Capsular polysaccharide–CRM197 protein conjugate (null)

Capsular polysaccharide–CRM197 protein conjugates are the active immunogenic components of many modern bacterial vaccines. The capsular polysaccharide (from pathogens such as *Streptococcus pneumoniae* or *Neisseria meningitidis*) is covalently linked to the carrier protein CRM197, a genetically detoxified (single amino acid mutant) version of diphtheria toxin. This conjugation is essential because polysaccharides alone induce relatively poor, T cell–independent immune responses; the CRM197 carrier converts the response to T cell–dependent, resulting in higher-affinity antibody production, immunologic memory, and improved efficacy, especially in infants and young children. CRM197 is non-toxic and structurally highly similar to wild-type diphtheria toxin but lacks catalytic activity due to a single amino acid substitution[1][2][3][4]. The immunological effect of the conjugate depends more on the polysaccharide composition, but CRM197 is a nearly universal carrier for such vaccines due to its excellent safety and immunogenicity profile. Note: For most biomedical/therapeutic target databases, “capsular polysaccharide–CRM197” is not listed as a single molecular target. Each component (polysaccharide type, CRM197 protein) could be separately classified; the conjugate itself is best described as a *vaccine technology* rather than a traditional target. The query is thus nonstandard for molecular target analysis.

Other names

CRM197-conjugateGlycoconjugate vaccine componentPolysaccharide-protein conjugateCapsular polysaccharide–CRM197

The carrier protein (CRM197) provides T cell epitopes, enabling polysaccharide antigens to elicit a T cell–dependent antibody response, thereby inducing immunological memory and boosting antibody titers upon re-exposure