Abstract
BackgroundActinobacillus suis disease has been reported in a wide range of vertebrate species, but is most commonly found in swine. A. suis is a commensal of the tonsils of the soft palate of swine, but in the presence of unknown stimuli it can invade the bloodstream, causing septicaemia and sequelae such as meningitis, arthritis, and death. It is genotypically and phenotypically similar to A. pleuropneumoniae, the causative agent of pleuropneumonia, and to other members of the family Pasteurellaceae that colonise tonsils. At present, very little is known about the genes involved in attachment, colonisation, and invasion by A. suis (or related members of the tonsil microbiota).ResultsBioinformatic analyses of the A. suis H91-0380 genome were done using BASys and blastx in GenBank. Forty-seven putative adhesin-associated genes predicted to encode 24 putative adhesins were discovered. Among these are 6 autotransporters, 25 fimbriae-associated genes (encoding 3 adhesins), 12 outer membrane proteins, and 4 additional genes (encoding 3 adhesins). With the exception of 2 autotransporter-encoding genes (aidA and ycgV), both with described roles in virulence in other species, all of the putative adhesin-associated genes had homologues in A. pleuropneumoniae. However, the majority of the closest homologues of the A. suis adhesins are found in A. ureae and A. capsulatus—species not known to infect swine, but both of which can cause systemic infections.ConclusionsA. suis and A. pleuropneumoniae share many of the same putative adhesins, suggesting that the different diseases, tissue tropism, and host range of these pathogens are due to subtle genetic differences, or perhaps differential expression of virulence factors during infection. However, many of the putative adhesins of A. suis share even greater homology with those of other pathogens within the family Pasteurellaceae. Similar to A. suis, these pathogens (A. capsulatus and A. ureae) cause systemic infections and it is tempting to speculate that they employ similar strategies to invade the host, but more work is needed before that assertion can be made. This work begins to examine adhesin-associated factors that allow some members of the family Pasteurellaceae to invade the bloodstream while others cause a more localised infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s13104-015-1659-x) contains supplementary material, which is available to authorized users.
Highlights
Actinobacillus suis disease has been reported in a wide range of vertebrate species, but is most commonly found in swine
As virtually nothing was known about these early steps in A. suis, the purpose of this study was to identify putative adhesins that may contribute to these processes in the genomes of several A. suis strains
Our analysis revealed that A. suis shares many of the same putative adhesins as A
Summary
Actinobacillus suis disease has been reported in a wide range of vertebrate species, but is most commonly found in swine. A. suis is a commensal of the tonsils of the soft palate of swine, but in the presence of unknown stimuli it can invade the bloodstream, causing septicaemia and sequelae such as meningitis, arthritis, and death. It is genotypically and phenotypically similar to A. pleuropneumoniae, the causative agent of pleuropneumonia, and to other members of the family Pasteurellaceae that colonise tonsils. Very little is known about the genes involved in attachment, colonisation, and invasion by A. suis (or related members of the tonsil microbiota). Actinobacillus suis, a member of the family Pasteurellaceae, is a Gram negative, facultative anaerobe, and a common commensal of the tonsils of the soft palate of swine [1]. Adhesins play an important role in the pathogenesis of most bacteria by allowing them to attach to, colonise, and invade their hosts. Adhesins are often classified as either fimbrial or afimbrial, where fimbrial adhesins are composed of multiple copies of one protein assembled into long appendages such as pili, and afimbrial adhesins are single proteins (e.g., autotransporters or outer membrane proteins) that have adhesive properties [10]
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