The inner-core region of the lipopolysaccharide of an UDPGalNAc-4-epimerase-deficient mutant of Yersinia enterocolitica 0 : 3, designated as Ye75R, was investigated using methylation analysis, 1 D-"C-NMR and 2D-"C-NMR and 'H-NMR, as well as 31P-NMR, fast-atom-bombardment mass spectrometry (FAB MS) and FAB M S N S in positive and negative modes. The isolated core heptasaccharide (0s) was composed of 2 units D-glucose, 3 units LD-heptose and 1 unit each of DD-heptose and 3-deoxy-~-manno-octulosonic acid. Methylation analysis indicated that 0s was highly branched with terminal location of the two glucoses and the DD-heptose unit, which was partially (to about 40%) phosphorylated at C7. These combined studies allowed us to formulate the structure of the inner core region as shown in Scheme 1.The substitution of the 7-position of the terminally linked DD-heptose unit by phosphate could be recognized by MS characterization of permethylated ~~-heptose-7-phosphate (alditol acetate) and the extent of the substitution by the ratio of the two well separated 'H signals of DD-heptose in 500-MHz 'H-NMR. Negative FAB MS of 0s also indicated the presence of smaller amounts of two hexasaccharides, differing from 0s in lacking either one terminal unit of D-glucose or of the tenninal DD-heptose, and additionally of a pentasaccharide lacking two heptosyl units, namely the terminal DD-heptose and and the subterminal LD-heptose. The presence of the smaller oligosaccharides in the 0s fraction was also recognized by the methylation analysis.Structural studies on the R-core region of a number of enterobacterial lipopolysaccharides (LPS) and of LPS of some phylogenetically rather remote bacterial species have been carried out in the past [l, 21. The core region, together with the lipid A component, are the two structural regions which are present in almost all Gram-negative bacteria and, as such, are of interest especially with regard to their immunoreactive properties [l]

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Serum samples from 134 patients showing by the microagglutination test serological cross-reactivity between Yersinia enterocolitica serotype 09 and Brucella spp. were analyzed by immunoblot and enzyme-linked immunosorbent assay techniques for the presence of antibodies directed against plasmid-encoded, yersiniaassociated outer membrane proteins (OMPs). Since these OMPs are exclusively expressed in pathogenic strains of Yersinia spp., this characteristic was chosen for serological differentiation of infections caused by these bacteria. The presence of antibodies against plasmid-encoded OMPs of pathogenic Yersinia spp. in patient sera appeared to be a suitable means to identify acute or recent infection with Y. enterocolitica serotype 09, whereas the failure to detect such antibodies indicated an acute or recent infection with Brucella spp. Serodiagnosis of acute and recent infections with Yersinia enterocolitica serotype 09 and Brucella spp. on the basis of

The presence and the relative amount of 4‐amino‐l‐arabinose in lipopolysaccharides of members of the Enterobacteriaceae family and in a single strain of Chromobacterium violaceum has been studied with regard to growth‐temperature dependent variations. Changes in the presence and the amount of 4‐amino‐l‐arabinose (4‐AA) were observed in almost all cases, but the variations observed were not consistent among different species. While Salmonella minnesota and Proteus mirabilis showed higher levels of incorporation at higher temperatures, the S‐ and R‐forms of Yersinia enterocolitica showed the opposite effect, i.e. only marginal incorporation by growth at 37°C, in contrast to rather high values by growth at 10°C. Chromobacterium violaceum, however, showed no significant alteration in the 4‐amino‐l‐arabinose content when growth either at 14 or at 37°C. DOC‐PAGE pattern of isolated lipopolysaccharides showed characteristic profiles indicating that the O‐chain‐synthesis of distinct Enterobacteriaceae is also differently influenced by changes in growth temperature.

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Rabbits were immunized with the enterobacterial common antigen (ECA)-immunogenic strain Escherichia coli F470. ECA-specific antiserum was obtained by absorbing the resulting antisera with the genetically closely related ECA-negative strain E. coli F1283. These two strains also served as positive and negative controls in the localization study of ECA in Yersinia enterocolitica strain 75, smooth and rough forms (Ye75S and Ye75R), by the indirect immunoferritin technique. Cells of Ye75S grown at 22 degrees C showed no labeling with ferritin after treatment with the ECA-specific antiserum and subsequent ferritin-conjugated goat anti-rabbit antibodies. If the cells were grown at 40 degrees C, however, most of the cells showed weak ferritin labeling. At this higher growth temperature, the lipopolysaccharide of this strain contains less O-specific chains (6-deoxy-L-altrose), as was shown in a previous study. The rough mutant Ye75R, which lacks O-specific chains completely, showed denser labeling with ferritin. These results indicate that ECA on the cell surface of Ye75S is covered by O-specific chains of the lipopolysaccharide if grown at 22 degrees C and is therefore not accessible to ECA antibodies. It becomes accessible, however, when O-chains are lacking (R mutants) or when they are reduced in size or amount (growth at 40 degrees C).

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