IMMUNOBLOT ANALYSIS OF BACTERIAL POLYSACCHARIDES - APPLICATION TO THETYPE-SPECIFIC POLYSACCHARIDES OF STREPTOCOCCUS-SUIS AND STREPTOCOCCUS-AGALACTIAE

A method for the immunoblot analysis of the type-specific capsular pol ysaccharides of streptococci was developed, The capsular polysaccharid es were extracted by sonication and subjected to polyacrylamide gel el ectrophoresis in the absence of sodium dodecyl sulphate (SDS). After e lectrophoresis the polysaccharides were transferred to charged PVDF-N membranes and probed with the type specific antibodies. A characterist ic ladder-like pattern of polysaccharide bands specific for the seroty pe (1, 2, 4, 7) was observed for capsular extracts of Streptococcus su is, Human immune sera against type-specific group B streptococcal poly saccharides reacted most strongly with the immunizing polysaccharide t ype (Ia, II, III). The previously observed crossreactions between the group B streptococcal type-specific capsular preparations were shown t o be due to binding to the isomeric polysaccharide molecules. Thus, ee l electrophoresis combined with immunoblot analysis seems to provide a novel method for the molecular and immunochemical characterization of bacterial polysaccharides and for the study of the specificity and pr operties of antibodies to capsular polysaccharides.