Sugars as Pharmaceuticals - The Sugar Code - page 479

charides that provide newborn babies with a mechanism for aborting infection
processes (Figure 28.10). A prominent example is the … Gal 1

… trisaccharide that has been proposed as a receptor for adherence of Streptococcus
pneumoniae to buccal epithelial cells. At corresponding concentrations, sialylated
milk oligosaccharides strongly inhibit binding of infl uenza A virus and S-
fi mbriated enteropathogenic E. coli to their respective host cells (see [15] for further
details).
An alternative strategy to prevent bacterial infections is to synthesize and admin-
ister capsular polysaccharides or fragments from bacterial cell surfaces that give
rise to highly specifi c immune responses. An example of this has been reported,
in which a spacer-containing nonasaccharide fragment of S. pneumoniae 19F, a
common cause of respiratory infections in children, was synthesized (Figure
28.11 ) [21] .
Although these synthetic structures have a lower relative molecular mass than
the natural polysaccharides, they are often of suffi cient size to function effi ciently
as immunogenic components of conjugate vaccines. Advantages of these synthetic

β 1 - 4GlcNAc β 1 - 3Gal β

Figure 28.10 Structures of some human milk oligosaccharides.

Figure 28.11 The capsular polysaccharide from S. pneumoniae 19F and the nonasaccharide
synthesized by Nilsson and Norberg.