Immunochemistry of group A and Inaba C antigen factors constituting the O antigen of O1 Vibrio cholerae

Detection of lipid A by monoclonal antibodies in S-form lipopolysaccharide after acidic treatment of immobilized LPS on Western blot

Lipopolysaccharides (LPSs) were separated by SDS-PAGE, transferred onto polyvinylidene difluoride membranes, and hydrolyzed under acid conditions known to liberate lipid A from a broad variety of bacterial species. Independent of whether bis- or monophosphorylated lipid was set free, it remained bound to the membrane during subsequent immunostaining with monoclonal antibodies (MAbs) specific for the 1,4'-bis- or 4'-monophosphorylated lipid A backbone. Lipid A could be detected in the smooth (S)-form LPS from Enterobacteriaceae (Salmonella enterica, Citrobacter, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Yersinia enterocolitica) , Pseudomonas aeruginosa, Chromobacterium violaceum, Acinetobacter, Vibrio cholerae and Legionella pneumophila, thus allowing LPS-phenotype determination. The procedure can be used for the majority of Gram-negative bacteria, since LPSs containing 2,3-diamino-2,3-dideoxy-glucose or glucosamine in the lipid A disaccharide backbone could be detected. It was shown to be sensitive (up to 20 ng of hydrolyzed LPS could be detected), and could be easily performed using isolated LPS or whole-cell lysates with or without prior digestion with proteinase K. In addition to opening several other application possibilities, the procedure may be particularly useful in cases where silver-staining of the O-chain in SDSpolyacrylamide gels fails and specific antibodies against the O-antigen are not available.

Identification of N-3-hydroxypropionyl-2-O-methyl-D-perosamine as a specific constituent of the lipopolysaccharide from Vibrio bio-serogroup 1875 which has Ogawa antigen factor B of Vibrio cholerae O1

A marine vibrio, designated Vibrio bio-serogroup 1875 Original (1875 Original), has both the Ogawa antigen factor B and the Inaba antigen factor C of Vibrio cholerae 01, in addition to its own O antigen factor. Its variant strain (1875 Variant) has the Inaba antigen factor C. The O polysaccharide chain (O-chain) of the lipopolysaccharide (LPS) isolated from this vibrio has been shown to consist of an ↬ (1 2)-linked homopolymer of N-3-hydroxypropionyl-D-perosamine. The present structural study revealed the presence of N-3-hydroxypropionyl-2- O-methyl-D-perosamine at the non-reducing terminus of the O-chain from the LPS of 1875 Original but not from that of the 1875 Variant. Since 2- O-methyl-D-perosamine is known as an Ogawa-specific constituent of the O-chain from V. cholerae O1 Ogawa O form, it appears that the presence of 2- O-methyl-D-perosamine at the non-reducing terminus of the ↬ (1 2)-linked D-perosamine homopolymer that forms the O-chain is responsible for the expression of the serological specificity of the Ogawa antigen factor B of 1875 Original.

The O-polysaccharide of lipopolysaccharide isolated from Vibrio fluvialis O19 is identical to that of Vibrio bioserogroup 1875 variant

A structural analysis has been carried out on the O-polysaccharide of lipopolysaccharide (LPS) isolated from Vibrio fluvialis 181-86 (Kobe) serotype O19 (O19) which has the Inaba antigen factor C of O1 V. cholerae and factors D and E in common with Vibrio bioserogroup 1875. The O-polysaccharide of O19 was characterized as an alpha (1-->2)-linked homopolymer of N-3-hydroxypropionyl-D-perosamine (4-amino-4,6-dideoxy-D-mannopyranose), which was identical to that of Vibrio bioserogroup 1875 Variant. Passive hemolysis and passive hemolysis inhibition analysis performed using anti-factor D, E and anti-factor E antisera, demonstrated that the LPS from O19 harbored O-antigenic factors identical to those of the LPS from Vibrio bioserogroup 1875 Variant.

