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Two pyrogenic mitogens, SePE-H and SePE-I, were characterized in Streptococcus equi, the cause of equine strangles. SePE-H and SePE-I have molecular masses of 27.5 and 29.5 kDa, respectively, and each is almost identical to its counterpart in Streptococcus pyogenes M1. Both genes are adjacent to a gene encoding a phage muramidase of 49.7 kDa and are located immediately downstream from a phage genomic sequence almost identical to a similar phage sequence in S. pyogenes M1. Strong mitogenic responses were elicited by both proteins from horse peripheral blood mononuclear cells. However, although both were pyrogenic for rabbits, only SePE-I was pyrogenic in ponies. Convalescent sera contained antibody to each mitogen and horses recovered from strangles or immunized with SePE-I were resistant to the pyrogenic effect of SePE-I. The immunogenicity of SePE-I suggests that it should be included in new generation strangles vaccines. In isolates of S. equi sepe-I and sepe-H were consistently present but they were absent from the closely related Streptococcus zooepidemicus, suggesting that phage mediated transfer was an important event in the formation of the clonal, more virulent, S. equi from its putative S. zooepidemicus ancestor., (Copyright 2002 Academic Press.)

Severe invasive disease associated with group A Streptococcus (GAS) has recently increased in frequency. Isolates of GAS from normally sterile sites were examined for the streptococcal pyrogenic exotoxin genes spe A, spe B and spe C to determine if they play a role in this disease. Four primers for each gene were used in a nested polymerase chain reaction (PCR) configuration. The first PCR generated fragments of 818, 1106, and 801 bp, respectively, for the extotoxin genes. The second PCR generated fragments of 500, 912 and 654 bp for the spe A, spe B and spe C genes using the fragments from the first PCR as template. Of 62 strains tested, 35 (56%) contained the spe A gene, and 17 (27%) contained the spe C gene. All GAS strains studied, regardless of disease association, contained the spe B gene. These data corroborate accumulating evidence that the genes encoding pyrogenic exotoxin types B and C are not associated with severe invasive streptococcal illness including streptococcal toxic shock-like syndrome. This PCR-based gene detection system has clinical and epidemiologic applications because of its ease of performance, non-isotope labelling, high specificity and sensitivity, and lack of requirement for purified DNA.