Bacteroides fragilis lipopolysaccharide and group B streptococcus serotype II glycocalyx have a common major antigenic determinant

Abstract

Linko, L. & Viljanen, M. K. Bacteroidesfragilis lipopolysaccharide and group B streptococcus serotype I1 glycocalyx have a common major antigenic determinant. APMIS 96: 805-8 12, 1988. A monoclonal antibody (MAB) to the p-1 -6-linked digalactose structure in the lipopolysaccharide (LPS) of Bacteroides fragilis reacted with 47 of 4 16 group B Streptococcus (GBS) strains tested by an immunofluorescence technique (IF). The reactivity of MAB was, with a few exceptions, limited to type I1 GBS. Gas chromatography-mass spectrometry analysis demonstrated that an antigen purified by immunoaffnity chromatography using MAB from type I1 GBS contained galactose, glucose and fatty acids. This confirmed that MAB is directed to the digalactose (which in earlier studies was found to occur) in the capsular lipocarbohydrate specific to type I1 GBS. The positive strains yielded a strong, apple-green surface stain by means of the IF using MAB. Various immuno-electron microscopic (IEM) methods showed that the determinant was located in the glycocalyx layer of GBS at a distance of about 15 nm from the streptococcal cell wall. The structure harbouring the determinant was found to be very loosely attached to the bacteria. However the cross-reactive determinant seemed to maintain its immunoreactivity whether it was extracted by gentle washing with saline or with harsher treatments usually reserved for preparing streptococcal polysaccharide antigens. In conclusion, the study shows that the determinant is an integral part of the type-specific antigen of type I1 GBS and that MAB has a potential use as a serotyping reagent.

Monoclonal antibodies to detect capsular diversity among Bacteroides fragilis isolates

“…The cross-reaction is probably due to a moiety containing quinovosamine (7). A MAb directed to the immunodominant epitope of B. fragilis LPS (␤-1-6-linked digalactose) cross-reacted with the polysaccharide of group B Streptococcus type II (11).…”