Streptococcus pneumoniae serotype 9V capsular polysaccharide

The Streptococcus pneumoniae serotype 9V capsular polysaccharide is a high molecular weight linear polymer composed primarily of D-glucuronic acid, D-galactose, N-acetyl-D-mannosamine, D-glucose residues with partial O-acetylation. It forms an unbranched pentasaccharide repeating unit on the bacterial surface. This structure is a major virulence factor for S. pneumoniae because it enables the bacterium to evade phagocytosis by host immune cells and contributes significantly to its ability to cause invasive diseases such as pneumonia and meningitis. The structural diversity among different pneumococcal capsules underlies differences in immunogenicity between strains. Serotype 9V is included in several licensed pneumococcal vaccines due to its clinical relevance; vaccination induces protective antibodies targeting this capsule type. The degree and position of O-acetylation distinguish it from closely related types like serotype 9A. The presence or absence of acetyl groups can affect both immunogenicity and recognition by monoclonal antibodies. This molecule is not a receptor or enzyme but rather a bacterial surface carbohydrate that serves as an important therapeutic target for active immunization strategies against S. pneumoniae infection.

Other names

Pneumococcal capsular polysaccharide type 9VStreptococcus pneumoniae type 9V capsular polysaccharide antigenPneumococcal polysaccharide serotype 9V vaccine

Induces production of specific antibodies that recognize the capsule and promote opsonization and clearance of the bacteria by the immune system