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Peter Kuhnert - One of the best experts on this subject based on the ideXlab platform.
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The Family Pasteurellaceae
The Prokaryotes, 2014Co-Authors: Henrik Christensen, Peter Kuhnert, Niels Nørskov-lauritsen, Paul J. PlanetAbstract:This chapter describes the systematics and evolution of Pasteurellaceae with emphasis on new information generated since the 3rd edition of The Prokaryotes which only included chapters dealing with Haemophilus, Actinobacillus, and Pasteurella. A major source of new information for the current chapter has been provided by whole genome sequences now available for many taxa of the family. Some 100 species and species-like taxa have been documented and 18 genera of Pasteurellaceae reported so far. Members of the family include specialized commensals, potential pathogens, or pathogens of vertebrates and mainly survive poorly in other habitats including the external environment. The pathogenic members are of major importance to animal production and human health. Members of Pasteurellaceae have relatively small genomes, probably as a result of adaption to a special habitat. The most important species in veterinary microbiology include Pasteurella multocida, Actinobacillus pleuropneumoniae, [Haemophilus] parasuis, Mannheimia haemolytica, Bibersteinia trehalosi, and Avibacterium paragallinarum, while Haemophilus influenzae and Aggregatibacter actinomycetemcomitans represent the most important species as to human disease. Traditional isolation techniques are still used in both human and veterinary clinical diagnostic laboratories although genetically based diagnostic methods have replaced traditional biochemical/physiological methods for characterization and identification. For all species, MALDI-TOF can now be used as a diagnostic tool. As control and if MALDI-TOF equipment is not at hand, PCR-based specific detection is possible for Pasteurella multocida, Actinobacillus pleuropneumoniae, [Haemophilus] parasuis, Mannheimia haemolytica, Avibacterium paragallinarum, Gallibacterium anatis, Haemophilus influenzae, and Aggregatibacter actinomycetemcomitans. A lot of work has been directed towards identification of virulence factors and understanding host microbe interactions involved in disease.
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mesenteric lymphangitis and sepsis due to rtx toxin producing Actinobacillus spp in 2 foals with hypothyroidism dysmaturity syndrome
Veterinary Pathology, 2012Co-Authors: Peter Kuhnert, Christiane V Lohr, Ulf Polster, Axel Karger, Fred R. Rurangirwa, Jens Peter TeifkeAbstract:Actinobacillus suis-like organisms (ASLOs) have been isolated from the genital, respiratory, and digestive tracts of healthy adult horses, horses with respiratory disease, and septic foals. Two foals with congenital hypothyroidism-dysmaturity syndrome from separate farms developed ASLO infection. At necropsy, both had contracted carpal flexor tendons, thyroid hyperplasia, and thrombotic and necrotizing mesenteric lymphangitis and lymphadenitis; one foal also had mandibular prognathism. Numerous ASLOs were isolated from tissues from both foals, including intestine. Biochemical testing and mass spectrometric analysis of the two Actinobacillus isolates did not allow unequivocal identification. Comparative genetic analysis was done on these and similar isolates, including phylogeny based on 16S rRNA, rpoB and recN genes, as well as RTX (repeat in toxin) toxin typing of apxIA-apxIVA and aqxA genes. One isolate was identified as Actinobacillus suis sensu stricto, based on the presence of apxIA and apxIIA but not aqxA, whereas the other isolate had aqxA but neither apxIA nor apxIIA, consistent with A equuli ssp haemolyticus. Based on genotypic analysis of the isolates included for comparison, 3 of 3 equine ASLOs and 2 of 5 A equuli isolates were reclassified as A equuli subsp haemolyticus, emphasizing the importance of toxin genotyping in accurate classification of actinobacilli.
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Comparative phylogenies of the housekeeping genes atpD, infB and rpoB and the 16S rRNA gene within the Pasteurellaceae.
