Filamentous Capsulated Streptococci from the Human Respiratory Tract II. Antigenic Structure of Provisional Capsular Types 89 and 83/89

ABSTRACT

Two immunologically distinct polysaccharides have been isolated from the filamentous alpha-hemolytic streptococcus of provisional capsular type 89, recovered from the human respiratory tract. Chemical analyses indicate that the capsular polysaccharide consists of glucose, galactose, and a small amount of rhamnose, whereas the cell wall-associated polymer contains galactosamine, glucosamine, glucose, and phosphorus. Immunological studies suggest that the capsular polysaccharide is type specific and that the cell wall-associated carbohydrate, which cross-reacts with the C₈, or cell wall-like capsular polysaccharide of pneumococcus, may be group specific. A noncapsulated variant of the prototypic streptococcus of provisional type 89 was shown to possess the same cell wall-associated carbohydrate as the strain from which it was derived, but it proved to be poorly antigenic in rabbits. A filamentous capsulated streptococcus reacting with antisera to filamentous streptococci of both provisional capsular types 83 and 89 has been found to produce two capsular polysaccharides, each of which reacts with antibody to one of the aforementioned unitypic strains and represents an unusual binary capsulated streptococcus.