Common Antigens of Streptococcal and Non-streptococcal Oral Bacteria: Isolation and Biochemical Characterization of the Extracellular Protein Antigen

Abstract
An extracellular soluble common protein (ECP) was purified from extracellular soluble fractions of exponential phase cultures of Streptococcus sanguis OMZ9, of a representative strain of each of Bratthall''s 7 serological groups of S. mutans and of 1 strain each of Lactobacillus salivarius and Actinomyces viscosus. The ECP antigens from the different strains were prepared from SDS[sodium dodecyl sulfate]-dissociated immunoprecipitates by affinity chromatography on an anti-rabbit Ig column. The identity of such purified ECP antigens was demonstrated by their behavior in immunodiffusion analysis, in SDS-PAGE [polyacrylamide gel electrophoresis], in which an identical MW (60,000) was found and by virtue of their similar amino acid and sugar compositions. This ECP consisted of 90% protein and 10% sugar.