The pyrogenic effect of scarlet fever toxin. IV. Pyrogenicity of strain C 203 U filtrate: comparison with some basic characteristics of the known types of scarlet fever toxin.

The pyrogenic activity of scarlet fever toxin has been described a number of times. The "classic" toxin, prepared from the Dochez NY 5 strain, was found to have a double specificity, designed by Hooker and Follensby as "A" and "B".1 More recently, Watson has analyzed the antigenic components of this toxin and found a third type, which he has denoted "C"1.2 In working with a mutant strain of streptococcus, C 203 U, which produces streptolysin 0 but not S, the present authors made the observation that broth culture filtrates of this strain were pyrogenic. An attempt has been made to determine the relationship of this pyrogen to other streptococcal pyrogens described previously.