Neisseria meningitidis serogroup A capsular polysaccharide-CRM197 conjugate (MenA-CRM197)

Neisseria meningitidis serogroup A capsular polysaccharide-CRM197 conjugate is a vaccine antigen used to elicit protective immunity against invasive meningococcal disease. The serogroup A polysaccharide is a polymer of N-acetyl-O-acetylmannosamine-1-phosphate, which serves as the primary target for protective antibodies (CDC, 2023). Because pure polysaccharides are poorly immunogenic in young children and do not induce immunological memory, they are conjugated to CRM197, a non-toxic recombinant variant of the diphtheria toxin (Pace et al., 2009). This conjugation transforms the polysaccharide into a T-cell dependent antigen, enabling the recruitment of T-helper cells and the subsequent production of high-affinity IgG antibodies (FDA, 2020). These antibodies facilitate the complement-mediated killing of the bacteria, providing robust protection against meningitis and sepsis (WHO, 2011). This conjugate is a critical component of multi-valent vaccines like Menveo, which are essential for controlling outbreaks, particularly in the African meningitis belt. The use of CRM197 as a carrier is advantageous because it is a well-characterized, non-toxic protein that has been safely used in various pediatric vaccines (Pace et al., 2009). Overall, this target represents a sophisticated approach to overcoming the limitations of the bacterial carbohydrate-based immune response.

Other names

Meningococcal group A polysaccharide-CRM197 conjugateMenA-CRMNeisseria meningitidis serogroup A polysaccharide conjugateMenA conjugate

The conjugate acts as a T-cell dependent antigen where the CRM197 carrier protein provides T-cell epitopes that allow for B-cell maturation, class switching to IgG, and the development of memory B-cells specific to the Neisseria meningitidis serogroup A polysaccharide (Pace et al., 2009; FDA, 2020).