**Acknowledgement**

This review is a part of the PhD thesis of Dodi Safari with the title: Development of new synthetic oligosaccharide vaccines: the immunogenicity of oligosaccharide- CRM197 neoconjugates and oligosaccharide/peptide hybrid gold nanoparticles based on the capsular polysaccharide structure of *Streptococcus pneumoniae* type. 14. Utrecht University. 2010. This work was supported by a grant from the European Commission under Contract No: MRTN-CT-2004-005645.
