Differences in SpeB protease activity among group A streptococci associated with superficial, invasive, and autoimmune diseaseReport as inadecuate




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The secreted cysteine proteinase SpeB is an important virulence factor of group A streptococci GAS, whereby SpeB activity varies widely among strains. To establish the degree to which SpeB activity correlates with disease, GAS organisms were recovered from patients with pharyngitis, impetigo, invasive disease or acute rheumatic fever ARF, and selected for analysis using rigorous sampling criteria; >300 GAS isolates were tested for SpeB activity by casein digestion assays, and each GAS isolate was scored as a SpeB-producer or non-producer. Highly significant statistical differences p < 0.01 in SpeB production are observed between GAS recovered from patients with ARF 41.5% SpeB-non-producers compared to pharyngitis 20.5%, invasive disease 16.7%, and impetigo 5.5%. SpeB activity differences between pharyngitis and impetigo isolates are also significant, whereas pharyngitis versus invasive isolates show no significant difference. The disproportionately greater number of SpeB-non-producers among ARF-associated isolates may indicate an altered transcriptional program for many rheumatogenic strains and-or a protective role for SpeB in GAS-triggered autoimmunity.



Author: Anhphan T. Ly , John P. Noto , Odaelys L. Walwyn, Robert R. Tanz, Stanford T. Shulman, William Kabat, Debra E. Bessen

Source: http://plos.srce.hr/



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