<i>Actinobacillus pleuropneumoniae</i>surface polysaccharides: their role in diagnosis and immunogenicity

Dubreuil, J. Daniel; Jacques, Mario; Mittal, K. R.; Gottschalk, Marcelo

doi:10.1017/s1466252300000074

Cited by 111 publications

(111 citation statements)

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“…MS of the deacylated LPS of the mutant 5.1 gave m/z ϭ 2346 as the most intense peak, and this corresponds to a structure of lipid A, 1Kdo, 1PO 4 , 4Hep, and 2Hex. There were also peaks at 2470 (ϩPEA), 2508 (ϩHex), 2632(ϩHex and PEA), 2672 (ϩ2Hex), 2714 (ϩHex and HexNAc, small peak), 2874 (ϩ2Hex and HexNAc), and 2996 (ϩ2Hex, HexNAc, and PEA) (TABLE FOUR).…”

Section: Resultsmentioning

confidence: 99%

“…MS of the deacylated LPS sample of the mutant CG3 gave several peaks all based on the m/z ϭ 2154 (lipid A, 1Kdo, 1PO 4 (Fig. 1D).…”

Section: Structure and Properties Of A Pleuropneumoniae Lps Mutantsmentioning

confidence: 99%

“…However, it has been reported that pigs may be subclinically infected without presenting clinical signs (2,3), and these pigs are thought to be the main cause of A. pleuropneumoniae dissemination (1). Fifteen serotypes of A. pleuropneumoniae based on capsular antigens have been identified, and the most predominant in Quebec, Canada, are serotypes 1, 5, and 7 (4). Among the many virulence factors of A. pleuropneumoniae, namely the RTX (repeats-in-toxin) toxins (5), the capsule, and the outer membrane proteins (6 -8), the lipopolysaccharides (LPS), 2 are known to be important, because of their involvement in the adhesion to host cells (9,10), and are also known to play a role in the stimulation of the host immune system.…”

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confidence: 99%

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Truncation of the Lipopolysaccharide Outer Core Affects Susceptibility to Antimicrobial Peptides and Virulence of Actinobacillus pleuropneumoniae Serotype 1

Ramjeet

Deslandes

Michael

et al. 2005

Journal of Biological Chemistry

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We reported previously that the core oligosaccharide region of the lipopolysaccharide (LPS) is essential for optimal adhesion of Actinobacillus pleuropneumoniae, an important swine pathogen, to respiratory tract cells. Rough LPS and core LPS mutants of A. pleuropneumoniae serotype 1 were generated by using a mini-Tn10 transposon mutagenesis system. Here we performed a structural analysis of the oligosaccharide region of three core LPS mutants that still produce the same O-antigen by using methylation analyses and mass spectrometry. We also performed a kinetic study of proinflammatory cytokines production such as interleukin (IL)-6, tumor necrosis factor-␣, IL1-␤, MCP-1, and IL8 by LPS-stimulated porcine alveolar macrophages, which showed that purified LPS of the parent strain, the rough LPS and core LPS mutants, had the same ability to stimulate the production of cytokines. Most interestingly, an in vitro susceptibility test of these LPS mutants to antimicrobial peptides showed that the three core LPS mutants were more susceptible to cationic peptides than both the rough LPS mutant and the wild type parent strain. Furthermore, experimental pig infections with these mutants revealed that the galactose (Gal I) and D,D-heptose (Hep IV) residues present in the outer core of A. pleuropneumoniae serotype 1 LPS are important for adhesion and overall virulence in the natural host, whereas deletion of the terminal GalNAc-Gal II disaccharide had no effect. Our data suggest that an intact core-lipid A region is required for optimal protection of A. pleuropneumoniae against cationic peptides and that deletion of specific residues in the outer LPS core results in the attenuation of the virulence of A. pleuropneumoniae serotype 1.

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Section: Resultsmentioning

confidence: 99%

“…MS of the deacylated LPS sample of the mutant CG3 gave several peaks all based on the m/z ϭ 2154 (lipid A, 1Kdo, 1PO 4 (Fig. 1D).…”

Section: Structure and Properties Of A Pleuropneumoniae Lps Mutantsmentioning

confidence: 99%

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confidence: 99%

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Truncation of the Lipopolysaccharide Outer Core Affects Susceptibility to Antimicrobial Peptides and Virulence of Actinobacillus pleuropneumoniae Serotype 1

Ramjeet

Deslandes

Michael

et al. 2005

Journal of Biological Chemistry

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“…Hitherto, an accurate diagnosis of porcine pleuropneumonia has depended on the isolation of the etiological agent and examination of its biochemical and morphological properties, and on the serological status of the herd [7]. Culture of A. pleuropneumoniae can be relatively insensitive, especially in chronic cases, and it is also time-consuming [16].…”

Section: Discussionmentioning

confidence: 99%

In situ hybridization for the detection of the apxIV gene in the lungs of pigs experimentally infected with twelve Actinobacillus pleuropneumoniae serotypes

