National Institute of Animal Health (NIAH)

Topics in Animal Health Research 2012

20. The capsule of Erysipelothrix rhusiopathiae is modified by phosphocholine: A critical modification for the virulence of this organism


The capsule has been implicated in the virulence of the swine pathogen Erysipelothrix rhusiopathiae. Genome analysis of the Fujisawa strain of E. rhusiopathiae revealed that the genetic locus for capsular polysaccharide synthesis (cps) is located next to a lic operon, which is involved in the incorporation and expression of phosphorylcholine (PCho). Reverse transcription-PCR analysis showed that cps and lic are transcribed as a single mRNA, indicating that the loci form an operon. The capsular materials were isolated from the Fujisawa strain by hot water extraction and treatment with DNase, RNase, pronase, and N acetylmuramidase, followed by anion-exchange and gel filtration chromatography. The materials were analyzed by high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy. The capsular polysaccharide of E. rhusiopathiae is heterogeneous and consists of the major monosaccharides galacturonic acid, galactose, mannose, glucose, arabinose, xylose, and N-acetylglucosamine, and some minor monosaccharides including ribose, rhamnose, and N-acetylgalactosamine. In addition, the capsule is modified by PCho, which comigrates with the capsular materials, as determined by western immunoblotting, and colocalizes on the cell surface, as determined by immunogold electron microscopy. Virulence testing of PCho-defective mutants in mice demonstrated that PCho is critical for the virulence of this organism.
(Bacterial and Parasitic Disease Research Division)


Shi F. et al. (2012) Infection and Immunity 80:3993-4003