International Journal of Systematic and Evolutionary Microbiology, 2004Co-Authors: Henrik Christensen, Peter Kuhnert, John Elmerdahl OlsenAbstract:Phylogenies of housekeeping gene and 16S rRNA gene sequences were compared to improve the classification of the bacterial family Pasteurellaceae and knowledge of the evolutionary relationships of its members. Deduced partial protein sequences of the housekeeping genes atpD, infB and rpoB were compared in 28, 36 and 28 representative taxa of the Pasteurellaceae, respectively. The monophyly of representatives of the genus Gallibacterium was recognized by analysis of all housekeeping genes, while members of Mannheimia, Actinobacillus sensu stricto and the core group of Pasteurella sensu stricto formed monophyletic groups with two out of three housekeeping genes. Representatives of Mannheimia, Actinobacillus sensu stricto, [Haemophilus] ducreyi and [Pasteurella] trehalosi formed a monophyletic unit by analysis of all three housekeeping genes, which was in contrast to the 16S rRNA gene-derived phylogeny, where these taxa occurred at separate positions in the phylogenetic tree. Representatives of the Rodent, Avian and Aphrophilus–Haemophilus 16S rRNA gene groups were weakly supported by phylogenetic analysis of housekeeping genes. Phylogenies derived by comparison of the housekeeping genes diverged significantly from the 16S rRNA gene-derived phylogeny as evaluated by the likelihood ratio test. A low degree of congruence was also observed between the individual housekeeping gene-derived phylogenies. Estimates on speciation derived from 16S rRNA and housekeeping gene sequence comparisons resulted in quite different evolutionary scenarios for members of the Pasteurellaceae. The phylogeny based on the housekeeping genes supported observed host associations between Mannheimia, Actinobacillus sensu stricto and [Pasteurella] trehalosi and animals with paired hooves.
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phylogenetic relationship of equine Actinobacillus species and distribution of rtx toxin genes among clusters
Veterinary Research, 2003Co-Authors: Peter Kuhnert, Helene Berthoud, Henrik Christensen, Magne BisgaardAbstract:Equine Actinobacillus species were analysed phylogenetically by 16S rRNA gene (rrs) sequencing focusing on the species Actinobacillus equuli, which has recently been subdivided into the non-haemolytic A. equuli subsp. equuli and the haemolytic A. equuli subsp. haemolyticus. In parallel we determined the profile for RTX toxin genes of the sample of strains by PCR testing for the presence of the A. equuli haemolysin gene aqx, and the toxin genes apxI, apxII, apxIII and apxIV, which are known in porcine pathogens such as Actinobacillus pleuropneumoniae and Actinobacillus suis. The rrs-based phylogenetic analysis revealed two distinct subclusters containing both A. equuli subsp. equuli and A. equuli subsp. haemolyticus distributed through both subclusters with no correlation to taxonomic classification. Within one of the rrs-based subclusters containing the A. equuli subsp. equuli type strain, clustered as well the porcine Actinobacillus suis strains. This latter is known to be also phenotypically closely related to A. equuli. The toxin gene analysis revealed that all A. equuli subsp. haemolyticus strains from both rrs subclusters specifically contained the aqx gene while the A. suis strains harboured the genes apxI and apxII. The aqx gene was found to be specific for A. equuli subsp. haemolyticus, since A. equuli subsp. equuli contained no aqx nor any of the other RTX genes tested. The specificity of aqx for the haemolytic equine A. equuli and ApxI and ApxII for the porcine A. suis indicates a role of these RTX toxins in host species predilection of the two closely related species of bacterial pathogens and allows PCR based diagnostic differentiation of the two.
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Host cell specific activity of RTX toxins from haemolytic Actinobacillus equuli and Actinobacillus suis.
Veterinary microbiology, 2003Co-Authors: Peter Kuhnert, Helene Berthoud, R StraubAbstract:We assessed and compared host cell specificity of the haemolytic and cytotoxic activity of the RTX toxins from Actinobacillus equuli, an equine pathogen, and Actinobacillus suis, which is pathogenic for pigs. The two bacterial species are closely related, phenotypically as well as phylogenetically, sharing the same 16S rRNA gene sequence. Both species contain specific protein toxins from the family of pore-forming RTX toxins, however, the two species differ in their RTX toxin profiles. Haemolytic A. equuli contains the operon for the Aqx toxin, whereas A. suis harbours genes for ApxI and ApxII. We tested the toxic activity of the corresponding proteins on erythrocytes as well as on lymphocytes isolated from horse and pig blood. The strength of the haemolytic activity for each of the toxins was independent of the origin of erythrocytes. When testing cytotoxic activity, the Aqx protein showed a higher toxic effect for horse lymphocytes than for porcine lymphocytes. On the other hand, ApxI and ApxII showed a strong cytotoxic effect on porcine lymphocytes and a reduced toxicity for horse lymphocytes; the toxicity of ApxII was generally much lower than ApxI. Our results indicate a host species specificity of the toxic activity of RTX toxins Aqx of A. equuli and ApxI and ApxII of A. suis.
