Serological analysis of core oligosaccharides of Shigella flexneri serotype 6 and its R mutants lipopolysaccharides.

The core oligosaccharides originating from Shigella flexneri 6 S strains and R mutants were examined by the complement fixation inhibition and passive hemolysis inhibition tests using antisera against the complete and partially degraded core regions. Strong cross reactivity between Shigella flexneri 6, Shigella sonnei phase II and E. coli C core fractions which all are of R1 type was observed. Terminal beta-D-glucosyl groups and alpha-D-galactosyl-1,2-alpha-D-galactosyl sequences are essential elements of R1 type immunodeterminants. Heptose region of the R1 cores seems not be involved in their serological specificity.