The structural basis for the serospecificity of Actinobacillus suis serogroup O:2

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From: Biochemistry and Cell Biology(Vol. 84, Issue 2)
Publisher: NRC Research Press
Document Type: Article
Length: 3,010 words
Lexile Measure: 1630L

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Abstract: Actinobacillus suis is an important bacterial pathogen of healthly pigs. An O-antigen (lipopolysaccharide; LPS) serotyping system is being developed to study the prevalence and distribution of representative isolates from both healthy and diseased pigs. In a previous study, we reported that A. suis serogroup O:1 strains express LPS with a (1[right arrow]6)-[beta]-D-glucan O-antigen chain polysaccharide that is similar in structure to a key cell-wall component in yeasts, such as Saccharomyces cerevisiae and Candida albicans. This study describes the O-antigen polysaccharide chemical structure of an O:2 serogroup strain, A. suis H91-0380, which possesses a tetrasaccharide repeating block with the structure: [right arrow]3)-[beta]-D-Galp-(1[right arrow]4)-[[alpha]-D-Galp-(1[right arrow]6)] -[beta]-D-Glcp-(1[right arrow]6)-[beta]-D-GlcpNAc-(1[right arrow]. Studies have shown that A. suis serogroup O:2 strains are associated with severely diseased animals; therefore, work on the synthesis of a glycoconjugate vaccine employing O:2 O-antigen polysaccharide to vaccinate pigs against A. suis serogroup O:2 strains is currently underway.

Key words: Actinobacillus suis, lipopolysaccharide, serogroup O:2, vaccine.

Resume: Actinobacillus suis est un pathogene bacterien important affectant le porc. Un systeme de typage serologique base sur les antigenes-O (lipopolysaccharides) a ete developpe afin d'etudier la prevalence et la distribution d'isolats representatifs chez les porcs sains et malades. Lors d'une etude precedente, nous avons rapporte que les souches de A. suis du groupe serologique O:1 expriment un LPS possedant une chaine polysaccharide antigenique O-(1[flecha diestra]6)-[beta]-D-glucane similaire celle de la structure d'une composante cle de la membrane cellulaire des levures telles Saccharomyces cerevisiae et Candida albicans. La presente etude decrit la structure chimique d'un lipopoysaccharide antigenique O- du groupe serologique O:2, A.suis H91-0380, qui possede un tetra-saccharide repete dont la structure est : [flecha diestra]3)-[beta]-D-Galp-(1[flecha diestra]4)-[[alpha]-D-Galp-(1[flecha diestra]6)] -[beta]-D-Glcp-(1[flecha diestra]6)-[beta]-D-GlcpNAc-(1[flecha diestra]. Les etudes ont demontre que les souches de A. suis du groupe serologique O:2 sont associees aux animaux severement malades; ainsi, nous travaillons actuellement a la synthese d'un vaccin glycoconjugue utilisant le polysaccharide antigenique O:2 afin de vacciner les porcs contre les souches de A. suis du groupe serologique O:2.

Mots cles : Actinobacillus suis; lipopolysaccharide, groupe serologique O:2, vaccin.

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Introduction

In recent years, the Gram-negative bacterium Actinobacillus suis has emerged as an important opportunistic pathogen of healthly pigs (Fenwick 1997; MacInnes and Desrosier 1999). In very young animals, A. suis infection can cause an acute and rapidly fatal septicemia; in older animals, it is associated with diseases such as meningitis, metritis, pneumonia, erysipelas-like lesions, and abortion (Taylor 1999; van Ostaaijen et al. 1997). Currently, there are no commercially available vaccines, and because the onset of the A. suis disease tends to be very rapid, effective treatment is difficult. Little is known about the pathogenesis of A. suis, but it has been hypothesized that homologs of virulence factors (e.g., urease and Apx toxins) found in the closely related swine pathogen Actinobacillus pleuropneumoniae may be involved in A. suis pathogenesis (Bosse et al. 2002). As with other Gram-negative organisms, it is expected that the cell lipopolysaccharides (LPSs) ([O-chain polysaccharide][right arrow][core oligosaccharide][right arrow][lipid A]cell) play a key role in A. suis--host interactions (Rietschel...

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Gale Document Number: GALE|A148577548