Immunochemical Aspects of the Cross-Reactivity between Groups A and C Streptococci as Detected by the Fluorescent Antibody Technique

Abstract
Summary: The cross-reactivity as detected by the fluorescent antibody method between Group A sera and Group C streptococci is dependent upon a rhamnose moiety that is shared by both Groups A and C carbohydrates and that, under certain circumstances, may be serologically reactive. The cross-reactivity is inhibited by A variant carbohydrate, and by a rhamnose disaccharide isolated from A variant carbohydrate by the rhamnosidase of McCarty. Cross-reactivity between Groups A and C carbohydrates is dependent, in part, upon the fact that this rhamnose disaccharide is a structural feature common to both antigens.