John Elmerdahl Olsen - One of the best experts on this subject based on the ideXlab platform.
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Agricultural University,
2013Co-Authors: Microbiology The Royal, Frederiksberg C, John Elmerdahl OlsenAbstract:recognition of a novel genomospecies for equine strains of Actinobacillus lignieresii
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Comparative phylogenies of the housekeeping genes atpD, infB and rpoB and the 16S rRNA gene within the Pasteurellaceae.
International Journal of Systematic and Evolutionary Microbiology, 2004Co-Authors: Henrik Christensen, Peter Kuhnert, John Elmerdahl OlsenAbstract:Phylogenies of housekeeping gene and 16S rRNA gene sequences were compared to improve the classification of the bacterial family Pasteurellaceae and knowledge of the evolutionary relationships of its members. Deduced partial protein sequences of the housekeeping genes atpD, infB and rpoB were compared in 28, 36 and 28 representative taxa of the Pasteurellaceae, respectively. The monophyly of representatives of the genus Gallibacterium was recognized by analysis of all housekeeping genes, while members of Mannheimia, Actinobacillus sensu stricto and the core group of Pasteurella sensu stricto formed monophyletic groups with two out of three housekeeping genes. Representatives of Mannheimia, Actinobacillus sensu stricto, [Haemophilus] ducreyi and [Pasteurella] trehalosi formed a monophyletic unit by analysis of all three housekeeping genes, which was in contrast to the 16S rRNA gene-derived phylogeny, where these taxa occurred at separate positions in the phylogenetic tree. Representatives of the Rodent, Avian and Aphrophilus–Haemophilus 16S rRNA gene groups were weakly supported by phylogenetic analysis of housekeeping genes. Phylogenies derived by comparison of the housekeeping genes diverged significantly from the 16S rRNA gene-derived phylogeny as evaluated by the likelihood ratio test. A low degree of congruence was also observed between the individual housekeeping gene-derived phylogenies. Estimates on speciation derived from 16S rRNA and housekeeping gene sequence comparisons resulted in quite different evolutionary scenarios for members of the Pasteurellaceae. The phylogeny based on the housekeeping genes supported observed host associations between Mannheimia, Actinobacillus sensu stricto and [Pasteurella] trehalosi and animals with paired hooves.
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reclassification of equine isolates previously reported as Actinobacillus equuli variants of a equuli Actinobacillus suis or bisgaard taxon 11 and proposal of a equuli subsp equuli subsp nov and a equuli subsp haemolyticus subsp nov
International Journal of Systematic and Evolutionary Microbiology, 2002Co-Authors: Henrik Christensen, Magne Bisgaard, John Elmerdahl OlsenAbstract:Members of Bisgaard taxon 11 have been isolated from horses. These bacteria are of importance in the veterinary clinic and also to the medical profession, since they may be isolated from infected wounds of humans bitten by horses. Six strains from different continents were identified as taxon 11, with 16S rRNA similarities between 98.0 and 99.7%. A single isolate that represented the so-called (+)L-arabinose-positive Actinobacillus equuli isolated from a diseased foal showed 99.9% 16S rRNA similarity to the type strain of A. equuli. DNA-DNA hybridizations showed that (+)L-arabinose-positive strains of A. equuli represent A. equuli sensu stricto. DNA-DNA hybridizations also showed that A. equuli and Bisgaard taxon 11 represent two genotypes. These genotypes differ with respect to disease pattern and epidemiology. For these reasons, two subspecies of A. equuli are proposed, Actinobacillus equuli subsp. equuli subsp. nov. (type strain NCTC 8529T = ATCC 19392T) and Actinobacillus equuli subsp. haemolyticus subsp. nov. (type strain F 154T = CCUG 19799T = NCTC 13195T).
