Erythrogenic toxin

Erythrogenic toxins, also referred to as streptococcal pyrogenic exotoxins, are secreted by strains of the bacterium . SpeA and SpeC are superantigens, which induce inflammation by nonspecifically activating T cells and stimulating the production of inflammatory cytokines. SpeB, the most abundant streptococcal extracellular protein, is a cysteine protease. Pyrogenic exotoxins are implicated as the causative agent of scarlet fever and . There is no consensus on the exact number of pyrogenic exotoxins. Serotypes A-C are the most extensively studied and recognized by all sources, but others note up to thirteen distinct types, categorizing SpeF-M as additional superantigens.

Erythrogenic toxins are known to damage the plasma membranes of blood capillaries under the skin and produce a red skin rash (characteristic of scarlet fever). Past studies have shown that multiple variants of erythrogenic toxins may be produced, depending on the strain of S. pyogenes in question. Some strains may not produce a detectable toxin at all.Bacteriophage T12 infection of Streptococcus pyogenes enables the production of Spe A, and increases virulence.

SpeB was identified in 1919 as an ectoenzyme secreted by certain strains of streptococci. It was originally studied as two separate toxins, streptococcal pyrogenic exotoxin B and streptococcal cysteine proteinase, until it was shown that both proteins were encoded by the speB gene and that the attributed pyrogenic activities were due to contamination by SpeA and SpeC.

Pyrogenic, in streptococcal pyrogenic exotoxin, means "causes fever."Erythrogenic refers to the typical red rash of scarlet fever. In older literature, these toxins are also referred to as scarlatina toxins or scarlet fever toxins due to their role as the causative agents of the disease.

SpeB is known as streptococcal pyrogenic exotoxin B, streptopain and streptococcal cysteine proteinase as a result of its original misidentification as two separate toxins, and is neither an exotoxin nor pyrogenic.

The speB and speJ genes are located in the core bacterial chromosome of all strains of S. pyogenes. However, despite its presence and high levels of conservation in the nucleotide sequence, 25-40% of these strains do not express the SpeB toxin in significant amounts.

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