An N-[(R)-(-)-2-hydroxypropionyl]-alpha-L-perosamine homopolymer constitutes the O polysaccharide chain of the lipopolysaccharide from Vibrio cholerae O144 which has antigenic factor(s) in common with V. cholerae O76

Chemical and serological studies were performed with the lipopolysaccharide (LPS) from Vibrio cholerae O144 (O144). The LPS of O144 contained D-glucose, D-galactose, L-glycero-D-manno-heptose, D-fructose, D-quinovosamine (2-amino-2,6-dideoxy-D-gluco-pyranose) and L-perosamine (4-amino-4,6-dideoxy-L-manno-pyranose). The perosamine, a major component sugar of the LPS from O144, was in an L-configuration, as is also the case in the LPS from V. cholerae O76 (O76), in contrast to the D-configuration of the perosamine in the LPS of V. cholerae O1. A structural analysis revealed that the O polysaccharide chain of the LPS from O144 is an alpha(1-->2)-linked homopolymer of (R)-(-)-2-hydroxypropionyl-L-perosamine. The serological cross-reactivity between O144 and O76 was clearly revealed by cross-agglutination and cross-agglutinin absorption tests with whole cells, as well as by passive hemolysis tests with sheep red-blood cells that had been sensitized with the LPS from O144 and O76. In contrast, in passive hemolysis tests, the LPS of O144 did not cross-react serologically with the LPSs from other strains such as V. cholerae O1 (Ogawa and Inaba), V. cholerae O140, Vibrio bio-serogroup 1875 (Original and Variant) and Yersinia enterocolitica O9. The LPSs from these strains consist of O polysaccharide chains composed of alpha(1-->2)-linked homopolymers of D-perosamine with various N-acyl groups, and they share the Inaba antigen factor C of V. cholerae O1 in common. The results obtained in this study demonstrate that the absolute configuration of the perosamine residue in homopolymers plays a very important role in the expression of the serological specificity of the Inaba antigen factor C of V. cholerae O1.

Lipopolysaccharides of Escherichia coli K12 strains that express cloned genes for the Ogawa and Inaba antigens of Vibrio cholerae O1: identification of O-antigenic factors

Structural and serological studies were performed with the lipopolysaccharide (LPS) expressed by Escherichia coli K12 strains No. 30 and No. 64, into which cosmid clones derived from Vibrio cholerae O1 NIH 41 (Ogawa) and NIH 35A3 (Inaba) had been introduced, respectively. The two recombinant strains, No. 30 (Ogawa) and No. 64 (Inaba), produced LPS that included, in common, the O-polysaccharide chain composed of an alpha (1-->2)-linked N-(3-deoxy-L-glycero-tetronyl)-D-perosamine (4-amino-4,6-dideoxy-D-manno-pyranose) homopolymer attached to the core oligosaccharide of the LPS of E. coli K12. Structural analysis revealed the presence of N-(3-deoxy-L-glycero-tetronyl)-2-O-methyl-D-perosamine at the non-reducing terminus of the O-polysaccharide chain of LPS from No. 30 (Ogawa) but not from No. 64 (Inaba). Serological analysis revealed that No. 30 (Ogawa) and No. 64 (Inaba) LPS were found to share the group antigen factor A of V. cholerae O1. They were distinguished by presence of the Ogawa antigen factor B [co-existing with relatively small amounts of the Inaba antigen factor (c)] in the former LPS and the Inaba antigen factor C in the latter LPS. It appears, therefore, that No. 30 (Ogawa) and No. 64 (Inaba) have O-antigenic structures that are fully consistent with the AB(c) structure for the Ogawa and the AC structure for the Inaba O-forms of V. cholerae O1, respectively. Thus, the present study clearly confirmed our previous finding that the Ogawa antigenic factor B is substantially related to the 2-O-methyl group at the non-reducing terminus of the alpha (1-->2)-linked N-(3-deoxy-L-glycero-tetronyl)-D-perosamine homopolymer that forms the O-polysaccharide chain of LPS of V. cholerae O1 (Ogawa).