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Final classification of Bisgaard taxon 9 as Actinobacillus arthritidis sp. nov. and recognition of a novel genomospecies for equine strains of Actinobacillus lignieresii
International Journal of Systematic and Evolutionary Microbiology, 2002Co-Authors: Henrik Christensen, Øystein Angen, Magne Bisgaard, John Elmerdahl OlsenAbstract:Phenotypic characterization of bacteria from diseased and healthy horses identified 18 isolates as Bisgaard taxon 9 and 11 isolates as Actinobacillus lignieresii. All strains of taxon 9 were alpha-galactosidase- and raffinose-positive and showed variable fermentation of (+)L-arabinose and (-)D-sorbitol. Strains of A. lignieresii were negative for these characteristics, with the exception of raffinose. Two strains from the (-)D-sorbitol-negative group of taxon 9 showed a 16S rRNA similarity of 99-6%, while 99.5% similarity was found between two strains of the (-)D-sorbitol-positive group. DNA-DNA hybridization between the two strains representing the (-)D-sorbitol-negative group showed 98% binding, and their closest relationship was to a strain of A. lignieresii (64%). The two strains of the (-)D-sorbitol-positive group showed 83% binding and were related to the (-)D-sorbitol-negative group at a 76% DNA binding level. Actinobacillus arthritidis sp. nov. is proposed for 12 strains of the (-)D-sorbitol-positive group. Actinobacillus genomospecies 2 is suggested for the six strains of the (-)D-sorbitol-negative group. Phenotypically, strains of A. arthritidis and Actinobacillus genomospecies 2 differ in (-)D-sorbitol fermentation and can be separated from Actinobacillus equuli by being trehalose-negative, while a positive reaction for alpha-galactosidase separates the taxa from A. lignieresii. The type strain of A. arthritidis, CCUG 24862T, was isolated from a joint of a horse. Three equine isolates of A. lignieresii that could not be separated from the type strain by means of phenotypic characteristics showed 98.6-100% 16S rRNA similarity, but only 96.4-96.7% similarity to the type strain. DNA-DNA hybridization between two strains of this group showed 92% binding but only 70% binding to the type strain of A. lignieresii. Consequently, these equine isolates of A. lignieresii represent a new genomospecies of Actinobacillus, suggested as genomospecies 1 because phenotypic characteristics are not presently available to separate it from the type strain of A. lignieresii.
Henrik Christensen - One of the best experts on this subject based on the ideXlab platform.
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The Family Pasteurellaceae
The Prokaryotes, 2014Co-Authors: Henrik Christensen, Peter Kuhnert, Niels Nørskov-lauritsen, Paul J. PlanetAbstract:This chapter describes the systematics and evolution of Pasteurellaceae with emphasis on new information generated since the 3rd edition of The Prokaryotes which only included chapters dealing with Haemophilus, Actinobacillus, and Pasteurella. A major source of new information for the current chapter has been provided by whole genome sequences now available for many taxa of the family. Some 100 species and species-like taxa have been documented and 18 genera of Pasteurellaceae reported so far. Members of the family include specialized commensals, potential pathogens, or pathogens of vertebrates and mainly survive poorly in other habitats including the external environment. The pathogenic members are of major importance to animal production and human health. Members of Pasteurellaceae have relatively small genomes, probably as a result of adaption to a special habitat. The most important species in veterinary microbiology include Pasteurella multocida, Actinobacillus pleuropneumoniae, [Haemophilus] parasuis, Mannheimia haemolytica, Bibersteinia trehalosi, and Avibacterium paragallinarum, while Haemophilus influenzae and Aggregatibacter actinomycetemcomitans represent the most important species as to human disease. Traditional isolation techniques are still used in both human and veterinary clinical diagnostic laboratories although genetically based diagnostic methods have replaced traditional biochemical/physiological methods for characterization and identification. For all species, MALDI-TOF can now be used as a diagnostic tool. As control and if MALDI-TOF equipment is not at hand, PCR-based specific detection is possible for Pasteurella multocida, Actinobacillus pleuropneumoniae, [Haemophilus] parasuis, Mannheimia haemolytica, Avibacterium paragallinarum, Gallibacterium anatis, Haemophilus influenzae, and Aggregatibacter actinomycetemcomitans. A lot of work has been directed towards identification of virulence factors and understanding host microbe interactions involved in disease.
