAbstract:Salmonella gallinarum is the causative agent of fowl typhoid, a severe septicaemic disease that affects birds of all ages, whereas S. Pullorum causes pullorum disease, a systemic disorder affecting primarily young birds. A proportion of birds with pullorum disease become carriers and are thereby able to transmit S. Pullorum vertically. Although these two pathogens cause distinct diseases, they are otherwise phenotypically and genetically similar. Therefore, the small variations that lead to the differences in virulence must have a genetic basis which currently is unknown. In the present study, we compared the genome sequences of S. gallinarum (strains: SG287/91 and SG9) and S. Pullorum (strains: SP_CDC, SP_RKS, SP_FCAV, SP_S06) and identified 223 regions of difference (RODs), characterized by indels which were detected by using the software Artemis Comparison Tool. Some of the RODs led to pseudogenes frequently formed by frameshifts and premature stop codons in genes primarily involved in virulence and metabolism. We further verified the presence of some conserved RODs by PCR in 26 isolates of S. gallinarum and 17 of S. Pullorum in order to extrapolate data analyses from genome comparison to field strains. The variations observed in virulence-related genes of S. gallinarum and S. Pullorum appear not to be sufficient to explain the differences between the distinct biology of infection of fowl typhoid and pullorum disease. Thus, we suggest that the identified pseudogenes affecting metabolism might play a greater role during infection than previously thought.
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Infection of commercial laying hens with Salmonella gallinarum: clinical, anatomopathological and haematological studies
Brazilian Journal of Poultry Science, 2007Co-Authors: Oc Freitas Neto, W Arroyave, Antonio Carlos Alessi, José Jurandir Fagliari, A. BerchieriAbstract:This study aimed at evaluating the susceptibility of commercial laying hens to Salmonella gallinarum (SG). Two experiments were carried using a mutant strain of Salmonella gallinarum resistant to nalidix acid (SGNALr). In the first trial, the resistance of birds was evaluated based on clinical signs, faecal shedding, and mortality. It was carried out with six lines of commercial layers being three light white layers, considered to be resistant to SG (W1, W2, W3), and three semi-heavy brown varieties (B1, B2, B3), considered susceptible to SG. Each group contained 15 one-day-old birds. Hens were inoculated in the crop at 5 days of age with 0.2 mL of SGNALr neat culture. In addition, to each brown variety, a new group of 15 birds was challenged with 0.2mL of the same SGNALr culture diluted at 10-3. At the end of the first experiment, the surviving birds were sacrificed, and microbiological culture of liver and spleen was performed. In the second experiment, white and brown birds were inoculated with neat culture at five days of age. Samples were collected for evaluation of blood parameters and histopathology assessment at 1, 3, 5, 7, 9, 12, and 14 days post-infection. The results of the first experiment showed higher resistance of white birds (p
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infection of commercial laying hens with Salmonella gallinarum clinical anatomopathological and haematological studies
Brazilian Journal of Poultry Science, 2007Co-Authors: O Freitas C Neto, W Arroyave, Antonio Carlos Alessi, José Jurandir Fagliari, A. BerchieriAbstract:This study aimed at evaluating the susceptibility of commercial laying hens to Salmonella gallinarum (SG). Two experiments were carried using a mutant strain of Salmonella gallinarum resistant to nalidix acid (SGNALr). In the first trial, the resistance of birds was evaluated based on clinical signs, faecal shedding, and mortality. It was carried out with six lines of commercial layers being three light white layers, considered to be resistant to SG (W1, W2, W3), and three semi-heavy brown varieties (B1, B2, B3), considered susceptible to SG. Each group contained 15 one-day-old birds. Hens were inoculated in the crop at 5 days of age with 0.2 mL of SGNALr neat culture. In addition, to each brown variety, a new group of 15 birds was challenged with 0.2mL of the same SGNALr culture diluted at 10-3. At the end of the first experiment, the surviving birds were sacrificed, and microbiological culture of liver and spleen was performed. In the second experiment, white and brown birds were inoculated with neat culture at five days of age. Samples were collected for evaluation of blood parameters and histopathology assessment at 1, 3, 5, 7, 9, 12, and 14 days post-infection. The results of the first experiment showed higher resistance of white birds (p<0.05), although there was no uniformity in the responses against fowl typhoid among the birds within these groups. In the second experiment, there were differences between white and brown birds both in blood parameters and in organ lesion intensity.
F Van Immerseel - One of the best experts on this subject based on the ideXlab platform.
