A SEROLOGICALLY INACTIVE POLYSACCHARIDE ELABORATED BY MUCOID STRAINS OF GROUP A HEMOLYTIC STREPTOCOCCUS

Abstract

It has been clearly demonstrated that immunologically reactive polysaccharides of individually distinct chemical structure are responsible for the characteristic type specificity and immunological behavior of encapsulated pathogenic microorganisms such as pneumococcus (1). The pneumococci also contain proteins which are serologically related throughout the entire group, a somatic polysaccharide, C, which is serologically reactive and characteristic for the entire group (2, 3), and produce a serologitally inactive polysaccharide apparently related to chitin (3). On the other hand, the type-specific substance of the Group A, or human pathogenic, hemolytic streptococcus has been shown to be of protein nature (4). The hemolytic streptococcus is also characterized by other group-specific proteins (4-6) and by a group-specific, somatic polysaccharide, C, characteristic for all Group A streptococci, but different from corresponding substances isolated from animal pathogenic strains of streptococcus (4) and from the C substance of pneumococcus. Nevertheless, it is known that Group A hemolytic streptococci can exist in the mucoid phase (7). In this phase the organisms are encapsulated, and, when grown under appropriate conditions, produce large, watery colonies. Culturally and morphologically the mucoid phase of Group A organisms corresponds closely with that phase of pneumococci in which type-specific polysaccharides