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Comparative phylogenies of the housekeeping genes atpD, infB and rpoB and the 16S rRNA gene within the Pasteurellaceae.
International Journal of Systematic and Evolutionary Microbiology, 2004Co-Authors: Henrik Christensen, Peter Kuhnert, John Elmerdahl OlsenAbstract:Phylogenies of housekeeping gene and 16S rRNA gene sequences were compared to improve the classification of the bacterial family Pasteurellaceae and knowledge of the evolutionary relationships of its members. Deduced partial protein sequences of the housekeeping genes atpD, infB and rpoB were compared in 28, 36 and 28 representative taxa of the Pasteurellaceae, respectively. The monophyly of representatives of the genus Gallibacterium was recognized by analysis of all housekeeping genes, while members of Mannheimia, Actinobacillus sensu stricto and the core group of Pasteurella sensu stricto formed monophyletic groups with two out of three housekeeping genes. Representatives of Mannheimia, Actinobacillus sensu stricto, [Haemophilus] ducreyi and [Pasteurella] trehalosi formed a monophyletic unit by analysis of all three housekeeping genes, which was in contrast to the 16S rRNA gene-derived phylogeny, where these taxa occurred at separate positions in the phylogenetic tree. Representatives of the Rodent, Avian and Aphrophilus–Haemophilus 16S rRNA gene groups were weakly supported by phylogenetic analysis of housekeeping genes. Phylogenies derived by comparison of the housekeeping genes diverged significantly from the 16S rRNA gene-derived phylogeny as evaluated by the likelihood ratio test. A low degree of congruence was also observed between the individual housekeeping gene-derived phylogenies. Estimates on speciation derived from 16S rRNA and housekeeping gene sequence comparisons resulted in quite different evolutionary scenarios for members of the Pasteurellaceae. The phylogeny based on the housekeeping genes supported observed host associations between Mannheimia, Actinobacillus sensu stricto and [Pasteurella] trehalosi and animals with paired hooves.
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phylogenetic relationship of equine Actinobacillus species and distribution of rtx toxin genes among clusters
Veterinary Research, 2003Co-Authors: Peter Kuhnert, Helene Berthoud, Henrik Christensen, Magne BisgaardAbstract:Equine Actinobacillus species were analysed phylogenetically by 16S rRNA gene (rrs) sequencing focusing on the species Actinobacillus equuli, which has recently been subdivided into the non-haemolytic A. equuli subsp. equuli and the haemolytic A. equuli subsp. haemolyticus. In parallel we determined the profile for RTX toxin genes of the sample of strains by PCR testing for the presence of the A. equuli haemolysin gene aqx, and the toxin genes apxI, apxII, apxIII and apxIV, which are known in porcine pathogens such as Actinobacillus pleuropneumoniae and Actinobacillus suis. The rrs-based phylogenetic analysis revealed two distinct subclusters containing both A. equuli subsp. equuli and A. equuli subsp. haemolyticus distributed through both subclusters with no correlation to taxonomic classification. Within one of the rrs-based subclusters containing the A. equuli subsp. equuli type strain, clustered as well the porcine Actinobacillus suis strains. This latter is known to be also phenotypically closely related to A. equuli. The toxin gene analysis revealed that all A. equuli subsp. haemolyticus strains from both rrs subclusters specifically contained the aqx gene while the A. suis strains harboured the genes apxI and apxII. The aqx gene was found to be specific for A. equuli subsp. haemolyticus, since A. equuli subsp. equuli contained no aqx nor any of the other RTX genes tested. The specificity of aqx for the haemolytic equine A. equuli and ApxI and ApxII for the porcine A. suis indicates a role of these RTX toxins in host species predilection of the two closely related species of bacterial pathogens and allows PCR based diagnostic differentiation of the two.