2002

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-The detection of the apxIV gene in lung tissues from pigs experimentally infected with the 12 major A. pleuropneumoniae serotype (1 to 12) reference strains was studied by in situ hybridization using a non-radioactive digoxigenin-labeled DNA probe. In situ hybridization produced a distinct positive signal in all pigs inoculated with the 12 A. pleuropneumoniae serotypes. Positive hybridization typically exhibited a dark-brown to black reaction product in intracellular and extracellular locations, without background staining. A strong hybridization signal was seen in degenerated alveolar leukocytes ("oat cells") adjacent to the foci of coagulative necrosis and in the alveolar spaces. The in situ hybridization methodology developed for the detection of the apxIV gene is a valuable tool for the diagnosis of porcine pleuropneumonia caused by A. pleuropneumoniae when only formalin-fixed tissues are submitted for diagnosis.Actinobacillus pleuropneumoniae / Apx toxin / in situ hybridization / lung / pig Résumé -Détection par hybridation in situ du gène apxIV dans les poumons de porcs infectés expérimentalement par douze sérotypes de Actinobacillus pleuropneumoniae. La détection du gène apxIV dans les tissus pulmonaires de porcs infectés expérimentalement par les douze sérotypes majeurs des souches de référence (1 à 12) de Actinobacillus pleuropneumoniae a été effectuée par hybridation in situ utilisant une sonde à ADN non radioactive marquée à la digoxigénine. L'hybridation in situ a produit un signal positif distinct chez tous les porcs inoculés par les douze sérotypes de A. pleuropneumoniae. Un résultat positif d'hybridation entraînait typiquement un produit de réaction marron foncé à noir localisé en intra-et en extra-cellulaire, sans bruit de fond. Un signal fort d'hybridation a été observé dans les leucocytes alvéolaires dégénérés adjacents aux foyers de nécrose et dans les espaces alvéolaires. La méthode d'hybridation in situ développée pour la détection du gène apxIV est un outil précieux pour le diagnostic de la pleuropneumonie porcine causée par A. pleuropneumoniae lorsque seuls les tissus fixés dans le formol sont soumis pour le diagnostic.Actinobacillus pleuropneumoniae / Apx toxine / hybridation in situ / poumon / porc 653 Vet.

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“…Two additional serotypes of NAD-independent A. pleuropneumoniae have been reported (20). In North America, serotypes 1, 5, and 7 are the most prevalent serotypes recovered from diseased animals (4).…”

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Isolation of an Atypical Strain ofActinobacillus pleuropneumoniaeSerotype 1 with a Truncated Lipopolysaccharide Outer Core and No O-Antigen

et al. 2005

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A field isolate of Actinobacillus pleuropneumoniae, the causative agent of porcine fibrinohemorrhagic necrotizing pleuropneumonia, was sent to the diagnostic laboratory for serotyping. The isolate presented a clear reaction, with both polyclonal antibodies against serotype 1 and monoclonal antibodies against the capsular polysaccharide of serotype 1. It also exhibited a PCR profile of Apx toxins expected for serotype 1. The isolate, however, failed to react with monoclonal antibodies against the O-antigen of serotype 1 lipopolysaccharide (LPS), suggesting a rough phenotype. The lipid A-core region of the isolate migrated faster than the corresponding region of the serotype 1 reference strain S4074 by Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting the presence of a truncated core. Sugar analysis and mass spectrometry analysis of the O-deacylated LPS from the field isolate were consistent with the absence of O-antigen and truncation of the outer core compared to the wild-type reference strain. Experimental infection of pigs confirmed the virulence of the isolate. This is the first report of an isolate of A. pleuropneumoniae serotype 1 with a truncated outer core and a rough LPS phenotype. Veterinary diagnostic laboratories should be vigilant, since infections caused by such an isolate will not be detected by serological tests based on LPS O-antigen.Actinobacillus pleuropneumoniae is the etiologic agent of porcine pleuropneumonia, a highly contagious respiratory disease with major economic implications for the swine industry worldwide (27). Twelve serotypes of NAD-dependent A. pleuropneumoniae have been recognized based on capsular polysaccharide (CPS) and lipopolysaccharide (LPS) antigens (19), and an additional serotype has recently been proposed by Blackall et al. (2). Two additional serotypes of NAD-independent A. pleuropneumoniae have been reported (20). In North America, serotypes 1, 5, and 7 are the most prevalent serotypes recovered from diseased animals (4).Infection by A. pleuropneumoniae is a multifactorial process governed by many virulence factors acting alone or in concert and by host susceptibility. Several virulence factors, such as CPS, LPS, outer membrane proteins, and Apx toxins, have already been identified (3, 5, 10). Studies by our group have focused on surface polysaccharides, namely, CPS and LPS, of A. pleuropneumoniae (4, 12). We have previously shown that the LPS molecule plays an important role in adherence of the bacterium to porcine respiratory tract cells and mucus (11). LPS molecules are a major constituent of outer membranes of gram-negative bacteria. They consist of a polysaccharide and a lipid moiety. The polysaccharide part is composed of a core region, which is an oligosaccharide containing 3-deoxy-Dmanno-2-octulosonic acid (Kdo), and the O antigen, a polysaccharide chain consisting of repeated units. We have generated rough LPS mutants as well as core LPS mutants by using transposon mutagenesis and showed that the core region of LPS seems to play a...

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Actinobacillus pleuropneumoniaesurface polysaccharides: their role in diagnosis and immunogenicity

Cited by 111 publications

References 118 publications

Truncation of the Lipopolysaccharide Outer Core Affects Susceptibility to Antimicrobial Peptides and Virulence of Actinobacillus pleuropneumoniae Serotype 1

Truncation of the Lipopolysaccharide Outer Core Affects Susceptibility to Antimicrobial Peptides and Virulence of Actinobacillus pleuropneumoniae Serotype 1

In situ hybridization for the detection of the apxIV gene in the lungs of pigs experimentally infected with twelve Actinobacillus pleuropneumoniae serotypes

Isolation of an Atypical Strain ofActinobacillus pleuropneumoniaeSerotype 1 with a Truncated Lipopolysaccharide Outer Core and No O-Antigen

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