Group a streptococcal polysaccharide antigens
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Updated: Aug 9, 2026

Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
1Department of Microbiology, Northwestern University Medical School, Chicago, Illinois 60611.
Abstract:
Cold trichloroacetic acid extracts of group A, type 3 streptococci were fractionated on Sephadex G50 and ECTEOLA cellulose columns. A glucose-N-acetylglucosamine polymer was isolated and shown by chemical, electrophoretic, and antigenic analysis to be distinct from the group A polysaccharide. The antigenic specificity was due to the glucosamine. A glycerol-phosphate-alanine-glucosamine teichoic acid polymer was isolated. The antigenic specificity was due to N-acetylglucosamine and d-alanine methyl ester, with the former possessing principal responsibility. The glucosamine and ester-linked alanine appear to be labile to the method of extraction and fractionation. Group A streptococcal whole cell antiserum, after adsorption with cells of a heterologous serological group and group A polysaccharide antigen, contained antibodies against both polymers.
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