Characterization of Shigella dysenteriae type 1 capsular polysaccharide by immunochemical methods.

We have isolated the capsular polysaccharide from the strain of Shigella dysenteriae type 1 8337. The product was purified by ultracentrifugation, treated with enzymes (proteinase K, DNA-RNAase) and analyzed by immunochemical methods. Polyclonal antibodies were obtained from rabbits immunized by whole cell antigens prepared from Shigella by ultrasonic treatment and by purified capsular polysaccharide. Crossed immunoelectrophoresis, PAGE and Western blot analysis showed that this product containing mainly the polysaccharide component also contained glycoprotein and lipopolysaccharide. Double diffusion in agarose gel confirmed that the capsular preparation contained at least three antigens reacting with rabbit polyclonal antiserum.