Abstract
We are developing a serotyping system for Actinobacillus suis based on its capsule (K) and lipopolysaccharide O-chain (O) structures. Previously, we have shown that less virulent strains of this swine pathogen express a (1→6)-β-D-glucan as both K- and O-chain polysaccharides and were serologically classified as K:1/O:1. Here, we show that representative A. suis strains with a high (H91-0380; serotype K:2/O:2) and intermediate (C84; serotype K:2/O:1) degree of virulence possess a capsule polysaccharide (K:2) composed of an O-acetylated diglycosyl phosphate repeat decorated with fructose: [→4)-3-O-Ac-β-D-GlcpNAc-(1→3)-[β-D-Fruf-(2→2)]-α-D-Galp-(1→PO(4)(-)→]. In addition, the serotype O:2 lipopolysaccharide was shown to express a sialylated O-chain [→3)-β-D-Galp-(1→4)-[Neu5Ac-(2→3)-α-D-Galp-(1→6)]-β-D-Glcp-(1→6)-β-D-GlcpNAc-(1→]. As (1→6)-β-D-glucan is ubiquitous in the environment, low levels of antibodies in the animals are predicted to prevent disease by K:1/O:1 strains. The greater potential associated with K:2/O:2 and K:2/O:1 strains is most likely due to the absence of (1→6)-β-D-glucan as the K antigen and, in the case of K:2/O:2, the presence of sialic acid in the lipopolysaccharide, a nonulosonic acid known to promote evasion of host recognition.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acetylation
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Actinobacillus Infections / immunology
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Actinobacillus Infections / microbiology*
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Actinobacillus suis / chemistry*
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Actinobacillus suis / immunology
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Actinobacillus suis / pathogenicity
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Animals
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Antigens, Bacterial / chemistry
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Antigens, Bacterial / immunology
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Antigens, Surface / chemistry
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Antigens, Surface / immunology
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Bacterial Capsules / chemistry*
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Bacterial Capsules / immunology
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Carbohydrate Sequence
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Lipopolysaccharides / chemistry*
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Lipopolysaccharides / immunology
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Lipopolysaccharides / isolation & purification
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Magnetic Resonance Spectroscopy
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Molecular Sequence Data
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N-Acetylneuraminic Acid / metabolism
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O Antigens / chemistry
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O Antigens / immunology
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Polysaccharides, Bacterial / chemistry*
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Polysaccharides, Bacterial / immunology
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Polysaccharides, Bacterial / isolation & purification
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Serotyping / methods*
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Sus scrofa / immunology
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Sus scrofa / microbiology
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Swine
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Swine Diseases / immunology
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Swine Diseases / microbiology*
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Virulence Factors / chemistry*
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Virulence Factors / immunology
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beta-Glucans / chemistry
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beta-Glucans / immunology
Substances
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Antigens, Bacterial
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Antigens, Surface
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K antigens
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Lipopolysaccharides
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O Antigens
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Polysaccharides, Bacterial
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Virulence Factors
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beta-Glucans
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N-Acetylneuraminic Acid