STUDIES ON THE ANTIGENIC COMPOSITION OF GROUP A HEMOLYTIC STREPTOCOCCI

Abstract

During a previous study of the effect of proteolytic enzymes on Group A hemolytic streptococci, it was observed that certain strains, classified in a given type by the M precipitin reaction, did not appear to contain the T antigen characteristic of that type. The expts. described in this paper show that these strains are not agglutinated by T antibodies, nor do they absorb anti-T antibody. Furthermore, immunization of rabbits with them does not induce T antibody formation. Since T antibodies usually appear early in the course of immunization, the fact that none appeared at any time in response to immunization with these unusual strains led to the conclusion that they did not contain T antigen. Certain other strains, known from previous study to contain T antigen, were also found to be inagglutinable in anti-T serum. With these strains, however, this lack of agglutination was correlated with the presence of large amts. of M antigen in variants made virulent by serial passage though mice. Susceptibility to T agglutinins appeared when these cultures were subjected to slightly unfavorable environments. The possession of T antigen by these strains was also readily demonstrated by immunization of rabbits and by absorption expts. An analysis of the antigenic composition of the available strains has been made in a limited number of types. Matt strains containing both M and T antigens apparently occur more frequently than matt strains containing M antigen alone or than glossy strains containing T antigen alone.