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reclassification of equine isolates previously reported as Actinobacillus equuli variants of a equuli Actinobacillus suis or bisgaard taxon 11 and proposal of a equuli subsp equuli subsp nov and a equuli subsp haemolyticus subsp nov
International Journal of Systematic and Evolutionary Microbiology, 2002Co-Authors: Henrik Christensen, Magne Bisgaard, John Elmerdahl OlsenAbstract:Members of Bisgaard taxon 11 have been isolated from horses. These bacteria are of importance in the veterinary clinic and also to the medical profession, since they may be isolated from infected wounds of humans bitten by horses. Six strains from different continents were identified as taxon 11, with 16S rRNA similarities between 98.0 and 99.7%. A single isolate that represented the so-called (+)L-arabinose-positive Actinobacillus equuli isolated from a diseased foal showed 99.9% 16S rRNA similarity to the type strain of A. equuli. DNA-DNA hybridizations showed that (+)L-arabinose-positive strains of A. equuli represent A. equuli sensu stricto. DNA-DNA hybridizations also showed that A. equuli and Bisgaard taxon 11 represent two genotypes. These genotypes differ with respect to disease pattern and epidemiology. For these reasons, two subspecies of A. equuli are proposed, Actinobacillus equuli subsp. equuli subsp. nov. (type strain NCTC 8529T = ATCC 19392T) and Actinobacillus equuli subsp. haemolyticus subsp. nov. (type strain F 154T = CCUG 19799T = NCTC 13195T).
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Final classification of Bisgaard taxon 9 as Actinobacillus arthritidis sp. nov. and recognition of a novel genomospecies for equine strains of Actinobacillus lignieresii
International Journal of Systematic and Evolutionary Microbiology, 2002Co-Authors: Henrik Christensen, Øystein Angen, Magne Bisgaard, John Elmerdahl OlsenAbstract:Phenotypic characterization of bacteria from diseased and healthy horses identified 18 isolates as Bisgaard taxon 9 and 11 isolates as Actinobacillus lignieresii. All strains of taxon 9 were alpha-galactosidase- and raffinose-positive and showed variable fermentation of (+)L-arabinose and (-)D-sorbitol. Strains of A. lignieresii were negative for these characteristics, with the exception of raffinose. Two strains from the (-)D-sorbitol-negative group of taxon 9 showed a 16S rRNA similarity of 99-6%, while 99.5% similarity was found between two strains of the (-)D-sorbitol-positive group. DNA-DNA hybridization between the two strains representing the (-)D-sorbitol-negative group showed 98% binding, and their closest relationship was to a strain of A. lignieresii (64%). The two strains of the (-)D-sorbitol-positive group showed 83% binding and were related to the (-)D-sorbitol-negative group at a 76% DNA binding level. Actinobacillus arthritidis sp. nov. is proposed for 12 strains of the (-)D-sorbitol-positive group. Actinobacillus genomospecies 2 is suggested for the six strains of the (-)D-sorbitol-negative group. Phenotypically, strains of A. arthritidis and Actinobacillus genomospecies 2 differ in (-)D-sorbitol fermentation and can be separated from Actinobacillus equuli by being trehalose-negative, while a positive reaction for alpha-galactosidase separates the taxa from A. lignieresii. The type strain of A. arthritidis, CCUG 24862T, was isolated from a joint of a horse. Three equine isolates of A. lignieresii that could not be separated from the type strain by means of phenotypic characteristics showed 98.6-100% 16S rRNA similarity, but only 96.4-96.7% similarity to the type strain. DNA-DNA hybridization between two strains of this group showed 92% binding but only 70% binding to the type strain of A. lignieresii. Consequently, these equine isolates of A. lignieresii represent a new genomospecies of Actinobacillus, suggested as genomospecies 1 because phenotypic characteristics are not presently available to separate it from the type strain of A. lignieresii.
Magne Bisgaard - One of the best experts on this subject based on the ideXlab platform.
