T virulence mechanism and function to a growing list of streptokinase activities.MATERIALS AND METHODSBacterial strains and culture conditions. GAS serotype M49 strain 591 was obtained from R. L ticken (Aachen, Germany). GAS M1 strain 90226 was obtained from the World Health Organization Center for Reference and Research on Streptococci at the University of Minnesota. It was originally isolated fr