The serum opacity reaction of Streptococcus pyogenes. The demonstration of multiple, strain-specific lipoproteinase antigens.

Investigation into the antigenicity of streptococcal lipoproteinase has revealed the existence of multiple, immunologically distinct enzymes. Each lipoproteinase identified was found to be strain specific in that it was found only in strains of a particular T-agglutination pattern. In some T patterns, all streptococci of that T pattern which were examined shared a common lipoproteinase antigen. In other T patterns, strains which produced antigenically different lipoproteinases were identified. Evidence that the lipoproteinase antigen is distinct from other well-established cellular antigens of Group A streptococci has been presented. The production of this strain-specific enzyme by strains currently difficult to type by the standard M precipitin method may facilitate more precise identification of these strains and a better assessment of their role in the pathogenesis of Group A streptococcal infections and their sequelae.