What are bacterial polysaccharides vaccines?

— Capsular polysaccharides (PS) contribute to the virulence of certain bacteria (resistance to phagocytosis) — Anti-PS antibodies — Neutralize bacteria binding to epithelium — activate C’ and macrophages: opsonisation — Vaccine against Streptococcus pneumoniae — Streptococcus pneumoniae causes pneumococcal pneumonia. Complications: meningitis — Vaccine made of 23 different polysaccharides: Pneumovax 23 or PPSV23 given to people over 65 year old — Vaccine against Neisseria meningitidis — Neisseria meningitidis causes bacterial meningitis — Vaccine made of capsular polysaccharides