Secretion of EndoS and SpeB during growth of S. pyogenes strain AP1. Panel A, growth of wild type AP1 and measurements of optical density at 620 nm over time. Samples were withdrawn for analysis at indicated time points. Panel B, detection of EndoS in samples from indicated time points using antiserum against full-length EndoS. Panel C, detection of SpeB in the culture supernatants using antiserum against the 40 kDa zymogen form of SpeB.