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BRIEF COMMUNICATION Open Access
2013Co-Authors: Branko Kokotovic, Øystein Angen, Magne BisgaardAbstract:Genetic diversity of Actinobacillus lignieresii isolates from different host
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prevalence of organisms described as Actinobacillus suis or haemolytic Actinobacillus equuli in the oral cavity of horses comparative investigations of strains obtained and porcine strains of a suis sensu stricto
Acta Pathologica Microbiologica Scandinavica Series B: Microbiology, 2009Co-Authors: Magne Bisgaard, K Piechulla, Y T Ying, Wilhelm Frederiksen, W MannheimAbstract:: Evidence was obtained to indicate that equine strains of organisms previously described as Actinobacillus suis or hemolytic variants of Actinobacillus equuli might constitute a separate group of organisms provisionally designated taxon 11. Four biovars were noticed within taxon 11. Selected DNA:DNA hybridizations support the classification of the mannitol positive biovar 2 of taxon 11 distinct from porcine A. suis. The final taxonomical position of taxon 11, however, has to await more detailed genetic studies including all biovars of taxon 11. A species name has not been suggested for the same reasons. The present observations also indicate that strains identified as taxon 11 apparently constitute a part of the normal bacterial flora in the oral cavity of horses.
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phylogenetic relationship of equine Actinobacillus species and distribution of rtx toxin genes among clusters
Veterinary Research, 2003Co-Authors: Peter Kuhnert, Helene Berthoud, Henrik Christensen, Magne BisgaardAbstract:Equine Actinobacillus species were analysed phylogenetically by 16S rRNA gene (rrs) sequencing focusing on the species Actinobacillus equuli, which has recently been subdivided into the non-haemolytic A. equuli subsp. equuli and the haemolytic A. equuli subsp. haemolyticus. In parallel we determined the profile for RTX toxin genes of the sample of strains by PCR testing for the presence of the A. equuli haemolysin gene aqx, and the toxin genes apxI, apxII, apxIII and apxIV, which are known in porcine pathogens such as Actinobacillus pleuropneumoniae and Actinobacillus suis. The rrs-based phylogenetic analysis revealed two distinct subclusters containing both A. equuli subsp. equuli and A. equuli subsp. haemolyticus distributed through both subclusters with no correlation to taxonomic classification. Within one of the rrs-based subclusters containing the A. equuli subsp. equuli type strain, clustered as well the porcine Actinobacillus suis strains. This latter is known to be also phenotypically closely related to A. equuli. The toxin gene analysis revealed that all A. equuli subsp. haemolyticus strains from both rrs subclusters specifically contained the aqx gene while the A. suis strains harboured the genes apxI and apxII. The aqx gene was found to be specific for A. equuli subsp. haemolyticus, since A. equuli subsp. equuli contained no aqx nor any of the other RTX genes tested. The specificity of aqx for the haemolytic equine A. equuli and ApxI and ApxII for the porcine A. suis indicates a role of these RTX toxins in host species predilection of the two closely related species of bacterial pathogens and allows PCR based diagnostic differentiation of the two.
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reclassification of equine isolates previously reported as Actinobacillus equuli variants of a equuli Actinobacillus suis or bisgaard taxon 11 and proposal of a equuli subsp equuli subsp nov and a equuli subsp haemolyticus subsp nov
International Journal of Systematic and Evolutionary Microbiology, 2002Co-Authors: Henrik Christensen, Magne Bisgaard, John Elmerdahl OlsenAbstract:Members of Bisgaard taxon 11 have been isolated from horses. These bacteria are of importance in the veterinary clinic and also to the medical profession, since they may be isolated from infected wounds of humans bitten by horses. Six strains from different continents were identified as taxon 11, with 16S rRNA similarities between 98.0 and 99.7%. A single isolate that represented the so-called (+)L-arabinose-positive Actinobacillus equuli isolated from a diseased foal showed 99.9% 16S rRNA similarity to the type strain of A. equuli. DNA-DNA hybridizations showed that (+)L-arabinose-positive strains of A. equuli represent A. equuli sensu stricto. DNA-DNA hybridizations also showed that A. equuli and Bisgaard taxon 11 represent two genotypes. These genotypes differ with respect to disease pattern and epidemiology. For these reasons, two subspecies of A. equuli are proposed, Actinobacillus equuli subsp. equuli subsp. nov. (type strain NCTC 8529T = ATCC 19392T) and Actinobacillus equuli subsp. haemolyticus subsp. nov. (type strain F 154T = CCUG 19799T = NCTC 13195T).
