Characterization of pathogenic roles of two Erysipelothrix rhusiopathiae surface proteins.

Erysipelothrix rhusiopathiae is the causative agent of animal erysipelas and human erysipeloid. E. rhusiopathiae HP0728 and HP1472 have been reported to be down regulated in low-virulence or avirulent strains, but their pathogenic roles are not known. In this study, it was found that E. rhusiopathiae HP0728 and HP1472 were displayed on the surface of E. rhusiopathiae. Moreover, recombinant HP1472 could adhere to pig vascular endothelial cells. Recombinant HP0728 could bind host plasminogen but could not bind fibronectin. In conclusion, our work suggested that HP0728 and HP1472 are virulence factors of E. rhusiopathiae.

Erysipelothrix rhusiopathiae neuraminidase and its role in pathogenicity.

The role of the enzyme neuraminidase in pathogenicity of the bacillus Erysipelothrix rhusiopathiae was studied. Different substances with low and high molecular weight were tested as inducers of E. rhusiopathiae neuraminidase biosynthesis. It was found that macromolecular complexes induce the secretion of the enzyme. K(M) values for different substrates showed that the affinity of the E. rhusiopathiae neuraminidase increases in parallel with the enlargement of the molecular weight of glycoproteins. Results from the rabbits skin test confirmed the role of E. rhusiopathiae neuraminidase as a factor of pathogenicity with spreading functions.

Possible role of neuraminidase in the pathogenesis of arteritis and thrombocytopenia induced in rats by Erysipelothrix rhusiopathiae.

The role of the neuraminidase produced by Erysipelothrix rhusiopathiae (E. rhusiopathiae) in the pathogenesis of arteritis and induced thrombocytopenia was examined using young and adult rats. There was a close correlation between bacterial invasion, desialation and cell infiltration in the common iliac artery. E. rhusiopathiae induced arteritis from the second and third day after inoculation with 3 X 10(8) viable bacteria in the young and adult rats, respectively. This delay with age was closely related to the increase of free sialic acid in the plasma. The sites invaded by E. rhusiopathiae coincided with the desialated lesions, and the bacteria invaded the periarterial region which was always accompanied by desialation when examined with FITC-conjugated peanut lectin. The free sialic acid in the plasma was, at least partly, considered to originate from the desialation of the arterial wall caused by E. rhusiopathiae. The platelet number decreased significantly after inoculation. The sialic acid content of the platelets prepared from circulating blood at 12 and 18 hours after inoculation showed a slight decrease and decreased further when the platelets were incubated with the bacteria. Platelets obtained from circulating blood within 24 hours after inoculation or incubated with the bacteria had demonstrated desialated sites as detected by immunofluorescent staining with FITC-conjugated peanut lectin. In conclusion, free sialic acid in the plasma was considered to be a good marker of the desialation of the arteries caused by E. rhusiopathiae, and the neuraminidase produced by the bacteria would be a key to solve the pathogenesis of the arteritis and thrombocytopenia.

Erysipelas arthritis in swine: lysosomal enzyme levels in synovial fluids.

Arthritic and histologically normal joints from swine in which arthritis had been produced by the intravenous inoculation of Erysipelothrix rhusiopathiae were used as a source of fluids for lysosomal enzyme determinations. Mean lysozyme activities in synovias from arthritic and histologically normal joints were 16.60 and 5.79 mug/ml, respectively. Acid phosphatase (ACP) was increased more than 8 times the activity in histologically normal joints, but there was no relationship between lysozyme and ACP, indicating the probability that 1 of these enzymes came from another source. The cytoplasmic enzyme, lactic dehydrogenase (LDH), was increased in proportion to ACP, indicating that cell death and not selective extrusion of lysosomal enzymes during phagocytosis was an important mechanism of enzyme release in arthritic joints. Lysozyme activities in synovias from histologically normal joints were often increased above companion serum concentrations, indicating the enzyme has a special role in the joint. Also, the ratio of activities of lysozyme to ACP in pig buffy coat lysates was different from the ratio of the 2 enzymes in synovias from arthritic joints.