Immunochemical characteristics of Shigella sonnei and serotype 6 Shigella flexneri lipopolysaccharides and enterobacterial common antigen.

Immunochemical studies on Shigella sonnei and serotype 6 Shigella flexneri 0 antigens (lipopolysaccharides) and enterobacterial common antigen (ECA) isolated from Shigella sonnei were carried out. Oligosaccharide structure of 0-specific chain of serotype 6 Shigella fiexneri lipopolysaccharide was defined and beta-L-rhamnosyl-1,3-N-acetyl-D-galactosamin as immunodeterminant of type VI specificity was recognized. The structures of core regions of lipopolysaccharides isolated from R mutants of both Shigella subgroups were established. On the base of the serological and structural results it has been suggested that these core regions are identical and very close to RI core structure of E. coli C. The effective method of isolation and purification of enterobacterial common antigen from Shigella sonnei was elaborated and its immunological properties as well as chemical character defined.