The chemical structure and genetic locus of Campylobacter jejuni CG8486 (serotype HS:4) capsular polysaccharide: the identification of 6-deoxy-D-ido-heptopyranose.

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-beta-D-glucopyranosamine and 3-substituted 6-deoxy-beta-D-ido-heptopyranose. A small number of 6-deoxy-beta-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.