In line with our on-going efforts to create a multivalent anti-Campylobacter jejuni vaccine based on its capsule polysaccharides (CPSs), we report here the chemical structure and the genetic locus of the CPS produced by C. jejuni strain CG8486, which belongs to the serotype HS:4 CPS complex. C. jejuni CG8486 CPS was observed to be composed of approximately 17 disaccharide repeating blocks of 4-substituted N-acetyl-β-d-glucopyranosamine and 3-substituted 6-deoxy-β-d-ido-heptopyranose. A small number of 6-deoxy-β-d-ido-heptopyranose units were observed to carry O-methyl phosphoramidate moieties at the O-2 or O-7 position. The gene content and organization of the CPS locus of C. jejuni CG8486 were comparable to those of C. jejuni strains NCTC 11168 and 81-176, but several CG8486 CPS genes were observed to be more divergent from those present in the CPS loci of NCTC 11168 and 81-176 CPS, which indicated that there are genetic characteristics specific to the C. jejuni HS:4 CPS complex. The efficacy of a glycoconjugate vaccine based on C. jejuni CG8486 CPS is presently being tested in an animal model, the results of which will be presented in future communications.

The distribution of the d-galactosyl side-chains in guaran has been studied by a specific degradation procedure. A methylated guaran derivative having only HO-6 unsubstituted was subjected to an oxidation-β-elimination-mild acid hydrolysis procedure, whereby the d-galactosyl side-chains and the unbranched d-mannosyl residues were degraded, leaving intact only branched d-mannosyl residues having one or more, adjacent, branched d-mannosyl residues. Methylation analysis of the degradation mixture showed that the d-galactosyl side-chains in guaran were distributed mainly in pairs or triplets.

The structure of the polysaccharide antigen produced by Eubacterium saburreum, strain L 32, has been investigated. The principal methods used were methylation analysis, graded hydrolysis with acid, and n.m.r. spectroscopy. The polysaccharide, which contains the unusual sugar 3,6-dideoxy-D-arabino-hexose (tyvelose, Tyv), is composed of trisaccharide repeating-units having the following structure:

The structure of the polysaccharide antigen produced by Eubacterium saburreum, strain L 452, has been investigated. Methylation analysis, graded hydrolysis with acid, and n.m.r. spectroscopy were the principal methods used. The polysaccharide is composed of trisaccharide repeating-units having the following structure: The assignment of the β configuration to the d-ribofuranosyl residue is tentative.

The polysaccharide antigen produced by Eubacterium saburreum, strain L 49, is composed of D-glycero-D-galacto-heptose and a new sugar, tentatively identified as 6-deoxy-D-altro-heptose. It contains chains of alternating (1 leads to 3)- and (1 leads to 6)- linked beta-D-glycero-D-galacto-heptopyranosyl residues, the latter being substituted with 6-deoxy-alpha-heptofuranosyl groups at O-3. The polysaccharide further contains 0-acetyl groups, linked to O-7 of part of the heptosyl residues and to O-2 of part of the 6-deoxyheptosyl groups.

Structural studies of the polysaccharide antigen produced by the anaerobic, oral filamentous micro-organism Eubacterium saburreum, strain L44, are reported. It is concluded that the polysaccharide is linear and composed of β-(1→6)-linked D-glycero-D-galacto-heptopyranose residues. About 65% of these residues carry an O-acetyl group in the 7-position.