Identification, cloning and characterization of<i>rfaE</i>of<i>Actinobacillus pleuropneumoniae</i>serotype 1, a gene involved in lipopolysaccharide inner-core biosynthesis

Provost, Marilou; Harel, J; Labrie, J.-P.; Suquet, Marc; Jacques, Mario

doi:10.1016/s0378-1097(03)00247-7

Cited by 6 publications

(3 citation statements)

References 27 publications

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“…LPSs of Gram-negative bacteria are essential structural components of the cell membrane and are considered to be virulence determinants [40] . These substances are complex molecules composed of three well-defined biochemical moieties: the lipid A; the core oligosaccharide, which contains 3-deoxy-D-manno-oct-2-ulosonic acid (KDO) and is essential for optimal adhesion of A. pleuropneumoniae to the host [3] ; and the O-antigen, a polysaccharide consisting of repeating sugar units [41] .…”

Section: Resultsmentioning

confidence: 99%

Genome Biology of Actinobacillus pleuropneumoniae JL03, an Isolate of Serotype 3 Prevalent in China

Zhao

Zhou

et al. 2008

PLoS ONE

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Actinobacillus pleuropneumoniae is the etiologic agent of porcine contagious pleuropneumonia, a cause of considerable world wide economic losses in the swine industry. We sequenced the complete genome of A. pleuropneumoniae, JL03, an isolate of serotype 3 prevalent in China. Its genome is a single chromosome of 2,242,062 base pairs containing 2,097 predicted protein-coding sequences, six ribosomal rRNA operons, and 63 tRNA genes. Preliminary analysis of the genomic sequence and the functions of the encoded proteins not only confirmed the present physiological and pathological knowledge but also offered new insights into the metabolic and virulence characteristics of this important pathogen. We identified a full spectrum of genes related to its characteristic chemoheterotrophic catabolism of fermentation and respiration with an incomplete TCA system for anabolism. In addition to confirming the lack of ApxI toxin, identification of a nonsense mutation in apxIVA and a 5′-proximal truncation of the flp operon deleting both its promoter and the flp1flp2tadV genes have provided convincing scenarios for the low virulence property of JL03. Comparative genomic analysis using the available sequences of other serotypes, probable strain (serotype)-specific genomic islands related to capsular polysaccharides and lipopolysaccharide O-antigen biosyntheses were identified in JL03, which provides a foundation for future research into the mechanisms of serotypic diversity of A. pleuropneumoniae.

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Section: Resultsmentioning

confidence: 99%

Genome Biology of Actinobacillus pleuropneumoniae JL03, an Isolate of Serotype 3 Prevalent in China

Zhao

Zhou

et al. 2008

PLoS ONE

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“…The oligosaccharide core of lipopolysaccharides seems to play a role in this phenomenon. Knocking out the rfaE gene, which is involved in biosynthesis of lipopolysaccharides, resulted in a mutant strain that was no longer able to adhere [92]. …”

Section: Interactions Of a Pleuropneumoniae With The Lower Respiratomentioning

confidence: 99%

Virulence factors ofActinobacillus pleuropneumoniaeinvolved in colonization, persistence and induction of lesions in its porcine host

et al. 2010

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-Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia. The virulence factors of this microorganism involved in colonization and the induction of lung lesions have been thoroughly studied and some have been well characterized. A. pleuropneumoniae binds preferentially to cells of the lower respiratory tract in a process involving different adhesins and probably biofilm formation. Apx toxins and lipopolysaccharides exert pathogenic effects on several host cells, resulting in typical lung lesions. Lysis of host cells is essential for the bacterium to obtain nutrients from the environment and A. pleuropneumoniae has developed several uptake mechanisms for these nutrients. In addition to persistence in lung lesions, colonization of the upper respiratory tract -and of the tonsils in particular -may also be important for long-term persistent asymptomatic infection. Information on virulence factors involved in tonsillar and nasal cavity colonization and persistence is scarce, but it can be speculated that similar features as demonstrated for the lung may play a role.

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“…Genes known to be involved in the biosynthesis of the O-antigen (open reading frame 6 [ORF6] to ORF18 [this study and reference 14]) or the core oligosaccharide (ORFcg1 and ORFcg3 [7,14], rfaE [21], galU [23], and rfaD and waaF [this study]) of A. pleuropneumoniae serotype 1 were amplified by PCR (Table 1) as previously described (14). The A. pleuropneumoniae serotype 1 reference strain S4074 served as the control.…”

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confidence: 99%

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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Identification, cloning and characterization ofrfaEofActinobacillus pleuropneumoniaeserotype 1, a gene involved in lipopolysaccharide inner-core biosynthesis

Cited by 6 publications

References 27 publications

Genome Biology of Actinobacillus pleuropneumoniae JL03, an Isolate of Serotype 3 Prevalent in China

Genome Biology of Actinobacillus pleuropneumoniae JL03, an Isolate of Serotype 3 Prevalent in China

Virulence factors ofActinobacillus pleuropneumoniaeinvolved in colonization, persistence and induction of lesions in its porcine host

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

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