Polysaccharide-antigen Group

C-N.m.r.-spectroscopic analyses have been successfully made for determination of the position of O-acetyl groups in sialic acids, using the 9-O-acetyl- and 4,9-di-O-acetyl derivatives of Neu-/3-Me methyl ester as model compounds,9 1 or in the sialic acid residues of polysaccharide antigens ofN. meningitidis.166 1... 

Leon and Young found that the specificity of anti-pneumococcal C myeloma immunoglobulins is for the phosphorylcholine or choline determinant of this antigen.72 Many other antigens, such as polysaccharides from groups O and H streptococcus,66 Ascaris,73 Lac-... 

Like with the KDO containing K-polysaccharides, one can observe also in this group of polysaccharides antigen modification by O-acetylation the K1 antigen and the K2 antigen occur in non acetylated and in acetylated forms (14, 18). Bacteria with the non acetylated polymers (Klac" and K2a) seem to be more pathogenic. 

Several variations of this concept have been reported.50-52 For example, Ley and Priepke50 prepared the trisaccharide unit, which is derived from the common polysaccharide antigen of a group B Streptococci by a facile one-pot two-step synthesis (Scheme 4.18). In this... 

Correia Barbosa, S.F., Alkmin, M.G., Landgraf, I.M. Detecting polysaccharide antigen of Neisseria meningitidis group C in cerebrospinal fluid by dot-ELISA assay. Braz J Infect Dis 4 (2000) 144-150. 

Fig. (13A). Inhibition patterns for anti-S. pyogenes antibodies. Ab=antibody, I, =Ab + GlcNAc, l2=Ab + Rha. Wells 106 and other outside wells contain decreasing amounts (20-1 pg) of antigen (group A polysaccharide).

Fig. 1.—Fourier-transformed, C-N.m.r. Spectrum of the Native Polysaccharide Antigen of Group A Neisseria meningitidis. [Upper, containing (a) O-acetylated and (b) unacetylated residues, and lower, its fully O-deacetylated form.]...

The Four Different, N-Acetylneuraminic Acid Residues in the Native Polysaccharide Antigen of Group C Neisseria meningitidis. 

Fig. 4.—Proposed Conformation of the Repeating Unit of the Type III Polysaccharide Antigen of Group B Streptococcus.

Fig. 6. —Structure of the Group C (uppermost), B (middle), and Terminally Reduced Group A (lowest) Polysaccharide Antigens of Neisseria meningitidis, Depicting the Positions of Cleavage on Oxidation by Periodate.

A facile one-pot synthesis of a trisaccharide unit from the 51. common polysaccharide antigen of group B Streptococci using cyclohexane-1,2-diacetal (CDA) protected rhamnosides. Angew. 

While most polysaccharide antigens act in a T-cell independent fashion, zwitterionic polysaccharides have been shown to induce T-cell mediated immunity [358]. Several bacteria produce zwitterionic CPS, which contain both free amine and free carboxyl groups in the repeating unit. These include CPS types 5 and 8 of Staphylococcus aureus, PSA from B. frag-ilis and the type 1 S. pneumoniae polysaccharide (O Fig. 28). Vaccination with zwitterionic polysaccharides have been shown to produce T-cell mediated immunity in mice [359], and vaccines based on zwitterionic CPS may be useful for combating several common bacterial pathogens. 

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