Cloning, Expression, and Characterization of the Superantigen Streptococcal Pyrogenic Exotoxin G from Streptococcus dysgalactiae

Abstract

We identified seven novel variants of streptococcal pyrogenic exotoxin G (SPEGG), a superantigen, in Streptococcus dysgalactiae subsp. dysgalactiae or equisimilis isolates from clinical cases of infection in humans and animals. Phylogenetic analysis of the SPEGG variants indicated two clades in the dendrogram: one composed of variants derived from the bacteria isolated from the humans and the other composed of variants from the bacteria isolated from the animals. Bovine peripheral blood mononuclear cells (PBMCs) were stimulated effectively by recombinant SPEGGs (rSPEGGs) expressed in Escherichia coli, while human PBMCs were not stimulated well by any of the rSPEGGs tested. SPEGGs selectively stimulated bovine T cells bearing V␤1,10 and V␤4. Bovine serum showed reactivity to the rSPEGG proteins. These results indicated that SPEGGs have properties as superantigens, and it is likely that SPEGGs play a pathogenic role in animals.

Virulence Gene Pool Detected in Bovine Group C Streptococcus dysgalactiae subsp. dysgalactiae Isolates by Use of a Group A S. pyogenes Virulence Microarray

“…By using other primers (designed in this study) targeting the speM and speK genes of S. pyogenes and spegg of S. dysgalactiae subsp. equisimilis (73), eight bovine isolates that carried speK, one bovine isolate that carried speM, one bovine isolate that carried speK and speM, and five human isolates that carried spegg were found.…”

“…In addition, it was not clear how many isolates carried the speG gene by both the array and PCR amplification results. The latter may be due to a lack of homology between the primers used and the speG gene of S. dysgalactiae (named spegg), as variants of this gene may occur (73). By using other primers (designed in this study) targeting the speM and speK genes of S. pyogenes and spegg of S. dysgalactiae subsp.…”

Soft tissue infection caused by Streptococcus dysgalactiae subsp. equisimilis possessing group Aantigen: a and review of the literature

“…However, scarce occurrences of SDSE strains have been described, having one of those genes [32,43]. The only superantigen gene which is often found in SDSE strains is spe G, which encodes exotoxin G [12,22,24,32,35,36,[39][40][41][42]44]. Between both of these closely related bacteria, interspecies DNA transfer occurs [6,45,46] by means of mobile genetic elements.…”

“…Three cases of iatrogenic SDSE infection following transfusion of platelet concentrates were described [19], as well as cases of nosocomial infections [30]. It was found that most patients with invasive infections caused by SDSE were suffering from additional disorders, especially with cardiovascular diseases of atherosclerotic etiology, diabetes, obesity, [72,73], dogs [74], camels [75], cattle [44] and sea otters [76]. Marked differences have been found between SDSE strains deriving from humans and animals [44,73].…”

“…It was found that most patients with invasive infections caused by SDSE were suffering from additional disorders, especially with cardiovascular diseases of atherosclerotic etiology, diabetes, obesity, [72,73], dogs [74], camels [75], cattle [44] and sea otters [76]. Marked differences have been found between SDSE strains deriving from humans and animals [44,73]. Kawata et al [73] discovered no streptokinase activity on human plasminogen in any of 11 SDSE strains isolated from pigs, such activity being one of the most important distinctive features of this bacterium [1].…”