earticle

영어

Nesseria meningitidis is a type of bacteria which causes meningococcal meningitis and meningococcal septicemia. It often infects children under two years old and causes infant dead. Meningococcal diseases are prevalent in developing countries, like China and Africa. Based on their surface capsular polysaccharides, they are classified into 13 serogroups, while group A, B, C, Y, W135 are the major epidemic strains in the world. Though, some efforts have devoted to develop polysaccharide vaccines against N. meningitidis, but these vaccines often elicit weak immune responses and short immune memories. Therefore, polysaccharide-protein conjugate vaccines were developed to tackle the problem and the immunogenicity improved greatly. However, the compositions of commercial available vaccines are very heterogeneous and the quality is hard to control. In this study, we synthesized the N. meningitidis W135 capsular oligosaccharide in different lengths and acquired the homogeneous form to detect the immunogenicity. Because the N. meningitidis W135 capsular oligosaccharide is silalic acid-galactose repeating structure, we used sialyl phosphate as a donor to conjugate thiol galactoside to form the basic repeat unit. By linking the repeat units, we have obtained various length of oligosaccharide from disaccharide to decasaccharide. We conjugated these different length of oligosaccharides to carrier protein CRM197 (a mutated diphtheria toxin) and injected these conjugates to mice to search for the best vaccine composition.