STRUCTURAL STUDIES OF SHIGELLA-FLEXNERI O-ANTIGENS

The structures of the O‐antigens of all known serotypes and subserotypes of Shigella flexneri have been reinvestigated. The results support the assumption that these antigens are composed of a basic tetrasaccharide repeating unit (1), to which α‐D‐glucopyranosyl and/or O‐acetyl groups are attached at different positions. (Formula Presented.) The immunological determinants responsible for O‐factors I, II, IV, V and 7,8 contain α‐D‐glucopyranosyl groups, the locations of which have been determined. O‐Factor 6 is due to O‐acetyl groups, linked to O‐2 of the 3‐substituted α‐L‐rhamnopyranosyl residue in unit 1 and O‐factor III seems to be due to the same groups. The chemical natures of the determinants responsible for O‐factors 4 and 3, 4 are still obscure. The structural studies indicate that the immunological classification of Sh. flexneri serotypes and subserotypes, as regards these O‐factors, may need revision. Copyright © 1978, Wiley Blackwell. All rights reserved