Role in the Immunospecificity of Bacterial Antigens

LPSs carry the major immunogenic determinants on the cell surface of Gram-negative bacteria and, in many instances, serve as the basis for their serological classification. In this section, contribution of LPSs that contain 5,7-diamino-3,5,7,9-tetradeoxynon-2-ulosonic acids to the immunospecificity and serological classification of two human pathogens, viz. L. pneumophila and P. aeruginosa, are reviewed. 

The 8-O-acetyl-associated epitope of legionaminic acid was also found in P. fluorescens ATCC 49271, which has the same OPS structure 17 as L. pneumophila serogroup l32,56 (Fig. 5). This epitope, possibly along with other, yet uncharacterized cross-reactive epitopes, is likely responsible for the serological cross-reactivity exhibited by P. fluorescens and distantly related L. pneumophila. 

A role of the 5-A-acyl group of pseudaminic acid in serospecificity was demonstrated in studies of P. aeruginosa serogroup 07 strains, which could be divided into three subgroups 07a,7b,7c, 07a,7b,7d, and 07a,7d (Section II.2, Fig. 3). It was concluded that epitopes 07c and 07d are linked to the 5-TV-[(R)-3-hydroxybutanoyl] and 5-A-acetyl group, respectively.23 

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