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Final classification of Bisgaard taxon 9 as Actinobacillus arthritidis sp. nov. and recognition of a novel genomospecies for equine strains of Actinobacillus lignieresii
International Journal of Systematic and Evolutionary Microbiology, 2002Co-Authors: Henrik Christensen, Øystein Angen, Magne Bisgaard, John Elmerdahl OlsenAbstract:Phenotypic characterization of bacteria from diseased and healthy horses identified 18 isolates as Bisgaard taxon 9 and 11 isolates as Actinobacillus lignieresii. All strains of taxon 9 were alpha-galactosidase- and raffinose-positive and showed variable fermentation of (+)L-arabinose and (-)D-sorbitol. Strains of A. lignieresii were negative for these characteristics, with the exception of raffinose. Two strains from the (-)D-sorbitol-negative group of taxon 9 showed a 16S rRNA similarity of 99-6%, while 99.5% similarity was found between two strains of the (-)D-sorbitol-positive group. DNA-DNA hybridization between the two strains representing the (-)D-sorbitol-negative group showed 98% binding, and their closest relationship was to a strain of A. lignieresii (64%). The two strains of the (-)D-sorbitol-positive group showed 83% binding and were related to the (-)D-sorbitol-negative group at a 76% DNA binding level. Actinobacillus arthritidis sp. nov. is proposed for 12 strains of the (-)D-sorbitol-positive group. Actinobacillus genomospecies 2 is suggested for the six strains of the (-)D-sorbitol-negative group. Phenotypically, strains of A. arthritidis and Actinobacillus genomospecies 2 differ in (-)D-sorbitol fermentation and can be separated from Actinobacillus equuli by being trehalose-negative, while a positive reaction for alpha-galactosidase separates the taxa from A. lignieresii. The type strain of A. arthritidis, CCUG 24862T, was isolated from a joint of a horse. Three equine isolates of A. lignieresii that could not be separated from the type strain by means of phenotypic characteristics showed 98.6-100% 16S rRNA similarity, but only 96.4-96.7% similarity to the type strain. DNA-DNA hybridization between two strains of this group showed 92% binding but only 70% binding to the type strain of A. lignieresii. Consequently, these equine isolates of A. lignieresii represent a new genomospecies of Actinobacillus, suggested as genomospecies 1 because phenotypic characteristics are not presently available to separate it from the type strain of A. lignieresii.
Anders Johansson - One of the best experts on this subject based on the ideXlab platform.
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il 1beta secretion induced by aggregatibacter Actinobacillus actinomycetemcomitans is mainly caused by the leukotoxin
International Journal of Medical Microbiology, 2008Co-Authors: Peyman Kelk, Casey Chen, Rolf Claesson, Anders Sjöstedt, Anders JohanssonAbstract:Aggregatibacter (Actinobacillus) actinomycetemcomitans forms a leukotoxin that selectively lyses primate neutrophils, monocytes and triggers apoptosis in promyeloic cells and degranulation of human ...
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cytokine responses of human gingival fibroblasts to Actinobacillus actinomycetemcomitans cytolethal distending toxin
Cytokine, 2005Co-Authors: Georgios N. Belibasakis, Casey Chen, Sotirios Kalfas, Anders Johansson, Yu Wang, Teresa Lagergård, Ulf H. LernerAbstract:Actinobacillus actinomycetemcomitans is implicated in the pathogenesis of localized aggressive periodontitis, and has the capacity to express a cytolethal distending toxin (Cdt). Gingival fibroblas ...
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abundant secretion of bioactive interleukin 1β by human macrophages induced by Actinobacillus actinomycetemcomitans leukotoxin
Infection and Immunity, 2005Co-Authors: Peyman Kelk, Rolf Claesson, Ulf H. Lerner, L. Hanstrom, Sotirios Kalfas, Anders JohanssonAbstract:Actinobacillus actinomycetemcomitans produces a leukotoxin that selectively kills human leukocytes. Recently, we reported that macrophages are highly sensitive to leukotoxin and that their lysis in ...
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caspase 1 involvement in human monocyte lysis induced by Actinobacillus actinomycetemcomitans leukotoxin
Infection and Immunity, 2003Co-Authors: Peyman Kelk, Rolf Claesson, L. Hanstrom, Sotirios Kalfas, Anders JohanssonAbstract:Actinobacillus actinomycetemcomitans, an oral bacterium implicated in the etiology of periodontal diseases, produces a leukotoxin that selectively lyses primate neutrophils and monocytes, the major ...
