STUDIES ON THE ANTIGENIC COMPOSITION OF GROUP A HEMOLYTIC STREPTOCOCCI

Abstract

The present report is concerned with an analysis of distinct M and related T antigens occurring in each of 2 series of specific types of Group A hemolytic streptococci. The 11 types in these series possess distinct M substances. The combination of M antigen with its antibody is the basis of differentiation of these types by the precipitin test, which is independent of the T substance since the latter, apparently, does not take part in this reaction. It has been found, however, that T substances are responsible for the cross relationships consistently observed in agglutination reactions among types within these 2 series. In the series consisting of Types 15, 17, 19, 23, and 30 related T antigens were found present in all 5 types. Additional related T antigens could also be demonstrated in Types 15, 17, and 23, on the one hand, and in Types 19 and 30 on the other. In the 2d series, composed of Types 4, 24, 26, 28, 29, and 46, such clear relationships among the T antigens were not observed. Since Griffith distinguished these 11 types by means of the slide agglutination technique, apparently some antigen other than T formed the basis of his classification of these types. Because of the close agreement we have observed between type-specific agglutination and precipitin reactions, probably Griffith differentiated these 11 types on the basis of M antigen antibody reactions. In certain other types, however, classifications based on either M or T antigens gave comparable results. Difficulties encountered in distinguishing certain types by means of the agglutination reaction may be overcome by ascertaining the antigens with which the types were originally differentiated and preparing antisera which contain only the specific antibodies for the antigens concerned. These are M antigens in most instances; whereas the substances related to cross agglutination among the types in certain series are usually T antigens. Methods are described for preparing special antisera by means of which the slide agglutination technique may be used to differentiate the 11 types included in these 2 series. These sera are also of value in ascertaining the presence or absence of M and T antigens in these strains. By employing these antisera in the slide agglutination technique, Group A hemolytic streptococci of these particular types may be classified with results similar to those described by Griffith. This type classification is also the same as that obtained with the precipitin technique since both methods are largely based upon the reaction of the M antigen with its respective antibody.