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Salmonella gallinarum field isolates from laying hens are related to the vaccine strain sg9r
Vaccine, 2013Co-Authors: F Van Immerseel, David J Studholme, Venessa Eeckhaut, Marc Heyndrickx, Jeroen Dewulf, I Dewaele, S Van Hoorebeke, Freddy Haesebrouck, H Van Meirhaeghe, Richard DucatelleAbstract:a b s t r a c t Salmonella enterica subspecies enterica serotype gallinarum can cause severe systemic disease in chick- ens and a live Salmonella gallinarum 9R vaccine (SG9R) has been used widely to control disease. Using whole-genome sequencing we found point mutations in the pyruvate dehydrogenase (aceE) and/or lipopolysaccharide 1,2-glucosyltransferase (rfaJ) genes that likely explain the attenuation of the SG9R vac- cine strain. Molecular typing using Pulsed Field Gel Electrophoresis and Multiple-Locus Variable number of tandem repeat Analysis showed that strains isolated from different layer flocks in multiple countries and the SG9R vaccine strain were similar. The genome of one Salmonella gallinarum field strain, isolated from a flock with a mortality peak and selected on the basis of identical PFGE and MLVA patterns with SG9R, was sequenced. We found 9 non-silent single-nucleotide differences distinguishing the field strain from the SG9R vaccine strain. Our data show that a Salmonella gallinarum field strain isolated from lay- ing hens is almost identical to the SG9R vaccine. Mutations in the aceE and rfaJ genes could explain the reversion to a more virulent phenotype. Our results highlight the importance of using well defined gene
Oliveiro Caetano De Freitas Neto - One of the best experts on this subject based on the ideXlab platform.
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inactivation of phopq genes attenuates Salmonella gallinarum biovar gallinarum to susceptible chickens
Brazilian Journal of Microbiology, 2018Co-Authors: Lucas Bocchini Rodrigues Alves, Paul Barrow, Diego Felipe Alves Batista, Oliveiro Caetano De Freitas Neto, Fernanda O Barbosa, Marcela Da Silva Rubio, Andrei Itajahy Secundo De Souza, Adriana Maria De Almeida, Angelo BerchieriAbstract:Abstract Salmonella gallinarum is a host-restrict pathogen that causes fowl typhoid, a severe systemic disease that is one of the major concerns to the poultry industry worldwide. When infecting the bird, SG makes use of evasion mechanisms to survive and to replicate within macrophages. In this context, phoPQ genes encode a two-component regulatory system (PhoPQ) that regulates virulence genes responsible for adaptation of Salmonella spp. to antimicrobial factors such as low pH, antimicrobial peptides and deprivation of bivalent cations. The role of the mentioned genes to SG remains to be investigated. In the present study a phoPQ-depleted SG strain (SG ΔphoPQ) was constructed and its virulence assessed in twenty-day-old laying hens susceptible to fowl typhoid. SG ΔphoPQ did cause neither clinical signs nor mortality in birds orally challenged, being non-pathogenic. Furthermore, this strain was not recovered from livers or spleens. On the other hand, chickens challenged subcutaneously with the mutant strain had discreet to moderate pathological changes and also low bacterial counts in liver and spleen tissues. These findings show that SG ΔphoPQ is attenuated to susceptible chickens and suggest that these genes are important during chicken infection by SG.
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identification and characterization of regions of difference between the Salmonella gallinarum biovar gallinarum and the Salmonella gallinarum biovar pullorum genomes
Infection Genetics and Evolution, 2015Co-Authors: Diego Felipe Alves Batista, Paul Barrow, Oliveiro Caetano De Freitas Neto, Marcos T Oliveira, A M Almeida, Antonio Sergio Ferraudo, A. BerchieriAbstract:Salmonella gallinarum is the causative agent of fowl typhoid, a severe septicaemic disease that affects birds of all ages, whereas S. Pullorum causes pullorum disease, a systemic disorder affecting primarily young birds. A proportion of birds with pullorum disease become carriers and are thereby able to transmit S. Pullorum vertically. Although these two pathogens cause distinct diseases, they are otherwise phenotypically and genetically similar. Therefore, the small variations that lead to the differences in virulence must have a genetic basis which currently is unknown. In the present study, we compared the genome sequences of S. gallinarum (strains: SG287/91 and SG9) and S. Pullorum (strains: SP_CDC, SP_RKS, SP_FCAV, SP_S06) and identified 223 regions of difference (RODs), characterized by indels which were detected by using the software Artemis Comparison Tool. Some of the RODs led to pseudogenes frequently formed by frameshifts and premature stop codons in genes primarily involved in virulence and metabolism. We further verified the presence of some conserved RODs by PCR in 26 isolates of S. gallinarum and 17 of S. Pullorum in order to extrapolate data analyses from genome comparison to field strains. The variations observed in virulence-related genes of S. gallinarum and S. Pullorum appear not to be sufficient to explain the differences between the distinct biology of infection of fowl typhoid and pullorum disease. Thus, we suggest that the identified pseudogenes affecting metabolism might play a greater role during infection than previously thought.
Paul Barrow - One of the best experts on this subject based on the ideXlab platform.
