Action of group A streptococcus extracellular product(s) on the connective tissue of the bovine heart valve.

Group A streptococcal strains isolated from rheumatic fever patients were cultivated in the presence of bovine heart valves in a medium devoid of components from animal origin. Other group A streptococci and various bacteria were used as controls. The supernatant of these cultures was extracted and analyzed chemically and immunologically. The extracts prepared from cultures of two "rheumatogenic" strains in the presence of bovine heart valves showed fraction(s) containing proteins, oses (neutral and amined), and uronic and sialic acids. This fraction(s) was immunologically active with both anti-group A streptococcus and antisoluble connective glycoprotein antisera, with a partial identity reaction. Experiments with a diffusion chamber and attempts to precipitate a postulated enzyme from the culture of these strains by ammonium sulfate suggest that this action is due to an extracellular product of the bacteria. The meaning of these data in the physiopathology of rheumatic cardiac lesions is briefly discussed.