Somatic Antigens of Pseudomonas aeruginosa

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Abstract
Structural and immunochemical studies have been performed on the 0‐specific antigens of two serologically related types of Pseudomonas aeruginosa 0 : 2a,b and 0 : 2a,c (Lanyi's classification). The 0‐specific polysaccharide chains of the two serotypes were shown to be acidic polysaccharides composed of repeating trisaccharide units consisting of l‐rhamnose, N‐acetyl‐d‐quinovosamine and N‐acetyl‐L‐galactosaminuronic acid residues. Based on 1 H and 13C nuclear magnetic resonance spectroscopy, data of methylation analysis and selective solvolysis with hydrogen fluoride, the repeating unit of the 0 : 2a,c 0‐specific polysaccharide was assigned the following structure →4)l‐GalNAcA(α1→ 3)d QuiNAc(αl→ 3)LRha(α1, where GalNAcA =N‐acetylgalactosaminuronic acid, QuiNAc= acetylquinovosamine and Rha = rhamnose.The 0:2a,b 0‐specific polysaccharide had the same structure of the trisaccharide repeating unit but was distinguished by the presence of 0‐acetyl groups on 70–80% of the rhamnose residues in position 2. The 0‐acetyl groups were located both by methylation with methyltrifluoromethane sulphonate and by comparison of the 13C nuclear magnetic resonance spectra of the native and 0‐deacetylated polysaccharides.Serological studies revealed the determinant role of the 0‐acetyl groups in the 0‐antigen 0 : 2a,b and suggested the 0‐factor 2b to be related to the 2‐0‐acetyl‐l‐rhamnose residue, whereas the 0‐factor 2c was probably deter‐ mined by the nonacetylated rhamnose residue. The dominant moiety of the determinant 2a common to the two antigens was obviously presented by the N‐acetyl‐l‐galactosaminuronic acid residue.