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inactivation of phopq genes attenuates Salmonella gallinarum biovar gallinarum to susceptible chickens
Brazilian Journal of Microbiology, 2018Co-Authors: Lucas Bocchini Rodrigues Alves, Paul Barrow, Diego Felipe Alves Batista, Oliveiro Caetano De Freitas Neto, Fernanda O Barbosa, Marcela Da Silva Rubio, Andrei Itajahy Secundo De Souza, Adriana Maria De Almeida, Angelo BerchieriAbstract:Abstract Salmonella gallinarum is a host-restrict pathogen that causes fowl typhoid, a severe systemic disease that is one of the major concerns to the poultry industry worldwide. When infecting the bird, SG makes use of evasion mechanisms to survive and to replicate within macrophages. In this context, phoPQ genes encode a two-component regulatory system (PhoPQ) that regulates virulence genes responsible for adaptation of Salmonella spp. to antimicrobial factors such as low pH, antimicrobial peptides and deprivation of bivalent cations. The role of the mentioned genes to SG remains to be investigated. In the present study a phoPQ-depleted SG strain (SG ΔphoPQ) was constructed and its virulence assessed in twenty-day-old laying hens susceptible to fowl typhoid. SG ΔphoPQ did cause neither clinical signs nor mortality in birds orally challenged, being non-pathogenic. Furthermore, this strain was not recovered from livers or spleens. On the other hand, chickens challenged subcutaneously with the mutant strain had discreet to moderate pathological changes and also low bacterial counts in liver and spleen tissues. These findings show that SG ΔphoPQ is attenuated to susceptible chickens and suggest that these genes are important during chicken infection by SG.
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identification and characterization of regions of difference between the Salmonella gallinarum biovar gallinarum and the Salmonella gallinarum biovar pullorum genomes
Infection Genetics and Evolution, 2015Co-Authors: Diego Felipe Alves Batista, Paul Barrow, Oliveiro Caetano De Freitas Neto, Marcos T Oliveira, A M Almeida, Antonio Sergio Ferraudo, A. BerchieriAbstract:Salmonella gallinarum is the causative agent of fowl typhoid, a severe septicaemic disease that affects birds of all ages, whereas S. Pullorum causes pullorum disease, a systemic disorder affecting primarily young birds. A proportion of birds with pullorum disease become carriers and are thereby able to transmit S. Pullorum vertically. Although these two pathogens cause distinct diseases, they are otherwise phenotypically and genetically similar. Therefore, the small variations that lead to the differences in virulence must have a genetic basis which currently is unknown. In the present study, we compared the genome sequences of S. gallinarum (strains: SG287/91 and SG9) and S. Pullorum (strains: SP_CDC, SP_RKS, SP_FCAV, SP_S06) and identified 223 regions of difference (RODs), characterized by indels which were detected by using the software Artemis Comparison Tool. Some of the RODs led to pseudogenes frequently formed by frameshifts and premature stop codons in genes primarily involved in virulence and metabolism. We further verified the presence of some conserved RODs by PCR in 26 isolates of S. gallinarum and 17 of S. Pullorum in order to extrapolate data analyses from genome comparison to field strains. The variations observed in virulence-related genes of S. gallinarum and S. Pullorum appear not to be sufficient to explain the differences between the distinct biology of infection of fowl typhoid and pullorum disease. Thus, we suggest that the identified pseudogenes affecting metabolism might play a greater role during infection than previously thought.
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experimental Salmonella gallinarum infection in light laying hen lines
Brazilian Journal of Microbiology, 2000Co-Authors: Angelo Berchieri, Glaucia Helaine De Oliveira, Lucas Augusto Soeiro Pinheiro, Paul BarrowAbstract:Although the epidemiology of fowl typhoid in chickens supposedly involves a vertical transmission stage, a previous work run by the authors has suggested that this did not happen in a commercial line of laying hens highly susceptible to systemic disease with Salmonella gallinarum. A new experiment was carried out in two other lines of commercial layers, considerably more resistant than those used in the previous study. Clinical fowl typhoid was not observed, but Salmonella gallinarum was isolated from the spleen and liver four weeks after infection and, sporadically, from the ovary.
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resistance to Salmonella gallinarum s pullorum and s enteritidis in inbred lines of chickens
Avian Diseases, 1993Co-Authors: Nat Bumstead, Paul BarrowAbstract:SUMMARY. Chickens of six inbred lines were inoculated intramuscularly with a range of doses of either Salmonella gallinarum, S. pullorum, or S. enteritidis, and levels of mortality were compared. For each serotype, large differences in mean lethal doses were observed for the different lines: Lines that had previously been shown to be resistant to S. typhimurium were also found to be resistant to S. gallinarum, S. pullorum, and S. enteritidis, and lines susceptible to S. typhimurium were also more susceptible to the other serotypes. These results suggest that there may be a general mechanism of resistance that may apply to all serotypes of Salmonella in chickens.
