Immunochemical characterization of the carbohydrate antigens of serotype c/Lancefield group C “Streptococcus milleri”

Abstract

Carbohydrate antigens of the serotype c/Lancefield group C "Streptococcus milleri" were extracted by autoclaving whole cells of the type c reference strain K51Y. The type c and group C antigen molecules were separated and partially purified by a DEAE-Sephadex A-25 column chromatography followed by Sephadex G-100 gel filtration. The purified type c antigen and group C antigen were homogeneous in the double diffusion and in the immunoelectrophoresis. The type c antigen was composed principally of glycerol, rhamnose, glucose and N-acetylglucosamine in a molar ratio of 0.22:0.27:1.00:0.48. The quantitative precipitin inhibition test indicated that N-acetylglucosamine played a major role in immunodeterminant structure. Thus, the type c antigen of "S. milleri" is a new carbohydrate type antigen and is immunochemically different from the Ottens-type antigen III found occasionally in group C streptococci. In contrast, the group C antigen preparation contained a high proportion of N-acetylgalactosamine in addition to glycerol, rhamnose, glucose and N-acetylglucosamine, and the N-acetylgalactosamine residue was involved in the immunodominant epitope, being in good agreement with the previously proposed chemical structure of the group antigen. N-acetylgalactosamine was detected in the autoclaved extracts of a nontypeable/group C strain but not of a type c/ungroupable strain.

Immunochemical characterization of the carbohydrate antigens of serotype k and Lancefield group G “Streptococcus milleri”

“…Molecular characterization of these type antigens would be of great value not only in terms of taxonomy but also for immunobiological reasons. In our previous studies, immunochemical properties of the type-specific antigens of serotypes b, c, g and i "S. milleri" have been characterized {13, 16,17,39). This article describes the immunochemical characteristics of the serotype k antigen together with the Lancefield group G antigen simultaneously obtained from a "S. milleri" (S. anginosus) strain and considers the differences between the type k antigen and other carbohydrate type and group antigens found with "5".…”